摘要:

THE ROYAL SOCIETY OF CHEMISTRY Journal of Materials Chemistry Scientific Advisory Editor Editorial Manager Dr. Martin R. Bryce Dr. Robert J. Parker Department of Chemistry The Royal Society of Chemistry University of Durham Thomas Graham House South Road Science Park Durham DH1 3LE, UK Cambridge CB4 4WF, UK Staff Editor: Mrs. Janet M. Leader Senior Assistant Editor: Mrs. S. Shah Assistant Editor: Mrs. S. Youens Editorial Secretary: Miss D. J. Halls Graphics Designer: Ms. C. Taylor-Reid Materials Chemistry Editorial Board Allan E. Underhill (Bangor) (Chairman) Peter G. Bruce (St. Andrews) John W. Goodby (Hull) Martin R. Bryce (Durham) Klaus Praefcke (Berlin) David A. Dunmur (Sheffield) Brian J. Tighe (Aston) Jean Etourneau (Bordeaux) Anthony R.West (Aberdeen) Wendy R. Flavell (UMIST) John D. Wright (Canterbury) Robert J. Parker (Secretary) International Advisory Editorial Board K. Bechgaard (Risa, Denmark) J. S. Miller (Salt Lake City, UT, USA) J. Y. Becker (Beer-Sheva, Israel) K. Mullen (Mainz, Germany) J. D. Birchall (Runcorn, UK) M. Nygren (Stockholm, Sweden) A. J. Bruce (Murray Hill, USA) Y. W. Park (Seoul, Korea) A. K. Cheetham (Santa Barbara, USA) V. Percec (Cleveland, OH, USA) E. Chiellini (Pisa, Italy) N. Plate (Moscow, Russia) D. Coates (Poole, UK) M. Prato (Trieste, Italy) P. Day (London, UK) C. N. R. Rao (Bangalore, India) B. Dunn (Los Angeles, USA) J. Rouxel (Nantes, France) W. J. Feast (Durham, UK) R. Roy (University Park, PA, USA) A. Fukuda (Tokyo, Japan) J. L.Serrano (Zaragoza, Spain) D. Gatteschi (Florence, Italy) J. N. Sherwood (Glasgow, UK) J. B. Goodenough (Austin, TX, USA) J. Simon (Paris, France) A. C. Griffin (Hattiesburg, USA) J. F. Stoddart (Birmingham, UK) S-i. Hirano (Nagoya, Japan) S. Takahashi (Osaka, Japan) P. Hodge (Manchester, UK) J. 0.Thomas (Uppsala, Sweden) H. lnokuchi (Okazaki, Japan) G. J. T. Tiddy (Bebington and Salford, UK) W. Jeitschko (Munster, Germany) Yu. D. Tretyakov (Moscow, Russia) 0. Kahn (Orsay, France] J. W. White (Canberra, Austra4ia) R. McCullough (Pittsburgh, USA) R. Xu (Changchun, China) Y. Yamashita (Okazaki, Japan) Journal of Materials Chemistry (ISSN 0959-9428) is published monthly by The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB44WF, UK.All orders accompanied with payment should be sent directly to The Royal Society of Chemistry, Turpin Distribution Services Ltd., Blackhorse Road, Letchworth, Herts SG6 lHN, UK. NB Turpin Distribution Services Ltd., distributors, is wholly owned by The Royal Society of Chemistry. 1994 Annual subscription rate EC (inc. UK) f381.00, USA $718.00, Canada f431.00 (plus GST), Rest of World f410.00. Customers should make payments by cheque in sterling payable on a UK clearing bank or in US dollars payable on a US clearing bank. Air freight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003. USA POSTMASTER: send address changes to Journal of Materials Chemistry, Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003.Second Class postage paid at Jamaica, NY 11431. All other dispatches outside the UK by Bulk Airmail within Europe, Accelerated Surface Post outside Europe. PRINTED IN THE UK. 0 The Royal Society of Chemistry, 1994. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, mechanical, photographic, recording, or otherwise, without the prior permission of the publishers. Dr. R. J. Parker, Editorial Manager Tel.: Cambridge (01223) 420066 E-Mail (INTERNET): RSCl@RSC.ORG Fax: (01223) 426017, 420247 or 423623 Advertisement sales: Tel. +44 (0171-287 3091; Fax +44 (0171-494 1134 INFORMATION FOR AUTHORS The Royal Society of Chemistry welcomes submission of manuscripts intended for publication in two forms, Articles and Materials Chemistry Communications.These should describe original work of high quality dealing with the synthesis, structures, properties and applications of materials, particularly those associated with advanced technology. Articles Full papers contain original scientific work that has not been published previously. However, work that has appeared in print in a short form such as a Materials Chemistry Communication is normally acceptable. Four copies of Articles includ- ing a top copy with figures etc. should be sent to The Editor, Journal of Materials chemistry, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK.Materials Chemistry Communications Materials Chemistry Communications con- tain novel scientific work in short form and of such importance that rapid publication is warranted. The total length is normally restricted to two pages of the double-column A4 format. For a Communication consisting entirely of text and ten refer-ences, with no figures, equations or tables, this corresponds to approximately 1600 words plus an abstract of up to 40 words. However, special consideration will be given to communications with a large amount of essential diagramatic information. Submission of a Materials Chemistry Communication can be made either to The Editor, Journal of Materials Chemistry, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK, or via a member of the International Advisory Editorial Board. In the latter case, the top copy of the manuscript including any figures etc., together with the name of the person to whom the Communication is being submit- ted, should be sent simultaneously to the Editor at the Cambridge address.Authors may wish to contact the Board member to ensure that he is available to arrange review of the manuscript within reasonable time. In order to avoid delay in publication, proofs of Communications are not sent to authors unless this is specifically requested. Full details of the form of manuscripts for Articles and Materials Chemistry Communications, conditions for accept-ance etc. are given in issue number one of Journal of Materials Chemistry published in January of each year, or may be ob- tained from the Staff Editor. There is no page charge for papers pub- lished in Journal of Materials Chemistry. Fifty reprints are supplied free of charge. Any author who is publishing in Journal of Materials Chemistry is entitled to a free copy of the issue in which the paper appears.

ISSN:0959-9428    

DOI:10.1039/JM99404FX037

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Each Issue with Subject-, A uthor- and Materials Indexes Additional 70-Volume Indexes 72 volumes per year Annual Subscription Rate: SFr 7320.00 Posfa g e/Ha n dling : SFr 720.00 Agency Discount: 7 0% ISSN 0377-6883 ED IT0 RS : Professor G.E. Murch Department of Mechancal Engineering, The University of Newcastle, NSW 2308, Australia H. Neber-Aeschbacher Scitec Publications Untermuehleweg 11 CH-6300 Zug, Switzerland Dr. Fred H. Wohlbier Trans Tech Publications Hardstrasse 13 CH-4714 Aedermannsdorf Switzerland ABSTRACT EDITOR: Dr. David J. Fisher Cardiff, United Kingdom Scitec Publications Member of the Trans Tech Group of Publishers Materials Science Solid State Physics Engineering Untermuehleweg 1I CH-6300 Zug Switzerland Fax: ++41 -42 32 52 12 E-Mail: ddf@scitec.ch The International Journal of the Defect Solid State Pt.A of Diffusion and Defect Data efect and Diffusion Forum is an international journal serving the advanced materials research community as a permanent record of significant developments in the general area of the defect solid state. Started in 1967 as Diffusion Data, the material pre- sented today encompasses the well-known ex-tended abstract section which has made this series a standard in its field, as well as critical reviews, data collections and original contributions. Complete spe- cial issues regularly focus on topics of current inter- est. Particular emphasis is placed on atomic and ionic transport, solid-state defect properties (both structural and electronic), radiation damage and de- fect production. In order to shorten publication time, correspondence can be sent electronically, and manuscripts can be accepted in electronic form. Distributed by: Trans Tech Publications Ltd U Trottenstr. 20 / CH-8037 Zurich / Switzerland Fax: (++41) I2 72 10 92 E-Mail: ddf@transtech.ch Write us for: -Detailed scope of coverage -Instructions for authors -Information on further Materials Science titles

ISSN:0959-9428    

DOI:10.1039/JM99404BX039

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

ISSN 0959-9428 JMACEP(10) 1511-1657 (1994) Journal of Materials Chemistry Synthesis, structures, properties and applications of materials, particularly those associated with advanced technology 1511 Novel aromatic poly(ether ketone)s. Part 1-Synthesis and thermal properties of poly(ether keto imide)s A. J. Lawson, P. L. Pauson, D. C. Sherrington, S. M. Young and (in part) N. O’Brien 1521 Novel aromatic poly(ether ketone)s. Part 2.-Synthesis and thermal properties of poly(ether keto amide)s A. J. Lawsou, P. L. Pauson, D. C. Sherrington and S. M. Young 1527 Novel aromatic poly(ether ketones)s. Part 3.-Synthesis of diamine precursors with 4-8 benzene rings linked by ether, ketone and sulfone groups A. J. Lawson, P. L. Pauson, D. C. Sherrington, S. M. Young and (in part) N.O’Brien 1533 A new single-layer plasma-developable photoresist using the catalysed crosslinking of poly( 4-hydroxystyrene) via photogenerated acid J. T. Fahey, J. M. J. Frkhet and Y. Shacham-Diamand 1539 Laser photolytic studies on sensitizers for negative photoresists: 4,4-Diazido-3,3’-dimethoxybiphenylin poly(methy1 methacrylate) films A. Itaya, T. Inoue, T. Yamamoto, T. Nobutou, H. Miyasaka, M. Toriumi and T. Ueno 1547 Molecular design of amphotropic materials: Double-headed diol-based mesogens incorporating rigid structural units F. Hentrich, C. Tschierske,S. Diele and C. Sauer 1559 Crystal structures and electrical properties of the radical salts of the unsymmetrical donor EOTT (4,5-ethylenedithio-,4,5’-(2-oxatrimethylenedithio) tetrathiafulvalene) A.Tateno, T. Udagawa, T. Naito, H. Kobayashi, A. Kobayashi and T. Nogami 1571 Synthesis and second-harmonic generation properties of 2-( 4-nitroani1ino)- 1,3,5-triazine derivatives H. Yonehara, W-lL Kang, T. Kawara, and C. Pac 1579 Structure of LiN(CF,SO,),, a novel salt for electrochemistry J. L. Nowinski, P. Lightfoot and P. G. Bruce 1581 Preparation of gold-dispersed vanadium oxide thin films by an alternate spin-coating method for electrochromic applications K. Nagase, S. Izaki, Y. Shimizu, N. Miura and N. Yamazoe 1585 YBCO and BSCCO thin films prepared by wet MOCVD 0. Yu Gorbenko, V. N. Fufiyigin, Yu. Yu. Erokhin, I. E. Graboy, A. R. Kaul, Yu. D. Tretyakov, G. Wahl and L. Klippe 1591 Investigations into the growth of AlN by MOCVD using tri-tert-butylaluminium as an alternative aluminium source A.(I. Jones, J. Auld, S. A. Rushworth, D. J. Houlton and G. W. Critchlow 1595 Role of additives in the sintering of silicon nitride: A 29Si, 27Al, 25Mg and 89Y MAS NMR and X-ray diffraction study K. J. D. MacKenzie and R.H. Meinhold 1603 New Routes to Alkali-metal-rare-earth-metal sulfides J. P. Cotter, J. C. Fitzmaurice, and I. P. Parkin 1611 Preparation of zinc oxide and zinc sulfide powders by controlled precipitation from aqueous solution T. Trindade, J. D. Pdrosa de Jesus and P. O’Brien 1619 ?-Radiation sol-gel synthesis of glass-metal nanocomposites Y. Zhu, Y. Qian, M. Zhang, Z. Chen and G. Zhou 1621 Absorption-desorption properties of nitric oxide over layered cuprates, La,- .Ba$rCu,O, M.Machida, H. Murakami, and T. Kijima 1627 Thallium solubility range in T1, -,Ba,Ca, -1C~,02n -,superconductors K. S. Nanjundaswamy, A. Manthiram and J. B. Goodenough+ 1635 Thermal behaviour and reactivity of manganese cobaltites Mn,Co3-,04 (0.0<x< 1.0) obtained at low temperature R. M. Rojas, E. Vila, 0. Garcia and J. L. Martin de Vidales 1641 Bulk and surface characterization of some heteropolymolybdates and the products of their reduction and sulfidation P. Porta, G. Minelli, G. Moretti, I. Pettiti, L. I. Botto, C. Cabello and H. J. Thomas 1647 Investigation of the oxidation of Na,W03 surfaces F. H. Potter and R.G. Egdell 1653 Role of oxoanions in the stabilization of tetragonal zirconia P. Afanasiev, C. Geantet and M.Breysse i Cumulative Author Index iv Conference Diary Note: Where an asterisk appears against the name of one or more authors, it is included with the authors’ approval to indicate that correspondence may be addressed to this person. COPIES OF CITED ARTICLES The Royal Society of Chemistry Library can usually supply copies of cited articles. For further details contact: The Library, Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN, UK. Tel: +44 (0)71-437 8656, Fax: t-44(0)71-287 9798, Telecom Gold 84: BUR210, Electronic Mailbox (Internet) LIBRARY@RSC.ORG. If the material is not available from the Society’s Library, the staff will be pleased to advise on its availability from other sources. Please note that copies are not available from the RSC at Thomas Graham House, Cambridge. SPECIAL ISSUE ON MOLECULAR CONDUCTORS A special issue is planned for publication in 1995 on the topic of molecular conductors. Anyone interested in submitting a paper for this issue is asked to contact Dr Martin Bryce Department of Chemistry University of Durham South Road Durham DH1 3LE UK The deadline for submission of manuscripts for this special issue is 31st March 1995.

ISSN:0959-9428    

DOI:10.1039/JM99404FP087

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Cumulative Author Index 1994 Aarik J., 1239 Blasse G., 1349 Cook S. L., 81 Fujii T., 635 Hodson A. G. W., 1387 Abrahams I., Abser M. N., 185. 775 1173 Bonanos N., 899 Bonardi A., 713 Cooney R. P., 557 Copplestone F. A,, 421 Fujimoto T., 61, 533, 537 Fujita T., 955 Holmes M. C., 11"3 Holmes P. A,, 365 Afanasiev P., 1653 Bond S. E., 23 Corriu R. J. P., 987 Fujiwara Y., 1219 Holmgren A., 413 Agullo J. M.. 695 Ahmet M. T., 1201 Booth C., 591, 1507 Booth C. J., 747 Costa Bizzarri P., 1035 Costa F. M. A., 515 Fukuda A,, Gaillon L., 237, 997 1215 Hong L.. 1041 Hopkins J.. 1055 Ahn S-K., 949 Botto L. I., 541, 1641 Cotter J. P., 1603 Gale J. D., 781, 831 Horigome K., 150 ; Aidla A,, 1239 Bowden K., 1201 Cox P. A,, 805 Galikova L., 265, 271 Hosokoshi Y., 121') Ainslie B.J., 1233 Bradley R. H., 487, 1157, Craig S. R., 977 Gallagher M. J., 1359 Houlton D. J., 1245, 1249, Airoldi C.. 1479 1189 Crayston J. A., 1093 Gallardo Amores 1591 AkaG., 907 Branitsky G. A., 373 Crespin M., 895 J. M., 965, 1123 Hourd A. C., 393 Akhtar M. J., 1081 Branton P. J., 1309 Critchlow G. W., 1245, Galli G., 429, 437 Howlin B. J., 379, 385 Akhtar Z.-u.-N., 1081 Akimoto H.. 61 Aksay I. A,, 353 Alagna L.. 943 Braybrook J. H., 1157, 1357 Brewis D. M., 487, 683 Breysse M., 1653 Brisdon B. J., 1387 1249, 1591 Cumberbatch T. J., Dan M., 1195 Daolio S., 1255 1393 Ganguli P., 331 Garcia A,, 311 Garcia O., 1635 Garcia-Martin S., 1307 Hu Y., 469 Hubert-Pfalzgraf L.G., 1409 Hudson M. J., 99, 113, 1337 Ali-Adib Z., 1 Britt S., 161 Darriet B., 463 Garcia-Martinez 0.. 61 1 Hudson S. A,, 479 Aliev A. E., 35 Allan N. L., 817 A1 Raihani H., 1331 Brock T., 229 Brodsky C. J., 651 Brown T., 771 David L., 1047 Davidson I. M. T., Davies A,, 113 13 Gatteschi D., 319, 1047 Geantet C., 1653 Gee M. B., 337 Hughes A. E., 257 Huxham I. M., 25 i Ibanez A., 1101 Alves 0.L., 389, 529 An Y.. 985 Bruce D. W., 479, 1017 Bruce P. G., 167, 1579 Davies M. J., 813 Davis T. P., 1359 Gellman L. J., 1427 Gibb T. C., 1445, 1451 Ibn-Elhaj M., 135 I Ichimura K.. 883 Ando M., 631 Andreani F.. 1035 Bryant G. C., 209 Buckley C. M.. 1173 Deazle A. S., 385 De Battisti A., 1255 Gibson R. A. G., 393 Gier T. E., 11 11 Ikemoto H., Imanishi N., 537 19 Angeloni A.S., 429, 437 Buist G. J., 379, 385 Dekker J. P., 689 Gil A., 1491 Imayoshi K.. 19 Angeloni L., 1047 Bujanowski V. J., 1181 del Arc0 M., 47 Gil-Llambias F-J., 47 Inabe T., 1377 Annila A., 585 Aoki H., 1497 Bujoli B., 1319 Bulmer G., 1149 del Carmen Prieto M., Della Casa C., 1035 1123 Gittens G. J., 1508 Glomm B., 55 Inada H., 171 Inagaki M., 1475 ap Kendrick D., 399 Burnell G., 1309 Delmon B., 903 Godinho M. M.. 515 Indira L., 1487 Ara K., 551 Busca G., 965, 1123 Dennison S., 41 Goodby J. W.. 71. 747 Inman D.. 1331 Arai H., 653 Bush T. S., 831 Depaoli G., 407 Goodenough J. B., 1627 Inoue T., 1539 Arai K., 275 Cabello C., 1641 Deschenaux R., 679. 1351 Gopalakrishnan J., 703 Irvinc J.T. S., 995 Aranha N., 529 Cairns J. A., 393 De Stefanis A,, 959 Gorbenko 0.Yu.. 1585 Ishikawa K., 997 Armelao L., 407 Armes S. P., 935 Campelo J. M., 311 Caneschi A., 319, 1047 Devynck J., Dhas N. A,, 1215 491 Gormezano A., Goto T., 915 8 I7 Islam M. S., 299 Ismail H., 1189 Armigliato A., 361 Arnold Jr. F. E., 105 Cao X., 417 Capelletti R.. 713 Diamond D., 145, 217 Diele S., 1547 Gozzi D., 579 Graboy I. E., 1585 Isoda S.. 291 Isozaki T., 237, 997 Aruga Katori H., 915 Cardwell D. A,, 1393 Dissanay ake Grange P., 1343 Itaya A,, 1539 Asaka N.. 291 Carlino S., 99 M. A. K. L., 1075. 1307 Granozzi G., 407 Ivanovskaya M. I., 373 Aspin I. P., 385 Carr S. W., 421 Dong C., 1365 Gravereau P., 463 Iyer R.M., 1077 Attfield J. P., 475, 575 Carrazan S. R. G., 47 Douglas W. E., 1167 Greaves C., 931, 1463, 1469, Izaki S., 1581 Atwood M. P., 1393 Carruthers B., 805 Drabik M., 265, 271 1507 Jacobson A. J., 14: 9 Auld J., 1245, 1249, 1591 Carvalho A., 515 Drennan J., 245 Gregory D. H.. 921 Jaek A,, 1239 Auroux A.. 125 Casciola M., 1313 Dunmur D. A,, 747 Grins J., 445, 1293 James M., 575 Awaga K.. AzumaK.. 1377 139 Cassagneau T., Castellanos M., 189 1303 Durand B., 1331 Eda K., 205, 775 Guillon D., 679, 1359 Guo Z., 321 Janes R.. 1071 Jennings R. A., 93 i Baba A,, 51 Babu G. P., 331 Castiglioni M., 1067 Castillo R., 903 Egdell R. G., 1647 Eguchi K., 653 Gutierrez M. P., 1303 Hall P.G., 1309 Jimenez R., 5 Jimenez-Lopez A,, 179 Babushkin O., 413 Catlow C. R. A., 781, 831, Ekstrand A,, 615 Hamerton I.. 379, 385 Jin-Hua C., 1041 Bach S., 133, 875 1081 Eldred W. K., 305 Hamstra M. A,, 1349 Joachimi D., 1021 Bachir S., 139 Causa M., 825 Ellis A. M., 13 Han Y-S., 1271 Jones A. C., 1245, 1249, Badwal S. P. S., 257. 1437 Cellucci F., 579 Elsegood M. R. J., 891 Hannington J., 869 1591 Badyal J. P. S., 1055 Bae M-K.. 991 Cervini R., 87 Cesar C. L., 529 Endregard M., 943 Ericsson T., 1101 Harris F. W., 105 Harris K. D. M., 35 Jones D. J., Jones J. R., 189 379, 3:+3 Baetzold R. C., 299 Chaair H., 765 Erokhin Yu. Yu., 1585 Harris S. J., 145, 217 Jones P. J. V., 805 Baffier N., 133, 875 Challier T., 367 Errington R.J., 891 Harrison W. T. A,, 1111 Jouanneaux A., 13 19 Bagshaw S. A., Baiios L., 445 557 Chang S-H., Charlton A., 1271 1233 Etourneau J., 463 Fabretti A., 1047 Haslam S. D., 209, 1205 Hastie G. P., 977 Jung K.. 161 Jung W-S., 949 Baram P. S.. 817 Barbieri A., 1255 Chassagneux F., Cheetham A. K., 1331 641, 707, Facchin B., 1255 Faguy P. W., 771 Hatayama F., 205, 775 Hayashi A,, 915 Kadokawa J-i., 55 I Kaharu T.. 8.59 Barbosa L. C., 529 1457 Fahey J. T., 1533 Heath K. D., 825 Kahn-Harari A,, (9437 Barker C. P., 1055 Chehimi M. M., 305, 741 Fau-Canillac F., 695 Heath R. J., 487, 683 Kakkar A. K., 1227 Barriga C., 11 17 Barton J. M., 379, 385 Bashall A,, 1201 Chen C., Chen Q., Chen Z.. 469 327 1619 Feast W.J., 1159 Feng S., 985 Fernandez J. M., 1117 Hector A. L., 279 Heinrich B., 679 Henshaw G. S., 1427 Kamath P. V., 1437 Kang J. S., 747 Kall P-O., 1293 Battaglin G., 407 Battle P. D., 421, 641, 707, Cheng S. Z. D., Chernyaev S. V., 1107 105, 719 Ferraro F., 1047 Fettis G. C., 1157, 1357 Hentrich F., 1547 Hermansson L., 413 Kang W-B., 1571 Karasu M.. 551 831, 1457 Chevalier B., 463 Fisher G. A., 891 Herod A. J., 1451 Kareiva A,. 1267 Batyuk V. A., 761 Bautista F. M., 31 1 Bazin D., 1101 Bechgaard K., 675 Bedioui F., 1215 Bedson J., 571 Beguin F.. 669 Bell R. G.. 781 Chiba K., 551 Chiellini E., 429, 437 Choisnet J., 895 Chu P., 719 Ciacchi F. T., 257 Clegg W., 891 Colbourn E. A,, 805 Choy J-H., 1271 Fitmaurice J. C., 285, 1603 Fitzpatrick A.D., 1055 Fleming R. J., 87 Fletcher J. G., 1303 Flint S. D., 509 Folkerts H. F., 1349 Forsyth M., 1149 Foster D. F., 657 Herrero P., 1433 Hervieu M., 1353 Heughebaert J-C., 765 Heughebaert M., 765 Heywood B. R., 1387 Hickey E., 463 Higuchi A,, 171 Hill C. A. S., 1233 Karppinen M., 1257 Kassabov S., 153 Kato C., 519 Kato R., 915, 121') Katsoulis D. E., 317, 1181 Kaul A. R., 1585 Kawamura I., 237 Kawara, T., 1571 Bellwood M., 1173 Cole-Hamilton D. J., 657 Fragala I. L., 1061 Hinds B. J., 1061 Kennedy B. J., 87 Benzi P., 1067 Bertoncello R., 407 Beveridge M., 119 Bigi S., 361 Bignozzi M. C., 429 Billingham N. C., 1508 Bjsrnholm T., 675 Coles G. S. V., 23 Coles H., 869 Colque S., 1343 Connell J. E., 399 Conroy M., 1 Conway L. J., 337 Cook M.J., 209, 1205 Fraoua K., 305 Freakley P. K., 1189 Frechet J. M. J., 1533 Frederiksen P., 675 Friend R. H., 1227 Frialova M., 271 Fuflyigin V. N., 1585 Hirose N., 9 Hitchman M. L., 81 Hix G. B., 189 Hobson R. J., 113 Hochi K., 599 Hodby J. W., 469 Hodge P., 1, 869 Kerridge D. H., 1 ;31 Kershaw S.. 1233 Khan M. S.. 1227 Kijima T., 1621 Kim H-B., 883 King T., I Kinoshita M., 915 1219 i Kiyozumi Y., Klein M. L., 585 793 Malet P., 47 Malik M. A,, 1249 Neuniayer D. A,, Newton J., 869 1061 Reau J. M., 1433 Reid M., 1149 Solzi M. 361 Song S-W.. 1271 Klippe L., 1585 Klissurski D.. 153 Malins C., Mani R. S., 1029 623 Nguyen P., 1227 Nicol I., 29 Rettig W., 1021 Reynolds C. A,, 1201 Sotani N., Spagna A.. 205, 775 437 Knight K.S., 899 Knowles J. C.. 185. 775 KO E. I., 651 Mann S., 1387 Manning R. J., 1233 Manthiram A,, 1627 Nielsen K., Niinisto L., 1409 867 1239, 1267, Rhomari M., 189 Richards B. C., 81 Richardson R. M., 209, Sprik M., 793 Stainton h.M., 1159 Stedrnan K.J., 641, 707, Kobayashi A,, Kobayashi H., Kobayashi T., 1559 1559 291 Marcos M. D., 475 Marder T. B., 1227 Marinas J. M., 311 Nishiyama I., 449, 983 Niwa S-i., 585, 1131 Nix R. M., 1403 Rives V., 47, 11 17 Roberts K. J., 977 1205 Stern C. L... 1061 Stucky G. D., 1111 1457 Koch B., 903 Kohmoto T., 205, 775 Marks G., 399 Marks T. J., 1061 Nobutou T., Nogami T., 1539 1559 Robertson A. D., Robertson M. I., 457 29, 119 Styring P., 71, 1365 Su Q., 417 Komatsu T.. Komppa V.. 533, 537 585 Marsden J.R., 1017 Martin C., 1353 Nomura R., Nomura S., 51 171 Rockliffe J. W., 331 Rodriguez-Castellon E., 179 Suckut C.. 5 Sugiyama K., 1497 Kossanyi J.. 139 Martin de Vidales Norman N. C., 891 Rodriguez-Reinoso F., 1137 Sumathipala H. H., 1075, Kosztics I.. 1351 Kouyate D., 139 J. L., 1635 Martin T. L., 623 Nowinski J. L., 1579 Nunes M. R., 515 Rojas R. M., 1635 611, 1433, Sundholm F., 1307 499 Kristo J., 1255 Maruyama Y., 1377 Nygren M., 615, 1275 Rojo J. M., 1433 Sutherland I., 487, 683, KriStofik M.. 271 Mather G. C., 1303 Nykanen E., 1409 Romanovskaya V. V., 373 1189 Kubono K., 291 Mathieson I, 1157 O'Brien N., 1511, 1527 Ronfard-Haret J-C., 139 Suto s., 631 Kubranova M., 265 Matsuba T., 599 O'Brien P., 565, 1249, 1611 Rose R.G., 995 Suzuki T., 631 Kunitomo M., 205, 775 Kunou I.. 955 Matsubayashi G-e., Matsuda H., 51 1325 Ogawa M., 519 Ogura D., 653 Ross A., 119 Rossignol S., 1433 Suzuki Y., 237 Svensson G., 1293 Kuramoto N., 1195 Matsuda T., 955, 1497 Ohlmann A., 1021 Rothlisberger U., 793 Swindell J.. 229 Kuroda K.. Kuwano J.. 519 9. 973 Matsumoto M., 1377 Matsuzaki I., 853 Ohnishi K., 171 Ohta K., 61, 533, 537 Rourke J. P., 1017 Rowatt B., 253 Taga T., 291 Tagaya H.. 551 Labajos F. M., 1117 Lacey D., 1029 Maury F., 695 Maza-Rodriguez J., 179 Ohta S., 1503 Ohtaki M., 653 Rowley A. T., 285 Rozike J., 189 Tajbakhsh '4. R., 1017 Takahashi M., 519 Lahti P. M., 161 McCabe R. W., 1173 Oki K., 635 Ruiz P., 903 Takahashi S., 859 Laine-Ylijoki J., 1409 McCarrick M., 217 Okuno T., 1377 Rushworth S.A., 1245, Takanishi Y., 997 Landee C., 161 McGhee L., 29, 119 Oliver S. N., 1233 1249, 1591 Takano M.. 19 Laus M., 429. 437 McKeown N. B., 11 53 Olivera-Pastor P., 179 Russell D. K., 13 Takatoh K., 1365 Lavela P., 1413 McMeekin S. G., 29, 119 Osterlund R., 615 Ryan T. G., 209 Takebe Y., 599 Lawrence L. W., 571 McMurdo J., 1205 Overend A. S., 11 67 Sadaoka Y., 663 Takeda Y.. 19 Lawrenson B., Lawson A. J., 393 1511, 1521, McMurray H. N., 1283 McPartlin M., 1201 Owen J. 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M., 29, 119 Yamamoto H., 635 1527 Yu H., 327 Yue Y., 985 Zammit M.D., 1359 Zarbin A. J. G., 389 Zhang M., 1619 Zhang W-r., 161 Zhao L., 623 Zheng Q., 1041 Zhou G., 1619 Zhu Y., 1619 Zhuang Z., 1041 Ziemelis M. J., 1181 Zotov N.. 611 ... Conference Diary October 10-12 3rd International Symposium on Structural and Functional Gradient Materials Lausanne, Switzerland FGM '94, Swiss Federal Institute of Technology of Lausanne, Materials Department, LMM,CH-1015 Lausanne, Switzerland. Tel: +41 21 693 29 15/50; Fax: +41 21 693 46 64 October 10-13 1994 International Display Research Conference and Materials Workshop Monterey, USA SID do Palisades Institute for Research Services, 201 Varick Street, New York, NY 10014, USA October 11-13 10th Optical Fibre Sensors Conference Glasgow, UK Mrs.Aileen Mitchell, University of Strathclyde, Royal College Building, Glasgow, UK, G1 1xW Tel: +44 141 552 4400 ext.2543 October 16-21 Molecule-Based Magnets Salt Lake City, UT,USA Joel S. 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ISSN:0959-9428    

DOI:10.1039/JM99404BP089

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

J. MATER. CHEM., 1994, 4(10), 1511-1520 1511 Novel Aromatic Poly(ether ketone)s Part 1.-Synthesis and Thermal Properties of Poly(ether keto imide)s Anthony J. Lawson:+ Peter L. Pauson: David C. Sherrington,"* Stella M. Youngb* and (in part) Niall O'Brien§ a Deparfmenf of Pure and Applied Chemisfry, Universify of Sfrafhclyde, 295 Cafhedral Sfreef, Glasgo w, UKG7 7XL ICI Wilfon Maferials Research Centre, Middlesbrough, Cleveland, UK TS68JE A range of aromatic polyimides have been prepared by polycondensation of novel diamines, having four to eight benzene rings linked by ether, ketone and sulfone groups, with a number of commercially available acid dianhydrides. The effect of systematic structural alterations on the thermal properties of the polymers has been evaluated and discussed in the light of the literature.This approach has allowed the synthesis of poly(ether keto imide)s which retain the high Tg associated with polyimides (ca. 270°C) and yet have T,,, values of ca. 370°C which, in principle. would allow melt processing. Comparison is drawn with other favourable materials already described in the literature. Two important classes of thermally stable polymers are the aromatic polyimides' and the aromatic poly(ether ketone)s,2 the former in particular showing remarkably high thermo- oxidative stability. In general the polyimides have very high glass-transition temperatures, T,and decompose before melt- ing. They are also usually amorphous in nature, a factor which can influence some physical properties, e.g.toughness and tensile strength, rather adversely. Poly (ether ketone) s on the other hand have lower Tg values, but are often crystalline and melt-processable. Not surprisingly, therefore, attempting to combine the positive properties of these groups has been the centre of considerable research, most notably atby Hergenrother and co-worker~~-~ NASA. Indeed, by employing a diamine having four benzene rings linked by ether and ketone functions a semicrystalline polyimide, LARC- CPI, has been produced displaying a T, of 350°C with a Tp of 222°C. (Note: Tp of a simple polyimide is ca. 380"C, and of a simple poly(ether ketone) is ca. 150"C with T, x370 "C.) The polymer has excellent physical properties with the added crystallinity improving toughness and solvent resistance rela- tive to other polyimides, while retaining very satisfactory rigidity (q).This material has become something of a bench- mark in this area, and recently a nominally structurally identical polymer has been prepared via an alternative route employing a Friedel-Crafts acylation.' Indeed this approach has been used to generate a wide range of aromatic ether- ketone-X (EKX) polymers, where X includes imide, amide, ester, sulfone, azo and quinoxaline functionalities.*-1° The Tg and T, of a polymer are related by the phenomeno- logical Beaman" equation T,= 1.3 Tg (in K) so that reducing T, to enhance processability usually results in a fall in Tg, and loss of polymer backbone rigidity.However, since to a first approximation these thermal transitions have their origins within different regions in a polymer, i.e.the amorphous and crystalline domains, respectively, for Tg and T,, then in principle it may be possible to decouple these transitions by appropriate choice of backbone structure. Indeed for aromatic polyesters Brown et ~2.'~have demonstrated that the ratio T,/T, can be altered by increasing the proportion of rneta-t Present address: Vinamul Ltd., Mill Lane, Carshalton, Surrey SM5. $ Present address: I.C.I. plc, Fluon R & T, York House, Hillhouse International, Thornton, Cleveleys, Lancashire FY5 4QD.9 Present address: Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral St., Glasgow G1 1XL.substituted monomer components in the backbone, I()wering the T, significantly without any change in q. This paper describes our attempts to develop Hergenrother's approach further, to obtain semicr) stalline polyimides in which the Tp and T, are decoupled and to understand the structural design features which bring this about. The approach has been to synthesize 16 aromatic diamines with four to eight benzene rings linked together by ether, ketone and in one case sulfone groups, where, unlike in earlier poly(ether keto irnide)~,~-" the functionality adjacent to the imide unit is a ketone not an ether. We have also sought to define the contribution of rneta and para iinkages in these. Polyimides have been prepared from these using mainly pyromellitic and 3,3',4,4'-benzophenonetetracarboxylic acid dianhydrides, although three other acid dianhydrides have also been examined.Results and Discussion Polyimide Syntheses The structures of the diamines used in this work arc shown in Table 1 and their syntheses are described in Part 3 of this series. The corresponding commercially available acid dianhy- drides employed are shown in Table 2. Microanalytical data for polyimides prepared with PMDA and BTDA are shown in Tables 3 and 4 where the polymer is coded to show the precursor diamine and acid dianhydride employed. Since the polyimides are highly intractable, and in particular insoluble in organic solvents, it is impossible to determine or estimate (e.g.from reduced viscosity, RV) the molecular weights of the products. However, measurement of the RV of the precursor polyamic acid solutions is possible. From this point of view the two-step 'thermal imidisation' bynthesis (Tables 5-7) was favoured over the one-step 'solution syn- thesis' procedure using diphenyl sulfone (DPS) as the solvent (Table 8) (see Experimental section). In general therefore most syntheses used the 'thermal imidisation' procedure and, in particular, the 'thin-film casting' method (see Experimental section). It was also important that the RV of the precursor polyamic acid solution was not too high, otherwise gelation occurred and this tended to inhibit efficient imidisation. Generally RV values in the range 0.35-0.65dl 8-l were found to bc suitable (Tables 5-7), although some reached ca.3 dl 8-l very readily. The viscosity achieved was related to some extent to the reactivity of the diamine being used. Those amines with a J. MATER. CHEM., 1994, VOL. 4 Table 1 Diamines used in polyimide syntheses no. structure 1A 2A 3A 4A 5A NH2 \ 0-o-”qp””. 0 0 6A 7A 0 0 8A 9A NH2* 0 0hNH2 10A 11A 0 0 NH2-9poyJJyy7J12A ‘ \ ‘ \ 0&NH2 0 0 J. MATER. CHEM., 1994, VOL. 4 Table 1 (continued) no. structure 13A 0 0 NH2yJ0yJp0yJ&y0qP0~16A \ \ NH2 0 0 0 Table 2 Acid dianhydrides used in polyimide syntheses Table 3 Microanalytical data for polyimides synthesizcd from PMDA" code structure polymer code microanalysis found (YO) calcd.(%) PMDA CHN C II N ~~ PMDAJlA 71.6 3.0 4.7 73.2 3 1 4.7 PMDA/2A 72.5 2.9 4.7 73.2 3 1 4.7 PMDA/3Ab 72.2 3.0 4.6 73.2 3 1 4.7 PMDAJ4A 72.6 2.7 4.6 75.3 3 1 4.9 PMDAJ5 A 71.5 2.7 3.6 73.9 3 2 4.1 PMDAf6A 73.8 3.1 4.1 73.9 3.2 4.1 BTDA PMDAJ7A 73.0 2.9 4.0 73.9 3.4 4.1 PMDA/8A 72.7 3.0 3.3 74.4 1.4 3.6 PMDAJllA 74.5 3.1 2.9 75.5 3.4 3.1 PMDA/12A 74.3 3.2 3.1 75.5 ?.4 3.1 PMDAJ13A 74.3 3.0 2.9 75.5 ?.4 3.1 "'Thermal' imidisation method. "4% mol% excess of dianiine used in synthesis. ODPA Table 4 Microanalytical data for polyimides synthesized from BTDA" polymer code microanalysis BPDA found (YO) calctl. (%) ~~ CHN CHN BTDA/lA 73.6 3.0 3.6 74.4 i.2 4.0 BTDAJ2A 73.1 2.8 4.1 74.4 i.2 4.0 BTDA/3Ab 74.5 3.1 3.8 74.4 ;.2 4.0 DPSDA BTDAJSA 73.5 3.3 3.6 74.8 ;.3 3.6 BTDAJ6A 74.0 3.1 3.4 74.8 ;.3 3.6 BTDAJ7 73.7 3.1 3.4 74.8 i.3 3.6 BTDA/8A 74.2 3.4 3.5 75.2 ;.4 3.2 BTDA/l 1 A 74.9 3.4 2.7 76.0 3.4 2.8 BTDAJ12A 75.0 3.2 2.6 76.0 3.4 2.8 BTDA/13A 75.8 3.4 2.7 76.0 3.4 2.8 "'Thermal' imidisation method."5% mol% excess of diamine used in synthesis. J. MATER. CHEM., 1994, VOL. 4 Table 5 Thermal and physical properties of polyimides synthesized from PMDA using thermal imidisation natureno. of benzene RV" Tg Tm temp. of polymer code rings in diamine /dl g-l /OCb /OCb 10% Wt.loSS/°Cc of film PMDA/ 1A 4 0.44 527 663 brittle PMDA/2A 4 0.55 268 374 555 tough PMDA/3Ad 4 0.76 266 ->500 (5% wt. loss) tough --670PMDA/4A 4 0.65 tough PMDA/SA 5 0.41 230 -560 tough PMDA/6A 5 0.89 246 -561 tough PMDA/7A 5 0.46 250 449 518 brittle PMDA/8A 6 0.54 223 -528 tough PMDA/llA 7 0.56 223 42 1 504 tough PMD A/ 12A 7 0.45 234 -522 tough PMDA/13A 7 0.68 225 -5 64 tough PMDA/3Ae3f 4 244 PMDA/l 2Af 7 236 -PMDA/1 lAf 7 -223 PMDA/lA +3A( 1/1) 4 0.29 276 tough PMDA/2A + lA( 112) 4 0.36 -tough PMDA/2A + lA( 111) 4 0.36 282 tough PMDA/2A +3A( 1/1) 4 0.35 268 tough Of precursor polyamic acid.bFrom DSC trace. 'From TG curve. d4mol% excess of diamine. "5 mol% excess of diamine. fSolution imidisation in DPS. Table 6 Thermal and physical properties of polyimides synthesized from BTDA using thermal imidisation natureno. of benzene Rv" Tg Tm temp.of polymer code rings in diamine /dl g-' /oCh /oCb 10% Wt.l0SS/oCC of film BTDA/lA 4 0.58 258 376 500 (5% wt. loss) tough BTDA/2A 4 0.32 247 -560 tough BTDA/3Ad 4 1.65 226 -560 tough BTDA/5A 5 0.37 23 1 404 561 tough BTDA/6A 5 1.52 22 1 -496 tough BTDA/7A 5 0.56 22 1 320 440 tough BTDA/8A 6 0.64 205 -561 tough BTDA/llA 7 0.40 21 1 359 535 brittle BTDA/12A 7 0.42 213 -565 tough BTDA/13A 7 1.03 225 -544 tough BTDA/3A" 4 220 tough "Of precursor polyamic acid. bFrom DSC trace. 'From TG curve. d5 mol% excess of diamine. '5 mol% excess of diamine and solution imidisation in DPS. Table 7 Polymerisations using a variety of different acid dianhydrides via thermal imidisation ~~~~ ~~ no. of benzene excess of nature rings in acid solids diamine of RVh Tgcdiamine diamine dianh ydride endcapped" (%) (mol%) film /dl g-' 1°C 9A 6 PMDA 17.0 0 brittle -~ 239 9A 6 PMDA 9.2 5 brittle 1.89 237 9A 6 PMDA 13.2 4 brittle 1.8 213 9A 6 PMDA 9.9 5 creasable 0.5 227 9A 6 BTDA 15.1 5 brittle 0.7 199 9A 6 ODPA 15.2 5 creasa ble 0.4 220 9A 6 DPSDA 15.9 5 brittle 0.8 187 9A 6 BPDA 14.7 5 brittle 0.7 209 10A 6 PMDA 12.4 3 brittle 1OA 6 BTDA 12.8 5 brittle 0.7 227 1 OA 6 BPDA 12.0 5 brittle 0.8 233 1 OA 6 ODPA 11.0 5 brittle 0.6 220 15A 8 PMDA 10.0 3 creasable 2.1 210 15A 8 BTDA 12.3 3 brittle 3.1 213 15A 8 ODPA 10.0 5 brittle 0.8 190 15A 8 DPSDA 12.9 5 brittle 0.5 206 15A 8 BPDA 8.1 5 brittle -205 16A 8 PMDA 18.5 5 creasable 0.2 180 16A 8 BTDA 10.9 5 brittle 0.2 184 16A 8 ODPA 8.1 3 creasa ble -178 16A 8 BPDA 10.8 2 brittle 0.5 185 Using PA.'Of precursor polyamic acid. 'From DSC trace. J. MATER. CHEM., 1994, VOL. 4 Table 8 Polymerisations using a variety of different acid dianhydrides via solution imidisation in DPS" acid excess of nature diamine" dianhydride solids (YO) diamine (mol%) of film 'lJT 14A PMDA 15.5 creasable 250 14A BTDA 22.3 creasable (76 360) 223 14A ODPA 16.6 creasable 214 14A BPDA 14.8 creasable 226 15A PMDA 14.2 brittle 213 16A PMDA 22.3 creasable 189 16A PMDA - creasable - "PA endcapper used throughout. 'Diamines with eight benzene rings in the molecule. 'From DSC trace. carbonyl group in the immediate para position were of lower nucleophilicity. Amines with the carbonyl group in the meta position were more active, resulting in more rapid conden- sation and much higher RV values for their polyamic acid solutions.To control the rate of polymer formation and hence restrict the RV it was sometimes necessary to use phthalic anhydride (PA) as an endcapper, or to use an excess of diamine to lower the degree of polymerisation (see tables). The variation of the molecular weight of the polyamic acid has been shown previously to be related to the pK, of the diamine.'*13.14Low pK, values lower the rate constant of the forward amic acid formation step reducing the RV. With 4,4'-substituted amines, for example lA, the value of the RV was 0.44 with PMDA. Switching to 3A, with lower electron- withdrawing effect upon the amine, led to a rapid gelation of the polymeric acid with an RV of 0.76 dl g-' with the same acid dianhydride.Although molecular weights could not be determined for the final polyimide, the use of an identical thermal imidisation procedure for every polymer meant that any additional mol- ecular weight changes during the imidisation15 were expected to be more or less identical for every polymer. Thermal Properties of Polyimides All the polyimides were analysed by DSC (Tables 5-8). Typically two characteristic traces were obtained. Most poly- mers displayed a Tg transition with no evidence of a melt endotherm. Where semicrystallinity did occur, characterised by such a feature in the DSC trace, the sample was cooled and reheated to show the Tg transition more clearly.This thermal recycling generally quenched out any ~rystallinity.~ To ensure that the data were not influenced by differences in molecular weight, i.e. RV values, samples of BTDA/lA poly- amic acid were removed from the polymerisation medium at regular intervals, and the RV was measured. The samples were each cast onto borosilicate glass sheets, thermally imidised and then analysed by DSC. The results are shown in Table 9. For samples with RV ~0.2dl g-' Tg varies between 258 and 268°C. The variation seems to arise from minor differences in the nature of the polymer and also includes experimental error. For all practical purposes, however, the Tp can be considered as constant for samples with RV>O.2 dl g-'.Below this viscosity, however, the resultant polyimide has a Table 9 TJRV study for BTDA/1A RV/dl g-' 0.17 24 1 - 0.20 266 - 0.25 268 - 0.34 259 376 0.58 258 376 significantly lower q.Interestingly, when the polyamic acid was allowed to polymerise to yield a solution with an RV 30.35 dl g-' crystallinity was generated in the pollyimide product, with a discrete T, at 376 "C (entries 4 and 5, ?able 9). Structure-Property Relationships for Polyimides Most of the polyimides were essentially amorphous and those that did show a melt endotherm in the DSC did not possess any close structural relationship. Attempts to induce crystal- linity in other samples by various annealing procedures in the DSC were unsuccessf~l.~ These difficulties can be attributed to the fact that in both poly(ary1 ether ketone)s and poly(ether keto imide)s the aromatic rings are not ~oplanar'~-'~ when connected by either ether or ketone linkages, having a tor- sional angle of ca.70°L7 with respect to each other. For the polyimides an additional torsional angle of 30"16 aribes with respect to the imide. Continual repetition of these distortions is believed to produce a twisting structure in the polymer chain. Compounds modelled by O'Mahoney et all8 suggest that S-shaped structures exist for m-aminophenyl ether whilst p-aminophenyl ether structures adopt a straighter. comp- lementary self-stacking model. Although crystalline melt temperatures were not fcrund for all polyimides it was possible to look at the effect of structural changes upon the alone and those polymers that did show a melt endotherm allowed a tentative analysis of the Beaman relationship between Tp and T,.Effect of Diamine Size Increasing the size of the diamine component in order to improve the processability of polyimides has been a major aim of both Hergenrother and co-workers and Bell et Indeed, the latter group did attempt a quantitative study. The results from the present work are clear cut for the ciiamines 3A, 6A, 9A, 12A and 15A which have 4,5,6,7 and 8 benzene rings, respectively, all joined in a para configuration, and with amino groups meta to the last carbonyl linkage in each case.Table 10 shows the Tg data for polyimides prepared with PMDA and BTDA. The decrease in Tg is clearly larger for the PMDA series than for the BTDA series. It hias been suggested that the incorporation of flexible connecting groups into the acid dianhydride component (e.g. BTDA replacing PMDA) has the effect of lowering Tg more than the presence of the same flexibilising segment in the diamine component. However, increasing the size of the diamine component undoubtedly lowers the effect of the incorporation of the flexibilising group into the acid dianhydride portion of the polymer backbone to such an extent that at a diamine size of ca. eight aromatic rings changing from PMDA to BTDA does not affect the resultant polyimide at all. However, the presence of the rigid imide group, irrespective of how this is diluted by ether and ketone flexibilising linkages, raises the J.MATER. CHEM., 1994, VOL. 4 Table 10 Effect of increasing the size of the diamine upon Tgsfor PMDA and BTDA polyimides q/"cno. of aromatic code Ar rings in diamine PMDA -266 246 239 234 210 Table 11 TJTm data for semicrystalline polyimides BTDA ref. 240 26 226 this work 22 1 this work 199 this work 213 this work 213 this work no. of benzene nt polymer code rings in diamine RV/dl g-' PMDA/lA PMDA/2A PMDA/7A PMDA/llA BTDA/lA BTDA/5 A BTDA/7A BTDA/llA 0.44 0.55 0.56 0.56 0.58 0.37 0.56 0.40 LARC-CPI - by ca. 50°C from the corresponding values for poly(ary1 ether ketone)s.Clearly this in itself is of technical importance. Effect of the Substitution Pattern in the Diamine Residue In order to quantify the effect of altering the substitution pattern upon the Tg/Tmrelationship, polymerisations were carried out on a variety of isomeric four-, five- and seven-ring diamines with PMDA and BTDA. Those polyimides that showed a melt endotherm are listed in Table 11. (Note that temperatures are now in K for the Beaman relationship.) Several conclusions can be drawn from the results. First, altering the amine substitution from 4,4' to 3,3' gave polymers which failed to show any melt endotherms. This would suggest that crystallinity has been lost, although earlier X-ray diffrac- tion studies22 on polymers from compounds similar to the four-ring diamines in this work suggest that 3,3' amine substi- tution can still yield ca.16% crystallinity for PMDA-based polyimides. Altering the substitution pattern of a single amine group on the other hand, e.g. in polyimide PMDA/2A, did allow a retention of some crystallinity and a lowering of the T, from 800 K for PMDA/lA to 647 K for PMDA/2A. The Tg of PMDA/lA was unfortunately not detected by DSC so that no Tg/Tmratio could be calculated. Nevertheless, polyim- ide PMDA/2A is very interesting: its Tgis ca. 50°C higher than that of LARC CPI and yet its melting point is only ca. 25 "C higher. This is reflected in the high Beaman ratio, 0.83. Polyimides BTDA/1 A and BTDA/7A also have excellent combinations of Tgand T,.While BTDA/7A has the same Tg as LARC CPI its melting point is 30°C lower, showing an excellent combination of rigidity and potential processability. In order to look at the effect of increasing the amine meta content of Tp alone it was decided to synthesize a series of copolyimides based upon the isomers lA, 2A and 3A. Mixtures of the diamines were polymerised with PMDA. The polyamic acid solutions were cast as films and imidised thermally. The results are shown in Table 12. Clearly increasing the meta T,/TmT,/K Tm/K (Beaman relationship) -aoo -54 1 647 0.83 523 722 0.72 496 694 0.72 53 1 649 0.82 504 677 0.74 494 593 0.83 484 632 0.77 495 623 0.79 Table 12 PMDA copolyimides from isomers IA, 2A and 3A ~~ ~ ~~ ~~ amine meta mole polymer code RV/dl 8-l PMDA/lA 0.44 PMDA/2A + 1A ( 1:2) 0.36 PMDA/2A + 1A (1 :1) 0.36 PMDA/lA +3A ( 1:1) 0.29 PMDA/2A+ 3A (1: 1) 0.35 PMDA/3A" 0.76 "4 mol% excess of diamine used.fraction 7J"C 0.00 -0.17 -~ 0.25 282 0.50 276 0.75 268 1.oo 266 content of the terminal amine ring leads to an almost linear decrease in Tg. The monomer feed ratio of the diamines is a guide to the copolymer composition ratio. It can be seen that the Tp for PMDA/lA+ 3A (1 :1) (i.e. a nominal meta mole fraction of 0.5) is 276°C whilst the Tg of PMDA/2A (same equivalent meta mole fraction) is only 268 "C(Table 5). Given that the 3A component is more reactive a copolyimide with a lower Tg than that for PMDA/2A might have been expected, assuming a higher uptake of the more reactive species.The discrepancy is difficult to explain, but may be due to subtle physical differences in the polymer backbones, between the evenly spread meta linkages in PMDA/2A and the more block-like and uneven spread of the meta linkages in the copolymer. A second potentially important change in the structural pattern which might influence the thermal properties is a change from 1,4 to 1,3 aromatic substitution in the non-terminal or internal groups of the diamine. Polymers BTDA/5A and BTDA/7A were prepared from diamines con- taining five aromatic groups and differing only in the pattern of substitution of the central ring. Both polyimides were semicrystalline and offered a good opportunity for comparison with two polymers reported in the literature4 prepared from J.MATER. CHEM., 1994, VOL. 4 isomeric diamines. The latter again differ only in the pattern of substitution of the central aromatic ring, but also having the ether and ketone linkages interchanged relative to 5A and 7A. Table 13 shows the relevant Tg and T, data. Both pairs of polymers show a distinct fall in T, (ca. 70°C) for only a small fall in (ca. 10°C) when the 1,3 central pattern of substitution replaces the 1,4 pattern. Overall BTDA/7A shows the best combination of Tg and T, with a Beaman ratio of 0.83. In this case therefore the positioning of the ether linkages ‘inside’ the ketonic ones within the diamine residue seems the optimum arrangement.The close correspondence of all the Tg values for these four polymers is also interesting. However, the literature shows that the interchange of ether and ketone groups as above does not necessarily lead to identical Tg s as is the case for poly(ary1 ether ketone)^.^^ Rao and Bijim01~~ synthesized a series of ether ketone containing diamines with four aromatic groups with the structures shown in Table 14. The Tg data for polyimides prepared with PMDA and BTDA are shown in Table 14, along with the data for poly-imides prepared in this work from the diamines 1A and 3A in which the ether and ketone linkages are interchanged relative to Rao’s molecules. Clearly in this situation switching the ether linkage ‘inside’ the ketonic ones leads to an increase in Tg irrespective of the pattern of substitution of the terminal rings in the amine residue.Effect of Structural Changes in Acid Dianhydride Residue The generally lower Tgassociated with BPDA versus PMDA polyimides has been described earlier. The role of flexibilising groups in the acid dianhydride residue has been discussed in the first in terms of a comparison with flexible linkages in the diamine residue and secondly in terms of interrupting the intermolecular interactions between polymer chains. The ‘electronic isolation’ of acid anhydride residues in BTDA, ODPA, BPDA, DPSDA etc. play an important role in reducing the electron affinity of the imide rings, and the effect on reducing T, does seem to be higher than that on G.This was also the case in the present work as seen from the data in Table 15. T,/T, shifts from 0.71 to 0.77 for poljimides prepared from 11A with PMDA and BTDA, respectively, and from 0.72 to 0.83 for polymers from 7A with these acid dianhydrides; i.e. in each pair of polymers T, is lowered more than T,. With polyimides prepared from the longer diamines 9A, 10A, 14A, 15A and 16A with a variety of acid dianhydrides (Tables 7 and 8) the changes in 5 were rather small and in particular showed no regular pattern which could be corre- lated with acid dianhydride flexibility. Changing the structure of the acid dianhydride residue has also been examined previously in terms of its effect cm melt stability, itself an additional important parameter in a techno- logically exploitable species.” In the latter work none of the polymers containing PMDA or BTDA units had an acceptable melt stability, although the series containing 1,4,5,8-naphthalene imide did.All of these polymers were prepared via a Friedel-Crafts acylation route and it could be argued therefore that the different trace residues in these materials could be the source of the problem. Thermal Stability The stability of the polyimides deduced from TG analysis in air was expected to be high, but to decrease with increasing diamine size. Polymers based upon PMDA (Table 5) show a small initial decrease in thermal stability from 670°C for the highly rigid polymer based upon 4A to 663°C for LA and down as low as 518°C for the longer diamines residue containing five to seven aromatic rings.BTDA polymers Table 13 Effect of changing the substitution pattern of central aromatic ring in diamine component from 1,4 to 1,3 on the thermal properties of BTDA polyimides substitution pattern of central aroma tic diamine structure group T,/K Tm /K T,/% ref. 0 0 194 (54 504 677 } this 0.74 work 193 (74 494 593 0.83 NH2 NH2 174 700 0.72 4 \ NH2)?J0yJ+5JJJon 506 \ 0 0 NH2 1’3 495 623 0.79 4 Table 14 Effect of T,on interchanging ketone and ether linkages in the diamine component of BTDA and PMDA polyimides diamine structure amine subs ti tu tion T,rcPMDA T,rcBTDA rcf. 0 4,4’ 242 234 24 N H 2 - ~ 0 ~ 0 ~ N H 2 3,3‘ 218 213 24 4,4‘ (1A) -this NH2,, ‘0 &+NHz 3,3‘ (3A) 266 266 work& J.MATER. CHEM., 1994, VOL. 4 Table 15 Effect upon the TJT, relationship of polyimides prepared from different anhydrides PMDA BTDA diamine T,/K Tm/K T,/Tm T,/K Tm/K T,/Tm ref. 11A 496 694 0.71 484 632 0.77 this work 7A 523 722 0.72 494 593 0.83 this NH2/o-"aoa0 0 NH2 520 715 0.73 495 623 0.79 work 4 (Table 6) showed a smaller variation, being for the most part thermally stable up to ca. 560°C for polymers based upon 1 -3A. Again the longer diamines yielded BTDA polyimides of reduced stability. Overall, however, the polymers had the high stability expected. Experimental Materials N,N-Dimethylacetamide (DMAc), high-purity HPLC grade (Aldrich Chemical Co.), 99.9 +YO,was used as supplied; it was stored over molecular sieves.Diphenyl sulfone (DPS) (ICI) was recrystallised from hexane prior to use. All other solvents were used as supplied. Diamines 1-16A were synthesized as described in Part 3 of this work2* (see Table 1). Pyromellitic dianhydride (PMDA) (Aldrich) was sublimed (220 "C/lO mmHg) prior to use. 3,3'4,4'-Benzophenonetetracarboxylic acid dianhydride (BTDA) (Aldrich), high-purity sublimed grade was used as supplied. Oxydiphthalic anhydride (ODPA), biphenyl acid dianhydride (BPDA) and diphthalic acid sulfone dianhydride (DPSDA) (supplied by ICI Advanced Materials). Phthalic acid anhydride (PA) (Aldrich Chemical Co.) was used as supplied as an endcapper.Polyimide Syntheses Two methodologies were used. The first, referred to as 'thermal imidisation', involved preparation of a solution of polyamic acid from diamine and acid dianhydride in DMAc. The solvent was then removed and the polyamic acid imidised by heating the mixture under vacuum. The second method was a one-step procedure using DPS as a solvent, with water removed at high temperature. This will be referred to as 'solution imidisation'. Thermal Imidisation Typically the polyamic acid was formed initially at room temperature by charging a previously dried (220°C for 1h) three-necked round-bottomed flask with dried (under vacuum, 150 "C, 2 h) 1A (1.123 g, 2.75 x lop3mol). To this was added 50% of the DMAc solvent, (total volume of solvent 13.5 ml, 11.38% solids) in order to dissolve the diamine.The flask was then placed under a steady stream of nitrogen before the addition of the PMDA (0.600 g, 2.75 x mol) (dried as for diamine) and the remainder of the DMAc. The reaction solution was stirred with a magnetic stirrer overnight. The polymeric acid was then processed by one of two methods. 1. Thin-film casting: The polyamic acid was spread as a thin film onto a borosilicate glass plate. The film was then placed in a vacuum oven at 80°C overnight to evaporate the solvent before being imidised under vacuum, first at 150 "C for 2 h, then 200°C for a further 2 h and finally 2 h at 300°C to complete the process. 2. Polymer precipitation: The polyamic acid was precipi- tated out by adding the DMAc solution to deionised water.The solid was then macerated using a blender to produce course grains of polymer. These were collected by filtration and washed with deionised water (three times) to remove any remaining DMAc. Imidisation of the polyamic acid was then achieved identically to that of the cast film above. Solution Imidisation Typically 3A (2.667 g, 6.52~ mol, 5 mol% excess) (vacuum dried, 15OoC, 2 h), DPS C10.35 g, 30% solids and toluene (30 ml)] were loaded into the reaction vessel under nitrogen. The mixture was then heated to 110°C in order to melt the DPS and form a slurry with the diamine. At this point BTDA (2.001 g, 6.21 x mol) was added along with a further addition of toluene (10 ml) and the reaction mixture was then refluxed, with overhead stirring, at the boiling point of toluene (110°C) for 1.5 h before PA (0.138 g, 9.33 x lop4 mol) endcapper was added to the mixture.A Dean-Stark apparatus was then fitted and the polymerisation coproduct water was azeotroped off under reflux for a further 2 h before the remaining toluene was removed by distillation. The reac- tion temperature was finally raised to 170-80°C for 1 h in order to complete imidisation. At this point it was hoped that the hot reaction mixture would be a slurry; however, in all cases a gel was formed around the stirrer, yielding a hot rubbery solid which solidified on cooling. The solid was then pulverised into a fine powder and washed with acetone (three times) in order to remove residual DPS.Polymer Analysis Elemental microanalysis results are in Tables 3 and 4.Reduced viscosities (RV) of polyamic acid solutions in DMAc (1 wt.%) were measured using Ostwald Frenske viscometers (BDH BSU size B, and Fison's Scientific BSU size A) at 25°C. Solutions were pre-filtered through a porosity grade 1 glass sinter. Tp and T, were reduced from DSC traces. Analyses were carried out under nitrogen on a Du Pont 910 calorimeter controlled by a Du Pont 9900 thermal analyser. Polymer samples were heated on a dual thermal cycle. The first cycle heated the sample from 50 to 450°C at 20°C min-'. The polymer was then quenched to 100°C and the cycle was then repeated.Glass transitions were measured from the re-heat cycle. Crystalline melt transitions, where they occurred, were seen only on initial cycles and thus these values were used. J. MATER. CHEM., 1994, VOL. 4 The thermal stability of the polymers was determined by thermal gravimetry (TG). Several samples were analysed in air on a Stanton Redcroft STA 1500 instrument. All samples were heated at a constant rate of 10°C min-l up to 700°C with thermal stability being given as the temperature at which 5% weight loss occurs. The remaining samples were analysed (at Strathclyde University) on a Stanton Redcroft STA 750/770 instrument under air. Thermal stability was quoted from these results as the temperature at which 10% weight loss occurs.Heating was carried out at a rate of 10°C min-’ to 800°C. A crude estimate of the toughness of each sample was made by simply creasing the film samples by hand, and recording the behaviour as ‘brittle’ or ‘creasable’. The authors thank ICI plc for supporting this work; A.J.L. also thanks the SERC for a CASE studentship; P.L.P. thanks the Leverhulme Trust for the award of an Emeritus Fellowship which enabled him to participate in this work; D.C.S.acknowl-edges receipt of a visiting professorship at Tokyo Institute of Technology funded by Monbusho which allowed completion of this manuscript. References M. I. Bessonov, M. M. Koton, V. V. Kudryavtsev and L. A. Laius, Polyimides-Thermally Stable Polymers, ed. W. W. Wright, Plenum Press, New York, 1987.P. A. Staniland, Comprehensive Polymer Science, ed. G. Allen, J. C. Bevington, G. C. Eastmond, A. Ledwith, S. Russo and P. Sigwalt, Pergamon Press, London, 1989, vol. 5, p. 483. S. J. Havens and P. M. Hergenrother, US Pat. 4 820 791 (to NASA), 1989. P. M. Hergenrother, N. T. Wakelyn and S. J. Havens, J. Polym. Sci. A: Polym. Chem., 1987,25, 1093. P. M. Hergenrother and S. J. Havens, J. Polym. Sci. A: Polym. Chem., 1989,27, 1161. 6 P. M. Hergenrother, M. W. Beltz and S. J. Havens, J. Polym. Sci. A: Polym. Chem., 1991,29, 1483. 7 S. J. Havens and P. M. Hergenrother, J. Polym. Sci. A. Polym. Chem., 1992,30, 1209. 8 P. J. Horner and R. H. Whiteley, J. Muter. Chem., 1991, 1 271. 9 C. J. Borrill and R. H. Whiteley, J. Muter.Chem., 1991, 1, 655. 10 C. J. Borrill and R. H. Whiteley, J. Muter. Chem., 1992, 2, 997. 11 R. G. Beaman, J. Polym. Sci., 1952,9,470. 12 P. J. Brown, I. Karacan, J. Liu, J. E. McIntyre, A. H. Milburn and J. G. Tomka, Polym. Int., 1991,24,23. 13 V. M. Svetlichnyi, V. V. Krudyavtsev, N. A. Adrcva and M. M. Koton, J. Org. Chem. USSR, 1974,10,1907. 14 M. M. Koton, V. V. Krudyavtsev, N. A. Adrova, K. K. Kalnin’sh, A. M. Dubrova and V. M. Svetlichnyi, Vys. Soedin. Ser. A, 1974, 16, 2081; Polym. Sci. USSR, 1974,16,2411. 15 P. R. Young, J. R. J. Davies, A. C. Chang and J. N. Richardson, J. Polym. Sci. A: Polym. Chem., 1990,28,3107. 16 J. P. LaFemina, G. Arjavalingam and G. Haugham, I. Chem. Phps., 1989,90, 5 154. 17 S. A. Kafafi, J. P. Lafemina and J. L. Nauss, J. Am. Chzm. Soc., 1990,112,8742. 18 C. A. O’Mahoney, D. J. Williams, H. M. Colquhoun, K. Mayo, S. M. Young, A. Askari, J. Kendrick and E. Robson, Macromolecules, 1991,24,6527. 19 J. Kendrick and M. Fox, J. Mol. Graphics, 1991,9, 182. 20 V. L. Bell, W. L. Stump and H. Gager, J. Polym. Sci.: Poljm. Chem. Ed., 1976, 14, 2275. 21 V. L. Bell, L. Kilzer, E. M. Hett and G. M. Stokes, J. Apl’l. Polym. Sci.,1981,26, 3805. 22 C.E. Scroog, Macromolecular Synthesis, ed. N. G. Gaylo1 d, Wiley, New York, 1968,vol. 3, p. 83. 23 T. E. Attwood, P. C. Dawson, J. L. Freeman, L. R. J. Hoy, J. B. Rose and P. A. Staniland, Polymer, 1981,22, 1096. 24 V. L. Rao and J. Bijimol, Makromol. Chem., 1991, 192, l(125. 25 J. R. Pratt, D. A. Blackwell, T. L. St. Clair and N. L. Allphin, Polym. Prepr., 1988,29, 128. 26 C. R. Gantreauz, J. R. Pratt and T. L. St. Clair, J. Polyin. Sci. B: Polym. Phys., 1992,30, 71. 27 M. Fryd, Polyimides: Synthesis, Characterisation and Apillications, ed. K. L. Mittal, Plenum Press, New York, 1984,vol. I, p. 377. 28 Part 3: J. Muter. Chem., 1994, 4, 1527. Paper 4/02562H; Received 29th April, 1994.

ISSN:0959-9428    

DOI:10.1039/JM9940401511

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

J. MATER. CHEM., 1994, 4( lo), 1521-1525 Novel Aromatic Poly(ether ketone)s Part 2. -Synthesis and Thermal Properties of Poly(ether keto amide)s Anthony J. Lawson,"* Peter L. Pauson,a David C. Sherrington"* and Stella M. Youngbs a Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, UK G11XL ICI Wilton Materials Research Centre, Middlesbrough, Cleveland, UK TS6 8JE Three groups of poly(ether keto amide)s have been prepared from terephthalic (TERE), isophthalic (ISO) and sebacic (SB) acids condensed with six diamines containing four and five benzene rings linked together by ether and ketone groups. The polymers proved to be soluble in dipolar aprotic solvents and could, in principle, be processed more easily than current commercially available aromatic polyamides.The thermal properties (Tg,T,,, and decomlposition temperature) of each have been evaluated, and the effect of the size of the diamine component and the use of meta versus para linkages examined. Rigorous evaluation of the data was hindered by a significant dependence of the thermal properties on the molecular weight (as measured by inherent viscosity, IV) of the polymers. However, the Tg of polymers was found to lie between that of simple polyarylamides and simple poly(ary1 ether ketone)s, and to fall as the aryl ether and ketone content of the polymer increased. The polymers prepared with SB had lower Tgvalues, as expected from their aliphatic content, and likewise was significantly lower for the polymers from SB.Aromatic polyamides or Aramids are a class of polymer that is found in a number of applications but principally as high tensile strength fibres. There are two major commercially available polymers which dominate this field, Nomex and Kevlar.7 The former is the polycondensation product of isophthalic acid and rn-phenylenediamine, the latter is from terephthalic acid and p-phenylenediamine. Aramid fibres exhibit medium to low elongation at the break. They are also highly crystalline or ~rystallisable'-~ when spun as fibres from solution. One major disadvantage of these materials is their inability to be melt-processed since they decompose before and during melting. Indeed this shortcoming has probably limited their wider commercial exploitation.The problem can be partially overcome by using polyamides synthesized from a mixture of aromatic and aliphatic diacids (e.g. sebacic acid), but this reduces the products' thermal ~tability.~ Few attempts appear to have been made to mimic the approach used in making polyimides melt-processable by introducing aromatic ether and ketone functionalities in the polymer. A recent one,' however, utilises Friedel-Crafts acyl- ation reactions to form the polymers and generates structures in which the functionality adjacent to the amide is an ether. When poly(ether keto imide)s have been made, this allows the retention of high Tg values, and high thermal stability, while reducing T, to a level that makes melt-processing p~ssible.~-~The present paper describes our efforts to produce processable aromatic polyamides using diamine comonomers with four and five benzene rings linked by ether and ketone functions (Table 1).In addition, a related series of polymers with partial aliphatic character has also been prepared and characterised. Results and Discussion Polyamide Syntheses Syntheses were carried out using the method developed by Yamazaki et aL7 which proved far superior to the $ Present address: Vinamul Ltd., Mill Lane, Carshalton, Surrey SM5. t Part 1: J. Muter. Chem., 1994, 4, 0000. 5 Present address: ICI plc., Fluon R & T, York House, Hillhouse International, Thornton, Cleveleys, Lancashire FY 5 4QD. f Nomex and Kevlar are Trademarks of E.I.Du Pont de Nemours & Co. Inc. low-temperature interfacial polycondensation method8-12 employing acid chlorides. The use of TPP as an activating agent in NMP avoids the purity problems associated with acid chlorides, and the solubility limitations of many diamines. Tables 2 and 3 show the poly(ether keto amide)s prepared from the aromatic and aliphatic diacids, respectively Molecular weights, as assessed by IV values, varied con- siderably. The partially aliphatic polyamides from SB show values between 0.22 and 0.38 dl g-', and the wholly a-omatic polyamides, values between 0.22 and 0.72 dl g- '. N olecular weights seem to be adversely affected by the low reactivity of some of the diamines. The presence of the carbonyl substituent on the terminal rings of diamines, whether in the rnetri or para position, seems to reduce the nucleophilicity of the amino group in this reaction.This contrasts with the situation found in reactions with acid dianhydrides to form polyarnic acids (see Part 1 of this work),6 where amino groups rneltato the carbonyl substituent are much more reactive than the para isomers. The situation is, however, complicated by other factors. First, in order to achieve satisfactory rates of poly- condensation, relatively high concentrations of reactants were required in these polyamide syntheses. Secondly, somewhat higher temperatures were found necessary relative to the literature recommendations. Krigbaum et a1.I3 have indicated that these two factors encourage polymer phase separation, which itself tends to limit the polymer molecular weight achieved.This situation was certainly apparent in this work with many solutions tending to gel even at rather low IV values. Polymerisations employing IS0 were the least prob- lematical and as seen in Table2 these generally achieved higher IV values than those using TERE. Overall the reactions involving the aliphatic diacid SB were most adversely influenced, presumably because of the poor compati- bility of the long aliphatic chain in SB with the polar solvent NMP. A significant difference was also observed with work-up of the products. Whereas the polyamides from IS0 arid TERE precipitated to form hard particulate solids in methanol, the polymers from SB were soft and sticky presumably as a result of the plasticisation of the aliphatic carbon structure by methanol. Precipitation into water in this case, however, overcame the problem and yielded products in a miinageable physical form.1522 J. MATER. CHEM., 1994, VOL. 4 Table 1 Diamines used in polyamide syntheses Table 2 Microanalytical data of aromatic pol yamides code microanalysis no. structure found(%) calcd.(%) polymer code C H N C H N 1A TEREjlA 73.2 3.9 5.0 75.8 4.1 5.2 TERE/2A 72.4 4.1 5.3 75.8 4.1 5.2 TERE/3A 70.7 4.6 6.4 75.8 4.1 5.2 0 0 TERE/5A 72.5 4.0 3.7 76.2 4.1 4.4 TERE/6A 74.1 4.4 4.2 76.2 4.1 4.4 2A TERE/7A 72.9 3.9 3.9 76.2 4.1 4.4NH2/db-0mNH2 ISO/lA 72.4 3.4 4.8 75.8 4.1 5.2 IS0/2A 71.3 3.9 4.2 75.8 4.1 5.2 IS0/3A 73.9 4.0 5.0 75.8 4.1 5.2 1S0/5A 71.6 4.3 4.2 76.2 4.1 4.4 3A IS0/6A 69.0 4.2 4.3 76.2 4.1 4.4 IS0/7A 69.7 5.0 6.3 76.2 4.1 4.4 Table 3 Microanalytical data of partially aliphatic polyamides 5A microanalysis found (YO) ca1cd.lYO) polymer code C H N C HN 6A SB/lA 74.5 5.9 4.3 75.3 5.9 4.9 SB/2A 72.6 5.9 4.1 75.3 5.9 4.9 SB/3A 73.8 5.9 4.6 75.3 5.9 4.9 0 SB/5A 73.3 6.1 4.4 75.7 5.7 4.20 SB/6A 74.4 5.5 3.7 75.7 5.7 4.2 SB/7A 72.9 5.3 3.8 75.7 5.7 4.2 7A To check this further IS0/7A was combusted with the addition of WO, and the C, H and N contents found are summarised in Table4.Clearly the results are much improved, but the 1B discrepancy relative to the theoretical values is still significant and the reason for this remains unclear.Molecular Weight Dependence of Thermal Properties The thermal properties of all the polyamides synthesized are 2B shown in Tables 5 and 6. In order to make an accurateNH2& NH2 comparison of Tg and T, data it was necessary to quantify the effects of molecular weight, as measured by IV, upon the Tg and T, of the polymers. This was evaluated for the aromatic polyamide TSO/lA. The polymerisation was carried out as for 3B IS0/2A in the Experimental section. Aliquots of solution were removed from the polymerisation reaction at regular intervals and precipitated into methanol, then washed with further 0 amounts of methanol before being dried at 150°C under vacuum for 2 h. Each sample was then analysed by DSC and for its IV as before.The results are shown in Table 7.4B The control sample was prepared identically (240 min) but it was processed into a thin film prior to analysis. It is clear from these results that, unlike polyimides, there is an upward Microanalyses of Polyamides trend in Tp values as IV increases. (The sample taken at 210 min was anomalous for reasons unknown.) Thus compari- Elemental microanalytical data for all the polymers prepared sons between Tgs of polyamides must be made with due regard are shown in Tables 2 and 3. The consistently low values for the carbon content versus the expected theoretical values Table 4 Microanalytical data for IS0/7Acaused some concern. Inefficient combustion of polyaromatic polymers is sometimes a problem, and in this instance it was normal combustion combustion with calcd.thought that contamination with LiCl might worsen the element (%I added W03 (%) (Yo) ~ ~~situation. Indeed, typical chlorine contents of initially isolated polymers were ca. 1.5%. Reprecipitation from DMF and C 69.7 72.7 76.2 5.0 4.7 4.1washing with methanol and acetone reduced this typically to H 6.5 5.0 4.4 ca. 0.3%, yet despite this the carbon data were little changed. N J. MATER. CHEM., 1994, VOL. 4 Table 5 Thermal properties of aromatic polyamides temp. of polymer code IV/dl g-' y/"C T,"/"C 10% wt. loss/"C* ~~~ TERE/lA 0.52 187 -475 TERE/2A 0.54 -333 395 TERE/3A 0.34 189 -565 TERE/SA 0.22 224 -577 TERE/6A 0.39 210 -525 TERE/7A 0.26 190 388 572 ISO/l A 0.64 23 1 357 500 IS0/2A 0.57 204 -395 IS0/3A 0.38 191 -500 ISO/5A 0.28 198 -533 IS0/6A 0.30 202 -540 IS0/7A 0.72 214 -475 "From DSC traces.'From TG curves. Table 6 Thermal properties of partially aliphatic polyamides temp. of polymer 10% wt. loss/ code IV/dl g-' T/"C T,"/"C OCb ref. ~~ ~~ ~~~~ SB/lA 0.32 -3 34 SB/2A 0.20 148 -SB/3A 0.30 141 -SBI5A 0.27 130 334 SB/6A 0.30 144 -SB/7A 0.38 143 220 SB/lB 1.19 160 310 SB/2B 0.47 125 165 a From DSC traces. *From TG curves. to the IV value. As a further complication it is also known that the molecular weight of polyamides can change upon heating,14 and hence Tg also may shift. The data in Table 7 show that in contrast to Tp the T, values show only small fluctuations with the IV of the polymer presumably reflecting only the experimental variation in the technique.Clearly, therefore, the crystalline domains of these poly(ether keto amide)s are affected far less by molecular weight changes, than are the amorphous domains. The variation of IV noted in these experiments is also worthy of discussion. Diamine 1A was chosen for this study because it displayed rather low reactivity with acid dianhy- drides in the polyimide study (see Part 1 of this work),6 and it was believed that this would offer an optimal opportunity for varying the IV. However, the reactivity in these polycond- ensations proved to be such that an IV of 0.35dl g-' was achieved after 15 min and this increased slowly to a maximum Table 7 T,/IV study of polyamide ISO/lA reaction time/min IV/dl g-l T/"C T,"/"C 15 0.35 30 0.47 190 362 45 0.47 197 -60 0.40' 207 90 0.49 -357 120 0.54 214 348 150 0.46 -340 180 0.44 -338 210 0.44 179 34 1 240 0.45 -341 comparison 0.64 231 357 'From DSC trace.Sample solution left overnight prior to measure- ment of IV and thus probably slightly degraded. of 0.54 dl g-' after 120 min. The decrease with time thereafter has been reported before when this polymerisation procedure is used,14 and is believed to arise when undesirable side-reactions become significant. One of these appears to be the reaction of the acyloxy N-phosphonium salt intermediate with phenol derived from TPP to yield the corresponding phenyl ester.7 Correlationof Physical Properties of Aromatic Poly (ether keto amide)s The polyamides synthesized exhibit useful thermal pruperties particularly with respect to having consistently higher Gs than exhibited by simple poly(ary1 ether ketone) an,ilogues, whilst at the same time retaining Tm<400"C. The thermal properties are listed in Table 5.The polymers also exhibit useful physical properties, the most important of whic-h is the ability to dissolve in polar aprotic solvents such as DMAc and NMP. This allows for the formation of polymer films. Typical aromatic polyamides such as Kevlar and Nomex require processing in solvents such as concentrated sulfuric acid or HMPA with LiCl. This presents handling problems, particularly in the case of sulfuric acid which can degrade the polymer,15 forming insoluble crystals of terephthalic xid.Film formation was demonstrated for ISO/lA from a DMAc solution at room temperature cast onto a borosilicate glass sheet and then freed from solvent under vacuum at 135"C overnight. This produced a tough film of 7g 231 "C and T, 357°C. Other polymers such as IS0/7A although forming tough films, appeared to be totally amorphous and certainly showed no melt endotherm. Only a few of the aromatic polyamides (TERE/2A, TERE/7A and ISO/lA) showed crystalline end otherms whether tested as precipitates or films. As in the case of the corresponding polyimides (see Part 1)6none of the polymers based upon diamines containing more than one rnetln linkage exhibited a crystalline melt endotherm.The small numbers of polymers showing melt endotherms precluded any studies of T,/Tmrelationships. T,-structure relationships have been studied foI related aromatic polymer^.'^^^^ Rao and Prabhakaran16 synthesized polyamides from isomers of 4,4'-bis(aminophenox y) benzo-phenone with isophthalic and terephathalic acid using the Higashi meth~d.~ synthesized two polymers Abraham et ~1.'~ based upon novel diacids containing four benzene rings with 3,3'-bis(1,3-phenylenedioxy)dianilineas shown in Scheme 1. Comparison of Tg data from this work along with that of .~Imai et ~1 and the present work are shown in Table 8. In spite of different molecular weights several important struc- ture-property relationships can be seen from this table.First, Tp values lie between those of simple polyarylamides (ca. 300°C) and simple poly(ary1 ether ketone)s (ca. 150°C). As the number of aromatic connecting groups in the dramine is extended from two to five there is a decrease in the Tg of the polyamide. Furthermore, the Tg drops just beloM that of typical poly(ary1 ether ketone)s indicating that the free volume is larger in polyamides. This is in spite of the highly polar nature of the amide linkage which should provide good intermolecular interaction and the prospect of a high degree of crystallinity as found in most simple polyamide fibres. Secondly, as with polyimides (see Part 1)6rigidity factors play an important role.Comparing diamines of similar size, i.e. lA, 2A and 3A from this work and 3B and 4BI6 {Table 8), polyamides prepared from 1A-3A show a significant elevation in Tg over those derived from 3B and 4B. It is clear that a distinction can be made between flexibility derived from two carbonyl and one ether connecting groups in the diamine and that of two ether and one carbonyl connecting groups. This J. MATER. CHEM., 1994, VOL. 4 6B z=s02 5B 7B Z=CO low temperature polymerisation n Scheme 1 Synthesis of low Tg ether-containing polyamides” Table 8 T, data for structurally related polyetheramides polymer structure IV/dl g-’ T,/”C ref. ~~~ ~ TERE/lB 2.39 - 4 TERE/2B TERE/ 1 A TERE/2A TERE/3A 0.78 0.52 0.54 0.34 280 187 189 - } 4 this work TERE/3B TERE/4B TERE/5A TERE/6A TERE/7A 6B/5Ba 7B/5Ba 0.37 0.68 0.22 0.39 0.26 0.55 0.63 126 160 224 210 190 128 144 16 16 this1 work aSee Scheme 1.is confirmed from simple molecular modelling. Although sterically the connecting groups force similar planar geo- metries on the attached aromatic rings the extra bulk of the carbonyl group must raise the rotational energy required for free rotation of the aromatic rings. Physical Properties of Poly (ether keto amide)s from Sebacic Acid This type of polymer has been studied in great detail by Imai et who synthesized a whole series of polyamides, based upon the isomers of oxydianiline (1B and 2B), condensed with the complete homologous diacid series from succinic acid to 1,lO-decanedicarboxylic acid.The Tg and T, values for polymers based upon 2B were generally higher than for polymers based upon lB, with a downward trend in both and T, with increasing aliphatic nature of the backbone. All polymers showed a q/T, ratio higher than that predicted by the Beaman relationship. In this work it was hoped that the larger aromatic compo- nent in the diamine would raise the Tg and hence T,. The results are shown in Table6 along with the results of Imai et aL4 for 1B and 2B with sebacic acid as comparison. It is clear that in spite of the larger aromatic component of the polymer backbone the qs for the polymers from the present work are lower than those of polymers derived from 1B. It is, however, difficult to draw firm conclusions from these data because the IV for the polyamide from 1B was particularly high, and the effect of molecular weight may be dominant here.If the comparison is made with the polyamide from 2B whose IV though still a little higher than the polymers prepared in this work, is much closer, then indeed there is a significant and consistent increase in for the polyamides prepared from 1-7A. Correlation of T, is even more difficult; polymer structure IV/dl g-’ T,/”c ref. ~~ ISO/lB 1.98 270 16 lS0/2B ISO/lA IS0/2A IS0/3A 0.72 0.64 0.57 0.38 240 231 191 204 } 16 this work IS0/3B lS0/4B ISO/5A IS0/6A IS0/7a 0.32 0.48 0.28 0.30 0.72 118 145 198 202 214 16 161 work this indeed the difference seen by Imai et aL4 for polyamides from 1B and 2B is nearly 150°C.In general, however, the poly- amides from SB which did display a clear melt endotherm yielded T, values above 300°C. This is a reasonably high figure, bearing in mind the aliphatic content of the backbones and clearly the materials would be readily melt-processable. Thermal Stability The temperatures corresponding to 10% weight loss in air in the TG instrument are shown in Tables 5 and 6. As expected the polyamides based on IS0 and TERE show significantly higher thermal stability than those derived from SB, and somewhat lower than the poly(ether keto imide)s prepared from the same diamines.6 Overall the materials prepared from diamine 2A showed the poorest performance.The polymer from SB was particularly poor, but probably reflects the rather low molecular weight of this sample (IV ~0.20dl g-’) rather than any intrinsic instability arising from its specific structure. In general the all-aromatic species from IS0 and TERE compare favourably with other aromatic polyamides bearing in mind the aryl ether and ketone content. Experimental Pyridine was distilled from and stored over KOH. N-Methylpyrrolid@-2-one, NMP, was distilled from P,O, and stored over 4A molecular sieves. N,N-Dimethylacetamide (DMAc), high-purity, HPLC grade (Aldrich ChFmical Co.) (99.9+%) was used as supplied and stored over 4A molecular sieves. Lithium chloride was dried at 100°C under vacuum before use. Isophthalic (ISO), terephthalic (TERE) and sebacic acids (SB), and triphenyl phosphite (TPP) (Aldrich) were used as supplied.J. MATER. CHEM., 1994, VOL. 4 Diamines 1-7A (Table 1) were synthesized as described in Part 3 of this work.18 Polyamide Synthesis This is exemplified by the reaction of isophthalic acid (ISO) with diamine 2A, to yield a poly(ether keto amide) desig- nated IS0/2A. 2A (1.224 g, 3 mmol), IS0 (0.498 g, 3 mmol), lithium chlor- ide (0.465 g, 4% w/w) and TPP (1.57 ml, 6 mmol) were added to NMP (6 ml) and pyridine ( 1.5 ml). The solution was heated (1 15-120 "C) with stirring under nitrogen for 3 h. The solution was then precipitated into ethanol (200ml) and the polymer was filtered off and washed twice with ethanol (200 ml). The polymer was reprecipitated twice from DMAc and finally extracted with acetone in a Soxhlet apparatus. The polymer was then filtered and dried under vacuum at 150°C.In the case of polyamides prepared with sebacic acid as one component the work-up was modified slightly. At the end of the reaction the polymer was precipitated by pouring the reaction solution into deionised water (200 ml). The polymer was filtered off and washed with water (2 x 200 ml) prior to drying under vacuum at 150 "C. Polymer Analysis Inherent viscosities (IV) of the polyamides were determined in sulfuric acid (96%) at a concentration of 0.5 g dl-I using Ostwald Frenske viscometers (BDH BSU Size B and Fison's Scientific BSU size A) at 15 "C. Solutions were pre-filtered through a porosity grade 1 glass sinter.Glass-transition temperatures, q,and melting points, T,, were deduced from differential scanning calorimetry (DSC) traces. Analyses were performed on a Mettler DSC20 calorimeter controlled by a Mettler TC 1OA processor or on a Du Pont 910 calorimeter controlled by a Du Pont 9900 thermal analyser. All analyses were performed under N,. Preliminary DSC measurements displayed broad endo- therms between 100 and 200°C and these are known to be associated with post-condensation reactions, possibly ketimine crosslinking. These can mask the Tg transition and so the method of Rao and Prabhakaran16 was adopted to overcome this. Aromatic polyamide samples were pre-heated to 200 "C and 20°C min-' and then allowed to cool to 50°C.Each sample was then heated to 450°C to detect any crystalline melting point. A parallel sample was then quenched and reheated to 450°C to expose the Tg transition. The partially aliphatic polyamides were found not to require the preheating to 200°C. The thermal stability of the polymers was determined by thermal gravimetric analysis (TG) using a Stanton Kedcroft STA 750/770 instrument under air. Heating was carried out at a rate of 10°C min-' to 800°C. Thermal stability was quoted from these results as the temperature at which 10% weight loss occurs. The authors thank ICI plc for supporting this work; A.J.L. also thanks the SERC for a CASE studentship. P.L.P. thanks the Leverhulme Trust for the award of an Emeritus Fellowship which enabled him to participate in this work; D.C.S.acknowl- edges receipt of a visiting professorship at Tokyo Institute of Technology funded by Monbusho, which allowed completion of this manuscript. References 1 S. W. Kwolek, US Put. 3 671 542 (to E.I. Du Pont de Yemours and Co. Inc.), 1972. 2 H. Blades, US Put. 3 767 756 (to E.I. Du Pont de Nemours and Co. Inc.), 1973. 3 W. Sweeney, US Put. 3 287 324 (to E.I. Du Pont de Nemours and Co. Inc.), 1966. 4 Y. Imai, M. Kajiyama, S. I. Ogata and M. A. Kakimoto, J. Polym. Sci.: Polym. Chem. Ed., 1985,23, 1907. 5 P. J. Horner and R. H. Whiteley, J. Muter. Chem., 1991, 1,271. 6 See Part 1 of this series and references therein: J. Muttr. Chem., 1994,4,0000. 7 N. Yamazaki, M. Matsumoto and F. Higashi, J. Po/yrn. Sci.: Polym. Chem. Ed., 1975,13, 1373. 8 R. G. Beaman, P. W. Morgan, C. R. Koller, E. L. Wittbtbcker and E. E. Megat, J. Polym. Sci., 1959,40, 329. 9 M. Katz, J. Polym. Sci., 1959,40, 337. 10 V. E. Shashona and W. M. Eareckson 111, J. Polym. Sci., 1959, 40, 343. 11 C. W. Stevens, J. Polym. Sci., 1959,40, 359. 12 P. W. Morgan, Condensation Polymers: By Interfacial and Solution Methods, Interscience, New York, 1965. 13 W. R. Krigbaum, R. Kolek and Y. Mihara, J. Polym. S( i.: Polym. Chem. Ed., 1985,23, 1907. 14 C. P. Yang, S. H. Hsiao and C-J. Huang, J. Polym. Sci.: Polym. Chem. Ed., 1992,30,597. 15 R. J. Morgan and N. L. Butler, Polym. Bull., 1992,27,689. 16 V. L. Rao and P. V. Prabhakaran, Eur. Polym. J., 1992,28,363. 17 T. Abraham, E. J. Soloski and R. C. Evers, J. Polym. SIi. Polym. Chem. Ed., 1988,26,959. 18 Part 3: J. Muter. Chem., 1994, 4, 1527. Paper 4/02560A; Received 29th April, 1994

ISSN:0959-9428    

DOI:10.1039/JM9940401521

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

J. MATER. CHEM., 1994, 4( lo), 1527-1532 Novel Aromatic Poly(ether ketone)s Part 3.t-Synthesis of Diamine Precursors with 4-8 Benzene Rings Linked by Ether, Ketone and Sulfone Groups Anthony J. Lawson,as Peter L. Pauson: David C. Sherrington,”* Stella M. Youngbs and (in part) Niall O’Brienbn a Department of Pure and Applied Chemistry, University of Strathclyde, 295, Cathedral Street, Glasgo w, UK G1 1XL ICI Wilton Materials Research Centre, Middlesbrough, Cleveland, UK TS6 8JE Fourteen new diamines have been synthesized for use in the work described in parts 1 and 2. A combination of Friedel-Crafts acylation of arenes with nitro- and fluoro-benzoyl chlorides and benzene dicarbonyl chlorides, Ullmann synthesis of aryl ethers from phenols and fluoroarenes and reduction of nitro to amino groups by transfer hydrogenation has been employed.In the synthesis of poly(ether keto imide)s aimed at producing materials with the optimum combination of the properties of polyimides and poly(ether ketone)s attention has focussed mainly on precursor diamines with up to five benzene rings connected by ether and ketone functions. In the main the first linkage to the terminal aromatic amine has been an ether one.’ Recently Eastmond et aL2 have also been exploring the effect of introducing aromatic ether and ketone linkages in the acid dianhydride component. In the present paper we describe the synthesis of 14 new diamines with 4-8 benzene rings linked by ether, ketone and sulfone groups where the first linkage to the terminal aromatic amine is generally ketonic.These molecules were required to obtain the polyamides and polyimides which are the subject of the two preceding paper^.^ Discussion Most of these diamines were obtained by reduction of the corresponding dinitro compounds which, in turn, were the products of Friedel-Crafts reactions between diphenyl ether and its derivatives or biphenyl with 3-or 4-nitrobenzoyl chloride. Use of 2-2.2mol of the latter led directly to sym- metrical dinitro compounds, whereas equimolar quantities of substituted benzoyl chlorides and aryl ethers led cleanly to the monoacylated products, allowing a different aroyl chloride to be used in the second acylation step to obtain unsymmetri- cal dinitro compounds. The aromatic ethers containing four to six rings, required for the 6-8 ring diamines, were them- selves generated by two routes: either Friedel-Crafts acylation of simpler aryl ethers by terephthaloyl or isophthaloyl chlor- ides or Ullmann ether synthesis from phenols and fluoroarenes activated by carbonyl or sulfonyl groups.The specific compounds synthesized are shown in Tables 1-4 and one example of each procedure is given in full in the Experimental section. To facilitate relatively large-scale preparation and avoid the more toxic or highly flammable materials, dichloroethane was the preferred solvent for acyl- ation, rather than carbon disulfide which had commonly been employed in the earlier literature. Transfer hydrogenation employing cyclohexene as hydrogen source proved consist- t Part 2: J.Mater. Chem., 1994, 4, 1521. J, Present address: Vinamul Ltd., Mill Lane, Carshalton, Surrey SM5. $Present address: I.C.I. plc, Fluon R & T, York House, Hillhouse International, Thornton, Cleveleys, Lancashire FY5 4QD. 5[ Present address: Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL. ently convenient for nitro-group reduction; yields generally in the 50-70% region for this step were regarded as satisfactory in view of the low solubilities of both the nitro prccursors and the final amino compounds and the resultant handling problems. The only amines not prepared via the corresponding nitro-compounds were the five-ring diamine (7A), the six-ring diamine (8A) and the eight-ring diamine ( 16A), all synthesized, albeit in varying yields, by routes employing the IJllmann ether synthesis in the final step (see Table 4).Table 3 gives preparative details for and properties of the nitro compounds. The yields attained in refluxing 1,2-dichloroethane are seen to be appreciably better than by the much slower reaction at room temperature in dichloro-methane. Such conditions failed to yield the required ciisubsti- tution product (compound 4N) when applied to biphcnyl and 4-nitrobenzoyl chloride; assuming that the initial monosubsti- tuted product was deactivated by forming too strong a complex with aluminium chloride, we replaced the latter by iron(II1) chloride and obtained the required product in modest yield.Experimental The synthetic results are summarised in Tables 2-4; the following details are representative of the principal methods employed and significant variations are noted in the ‘tables. Literature methods were followed for the preparation of 1,4-diphenoxybenzene (hydroquinone diphenyl ether)4 and for compound 19(b).5 ‘H NMR spectroscopic data follow the preparative methods. Friedel-Crafts Acylations Compound 5N 1,4-Diphenoxybenzene (5.24 g, 0.02 mol) and 4-nitro benzoyl chloride (7.42 g, 0.04 mol) were dissolved in 1,2-dichloroethane ( 100 ml) and aluminium chloride (5.32 g, 0.04 mol) wa.; added. The mixture was refluxed for 2 h, then cooled and poured onto ice acidified with hydrochloric acid.The organic layer was separated, washed with 2 moll-’ sodium hydroxide and water, dried (MgS04) and evaporated. The residue wa.i recrys- tallised from dimethyl formamide-water to give the cream- coloured crystalline dinitro compound (5N) (10 g) (see Table 3). In some acylations product precipitated before separation of the layers; such precipitates were collected by filtration, well washed with water, dried and later combined with any product recovered from the organic layer. Analysis showed J. MATER. CHEM., 1994, VOL. 4 no. structure 1A: X=H 1N: X=O 2A: X=H 2N: X=O 3A: X=H 3N: X=O 4A: X=H 4N: X=O 5A: X=H 5N: X=O NX2 6A: X=H 6N: X=O 7A %A 9A: X=H 9N: X=O Table 1 List of diamines and precursors synthesized 0 0 0mNX2 0 0 NX2 0aoqp" 0 0 0 0 Nx2& \ 0&0hNX2 10A: X=H 10N: X=O 11A: X=H 11N: X=O 0 0 12A: X=H 12N: X=O J. MATER.CHEM., 1994, VOL. 4 1529 Table 1 (continued) no. structure 13A: X=H 13N: X=O 14A: X=H 14N: X=O 15A: X=H 15N: X=O 16A: X=H 16N: X=O 17(a)R= 3 -NO, 17(b)R=4 -NO, 17(~)R=3-F 17(d)R=4 -F 18A: X=H 18N: X=O 19(~):3,3’-F 19(b): 4,4’-F 20 21 Nx2* \ 0J0hNX2 NX2-o-”qp”qp”qp”~\ \ \ NXz 0 0 0 0 RhoD F&NX2 0 0 F-~o&-F F 0 0 F 0 0 that the less soluble products obtained in this way were pure enought for further work without recrystallisation. Some sparingly soluble nitro compounds, unsuitable for conven- tional recrystallisation, were placed in a Soxhlet apparatus and crystallised by prolonged extraction (1-3 days). For monoacylations of substrates liable to undergo disubsti- tution it was considered preferable to form the Perrier complex from a solution of the aroyl chloride and aluminium chloride and to filter this solution before adding the reactive arene (1:1:1 molar ratio).All aryl ketones synthesized had IR carbonyl peaks near 1650 cm-l; nitro groups gave rise to bands at 1510-1530 and at 1350 cm-l. Nitro Reduction by Pd-catalysed Transfer Hydrogenation Compound 1A Palladium on charcoal (1.06 g, 10%) was added to the dinitro compound (1N) (25 g, 0.053 mol) in DMF (250 ml) and cyclohexene (75 ml). This mixture was refluxed, employing a Dean and Stark trap, until no more water was seen tci collect in this trap and TLC indicated the complete disappearance of compound (1N) (typically 3 h).After removing the catalyst from the cooled mixture by filtration, a mixture of cyclo hexadi- ene and cyclohexene was distilled off and the residual DMF solution was diluted with water to precipitate a pale yellow solid. Recrystallisation from toluene gave the diamine (1A) (12.6 g) (see Table 2). Several of the higher-molecular-weight diamines N ere too insoluble to undergo satisfactory recrystallisation, but the products precipitating from the reaction mixture were found to be analytically pure or nearly so. Ullmann Ether Synthesis Diamine 7A To 4-amino-4-fluorobenzophenone ( 18A) (21.5 g, (1.1 mol) in N-methylpyrrolidin-2-one (200 ml), resorcinol (5.28 g, J.MATER. CHEM., 1994, VOL. 4 Table 2 Synthesis and analyses of amines (for structures see Table 1) found (%) calcd. (YO) molecular mlz amine precursor mp/"C yield (YO) formula C H N C H N found (theor.) 1A 1N 174-76" 76.5 4.7 7.0 76.5 4.9 6.9 -2A 2N 186-87 76.5 4.8 6.9 76.5 4.9 6.9 -3A 3N 144-46b 60 76.8 4.7 6.7 76.5 4.9 6.9 -4A 4N 227-29 79.0 5.3 7.3 79.6 5.1 7.1 -5A 5N 233-34 76.6 4.7 5.3 76.8 4.7 5.6 -6A 6N 178-80 76.7 4.8 5.6 76.8 4.7 5.6 -7A' 18A 172-74 25 77.2 4.8 5.6 76.8 4.7 5.6 -SAC 1 9b,d 168-70 12 77.0 4.4 4.7 77.0 4.7 4.7 -9A 9N 221 75 ------6O4( 604) 1 OA 1 ON 159.5-63.5 71.7 4.5 4.1 71.3 4.4 4.4 640(640) 11A 11N 201-03 77.3 4.1 3.6 77.95 4.55 4.0 -12A 12N 246-50 78.0 4.6 4.1 77.95 4.55 4.0 -13A 13N 200-01 52 77.9 4.5 3.9 77.95 4.55 4.0 -14A 14N (dec.) 50 80.4 3.4 5.0 80.9 3.7 4.8 756( 756) 15A 15N 231-34 77.3 4.7 3.3 77.6 4.6 3.6 788( 788) 16A' 20 dec 280 76.7 4.7 3.0 77.6 4.6 3.6 ~ 18A 18N 124-26d 37 72.2 4.2 6.5 72.5 4.6 6.5 -" Lit.? mp 177-78 "C.Lit.:6 mp 150-51 "C. 'see Table 4. dLit.:7 mp 129-30 "C. 0.048 mol) and potassium carbonate (13.82 g, 0.1 mol) were added and the mixture was refluxed until TLC showed complete consumption of the resorcinol. The cooled mixture was poured into ice-water (200 ml), causing a green oil to deposit. The aqueous layer was decanted off and the residual oil was heated with 2 mol 1-l hydrochloric acid (200 ml), producing an insoluble hydrochloride.This was collected by filtration and washed with water (500 ml). Addition to 2 mol 1-1 sodium hydroxide (500ml) regenerated the amine as a green solid which was collected, dried, and crystallised from toluene-ethanol to give the product (6.0 g, 25%) (see Table 4). Dimethylformamide and dimethylacetamide were substi-tuted as solvents for the syntheses of amines 8A and 16A, respectively. Amine 7A was the only one for which the above purification uia the hydrochloride was necessary. The others prepared by this route (Table 4) separated as solids when the reaction mixtures were poured on ice; they were therefore collected by filtration, washed and recrystallised directly. Typical reaction times were 2-3 h.'H NMR Data [in(CD,),SO unless otherwise specified] Compound (2N): 7.40 (4 H, dd, J 7.8, 2), 7.97 (1H, t, J 7.8), 8.00 (2 H, dd, J 7.8, 2), 8.08 (2 H, dd, J 7.8, 2), 8.27 (1 H, d, J7.8),8.47(2H,d,J7.8),8.57(1H,d,J7.8),8.57(1H,s). Compound (4N): 8.03 (4 H, d, J 9), 8.09 (4 H, d, J9), 8.12 (4 H, d, J 9), 8.49 (4 H, d, J 9). Compound (11N): 7.27 (4 H, d, J 9), 7.28 (4 H, d, J 7.5 7.78 (1H, t, J 7.7), 7.85 (4 H, d, J 8.8), 7.90 (4 H, d, J 8.8), 7.94 (4 H, d, J 8.8), 7.99 (1 H, s), 8.04 (2 H, d, J 7.7), 8.36 (4 H, d, J 8.8). Compound (18N): 7.45 (2 H, dd, J 8.5, 7.5), 7.90 (2 H, dd, J 8.5, 5), 8.00 (2 H, d, J 9), 8.42 (2 H, d, J 9). Compound (1A): 6.10 (4 H, s), 6.64 (4 H, d, J 8), 7.21 (4 H, d, J 8), 7.58 (4 H, d, J 8), 7.72 (4 H, d, J 8).Compound (2A): 5.40 (2 H, s), 6.16 (2 H, s), 6.60 (2 H, d, J8.7)6.81 (2H,dd, J7.8,2),6.94(lH, t, J2),7.17(1H, t, J 7.6), 7.21 (4H, dd, J 6.8, 2), 7.34 (2H, d, J8.7), 7.70 (2H, dd, J 6.8, 2), 7.79 (2 H, dd, J 6.8, 2). Compound (3A): 5.40 (4H, s), 6.82 (4 H, dd, J 8, 2), 6.94 (2 H, t, J 2), 7.16 (2 H, t, J 8), 7.24 (4 H, d, J 8.5), 7.81 (4 H, d, J 8.5). Compound (4A): 5.84 (4 H, s), 6.68 (4 H, d, J 9), 7.58 (4 H, d, J 9), 7.73 (4 H, d, J 9), 7.86 (4 H, d, J 8). Compound (5A): 6.20 (4 H, s), 6.59 (4 H, d, J 7), 7.08 (4 H, d, J 7), 7.22 (4 H, s), 7.52 (4 H, d, J 7), 7.66 (4 H, d, J 7). Compound (6A): 5.38 (4 H, s), 6.80 (4 H, d, J 8), 6.91 (2 H, s), 7.10 (4H, d, J 6.7), 7.18 (2 H, d, J 7.8), 7.25 (4 H, s), 7.76 (4 H, d, J 6.7).Compound (7A): 6.12 (4H, s), 6.59 (4H, d, J8.62), 6.87 (lH, t, J2.3), 6.94 (2H, dd, J8.2, 2.3) 7.12 (4H, d, J8.64), 7.49 (1H, t, J 8.7), 7.51 (4 H, dd, J 8.62,2), 7.66 (4 H, d, J 8.46). Compound (8A): 5.32 (4 H, s), 6.23 (2 H, dd, J 7.9, 2), 6.29 (2 H, t, J 2), 6.42 (2 H, dd, J 7.9, 2), 7.06 (2H, t, J 7.9), 7.07 (4 H, d, J 8.8), 7.25 (4 H, d, J 8.8), 7.78 (4 H. d, J 8.8), 7.81 (4 H, d, J 8.8). Compound (11A): 6.16 (4 H, s), 6.60 (4 H, d, J 8.8), 7.20 (4H, d, J 8.8), 7.24 (4H, d, J 8.8), 7.53 (4 H, d, J 8.8), 7.68 (4H, d, J8.8), 7.77 (1 H, t, J 8.8), 7.88 (4 H, d, J 8.8), 8.00 (2 H, d, J 8.8), 8.05 (1H, s). Compound (12A): 5.41 (4 H, s), 6.82 (4 H, dd, J 7.7, 2), 6.95 (2H, t, J 1.8), 7.18 (2 H, t, J 7.7), 7.26 (4 H, d, J 8.8), 7.27 (4 H, d, J 8.8), 7.82 (4 H, d, J 8.8), 7.89 (4H, s), 7.90 (4 H, d, J 8.8).Compound (13A): 5.40 (4 H, s), 6.82 (4 H, d, J 8), 6.95 (2 H, t, J2), 7.17 (2 H, t, J8), 7.24 (4 H, d, J 6.5). 7.27 (4 H, d, J 6.5), 7.78 (1 H, t, J 7.2), 7.81 (4 H, d, J 6.8), 7.90 (4 H, d, J 6.8), 8.01 (1H, s), 8.03 (2 H, d, J 7.2). Compound (18A): (in CDC13) 4.09 (2 H, s), 6.69 (2H, d, J9.3), 7.15 (2H, dd, J 8.5 Hz, 7.5 Hz), 7.69 (2 H, d, J9.3), 7.86 (2 H, dd, J 8.5, 7.5). Compound (17A): 7.23 (2 H, d, J 7.8), 7.26 (2 H, d, J 9), 7.36 (1 H, t, J 7.5), 7.58 (2 H, d, J 9), 7.95 (2 H, d, J 7.8), 7.96 (lH, t, J7.8), 8.24 (lH, d, J7.8), 8.54 (1H. s), 8.56 (lH, d, J 7.8). Compound (19a): (in CDC1,) 7.16 (4 H, d, J 8.9), 7.30 (2 H, dm), 7.48 (4 H, m), 7.57 (2 H, dt, J 6.3, 1.4), 7.88 (4 H, d, J 8.9).The authors thank ICI plc for supporting this work; A.J.L. also thanks SERC for a CASE studentship. P.L.P. thanks the Leverhulme Trust for the award of an Emeritus Fellowship which enabled him to participate in this work. D.C.S.acknowl-edges receipt of a Visiting Professorship at Tokyo Institute of WPTable 3 Synthesis of intermediates by Friedel-Crafts reactions W (a) From 3- or 4-nitrobenzoyl chlorides and arenes found (YO) calcd. (YO) reaction product yield mP solvent for mlz P chloride arene ratio time".b no. formula (%I 1°C C H N C H N recryst. found (theor.) -4-PhOPh 2: 1 18" 1N C26H16N207 51 226' 66.5 3.2 5.7 66.7 3.4 6.0 PY -3-PhOPh 1: 1 1" 80 94-96d 71.4 4.0 4.4 71.5 4.1 4.4 EtOH -4-PhOPh 1 :1.85 18" c19H 13N04 54 122" 71.5 4.0 4.2 71.5 4.1 4.4 EtOH 4-17a 1: 1 1" 81 179-8 1 66.9 3.4 5.9 66.7 3.4 6.0 DMF aq.-3-PhOPh 2: 1 18b 53 175' 66.5 3.3 5.8 66.7 3.4 6.0 EtOAc -4-PhPh 2.2: 1 4a.g 4N 33 211-12 69.3 3.5 6.2 69.0 3.5 6.2 DMF -4-4-PhOCsH4OPh 2: 1 2" 89 218-19 68.0 3.6 5.1 68.6 3.6 5.0 DMF aq. -E}3-2: 1 2" 77 201-03 68.4 3.6 4.8 68.6 3.6 5.0 3-2.2: 1 2.5" 9N 89 230 -----__ NMP aq. 664( 664) 4-1: 1 2" 18N 57 86-88' 64.2 3.1 5.7 63.7 3.2 5.7 EtOH -3-2.2: 1 2.5" 14N 95 257 -816(816) 3-2.2: 1 2.5" 15N 93 247.5 -848( 848) 3-2.2: 1 2.5" 1ON 93 189 -700( 700) (b)From other aroyl chloridesh ___ ~____ found (YO) calcd. (%) reaction product yield mP solvent mlz chloride arene ratio time"Sb no. formula (%I /"c C H N C H N recrystn.found (theor.) 3F PhOPh 2: 1 2" 19a C26H16N203 50 156-58 75.8 3.8 75.4 3.9 3.65 PhMe -4F (PhOC6H4),C0 2.2: 1 1" C39H24F205 85 279 -------612(610) tere 17b 1:2 6" 35 282-83 71.1 3.4 3.4 71.9 3.7 3.65 --tere 17a 1:2 6" 33 272 71.2 3.6 3.7 71.9 3.7 3.65 -__ is0 17b 1:2 6" 11N C46H28N2010 57 211-12 71.6 3.6 3.1 71.9 3.7 3.65 --is0 17a 1:2 6" 13N 73 218-19 72.1 3.7 3.7 71.9 3.7 3.65 --"h at reflux in 1,2-CzH,Cl2. "h at room temp. in CH2C12. Lit. :ti mp 226 "C. Lit. : mp 87-88 "C. " Lit. : mp 121-122 "C. f Lit. : mp 175 "C. Busing FeC13 in place of AlCl,. 3-F =3-fluorobenzoyl; 4-F = 4-fluorobenzoyl; tere =terephthaloyl; is0 =isophthaloyl. Lit. : mp 88-88.5 "C. J. MATER. CHEM., 1994, VOL. 4 Table 4 Ullmann ether syntheses fluoroarene or nitroarene phenol yield (YO) (4-FC,H,)ZCO PhOH 94 (~-FC,H~)ZSOZ(4-FC6H,)zCO (4-FC6H4)ZCO PhOH 4-PhOC6HdOH 4-PhC6HdOH 89 89 73 18A 19b 1,3-C6H4(OH)z 1,3-HOC,H,NHZ 25 12 20 1,3-HOC6H,NH, 70 “ Lit.:9 mp 146-147 “C.Technology funded by Monbusho which allowed completion of this manuscript. References 1 D. M. Hergenrother, N. T. Wakelyn and S. J. Havers, J. Polym. Sci.:Polym. Chem. Ed., 1987,25, 1093. 2 G. Eastmond, J. Paprotny and I. Webster, Polymer, 1993,34,2865. 3 Parts 1 and 2: J. Muter. Chem., 1994,4, 1511;1521. mlz mp/”C product found (theor.) 147“ (1,4-PhOC,jH4)zCO 366( 366) 142 1,4-PhOC,H4),SO, 402( 402) 199 197-99 172-74 (1,4-PhOC&0C6H4)zCO (1 ,4-PhC,H,OC,H,),CO 7A 548(550) 516( 518) - 168-70 8A - 280 16A 788(788) 4 F. Ullmann and P. Sponagel, Justus Liebig’s Ann. Chem., 1906, 350, 83. 5 P. M. Hergenrother, B. J. Jensen and S. J. Havens, Polymer, 1988, 29, 358. 6 W. Dilthey, C. Blankenburg, W. Braun, R. Dinklage, W. Huthwelker and W.Schommer,J. Prukt. Chem., 1931,129,189. 7 B. Staskun, J. Org. Chem., 1964,29,2856. 8 R. G. Pews, Y. Tsuno and R. W. Taft, J. Am. (‘hem. Soc., 1967, 89,2391. 9 W. Tadros and A. Latif, J. Chem. SOC.,1949,3337. Paper 4/02561J; Received 29th April, 1994.

ISSN:0959-9428    

DOI:10.1039/JM9940401527

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

J. MATER. CHEM., 1994, 4( lo), 1533-1538 A New Single-layer Plasma-developable Photoresist using the Catalysed Crosslinking of Poly(4-hydroxystyrene) via Photogenerated Acid James T. Fahey," Jean M. J. Frechet*" and Yosef Shacham-Diamandb a Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA School of Electrical Engineering, Cornell University, lthaca, NY 14853, USA A new single-layer, dry developable chemically amplified resist is described. The resist consists of poly(4-hydroxystyrene), 1,2,4,5-tetra(acetoxymethyl)benzene and triphenylsulfonium hexafluoroantimonate, and func- tions via crosslinking as a result of an acid-catalysed electrophilic aromatic substitution reaction. In contrast to the normal wet resist development process that leads to a negative-tone image, a gas-phase modification of the exposed polymer film, followed by reactive oxygen etching, leads to a positive-tone image.The post-exposure modification is accomplished using gaseous 1,1,1,3,3,3-hexamethyIdisilazane, a reagent that is able to diffuse selectively into the non- exposed, non-crosslinked regions of the polymer film to react with the poly(4-hydroxystyrene) and form silyl ethers. Dry-development of the treated film in an O2plasma removes those areas of the film that have remained unstlylated, producing a positive-tone relief image. In the present climate of rapidly advancing technology demands are made for ever-increasing circuit densities in micro-electronic devices. Meeting these demands requires that a much smaller feature size (<0.3 pm) be used in the integrated circuits.Designing for such tiny features elicits fabrication problems that did not exist with the larger geometries. The increasing demands on lithographic processes' have been compounded by the topology2 of the wafers used for normal device fabrication. Several solutions have been proposed, including the plasma- developed trilayer resist technology of Ha~as.~ Unfortunately, this complex process requiring numerous processing steps is costly and difficult to implement in mass prod~ction.~ Several bilayer systems in which resist materials function as both the radiation-sensitive imaging layer as well as the plasma-resist- ant layer have been These materials incorporate organometallic functionalities to deliver the necessary plasma etch resistance.After imagewise exposure to radiation, the pattern is developed by etching with an oxygen plasma which removes organic polymers by converting them into water and carbon dioxide, except in areas containing elements such as silicon or tin which can form a thin layer of refractory oxide that protects the underlying polymer. Numerous attempts have been made to implement this design. The use of imageable silicon-containing polymers is a particularly attractive method. After exposure and wet devel- opment, the pattern is transferred via oxygen plasma etch to the underlying planarizing layer. MacDonald et uE.~,~have developed a resist material based on a copolymer of 4-trimethylsilylmethyl styrene and 4-chlorostyrene while others have prepared similar silicon-containing polymer^.^,' To obtain adequate etch selectivity between the top imaging layer and the planarizing layer, it is necessary to incorporate more than 10 wt.% of silicon into the re~ist.~,~' However, silicon incorporation may affect drastically the properties of the resist, for example by effectively lowering its glass-trans- ition temperature (q).This may lead to thermal flow during the baking steps, a process that destroys the smaller features defined earlier by photoexposure.Lithographic processes that utilize entirely 'dry develop- ment' via plasma etching offer an attractive route to submic- rometre lithography using single-layer resists.The overall process can be simplified by combining the functions of the imaging and planarizing layers. Dry processing" offers several advantages over wet development, including anisotropic etch- ing which results in deep vertical profiles, reduced chemical waste and elimination of the swelling problem frequently associated with wet development processes. Several means of incorporating etch-resistant moieties into the resist are possible. For example, MacDonald et ai'.utilize a post-exposure procedure involving reaction of an appro-priate organic/organometallic vapour to deliver the etch- resistant material into the exposed or unexposed areas of the resist.I2 This process typically involves the incorporation of a silylating reagent such as 1,1,1,3,3,3-hexamethyldivlilazane (HMDS) into the exposed regions of the resists, based on the well known' poly(tert-butoxycarbonyloxy styrene) deep-UV imaging ~ystern.'~,'~ The DESIRE process of Coopmans et a1.l' is another excellent implementation of this approach.Because few experimental details of these practical approaches are found in the literature we evaluated The gas- phase functionalization process with resist systems baed on the cationic photo-crosslinking of poly( 4-hydroxystyrane) and polyfunctional latent electrophiles.'6 This system is based on a crosslinking mechanism that is well under~tood'~ and has been optimized to afford previously unheard of sensitivity level^.'^,'^ We have recently demonstrated that sensitivities as high as 0.15 mJ cm-' and 0.1 pC cm-2 can be achieved under UV irradiation at 254 nm or electron-beam (E-beam) expo- sure, respectively.These sensitivities are achieved for direct negative- tone imaging but the silylation procedure dcscribed herein is an image-reversal process that may be used to produce positive-tone images. Experimental General IR spectra were recorded on a Nicolet IR-44 spectrometer fitted with a DTGS detector using 1 pm thick films on undoped silicon wafers, polished on both sides to minimize light scattering. Deep-UV exposures were performed either by contact printing using a Canon HTG Systems I11 Contact Aligner from Solitec Inc. (proximity and contact adjustable) or an Optical Associates Inc.exposure system comprising of a low-pressure mercury lamp with a shutter system, an intensity controller and an exposure timer. Photon flux was measured using an Optical Associates Inc. 354 exposure monitor. The lamp output was filtered through a 254nm narrow-bandwidth filter from Oriel Corporation. Film thick- ness measurements were performed using a Tencor Alphastep 200 profilometer. E-beam exposures were performed on a Cambridge EBMF instrument with an accelerating voltage of 20 keV and a beam current of 1nA. Scanning electron micro- graphs were obtained on a Cambridge Stereoscan 200 micro- scope with an accelerating voltage of 20 keV. Micrographs were obtained by coating the samples with 10 nm of Au-Pd.The 0, reactive ion etching was performed on an Applied Materials Reactive Ion Etcher interfaced to an MN5-2000E Plasma-therm and an RF-5 plasma source from RF Plasma Products Inc. The etch parameters were as follows: 0, pressure 30 mTorr; 0, flow 30 (STP) cm3 min-'; power 0.25 mW. The conditions listed here were not optimized and were used according to normal procedures for etching resists. Poly(4-hydro~ystyrene)~~(M,=31500, Mw,Mn=2.6) and 1,2,4,5,-tetra(acetoxymethyl)ben~ene~~were prepared as described earlier. The 2 in7 undoped silicon wafers used in this study were a gift from IBM. The acid photogenerator, triphenylsulfonium hexafluoroantimonate," was obtained from General Electric and used without further purification.Propylene glycol monomethyl ether acetate (PM acetate) and HMDS were obtained from Aldrich and used without further purification. Gas-phase Silylation Apparatus and General Procedure All silylation reactions were performed in the gas phase using a custom-built stainless-steel vacuum chamber with gas inlets for nitrogen and HMDS. The reactor has a thick thermo- statted removable aluminium base fitted with a wafer-shaped groove and a vacuum chuck designed to secure the wafer to the base while ensuring good thermal contact with the reactor. The silylating reagent, HMDS, is introduced into the oven from an external heated flask connected to it by a heated stainless-steel transfer line. The exposed wafer is inserted onto the heated base and secured in place using vacuum suction.The chamber is then evacuated to ca. 1Torr and the system allowed to stabilize for 1min. The vacuum valve is then closed and the HMDS is delivered to attain the desired pressure. After the amount of time required for reaction, the chamber is evacuated to remove the unreacted HMDS. The chamber is then purged several times with N, and the wafer is removed and analysed or processed further. Resist System based on Poly (4-hydroxystyrene), Triphenylsulfonium Hexafluoroantimonate and 1,2,4,5-Tetraacetoxymethylbenzene Poly( 4-hydroxystyrene) ( 1.00 g), triphenylsulfonium hexa-Auoroantimonate (0.135 g), and 1,2,4,5-tetra(acetoxymethyl) benzene (0.216 g) were dissolved in PM acetate (5.41 g) to give a 20% (w/w) solution.After filtering through a 0.45 pm filter, the films were spin coated onto 2in undoped silicon wafers (both sides polished). The films were pre-baked at 90 "C for 15 min and analysed by FTIR. For the exposed studies, samples were exposed to 5 mJ cm-'. The films (exposed and unexposed) were then post-baked at 120 "C for 3 min and analysed by FTIR. Results and Discussion The system chosen for this study is based on the catalytic crosslinking of poly(4-hydroxystyrene) and 1,2,4,5-tetra(acetoxymethy1)benzene in the presence of photogener- t 1 inz2.54 x m. J. MATER. CHEM., 1994, VOL. 4 ated acid.16 The exposed areas become crosslinked and are impermeable to the silylating reagent allowing for selective incorporation of HMDS into the non-exposed regions.Scheme 1 outlines our general approach to 'image reversal' using these types of systems. In the traditional negative-tone imaging process, the resist film containing the acid photogenerator, Ph3S+SbF6-, is exposed and this generates a latent image consisting only of acid dispersed in the polymer film. Subsequent heating ('post- baking') of the wafer provides the necessary activation energy that allows the crosslinking to occur via electrophilic aromatic substitution. Subsequently, the unexposed regions of the film are selectively removed by wet development with aqueous base, affording a negative-tone image. In order to achieve dry-development with image tone reversal, the wafer is exposed to vapours of HMDS immedi- ately after the post-exposure heating step.The silylating reagent is able to diffuse into the unexposed areas of the film where it reacts with the phenolic polymer leading to a polymeric silyl ether material that has a very high content of silicon. In contrast, the crosslinking that has occurred in the exposed areas of the film leads to a very significant reduction of the rate of diffusion of the silylating agent into these exposed areas, leading to a very low extent of silylation. Upon exposure to oxygen reactive ion etching, the silicon-free areas are selectively etched away. The surfaces of the areas contain- ing the newly formed poly( trimethylsilyloxystyrene) are trans- formed into a thin layer of SiO, that acts as a refractory, preventing the plasma from etching away the underlying resist.In this manner the anisotropic nature of the 0, reactive ion etch (RIE) process may be exploited to produce positive- tone images having steep vertical sidewalls. Fig. 1 shows the FTIR spectrum of the non-exposed resist before and after silylation. A 1 pm thick film of the resist spin- coated onto a 2in silicon wafer was silylated for 20min at 100"C using 120 Torr of HMDS. The FTIR spectrum of the silylated resist shows the bands attesting to silicon incorpor- ation into the film. An interesting feature in the FTIR spectrum is the change in the shape of the carbonyl band near 1730 cm-' that corresponds to the acetoxymethyl groups on the crosslinker molecule. Before silylation, there are more car- bony1 moieties hydrogen-bonded to the phenols than non- bonded carbonyls. After silylation, the number of available hydroxy groups is decreased.As a result, the relative amount 4000 2000 1000 wavenumberkm-' Fig. 1 FTIR of negative-tone resist (exposed) before (a) and after (h) silylation (20 min at 120 Torr and 100 "C) J. MATER. CHEM., 1994, VOL. 4 irradiation exposed areas unexposed areas 1 latent image OH silylated image u negativetone 02RIE1 OSi(CH& - positivetone Scheme 1 of free, non-hydrogen-bonded carbonyls is increased and a change in the shape of the carbonyl absorbance is seen. Fig. 2 shows a plot of the difference spectrum obtained with an unexposed wafer before and after silylation.The bands at 845, 920, 1240 and 1500 cm-' result from silicon incorporation into the film.21 The band at 920cm-' corresponding to the silicon-oxygen bond was selected for use in quantitative FTIR studies. To confirm that selective HMDS incorporation is achieved in the unexposed regions of the resist, an exposed resist film was silylated under the same conditions as those used for the silylation of the unexposed wafers. Therefore, a 1pm thick film of the resist spin-coated onto a 2in silicon wafer was I 0.200-(d fl 0.100-z Da 0.000-0.088 I 1 i 1600 doo' I1i0o1 I I ld00' I ' 800 I wavenumbedcm-' Fig. 2 FTIR difference spectrum: FTIR absorbance spectrum obtained before silylation minus FTIR absorbance spectrum obtained after silylation for non-exposed resist first exposed to 5 mJ cm-2, then post-baked for 3 min at 120"C to crosslink the film, and finally silylated for 20 min at 100"C using 120 Torr of HMDS.FTIR analysis of the wafer confirmed that little or no silicon incorporation had taken place because the O-H and C-0 bands of the jtarting material remain unchanged and no Si-0 band is seen at 920cm-I. The lack of silylation is further Confirmed by difference FTIR spectroscopy as described above. In contrast, a difference FTIR spectrum for two films that were, respect- ively, unexposed/silylated and exposed/silylated is practically identical to that shown in Fig. 2. Effect of Silylation Time on Silicon Uptake Data showing the silicon uptake as a function of the amount of time the wafer is exposed to HMDS vapour are shown in Fig.3. These data were obtained by FTIR measurements with quantitative monitoring of the Si-0 band at 920 cm-' (Fig. 4). The experiments were carried out maintaining a constant HMDS pressure of 120 Torr and a constant reactor temperature of 100 "C. All samples were heated for 3 min at 120°C before the silylation reaction to mimic the 'post-bake' processing conditions used for the exposed wafers. Fig. 3 shows that the silicon uptake increases rapidly with time until a saturation level is achieved after about 1 h. Although this experiment was extended to silylation times of up to 2 h (Fig. 4), in practice silylation times of 3-5 min were found to be adequate to obtain good etch selectively. This is because only the top surface of the resist needs to be silylated in order to form a protective layer with a high silicon content that is 1536 ujn (0 -0.2 a,Y Qc.a 0 20 40 60 80 100 120 140 silylation timdmin Fig.3 Silicon uptake us.silylation time. The uptake was monitored by following the change in the absorbance at 920 cm-I I l¶I 111 lll~lll~lll~ll l3bO 12b0 1100 1000 900 800 wavenumberkm-' Fig. 4 Silicon uptake with increasing silylation time (times given in min on curves) able to prevent etching of the underlying material during subsequent oxygen plasma treatment effectively. Effect of Silylation Temperature on Silicon Uptake Fig.5 shows a plot of silylation temperature us. silicon uptake. Once again the absorption band at 920cm-1 was used as a measure of silicon uptake although measurements performed at 845 cm-' (Si-C bond) produced essentially identical data. The resist films were silylated for 20 min in 120 Torr HMDS at varying temperatures. The data show an increase in silicon uptake as the temperature increases from 80 to 110°C. At 110°C the rate of functionalization reaches a maximum and the silicon uptake levels off. Above 130 "C, a slight occurrence 0.4 f 5 0.3 0cu'i0, s 0.2q J. MATER. CHEM., 1994, VOL. 4 of thermally induced crosslinking is observed causing some inhibition of HMDS diffusion into the polymer coating. In practice, silylation temperatures of 100-1 10 "C were used leading to near ideal selectivity without the occurrence of thermal crosslinking.Effect of HMDS Pressure on Silicon Uptake The effect of HMDS pressure on silicon incorporation is shown in Fig. 6. These data were obtained by maintaining a silylation time of 20 min and a bake temperature of 100"C. An increase in silicon uptake is seen until the pressure reaches about 120 Torr of HMDS. A drastic decrease in silicon uptake is observed at 160Torr HMDS as some condensation of the silylating reagent onto the wafer is observed. Note that our silylation apparatus makes use of a direct flow of HMDS vapour without carrier gas. Some commercial silylation sys- tems employ a carrier gas, but these systems are seldom fully optimized to control the absolute HMDS content in the carrier gas that is needed to ensure reproducibility.In addition, it must be emphasized that optimum conditions for other silylating reagents vary significantly from those determined in this study for HMDS. Etch Rates Earlier studies have shown that a film of poly(4-hydroxy- styrene) in which all phenolic sites have been functionalized, has a net silicon content of 14.5 wt.%.12 In order to obtain good etch resistance, a silicon content of 10-15 wt.YO5 in the l film is recommended, depending on the etch conditions. To determine the appropriate etching times for removal of the unsilylated areas of the film, the etch rates of exposed resist films (ca. 1 pm thick) have been studied.Two exposure doses were chosen for this study. Fig. 7(a) shows the loss in film thickness as a function of etch time for a film exposed to 5 mJ cm-2 and Fig. 7(b) shows similar data for a resist exposed to 20 mJ cmP2. In both cases, etching was carried out under an arbitrary set of conditions: 30 m Torr 0, with an 0, flow of 30 cm3 min-' and a power of 0.25 mW. Fig. 7(a) shows clearly that the etch rat: varies as a function of depth wi!h a low etch rate of 1170 A rnin-' observed for the top 160! A layer nearest the surface and a faster etch rate of 4900 A min-' for the remainder of the film. This etch rate profile is not unexpected as the more highly crosslinked surface layer is more resistant to etching than the underlying less heavily crosslinked mate- rial.The same is observed [Fig. 7(b)]with a film exposed to a much higher dose of UV light (20mJ crnp2) except that, ,L-0.30 0 20.20 QvYa, = 0.10 c .-8.--%Irn c 60 80 100 120 140 0 50 100 150 200 silylation tempera ture/"C silylation pressureflorr Fig. 5 Silicon uptake us. silylation temperature (920 cm-') Fig. 6 Silicon uptake us. silylation pressure (920 cm-') J. MATER. CHEM., 1994, VOL. 4 1.0 r 0.8 0.6 iI(a) f 0.0 rO 50 100 150 200 .-f1.2r -.-t .c .c;1.0 cn -0 0.8 0.6 0.41 / time/s Fig. 7 Loss of film thickness as a function of etch time in an oxygen plasma for (a) resist exposed to 5 mJ cmP2; (b) resist exposed to 20 mJ in thi: case, a lower rate of etching prevails for the top 2600A0 of the film with a subsequent faster etch rate (4100A min-') observed for the remainder of the film.Although the experiments are not directly comparable, they are consistent with the expectation that a higher exposure dose results in the formation of a thicker zone of highly crosslinked material in the polymer film, which is the case with a lower exposure dose. Imaging of the Material with Dry Development A sample of the resist was coated onto a silicon wafer to form a 1 pm thick film, then the film was exposed through a mask to 20mJ cm-' of 254nm radiation using a Canon HTG contact aligner. The film was silylated for 5 min in 120 Torr of HMDS at 100°C. Fig.8 shows a typical image obtained after 3.5 min reactive ion etching in an oxygen plasma using the etch conditions described above. Although the image shown is of low resolution since contact printing was used for exposure, the value of the dry-development approach is con- firmed by the steep wall pattern that is obtained. A residue is seen in the previously exposed regions indicating that small amounts of the HMDS had penetrated the crosslinked areas. Since the main purpose of this work was to understand the chemistry of the image reversal process, no optimization of the image resolution was attempted. However, earlier work directed towards high-resolution imaging rather than a thor- ough understanding of the system, has demonstrated that very high-resolution images22 can be obtained using a related resist system and the type of sophisticated exposure equipment that is used in the actual commercial production of semicon- ductor devices.Fig. 8 Scanning electron micrograph of images in a silylated resist based on poly(4-hydroxystyrene), 1,2,4,5-tetra(acetoxyinethyl)-benzene and triphenylsulfoniurn hexafluoroantimonate Conclusions Our results confirm that it is possible to effect a selective gas- phase modification of a polymer film that has been crosslinked in defined areas. Diffusion of the substance effecting chemical modification of the film is hindered in crosslinked! areas leading to selective modification of the uncrosslinked areas of the film. This phenomenon demonstrated for negative-tone resists based on the cationic photocrosslinking of poly( 4- hydroxystyrene) and 1,2,4,5-tetra(acetoxymethyl)knzene allows their use as positive-tone imaging materials.This process of image tone reversal complements our earlier report involving the consecutive gas-phase modificatic )n of uncrosslinked polymer films." We have confirmed that gas-phase silylation rates of a phenolic polymer film using HMDS are strongly dependent on vapour temperature and pressure. As expected, silicon uptake is also affected by the amount of time the walers are exposed to the silylating vapours. These variables are depen- dent on the particular system being studied, gas-phase silyl- ation is a very complex process where optimizatxon of processing variables is essential to achieve a viable process.In addition, a route to dry-developable resists based on our highly ~ensitive'~-'~ negative-tone systems is shown. It allows access to positive-tone images via image reversal. Using this process, the swelling problems that are frequently asst )ciated with the wet development of negative-tone resists are avoided. Our results present a unique lithographic system. Very few similar systems have been described in which a negative working resist based on crosslinking can be used in b<)th the positive and negative tones. We have been able to combine the high sensitivity of a chemically amplified resist with the advantages of plasma etching to produce a single-layer, dry- developable resist with the properties of multilayer technology but without the complexity that is normally associated with it.Financial support of this research by IBM Corpora1:ion as well as partial support by the Semiconductor Rcsearch Corporation is acknowledged with thanks. Part of this work was performed at the National Nanofabrication Facility sup- ported by NSF grant ECS-8619049, Cornell University and Industrial Affiliates. References 1 S. A. MacDonald, C. G.Willson and J. M. J. Frechet, Act. Chem. Rex, 1994, 27, 151; C. G. Willson, in Introduction to 1538 J. MATER. CHEM., 1994, VOL. 4 2 3 4 5 6 7 8 9 10 11 Microlithography, ed. L. F. Thompson, C. G. Wilson and M. J. Bowden, American Chemical Society, Washington DC, 2nd edn., 1994, p.139. G. N. Taylor, 0.Nalamasu and L. E. Stillwagon, Microelectron. Eng., 1989,9, 513. J. R. Havas, Electrochem. Soc. Ext. Abstr., 1976,76,2; J. R. Havas, US Pat. 3 873 361,1973. L. P. Bushnell, L. V. Gregor and C. F. Lyons, Solid State Technol., 1986,29, 133. S. A. MacDonald, H. Ito and C. G. Willson, Microelectronic Eng., 1983, 1,269. Y. Ohnishi, M. Suzuki, K. Saigo, Y. Saotome and H. Gokan, Proc. SPIE, 1985,539,62. M. Suzuki, K. Saigo, H. Gokan and Y. Ohnishi, J. Electrochem. SOC.,1983,30, 1962. M. Morita, A. Tanaka, S. Imamura, T. Tamamura and 0.Kogure, Jpn. J. Appl. Phys., 1983, 1-659, 22; W. C. Cunningham and C. E. Park, Proc. SPIE, 1987,771,32. S. A. MacDonald, R. D. Allen, N. J. Clecak, C. G. Willson and J. M. J. Frechet, Proc. SPIE, 1986,631,28.E. Reichmanis and G. Smolinsky, Proc. SPIE, 1984, 469, 38; E. Reichmanis and G. Smolinsky, J. Electrochem. SOC., 1985, 132, 1178. J. W. Coburn, in Plasma Etching and Reactive Ion Etching, American Vacuum Society Monograph, American Institute of 13 14 15 16 17 18 19 20 21 22 4552833, 1985; S. A. MacDonald, H. Schlosser, H. Ito, N. J. Clecak and C. G. Willson, Chem. Muter., 1991,3,435. J. M. J. Frechet, E. Eichler, C. G. Willson and H. Ito, Polymer, 1983,24, 995. J. M. J. Frechet, H. Ito and C. G. Willson, Proc Microcircuit Eng. (Grenoble), 1982,260; C. G. Willson, H. Ito, J. M. J. Frechet and F. Houlihan, Proc. IUPAC 28th Macromol. Symp. Amherst, MA, 1982, p. 448. F. Coopmans and B. Roland, Solid State 7echnol., 1987, 93; B. Roland, R. Lombaerts, C. Jakus and F. Coopmans, Proc. SPIE, 1987,771,69. J. T. Fahey, K. Shimizu, J. M. J. FrCchet, N. Clecak and C. G. Willson, J. Polym. Sci. A., Polym. Chem. €d., 1993, 16, 353. S. M. Lee, J. M. J. Frechet and C. G. Willson, Macromolecules, 1994, in the press. S. M. Lee and J. M. J. Frechet, Macromolecules, 1994, in the press. J. M. J. Frechet and S. Lee, Proc. SPIE, 1993,1925, 102; S. M. Lee and J. M. J. Frkchet, Polym. Muter. Sci. Eng., 1993,68, 28. J. V. Crivello and J. H. W. Lam, J. Polym. Sci., Polym. Symp., 1976, 56, 383. J. V. Crivello and J. H. W. Lam, J. Polym. Sci., Polym. Chem. Ed., 1979,17,977. S. A. MacDonald, H. Schlosser, N. J. Clecak, C. G. Willson and J. M. J. Frkchet, Chem. Muter., 1992, 4, 1364. J. M. J. Frechet, J. Fahey, S. M. Lee, S. Matuszczak, Y. Shacham-Diamand, S. A. MacDonald and C. G. Willson, J. Photopolym. Sci. Technol., 1992,5, 17. 12 Physics, New York, 1982. H. Ito, S. A. MacDonald, R. D. Miller and C. G. Willson, US Pat. Paper 4/02637C;Receiwd 4th May, 1994

ISSN:0959-9428    

DOI:10.1039/JM9940401533

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

J. MATER. CHEM., 1994,4( lo), 1539-1545 Laser Photolytic Studies on Sensitizers for Negative Photoresists: 4,4'-Diazido-3,3'-Dimethoxybiphenyl in Poly(methy1 methacrylate) Films Akira Itaya,*" Takefumi lnoue: Tsutomu Yamamoto; Takahiro Mobutou,a Hiroshi Miyasaka," Minoru Toriumib and Takumi Uenob a Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Kyoto 606, Japan Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo 185,Japan The time evolution of the transient absorption spectra of 4,4'-diazido-3,3'-dimethoxybiphenyl (DADMB) (N3- R -N3), a sensitizers for negative photoresists, under laser irradiation with low and high fluences has been investigated in poly(methy1 methacrylate) (PMMA) films and in cyclohexane solution.The spectra were measured in the tima region 20 ns-1200 s. The results from a DADMB-cyclohexane solution containing diethylamine indicated that the triplet azido nitrene (N3- R-N:) was predominantly generated even at room temperature, not didehydroazepine derivatives. The formation of the triplet azido nitrene in solution and in PMMA films was complete within the duration of the laser pulse. The triplet azido nitrene underwent dimerization in solution within 1 ms, producing an azo compound (N3-R-N=N-R-N3). In contrast, a reaction related to the formation of azide nitrene in PMMA films continued up to 1200 s. Laser irradiation with a high fluence gave the dinitrene (:N-R-N:). The dinitrene in solution underwent dimerization and/or further polymerization.The results for PMMA films heavily doped with DADMB suggested that DADMB molecules form aggregates in PMMA films: A photoreaction with a high fluence was complete within 300 s. The photochemical behaviour of aromatic azides and nitrenes is of great importance not only for synthesis but also for photolithographic applications in the formation of negative images. The primary processes in the photodecomposition of aromatic monoazides (R'-N,) have been investigated in solution by laser flash photolysis,'-' but such studies on aromatic bisazides (N3-R"-N,) are few, although the pri- mary photochemical process of 4,4'-bisazidobiphenyl in cyclo- hexane solution has been reported.' In order to discuss the lithographic behaviour of these compounds, information on the primary photochemical processes of the compounds in polymer matrices is indispensable.Since the molecular motion of organic molecules doped in polymer matrices is highly suppressed compared with that in solution, the photochemical reactions of dopants in polymer matrices seem likely to be different from those in solution. Hence special features may appear in photochemical reactions of aromatic azides and their nitrenes in polymer matrices. Bearing in mind that conventional positive naphthoqui- nonediazide-Novolac-based photoresists are not suitable for use in the deep UV region, negative resists for KrF excimer laser lithography have been developed." When one of the sensitizers developed for such negative resists, DADMB, was OCH3 I employed with poly( hydroxystyrene) (PHS), the DADMB- PHS-based photoresist showed good optical characteristics, good sensitivity and good resist profiles.The quantum yield for the photodecomposition of DADMB in this resist is seven times larger at 248 nm than at 313 nm irrespective of whether the polymer matrix is PHS or PMMA." Although infor- mation on the photoreaction mechanism of aromatic bisazides such as DADMB in polymer matrices is valuable for their photolithographic applications, the primary photochemical processes of such compounds in polymer matrices have not yet been elucidated. A single shot from an intense pulsed-excimer laser produces certain photoproducts which are not detected under conven- tional lamp or laser irradiation with a low fluence.For bisazide compounds, for example, irradiation of 1,8-diazido- naphthalene in hexane with a single KrF excimer laser pulse at 20 "C gave benz [cd]indazole via intramolecular cc )upling of two nitreno groups generated by a two-photon process." Hence, it is of interest to investigate the effect of laser Buence on the photodecomposition of DADMB in polymer matrices. In the present work, using an excimer laser with low and high fluences, we have compared the photochemical behaviour of DADMB in PMMA films and in solution by means of time-resolved absorption spectroscopy. Experimental Laser Flash Apparatus A nanosecond microcomputer-controlled laser photolysis system was used for measuring transient absorption spectra in the nanosecond time region.An XeCl excimer laser (Lumonics EX-510; A =308 nm, pulse duration =12 tis) was used as the excitation source. The laser fluence was measured by Gentec ED-200 or ED-100A power meters. The analysing lamp was a 150 W dc Xe lamp (Wacom KXL 150) which was additionally pulsed for ca. 200 ps fwhm, synchronizad with laser oscillation. A heat-absorbing filter and UV cut-of€ filters were used to avoid photodecomposition by the analysing light. The analysing light was detected by a photomultiplier (Hamamatsu R1913) through a monochromator. Tht: signal obtained from a storage oscilloscope (IWATSU TS-8123) was transferred to a microcomputer (NEC PC9801F2). For measurements in the time region from microseconds to seconds, a polychromator and multichannel photodiode array system (Hamamatsu PMA-10) equipped with a microcom- puter (NEC 9801 RA) was used as the detector.An Xe flash lamp (Hamamatsu L4633; fwhm 1 ps) was used as the monitor- ing light, and this determined the time resolution. The delay time origin of Ops corresponds to the time when the absorbance of intermediates at 345 nm observed for DADMB- cyclohexane solution (vide infra) has its maximum intensity. Samples were replaced after each excitation. Materials DADMB was as used before.” Diethylamine (DEA) was distilled under a reduced pressure of N, gas. PMMA was reprecipitated three times from benzene-methanol. PMMA films doped with 1% w/w and 10% w/w DADMB relative to the polymer were prepared by solvent casting on a quartz substrate from benzene and spin coating from toluene, respect- ively.The films were dried under vacuum for more than 8 h. The film thickness was adjusted to obtain an absorbance of 1.2-1.5 at the excitation wavelength (308 nm). Results and Discussion Photodecomposition of DADMB in Solution With regard to photodecomposition of phenyl azide, which is a typical aromatic monoazide, the following process has been reported:12,13 Photolysis of phenyl azide (PhN,) generates singlet phenylni- trene (Ph’N:). The singlet nitrene undergoes intersystem cross- ing to the triplet nitrene (Ph3N:), which produces azobenzene (Ph-N=N-Ph) by dimerization in inert solvents such as cyclohexane.The singlet nitrene, on the other hand, undergoes ring expansion to form 1,2-didehydroazepine (ketene imine ’ ‘ ).In the presence of DEA, 1,2-didehydroazepine 0 reacts with the amine to produce 2-(diethylamino)-3H-azepine. In the absence of such amines, 1,2-didehydroazepine reacts with phenyl azide to form a tar or else it polymerizes. At low temperatures, the singlet nitrene does not undergo ring expan- sion and only the triplet nitrene is formed. In inert solvents, the substituent effect on such reactions indicated that the yield of azepines decreased as the electron-donating power of the para-substituent increased.12 For example, irradiation of p-methoxyphenyl azide in cyclohexane solution yielded 80% of the azo compound, but in cyclohexane containing 2.0 mol dm -3 DEA, 27% 2-(diethylamino)-5-methoxy-3H-azepine was obtained.J. MATER. CHEM., 1994, VOL. 4 Fig. 1 shows the transient absorption spectra of DADMB- cyclohexane solution in the absence of DEA. Because of the absorption of ground-state DADMB, spectra in the wave- length region below 330nm were not measured. The broad transient absorption with a peak at 385 nm at 4-20 ns decreased with increasing delay time and a new absorption at 350-370 nm appeared. The latter absorption spectrum is in agreement with the transient absorption spectrum with a peak at 345 nm at 0 ps [Fig. l(b)]. The rise curve of the transient absorption at 350 nm corresponded to the initial decay curve of the transient absorption at 385 nm, suggesting that the broad absorption around 385 nm is due to a precursor of a species with an absorption at 350 nm.The change of the initial absorbance was complete within the duration of the laser pulse. The transient spectrum at 0 ps maintained an isosbestic point at 375 nm. No evolution of the absorption spectra was observed in the time region > 1 ms, indicating that the reaction was complete within this period and that the absorption spectrum at 1ms is due to the final products of DADMB photolysis in cyclohexane solution. We performed flash photolysis of DADMB-cyclohexane solution containing DEA (0.5mol drn-,) to examine the intermediates. If the spectrum at 0 ps is due to a didehy- droazepine derivative [5-( 3-methoxy-4-azidophenyl)-7-methoxy-l,2-didehydroazepine], the transient absorption spectra should be different in the presence and absence of DEA because of the reaction of the dehydroazepine with DEA.The behaviour of the transient absorption of the tar solution was quite similar to that of Fig. 1(b).The time profiles of the transient absorption at 350 nm of DADMB-cyclohex- ane solution with various concentrations of DEA (0.1, 0.25, 0.5, and 1.0mol dmP3) also agreed with that of DADMB solution in the absence of DEA. These results combined with the results reported for phenyl azide suggest that the transient absorption spectrum at 0 ps is predominantly due to a triplet nitrene (:N-R-N,; 4-azide-3,3’-dimethoxy-4’-nitrenobi-phenyl) and not didehydroazepine derivatives.We also investigated the photolysis of DADMB in a rigid matrix of methylcyclohexane-isopentane at 77 K using a laser with a low fluence as the irradiation source. Fig. 2 shows the change in the absorption spectrum of DADMB induced by laser irradiation with a low fluence of 0.7 mJ cm-*. The spectrum observed on a single shot of the laser pulse is assigned to the azido nitrene (:N-R-N,). Since the bisazide (N,-R-N,) is converted into the dinitrene (:N-R-N:) via the azido nitrene intermediate (N, -R-N:),14 the spectrum observed after 1500 laser shots is assigned to the dinitrene, 4,4’-dinitreno-3,3’-dimethoxybi-phenyl. Note that the absorption spectrum observed after a single laser shot, attributed to the triplet nitrene, is similar to that at 0 ps in Fig.l(b). This also indicates that photolysis J. MATER. CHEM., 1994, VOL. 4 A 600 400 500 600 wavelengthhm Fig. 1 Transient absorption spectra of 2.9 x mol dmP3 DADMB-cyclohexane solution. Laser fluence =4.4 mJ cm-*. Time region: (A) ns and (B) ps and ms. (A) Gate times: 4-20 ns (a); 102-141 ns (0).(B) Delay times: (a), 0 ps; (b), 15 ps; (c), 30 ps; (d), 50 ps; and (e), 1 ms. 400 500 600 wavelengthhm Fig. 2 Absorption spectral change of 3.0 x mol dm-3 DADMB in a rigid matrix of methylcyclohexane-isopentane at 77 K induced by laser irradiation. Laser fluence~0.7 mJ cm-2. Number of laser shots: (a) 1, (b)5, (c) 12, (d)24, (e)200 and (f)1500. of DADMB in cyclohexane at room temperature gives the 0 0 50 time/ps Fig.3 (a)Time dependence of the transient absorbance monitored at 350 nm (a)and 400 nm (0).(b)Time dependence of the rccciprocal absorbance monitored at 350 nm (a)and 400nm (3).These data are obtained from the same data as Fig. 1. absorbance at 350 nm was plotted against time after the laser excitation in Fig. 3(b).In this figure, a relationship between the reciprocal portion of the final product and the reciprocal time is also exhibited. These plots indicate clearly t:hat the decay of the triplet azido nitrene and the formatiori of the final product obey second-order kinetics. These results, com- bined with the previous reports that azo compounds were produced by the dimerization of triplet nitrenes created from aromatic azide~,~,’~-’~ indicate that the final product of photolysis of DADMB is most probably the azo compound (N3 -R-N=N-R-N,), 6,6’-diazido-!,2’-5,S-tetramethoxy- 1,l’-azobiphenyl.Dependence of the Intermediate and Final Product in Solution on the Fluence of the Excitation Laser Fig. 4 shows the transient absorption spectra at 0 ps and the absorption spectra of the final products for DADMR-cyclo- hexane solution observed with various excitation hser flu- ences. As the irradiation intensity increases, the absorption of the intermediate around 415 nm increases [Fig. 4(a)- (e)] and the absorption spectrum of the final products shifts tt,) longer wavelengths and becomes broader [Fig. 4(f),( g)]. As described above, irradiation of DADMB in a rigid matrix with 1500 laser shots at 77 K gives the dinitrcne, 4,4’- dinitreno-3,3’-dimethoxybiphenyl,which is produced by the triplet azido nitrene, 4-azido-3,3’-dimethoxy-4’-nitrenobi-elimination of two nitrogen molecules from the bisazide.The phenyl. p-Dimethylaminophenyl azide is one of the few compounds that does not give didehydroazepine derivatives in cyclohexane,’2 as is DADMB. This is why DADMB is a good sensitizer for negative resists. By using the spectra at 0 ps and 10 ms as reference spectra, we resolved the transient spectra in the time region up to 100 ps into two components [Fig. 3(u)]. The reciprocal shape of the transient absorption at 0 ps in the longer- wavelength region after a single shot with a high laser fluence of 20.9 mJ cm-’ [Fig.4(e)] is similar to that of the tlinitrene in a rigid matrix, although the absorption peak of the former is slightly shifted to shorter wavelength compared with the latter and the spectrum of the former is broader. Hence, the broad absorption around 415 nm is assigned to the dinitrene, h m8 II .-> -0 7v 8 c me5:Ll m 400 500 600 wavelengthhm Fig. 4 (u)-(e) Transient absorption spectra observed at 0 ps. (f)and (g)Absorption spectra of the final products observed upon various irradiation-laser fluences. Laser fluence: (a)4.6, (b)9.4, (c) 11.4,(d)18.5, (e) 20.9, (,f)4.5 and (g)18.5 mJ cm-*. Sample=3.8 x lop5mol dm-3 DADMB-cyclohexane solution.i.e. the photodecomposition of DADMB induced by laser irradiation with a high fluence gives the dinitrene through the elimination of two nitrogen molecules from the bisazide. Hence, the absorption spectra of the final products under irradiation [Fig. 4(b)] are due to the superposition of spectra of various species produced by reaction between intermediates such as azido nitrenes and dinitrenes. The formation of dinitrenes from bisazide compounds by intense laser irradiation was also reported for 1,s-diazidonaphthalene.” Photodecomposition of DADMB in PMMA Films Fig. 5 shows the transient absorption spectra of 10% w/w samples in the nanosecond time region. The absorption spec- trum at 1044143 ns is similar to that of DADMB-cyclohexane solution at 102-141 ns and at 0 ps and is assigned to the triplet azido nitrene, 4-azido-3,3’-dimethoxy-4’-nitrenobi-phenyl; as a consequence, it is inferred that the didehydroazep- ine derivative is not generated in PMMA films.The absorption F8 0.2[Too tmLl b 0.1 Fig. 5 Transient absorption spectra observed for 10% W/W DADMB-doped PMMA films. Gate times: 4-20 ns (0);104-143 ns ns (0). Laser fluence =8.6 mJ cmP2. J. MATER. CHEM., 1994, VOL. 4 spectrum at 4-20 ns is different from that of the triplet azido- nitrene. The time profiles of the absorbance at 350 and 400 nm were similar to those for DADMB-cyclohexane solution, and changes in the initial absorbance were complete within the duration of the laser pulse, indicating that triplet azido nitrene production was complete. These results indicate that, in the nanosecond time region, the photoreaction of DADMB in PMMA films is similar to that in cyclohexane solution.The transient absorption spectra of DADMB-doped PMMA films were measured in the time region from 0 ps to 1200 s. Irrespective of the DADMB concentration, the absorp- tion spectra at 0 ps observed upon laser irradiation with a low fluence (ca. 4 mJ cm-2) (Fig. 6) were due to the triplet azido nitrene, judging from the spectral shape. Laser irradiation with a high fluence, on the other hand, gave absorption with a shoulder around 420 nm in addition to the absorption around 350 nm (Fig. 7 and 8). When sample films were irradiated by a laser with a more intense Auence (31.8 mJ cmP2), the absorption intensity around 420 nm was comparable with that around 350 nm.These results are similar to the dependence of the excitation intensity on the transient absorption of DADMB-cyclohexane solution at 0 ps [Fig. 4(u)-(e)], indicating that laser irradiation with a high fluence on DADMB-doped PMMA films gives the dinitrene, 4,4’-dinitreno-3,3’-dimethoxybiphenylin the films. To clarify the change in the transient absorption spectra for a low fluence, time profiles of the transient absorbances at 350, 400 and 500 nm are shown in Fig. 9. The absorbance at 350nm due to the triplet azido nitrene decreased out to 100 ms. The absorbance at 350 nm increased with time from 1 s to several hundred seconds.Although the increased absorp- tion is located at the same wavelength as the absorption of the triplet azido nitrene, the former spectrum is sharp com- pared with the latter. Hence, the former absorption is not considered to be due to triplet azido nitrene, but to final products related to the reaction with PMMA. 400 500 400 500 wavelengt h/nm Fig. 6 Transient absorption spectra of 1% w,/w DADMB-doped PMMA films. Laser fluence=4.5 mJ cmP2. (a)0 ps, (b)1 ms, (c) 10 ms, (d) looms, (e) 500ms, (f)1 s, (g) 5 s, (h) 60s, (i) 120s, (j) 300s, (k)600 s and (I) 1200 s. J. MATER. CHEM., 1994, VOL. 4 400 500 400 500 wavelengthhm Fig. 7 Transient absorption spectra of 10% wjw DADMB-doped PMMA films. Laser fluence=21.4 mJ cm-’. (a)0 ps, (b)1 ms, (c) 10 ms, (d) 100 ms, (e) 500 ms, (f) 5 s, (g) 5 s, (h) 60 s, (i) 120 s, (j) 300 s, (k) 600 s and (I) 1200 s.400 500 400 500 wavelengthhm Fig. 8 Transient absorption spectra of 1% w/w DADMB-doped PMMA films. Laser fluence =29.9 mJ cm-’. (a)0 p,(b)1 ms, (c) 10 ms, (d) 100 ms, (e) 500 ms, (f)5 s, (g) 5 s, (h) 60 s, (i) 120 s, (j) 300 s, (k)600 s and (1) 1200 s. 0.1 \ I 1o-~ 1oo time/s Fig. 9 Time dependence of the transient absorbance monitored at 350 (O), 400 (0)and 500 (A)nm. (a) 10% w/w DADMB-doped PMMA films. Laser fluence=4.3 mJ cm-’. (b) 1% w/w IIADMB- doped PMMA films. Laser fluence=4.5 mJ cm-’. The value at 0 ps was plotted at lop6s (1 ps). The time evolution of the absorption spectra of dilute samples (1%0 w/w) induced by laser irradiation with a low fluence of 4.5 mJ cmP2 (Fig.6) was markedly different from those under other conditions, i.e. in the time region from 1ms to 1 s, a broad absorption around 500nm was observed in addition to the absorption at 350 nm. As shown in Fig. 9(b), the absorbance at 500nm increased until lOnis, then decreased and disappeared within 5 s. The absorption intensity around 500 nm increased with decreasing DADMB concen-tration and with decreasing laser fluence. Hence. species showing this absorption are due to intermediates related to the triplet azido nitrene. However, since the decay of the absorbance at 500nm does not agree with the rise of the absorbance of the final products at 350 nm, the intermediate with the absorption around 500 nm is not a direct precursor of the final products.For low fluence, it is surprising that the spectral change of the transient absorption continues up to 1200 s (Fig. 9). For high fluence, the spectral change of the transient absorption was complete within 300 s. This shorter reaction time com- pared with that for low fluence is due to an increase in the concentration of intermediates with two active groups such as dinitrenes. Fig. 10 shows the absorption spectra of the final products with various laser fluences. The absorption spectra for 1YO w/w samples are almost independent of the laser fluence [Fig. lO(f)-(i)] and agree with that of 10% w/w samples irradiated with a low fluence (4.3 mJ cm-’).For 10% w/w samples, the broad absorption of the final product at 420 nm increased with laser fluence. The broad absorption, however, was never observed for dilute samples even upon irradiation with a high fluence. Hence, the broad absorption is not related to isolated dinitrenes, i.e. the absorption is observed only when the distance between azido nitrenes and/or dinitrenes is short. These results suggest that DADMB molecules form aggregates in PMMA films and that dimerizatioli and/or polymerization oftriplet azido nitrenes and/or dinitre nes takes J. MATER. CHEM., 1994, VOL. 4 400 500 400 500 wavelength/nm Absorption spectra of the final products observed upon various irradiation-laser fluences. (a)-@) 10% w/w DADMB doped PMMA films.(f)-(i) 1% w/w DADMB-doped PMMA films. Laser fluence: (a) 4.3, (b)8.7, (c) 15.3, (d) 21.4, (e) 31.8, (f)4.5, (g)8.9, (h)20.5 and (i) 29.9 J cm-'. place in the aggregates. This is supported by the fact that the spectrum is very similar to those of the final product in DADMB-concentrated cyclohexane solution irradiated with a high fluence (Fig. 4).The reaction time of the dimerization and/or polymerization in the polymer matrices was not deter-mined because of the difficulty in discriminating between the absorption spectra of the dinitrenes, their intermediates and final products. The present experimental results suggest the photoreaction mechanism for DADMB shown in Fig. 11. Let us consider the chemical reaction of nitrenes in polymer films.On the basis of TR results and a GPC measurement of the final photoproducts, the reaction of nitrenes in polymer N3-R-N3 (irradiation with (within the duration dthe laser pulse) J I, ,, readionwith { dimerbatbn polymers i(<300s) andor , ,, polymerization i matrices is considered to be as follow^:'^*^^ Ar-N:+ P-H + Ar-NH + P' (polymer) (arylamino radical) (polymer radical) Ar-NH+P-H+ Ar-NH, +P' (primary amine) Ar-NH+P'-Ar-NH-P (polymeric secondary amine) P +P-+ P-P (polymer with increased molecular weight) Irradiating the bisazide compounds with a single shot of low fluence gives predominantly the azido nitrene, as mentioned above. The probable intermediates are arylamino radicals N,-R-NH and polymer radical P'. The final products are primary amines N, -R-NH,, polymeric secondary amines N,-R-NH-P, and crosslinked polymers P -P.The transi-ent absorption spectra in the time region from 0 ps to 1200 s are similar except for the appearance of an absorption at 500nm and the difference in the sharpness of the 350nm absorption band between final products and azido nitrene (0 ps). Hence we could not deconvolute these spectra. As for the intermediates and final products, the absorption spectra of arylamino radicals and primary amines should be independent of the polymer matrix, while the absorption spectra of the polymer radicals and polymeric secondary amines seem to depend upon the polymer. The time profile of the transient absorption spectra of 1 wt.% DADMB-doped poly(n-propyl methacrylate) films irradiated with a low fluence of 4.5 mJ cmP2(an absorption at 500 nm at 1 ms-1 s, spectral change up to 1200 s and so on) was similar to that of 1 wt.% doped PMMA films irradiated under the same conditions.The absorption at 500nm, however, was not observed for photodecomposition of DADMB in Novolac films.17 Hence the intermediate that absorbs at 500nm, which is related to azido nitrene and is present only during the period 1 ms-1 s, cannot be assigned to arylamino radicals (N, -R-NH). Furthermore, although polymer radicals are produced under all experimental conditions, the absorption at 500 nm is observed only for dilute samples irradiated with a low fluence, as mentioned above.These results suggest that the photorec-tion mechanism for the nitrene of the present compound in --. I*-.--. I I-.-..-readionwith dlmerization I (4mq in ---.pp,lymers I-..(>12OoS) :(>1200 s) cycbhexane) --.-. I I I-.-. I ---.-..\ Fig. 11 Scheme of the photoreaction of DADMB in PMMA films J. MATER. CHEM., 1994, VOL. 4 polymer matrices is more complicated than that proposed generally on the basis of IR spectra and GPC measurements of the final products. On the other hand, since the absorption at 350nm in the final absorption spectra was commonly observed for these polymer matrices, the spectrum could be assigned to primary amines. That is. final products for irradiation with a low fluence in Fig.11 contain primary amines with &ax= 350 nm. Although the precursor of the primary amine is the arylamino radical, the absorption spec- trum of the radical is not identified in the wavelength region measured. The spectrum may also be similar to the spectra around 350 nm of azido nitrenes and primary amines. For high fluence, the dinitrene is produced in addition to the azido nitrene. Hence we should consider the following intermediates in addition to the aryl radical N, -R-NH and polymer radical P' : nitreno amino radical (:N-R-NH), bisamino radical (NH-R -NH), nitreno polymeric second- ary amine (:N-R-NH -P) and amino radical polymeric secondary amine (NH-R-NH-P). As a result, the probable final products are NH, -R-NH,, NH, -R-NH-P, P-NH-R-NH-P, N,-R-NH,, N,-R-NH-P and P-P.Since, for 10% w/w samples, dimerization and/or polymerization occurs in polymer matrices, these reactions should also be considered. Furthermore, since it is impossible to deconvolute the spectra, it is difficult to assign the spectra of these intermediates and final products. Since transient intermediates in the photoreaction of diazo compounds such as diazonaphthoquinones for positive photoresists do not react with polymer matrices, the identification of the inter- mediates was easy compared with the present compound, and the results in polymer matrices have been reported by Rosenfeld et a/." References 1 T. Yamaoka, H. Kashiwagi and S. Nagakura, Bull. Clrem. Soc.Jpn., 1972, 45, 361. 2 M. Sumitani, S. Nagakura and K. Yoshihara, Bull. Cltem. Soc. Jpn., 1976, 49,2995. 3 A. K. Schrock and G. B. Schuster, J. Am. Chem. SOC., 1984, 106, 5228. 4 A. K. Schrock and G. B. Schuster, J. Am. Chem. Soc., 1984, 106, 5234. 5 T. Kobayashi, H. Ohtani, K. Suzuki and T. Yamaoka. J. Phys. Chem., 1985,89,776. 6 E. Leyva, M. S. Platz, G. Persy and J. Wirz, J. Am. Chem. SOC., 1986,108,3783. 7 C. J. Shields, D. R. Chrisope, G. B. Schuster, A. J Dixon, M. Poliakoff and J. J. Turner, J. Am. Chem. Soc., 1987, 109,4723. 8 T-Y. Liang and G. B. Schuster, J. Am. Chem. Soc., 1987,109,7803. 9 A. Miura and T. Kobayashi, J. Photochem. Photohiol. .I: Chem., 1990,53, 223. 10 M. Toriumi, N. Hayashi, M. Hashimoto, S. Nonogaki, T. Ueno and T. Iwayanagi, Polym. Eng. Sci., 1989, 29, 868. 11 A. Yabe, A. Ouchi and H. Moriyama, J. Chem. SOC.,Chem. Commun., 1987, 1744. 12 Y-Z. Li, J. P. Kirby, M. W. George, M. Poliakoff and G. B. Schuster, J. Am. Chem. SOC., 1988,110,8092. 13 A. Marcinek, E. Leyva, D. Whitt and M. S. Platz, J. Am. Chem. Soc., 1193, 115, 8609. 14 A. Reiser, H. M. Wagner, R. Marley and G. Bowes, Trans. Faraday Soc., 1967,63,2403. 15 S. Nonogaki, Polym. J., 1987, 19,99. 16 M. Hashimoto, T. Iwayanagi, H. Shiraishi and S. Nonogaki, Polym. Eng. Sci., 1986,26, 1090. 17 A. Itaya, T. Inoue, H. Miyasaka, T. Ueno and M. Tcriumi, to be submitted. 18 A. Rosenfeld, R. Mitzner, B. Baumbach and J. Bendig, J. Photochem. Photohiol. A: Chem., 1990,55, 259. Paper 4/02611J; Received 3rd Mt.iy, 1994.

ISSN:0959-9428    

DOI:10.1039/JM9940401539

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

J. MATER. CHEM., 1994, 4( lo), 1547-1558 Molecular Design of Amphotropic Materials: Double-headed Diol-based Mesogens Incorporating Rigid Structural Units Frank Hentrich,” Carsten Tschierske,*a Siegmar Dieleb and Christiane Sauee a Martin-Luther-University Halle- Wittenberg, Department of Chemistry, Institute of Organic Chemistry, Weinbergweg 76, 0-06708 Halle, Germany Martin-Luther-University Halle- Wittenberg, Department of Chemistry, Institute of Physical Chemistry, Muhlpforte 7, 0-06708 Halle, Germany The syntheses of novel bolaamphiphilic trio1 and tetraol compounds incorporating rigid structural units are described. Their liquid-crystalline properties were investigated by polarizing microscopy, differential scanning calorimetry and in some cases also by means of X-ray diffraction.Most 4,4-disubstituted biphenyl derivatives exhibit one or more smectic phases (predominantly SA but also Sc, SB, SG and S,J and extraordinarily high clearing temperatures. No therrnotropic liquid-crystalline properties could be detected for bolaamphiphiles incorporating a single 1,4-disubstituted phenyl ring or a 2,6-disubstituted naphthalene ring system, but for naphthalene derivatives a lyotropic smectic A phase was induced by addition of water. If one of the diol groups of the biphenyl-derived bolaamphiphiles is replaced by a single hydroxy group or by a carboxylic acid group the mesophase stability is decreased. Mesomorphic properties are lost if the hydrogen-bonding density is further diminished by the replacement of one diol group by an ethyl carboxylate group.However, in these cases lyotropic liquid-crystalline phases can be induced by the addition of water. Synthetic amphiphiles that consist of a hydrophilic 1,2-diol unit connected to a higher alkyl chain (n>5) have recently been prepared.’,2 These compounds exhibit thermotropic and lyotropic liquid-crystalline behaviour. As for the large family of mesogenic carbohydrate derivative^,^^' and related poly- hydroxy corn pound^,^-^^ and also for diisobutylsilanediol,’2 the formation of hydrogen-bonding networks between the hydroxy groups is the driving force for the formation of liquid-crystalline phases. In very recent studies it was observed that the hydrophobic portion of these bilayer-forming amphi- philes can be replaced by a single chain containing a rigid segment, such as a phenyl or biphenyl gro~p.’~-’~ This gives rise to extended mesomorphic ranges.It was also found, that -a-o-type (bolaform) amphiphile~,’~~’~ which consist of two diol head groups connected by one hydrocarbon chain,, exhibit ordered and disordered lamellar liquid-crystalline phases with a largely increased mesophase stability, compared with the parent amphiphilic diol~.”-~’ There is an increasing interest in bolaamphiphiles since in aqueous solution they can aggregate to form thin monolayered lipid membranes and bolaform lipids are known to be constituents of the cell walls of archaebacterial thermophiles, which thrive xt high temperatures.’ As an extention of these studies, novel biamphiphjlic poly- hydroxy compounds incorporating rigid structural units are reported.It was the aim of the investigations to find out how spacer: = -(CH2)”--(CH2CH20)n-hydrophilichead group: OH OH calamitic unit: biamphiphilic calamitic polyol mesogen the rigid structural units influence the phase behaviour of these bipolar amphiphiles. Their structures are shown later. A single phenyl ring, a biphenyl ring system, the 2,6-disubstituted naphthalene unit or the 1,o-diphenoxyalk- ane units were connected via hydrophobic or hydrophilic spacers to the diol head groups or single hydroxy groups. With respect to spacer length and head-group structure symmetrical and desymmetrized bolaamphiphiles were synthesized. Synthesis According to Schemes 1-3 the symmetrical bolaamphiphilic compounds (1-6) were obtained by Mitsunobu etherifi-cation22 of commercially available bifunctional phenols ( hydroquinone, 4,4’-dihydroxybiphenyl or 2,6-dihydroxy-naphthalene).Compounds 7, which are structurally related to the biphenyl derivatives 3 but possess benzene rings that are decoupled by a more or less extended additional spacer, were synthesized in a multistep synthesis as outlined in Scheme 4. Hydroquinone monobenzyl ether 20 was thereby treated with 2,3-epoxypropanolZ4 to give the diol 21. The 1,2-diol group was protected as cyclic acetonide and the benzyl group was removed by reduction with lithium in liquid ammonia.25 After alkylation of the resulting phenol 22 with appropriate 1,w-dibromo alkanes and subsequent acidolytic deprotection of the diol group the bolaamphiphiles 7.1-7.3 were obtained.Bolaamphiphiles with a desymmetrized structure were syn- thesized according to Schemes 5-7. Mitsunobu etherification and osmium tetraoxide catalysed bishydroxylations26 were the key steps in the synthesis of compounds 3.4, 3.5 and 8. The bolaamphiphilic triols 9.1 and 9.3 (n=3 and 11, respectively) were obtained by alkylation of 4-allyloxy-4’-hydroxybiphenyl24 with 3-bromopropanol or 1 1-bromoundecanol in the presence of potassium ~arbonate,’~ 10 ’1 11-13 H20, MeOHI4, TosOH HO>(C O(CH2)n< OH HO OH1-3 Scheme 1 Synthesis of the bolaamphiphilic tetrols 1-3 (n= 1: 2.1, 3.1, 10.1, 12.1, 13.1; n=4: 1, 2.2, 3.2, 10.2, 11.2, 12.2, 13.2; n=9: 3.3, 10.3, 13.3) J.MATER. CHEM., 1994, VOL. 4 followed by dihydroxylation of the allylic double bond (Scheme 6). Owing to the readily occurring cyclization of 6-bromohexanol under basic conditions an alternative synthesis was used for the triol 9.2 (n=6). Ethyl 6-bromohexanoate was used as alkylating agent. After alky- lation, the carboxylate group was reduced to give the triol 9.2. Furthermore, the intermediate allylether 30 and the 6-(4‘-allyloxybiphenyl-4-yl)hexanoic acid, which was obtained by saponification of 30, were dihydroxylated to give the ethyl carboxylate 32 and the carboxylic acid 33, respectively. Thermotropic Behaviour The mesomorphic behaviour of the compounds synthesized was investigated by polarizing microscopy, differential scan- ning calorimetry and in some cases by X-ray diffraction measurements.The transition temperatures are given in Tables 1-3. No thermotropic liquid-crystalline properties could be detected for bolaamphiphiles incorporating a single 1,4-disubstituted phenylene ring or a 2,6-disubstituted naph- thalene ring. If the phenyl derivative 1 is compared with the 1,2,17,18-tetrahydroxyoctadecane3619 (Fig. 1 ), which could be regarded as the simple alkyl analogue of 1, the mesophase destabilizing influence of the benzene ring becomes evident. This behaviour is contradictory to that of amphiphilic diol compounds, whose liquid-crystalline phases are considerably stabilized by the introduction of a single 1.4-disubstituted phenyl ring (3813) or a 2,6-disubstituted naphthalene unit (3928in Fig.2). If the aliphatic compound 36 and the biphenyl derivative 3.2 are compared it is clearly visible that the liquid-crystalline phases of the bolaamphiphilic tetraols are significantly stabil- ized by the introduction of a rigid biphenylene unit. It can be concluded that for bolaamphiphiles a rigid unit consisting of at least two aromatic rings is necessary for the occurrence of mesophases. The biphenyl derivative 3.1 with two short chains between the rigid core and the diol groups exhibits an S, phase with a very high clearing temperature. Elongation of these alkylene groups (3.2 and 3.3) and separation of the phenyl rings by an alkylene spacer (7.1-7.3) diminishes the ability for liquid- crystal formation. The decrease of the mesophase stability with increasing spacer length is even more pronounced if these spacers are oligooxyethylene units.If 3.1 is compared with the oligoethy- lene glycol derivatives 4.1-4.3 (Table 2), it is obvious that the clearing temperature considerably decreases M ith elongation of the oligooxyethylene chains. Compound 5 with two hydrophilic propan-1,3-diol units separated from the biphenyl core by long alkylene chains forms an S, phase. The typical schlieren texture observed on cooling from the isotropic melt is shown in Fig. 3(a). Further cooling causes transition to a higher ordered phase [Fig.3(b)] and finally crystallization [Figure 3 (c)] occurs. From X-ray diffraction studies the Guinier patterns of 5 confirm the observed S, phase. An inner reflection, together with its second-order, and an outer diffuse scattering have been found, which prove the layer packing with statistically distributed lateral distances. At lower temperature this com- pound exibits a high-ordered smectic phase. In this phase the inner-layer reflection (up to 6 orders) and several outer interferences have been detected [Fig. 4(a)]. These inter-ferences could be indexed assuming a monoclinic cell. The ratio a/b< 1and the type of interferences suggest an SKphase? ~~ t It should be emphasized that this phase type is considered to be a strongly disordered crystalline one.See for example ref. 29. J. MATER. CHEM., 1994, VOL. 4 H-(OC H&H,),--OH 1. NaH, PhCH2Br, THF 2. soc121 PhCH2--(OCH2CH2),--CI 14 NaOH, H20, cat. Bu,N+ HS0,-10.1 ' PhCH2--(OCH2CH2)@4H2 15 Li. NH,, EtgJ H+OCH2CH2)"4H24=& 1 0 16 HO OH;;;-N=N-C02Et 0 ~0~CH2-(OCH2CH2)~0~~OCH2cH2~~0-cH2 17 HZO. MeOH, cat. Py TOSOHI HO >CH2-(OCHPH,)P* (OCH2CH2),,0-CH,,OH HO OH 4 Scheme 2 Synthesis of the bolaamphiphilic oligoethylene glycol derivatives 4 (n= 1: 4.1, 14.1, 15.1, 16.1, 17.1; n=2: 4.2, 14.2, 15.2, 16.2, 17.2; n=3: 4.3, 14.3, 15.3, 16.3, 17.3) with herring-bone packing of the short molecular axis within the ab plane. In order to investigate the influence of desymmetrization on the thermotropic behaviour of mesomorphic bolaamphi- philes, compounds with different spacers (3.4 and 3.5) and with different head groups at both terminals of the molecule have been synthesized (Table 3).Symmetrical and desymme- trized compounds that differ only in the spacer length exhibit comparable mesophase stabilities. Since the latter compounds exhibit lower melting temperatures larger mesomorphic ranges result and additional low temperature mesophases could be found. For example, on cooling the homeotropically oriented S, phase of 3.4 a phase transition was detected by the formation of star-like domains that grow fern-like and finally coalesce to a mosaic texture. This fern-like texture (shown in Fig.5)is a strong hint for a S, phase.? Compounds 3.5 and 9.2, which show dimorphism SB/SA, have also been studied by X-ray investigations. The Guinier patterns of the S, and SB phases exhibit an inner reflection and its high order indicates a layer packing. In the patterns of the SA phases a diffuse outer interference between 9" and 11O proves the statistical distribution of the lateral distances. t It should be emphasized that this phase type is considered to be a strongly disordered crystalline one. See for example ref. 29. In the SB patterns one outer reflection has been detected, which is well known for the SB phase [Fig. 4(b) and (c)]. Comparing the d values of the layer reflection in the SBphases with the length of the molecules (estimated by CPK models), a ratio of d/Lzl was found.This points to monomolecular smectic layers. The d values of the S, phases are slightly smaller. That means, that the alkyl chains are more flexible then in the SBphases. The lattice constants of the S,I:phases, which were calculated under assumption of a hexagc ma1 cell, are summarized in Table 4. Comparison of the tetra01 3.4 with the triol 9.2, in which one of the diol groups is replaced by a single hydroxy group, indicates a depression of the clearing temperature by approximately 25 K. The hydrogen- bonding density is further diminished by the replacement of one diol group by an ethyl carboxylate group (32), which only acts as proton acceptor in hydrogen bonding. However, liquid crystal- linity is restored if the ethyl carboxylate group of 32 is removed and replaced by an alkyl chain (3414in Fig.6). As became evident from X-ray investigation, the am phiphilic diol 34 forms a bilayered SA phase (d/L=1.84) whcreas the S, phase of the biamphiphilic triol 9.2 is monolayered. Miscibility studies reinforce the different phase structures of 9.2 and 34. Whereas in the binary system of the bolaamphi- philic tetrol 3.5 and triol 9.2 complete miscibility wm found, for the binary system of the bolaamphiphile 3.5 and the J. MATER. CHEM., 1994, VOL. 4 1. EtO2C-N=N-COgt, PPh3 2. HZO,MeOH, Py 'TosQHHO-(GH$H~0)3 Scheme 3 Synthesis of 4,4'-bis [11-(1,3-dihydroxypropyl-2-yl)undecyl-oxy] biphenyl 5 and 4,4'-bis( 9-hydroxy- 1,4,7-trioxanonyl)biphenyl623 20 '%OH KOH, MeOH I 23 MeOH, H20 Py TosOH10 ,H,<Ho>cHzo O(CH2)"O~ OH 10 3.Hfl,MeOH Et02C-N=N-C02Et, pYm PPh3 24 26 NMMNO, cat. OsO,I H20, MeOH TosOH 8.1 Scheme 5 Synthesis of the bolaamphiphilic tetrols 3.4, 3.5 and 8.1 (n=4: 3.4, 10.2; n=9: 3.5, 10.3) amphiphile 34 miscibility in the S, phase was not complete. It seems, that by decreasing the hydrogen bonding ability of one terminal it is possible to change from a monolayered phase structure (bipolar amphiphiles 9.2 and 3.5) to a bilay- ered one (monopolar amphiphiles such as 34). Fig. 6 illustrates the stepwise transition from the biamphiphilic polyol to the amphiphilic diol. The hydrogen-bonding networks at both terminals of the molecules forces the bolaamphiphiles strongly to self-organize into monolayers. Monopolar amphiphilic diols (eg.34) are also prone to form large hydrogen-bonding networks, but only one terminal can take part in hydrogen bonding and segregation of the different parts of the individual molecules gives rise to the formation of bilayered aggregates. If one terminal group of a biamphiphilic compound is polar and acts only as proton acceptor, it might also be incorporated in the hydrogen-bonding networks of the diol groups. The incorporation of these additional proton acceptors partially breaks the hydrogen-bonding networks and results in a lower 7 stability of the lamellar associates. Therefore these compounds Scheme 4 Synthesis of the 1,o-bis [4-(2,3-dihydroxypropoxy)phenyl]-exhibit a significant lower tendency to form smectic meso- alkanes 7.1-7.3 (n= 3: 7.1, 23.1; n=6: 7.2, 23.2; n= 12: 7.3, 23.3) phases. The crystalline carboxylate 32 and the nematic cyano biphenyl derivative 35 are examples of such materials.J. MATER. CHEM., 1994, VOL. 4 Ho> OH CH20*O(CH2h,< 8.2 2. NMMNO, cat. OsO,28 Et02C-N=N-CO,Et, PPh, 24 29 NMMNO, cat. OsO,I n= 3: 9.1 n= 11: 9.3 Scheme 6 Synthesis of the bolaamphiphilic tetrol 8.2 and the bolaamphiphilic triols 9.1 and 9.3 (n=3: 9.1, 29.1; n= 11: 9.3, 29.3) 30 LiAIH4. Et@I H2C=CH-CH20*O(CHIJa-OH 31 NMMNO, cat. OsO, 9.2 Scheme 7 Synthesis of the 4-( 3,4-dihydroxypropyl)-4’-(6-hydroxy-hexyloxy)biphenyl, 9.2 Effect of Water on the Mesomorphism It has been shown that the self-organization of diol mesogens is influenced by the addition of water.1,15”6,20Water molecules can be incorporated into the hydrogen-bonding networks of the diol groups and in this way their mesomorphic properties are significantly changed. Representative phase diagrams of binary systems consisting of amphiphilic diols and water have also been reported.1*15,30-32 These investigations have estab-lished that the mesophase stability of the diol compounds is continuously increased by the addition of water.However, above a certain diol-to-water ratio the transition temperatures remain constant and the excess of water forms a second phase.From this it can be concluded that the uptake of water is limited. One molecule of a simple n-alkane-1,2-diol’ can take up 2-3 molecules of water. Most of the bolaamphiphiles incorporating the biphenyl rigid core have thermotroplic clear-ing temperatures above 200°C. Therefore we have limited these investigations to compounds without therniotropic mesophases and to those with low clearing temperatures. Herein we only report the first investigations concerning the influence of water on the mesomorphic behaviour of these new materials. These compounds were investigated by heating-contact preparations in sealed capillaries with an excess of water on a hot-stage and with observation of the contact zone of the samples by means of polarizing microscopy.Applying this experimental procedure only a qualitative picture of the phase behaviour was obtained. However, the reproducibility of the results for the clearing temperatures of tho water-saturated samples was surprisingly good. The poor orientation of the rather thick samples in the capillaries made the investi-gation of the textures extremely difficult. In some cascs, when crystallization takes place well below 100°C we were also able to observe the textures of the mesophases by polarizing microscopy of the water-saturated samples between cover-glasses. The compounds investigated (e.g., 2.2,4 and 9) in this way generally exhibit an SA phase that is indicated by the formation of large pseudoisotropic areas separated by oily streaks.Fan-like textures are seldom observed. In addition a continuous increase of the clearing temperature on going from the water-free to the water-saturated regions of the contact preparations was observed. Hence there is no borderline between thermotropic and lyotropic liquid-crystallint: phases. Therefore we also use the descriptors of the therrnotropic phases (SA,S,, etc.) to describe the mesophases of the water-containing samples of bolaamphiphilic multiols incorporating calamitic structural units. The transition temperatures of the water-saturated samples of the newly synthesized compounds investigated are included in Tables 1-3. It is obvious that the addition of uater not only raises the clearing temperatures, but also lowers the melting temperatures.Thus it induces liquid-crystalline properties for bolaamphiphilic naphthalene derivatives 2,com-pounds with two separated phenyl rings 7 and boilaamphi-philes with extended spacer units 3.3. Compound 1 with a single benzene ring as rigid unit is the only compound without any liquid-crystalline properties. Smectic phases are also induced for bolaamphiles with restricted hydrogen-bonding ability at one terminal (32and 3516)or at both terminals (6). The comparison of the ethylene glycol derivatives 6 and 4.2 (Table 2) indicates the significance of the diol groups. Compound 6 with a single hydroxy group at each of the molecular terminals displays liquid-crystalline properties only in the presence of water. Here the formation of suifficiently large hydrogen-bonding networks is mediated by the water molecules between the oligoethylene glycol chains.However, the introduction of additional hydroxy groups (e.g., 4.2) enables the occurrence of liquid-crystalline phases also in the absence of water, because the inherent hydrogen .bonding ability of these molecules is again sufficient to form layered mesophases. We suggest that this novel structural principle of bolaamphiphilic multiols should be applied as a valuable source for the mesophase directed design of novel Lyotropic and amphotropic materials. Experimental The experimental procedures for the syntheses of some rep-resentative compounds are described. All other ho~inologues 1552 J. MATER.CHEM., 1994, VOL. 4 Table 1 Transition temperatures ("C) and associated enthalpy values (kJ mol-l, in parentheses) of the water-free and water-saturated samples of the bolaamphiphilic tetrols 1, 2, 3 and 7 HO x ~o~cHz)m<oHOH HO water-free sample water-saturated sample compound X n rn Cr S SA I Cr SA 1 1 440 108 ----0070--0 2.1 0 0 123 0 145 0 2.2 44 0 154 ----0 0 77 0 148 0(37.3) 245 --3.1 110 (13.5) 202.53.2 440 202 --2043.3 9 9 0 (58.7) ----0 0 118 0 169 0 * 3.4 1 4 180 SG 187 245 183 189 223 0-----3.5 1 9 0 (13.9) SB (5.7) (24.6) 7.1 11. 154 ----122 192 7.2 ~o(cHz)601 ~1 0 187 ----0 0 142 0 194 0 Cr =crystalline solid; S,, SB and SG =smectic A, B, G, and I =isotropic liquid.Table 2 Transition temperatures ("C)and associated enthalpy values (kJ mol-', in parentheses) of the water-free samples of the bolaamphiphilic oligooxyethylene derivatives 4 and 623 and 4,4'-bis [11-(1,3-dihydroxypropyl-2-yl)undecyloxy]biphenyl 5 (for the explanation of the abbreviations see Table 1). The clearing temperatures of the water-saturated samples are all above 100"C compound R Cr S sc SA 1 4.1 -O-CH2CH~-O-CH~-CH(OH)-CH~OH 162 ----0 177 0 (13.5) (10.2)4.2 -O-(CH2CH2-0)2-CCH~-CH(OH)-CH~OH 127 (SB 123) --_ --0 (60.4) (30.9) ----0-4.3 -0-(CH2CH2-0)3-CH, -CH(OH) -CH,OH 89 -6 -0-(CH,CH,), -0-CH, -CH20H 0 68 ------0 5 -0-(CH,), -CH(CH,OH), 158 SK 176 181 --0 (70.6) (20.4) (23.4) J. MATER. CHEM., 1994, VOL.4 Table 3 Transition temperatures ("C) and associated enthalpy values (kJ mol-', in parentheses) of the water-free samples 8, 9, 32 and 33 (for an explanation of the abbreviations see Table 1). The transition temperatures of the water-saturated sample of 32=Cr 105 S, 158 I HO compound R Cr N" I 8.1 8.2 9.1 9.2 9.3 32 33 -0-CH2 -CH(CH,OH), -O-(CH,),l-CH(CH~OH), -0-(CH,), -OH -0-(CH,), -OH -O-(CH,),l-OH -0-(CH,), -COOC2H5 -0-(CH,), -COOH 0 0 a 0 0 0 210 (6.3)180 (22.8)227 (14.6) (14.7) (26.5) (36.0) (24.6) 172 184 154 177 260 207 242 209 188 (16.2) (26.2) ( 16.9) (17.3) (22.1) -23 1 ( 13.8) -~ --~ - --~ --~ - a a 0 0 0 0 0 N =nematic. 202.5 202 SA 180 160 140 137 134 La Y 120 I- 100 108 80 79 60 compound: 36 1 2.2 3.2 Fig.1 Comparison of the thermotropic properties of the structurally related bolaamphiphilic tetrols 36,'' 1, 2.2 and 3.2 (black areas indicate the crystalline state) were obtained by analogous procedures and gave satisfactory elemental analyses and 'H nuclear magnetic resonance (NMR) spectra. Confirmation of the structures of intermediates and products was obtained by 'H and 13C NMR spectroscopy (Bruker WP 200 spectrometer), infrared (IR) spectroscopy (Specord 71 IR) and mass spectrometry (AMD 402, electron impact, 70 eV). Microanalyses were performed using an Italian Carlo-Erba 1102 elemental analyser. All final compounds were purified by repeated crystallization from distilled chloro- form until the transition temperatures remain constant.Their purity was checked by thin-layer chromatography (Merck, silica gel 60 F254).Chloroform-methanol mixtures were used as eluents and the spots were detected either by ultraviolet (UV) irradiation or by spraying with Bromothymol Blue solution. Transition temperatures were measured using a Mettler FP 82 HT hot-stage and control unit in corijunction with a Nikon Optiphot 2 polarizing microscope. The trans- ition temperatures were confirmed using differential scanning calorimetry (Perkin Elmer DSC-7 and Perkin Elmer Series 1020 data station). 2,6-Dihydroxynaphthalene, 1,2-O-isopro-pylideneglycerol, diethyl azodicarboxylate, 1,12-dibiromodo- decane, ethyl 6-bromohexanoate, hexane-1,2,6-triol ( Aldrich), 4,4'-dihydroxybiphenyl, 1,3-dibromopropane and 1,6-dibro-mohexane (Merck) were used as supplied.Triphenylp hosphine (Merck) was crystallized twice from ethanol and dried in uucuu (0.1Torr) at 60 "C for 12 h. Ethylene glycol, dlethylene glycol, triethylene glycol and 2,3-epoxypropanol (Merck) were distilled in uucuu prior to use. 4-Allyloxy-4'-hydroxy biphenyl, 4-allyloxyphenol, 4-benzyloxyphenol, I-chloro-4-phenyl-3-oxabutane, l-chloro-7-phenyl-3,6-dioxaheptane,1-chloro-10- J. MATER. CHEM., 1994, VOL. 4 194 180--160-160 -140-13' m0 ' e, 120-119I--100-60-61 -(57) compound: 37 38 39 34 Fig. 2 Comparison of the thermotropic properties of the structurally related amphiphilic diols 37,' 38,13 39 and 3414 (black areas indicate the crystalline state) phenyl-3,6,9-trioxadecaneand 5-hydroxymethyl-2-isopropyl-1, was removed by evaporation and the residue crystallized from 3-dioxane were synthesized according to standard literature procedure^.^^-^^ 1,2-O-Isopropylidenehexane-1,2,6-triol(10.2) and 1,2-O-isopropylideneundecane-1,2,1l-triol(10.3) were obtained by acetalization of hexane-1,2,6-triol and undecane-1,2,11 -tri01~*,~~ with 2,2-dimethoxypropane. 2,6-Bis [2,3-(isopropylidenedioxy) propoxy ]naphthalene (12.1) 2,6-Dihydroxynaphthalene (0.48 g, 3.0 mmol) and tri-phenylphosphine (2.36 g, 9.0 mmol) were dissolved in tetrahydrofuran (30 ml).After addition of 1,2-O-isopropylid- eneglycerol (10.1; 0.92 g, 7.0 mmol) the mixture was cooled to between 0 and 5 "C.At this temperature diethyl azodicarboxyl- ate (1.56 g, 9.0 mmol) was added dropwise within 5 min to the stirred mixture. The solution was stirred for an additional 24 h at room temperature. Afterwards the solvent was evapor- ated offand the residue was crystallized twice from methanol- water (10 + 1) to remove the triphenylphosphine oxide. The crude product was repeatedly recrystallized (methanol) to leave white crystals (R,= 0.75, eluent CHC1,-MeOH, 10+0.5). Yield: 0.92 g (79%); mp 131 "C (Found: C, 67.94; H, 7.39%. C22H2806 requires C, 68.01; H, 7.27%); 'H NMR 6, (200 MHz, ['H6] DMSO): 1.26 (6 H, s, CH,), 1.31 (6 H, s, CH,), 3.58 (2 H, m, HCH-0), 3.90-4.11 (8H,m, CH,O-arom, HCH-0, CH-0), 7.03-7.25 (4 H, m, CH-arom), 7.69 (2 H, d, CH-arom).2,6-Bis( 2,3-dihydroxypropoxy)naphthalene (2.1) Compound 12.1 (0.39g, 1.0mmol) was dissolved in wet methanol (50 ml, containing 5% water). After addition of pyridinium toluene-p-sulfonate (50 mg) the solution was refluxed until the starting material could no longer be detected by thin-layer chromatography using light petroleum-ethyl acetate (10+1) as eluent (4 h). Afterwards the solvent was evaporated. The residue was dissolved in ethyl acetate (100 ml) and successively washed with water, saturated NaHCO, solu- tion, water and brine. After drying over Na2S04 the solvent light petroleum (bp 65-80 "C). Yield: 0.24 g (79%); mp 209 'C (Found: C, 62.27; H, 6.49 %. C16H2,06 requires C, 62.32; H, 6.54%); 'H NMR 6, (200 MHz, C2H6] DMSO): 3.47 (4 H, dd, CH20H), 3.75-4.12 (6 H, m, CH,O, CH-OH), 4.7 (2 H, t, CH,OH), 4.99 (2 H, d, CH-OH), 7.05 -7.18 (2 H, dd, CH-arom), 7.25 (2H,d, CH-arom), 7.70 (2H,d, CH-arom).4,4'-Bis( 2,3-dihydroxypropoxy) biphenyl, 3.1 This compound was synthesized according to the procedures given for 2.1 via 12.1, but starting from 4,4'-dihydroxybiphenyl (0.49 g, 3.0 mmol) and 1,2-O-isopropylideneglycerol(0.92 g, 7.0 mmol). Overall yield: 0.37 g (42%); transition temperatures ( OC): Cr 245 SA294 I; (Found: C, 64.27; H, 6.49%. CI8H2,O6 requires C, 64.65; H, 6.63%); 'H NMR 6, (200 MHz, C2H,]DMSO): 3.44 (4H, dd, CH,OH), 3.73-4.08 (6 H, m, CH,O, CH-0), 4.70 (2 H, t, CH,OH), 4.98 (2 H, d, CH-0), 6.97 (4 H, d, CH-arom), 7.52 (4 H, d, CH-arom).1,2-Isopropylidenedioxy-11-phenyl-4,7,1O-trioxaundecane, 15.2 A mixture of l-chloro-7-phenyl-3,6-dioxaheptane(14.2; 21.5 g, 0.1 mol), 1,2-O-isopropylideneglycerol(10.1; 13.2 g, 0.1 mol) tetrabutylammonium hydrogensulfate (0.5 g) and aqueous sodium hydroxide solution (50°/b, 50 ml) was vigorously stirred under reflux for 16 h. After cooling, water (100 ml) and diethyl ether (100 ml) were added and the organic layer was separated, washed twice with water (2 x 20 ml), once with NaHCO, (5%, 20 ml) and dried ( Na2S04). The oily residue obtained after evaporation of the solvent was fractionated in mcuo to give 15.2. Yield: 14.6g (47.1%); bp 145°C at 0.015 Torr. 'H NMR 6, (200 MHz, CDCI,): 1.31 (3 H, s, CH,), 1.40 (3 H, s, CH,), 3.44-4.40 (13 H, m, CH,O, CH-0), 4.55 (2H, s, Ph-CH,O), 7.31 (5 H, s, CH-arom).J. MATER. CHEM., 1994, VOL. 4 Fig. 3 Polarized optical microscopic texture of the mesophases of 5 as obtained by cooling from the isotropic melt: (a) at 179'C (S,-); (b)at 173 -C (S,); (c) at 155 "C (crystalline) 8,9-Isopropylidenedioxy-3,6-dioxanonane-l-ol,16.2 The benzyl protective group of 15.2 (15.5 g, 0.05 mol) was removed using lithium (0.87 g, 0.11 mol) in liquid ammonia (150 ml) according to the procedure given for 22. The residue, obtained after treatment with n-hexane, was dissolved in benzene (100 ml), dried over sodium sulfate and the solvent evaporated off to give an oily residue, which was distilled in vacuo. Yield: 5.4 g (49.1%); bp 110 "C at 0.02 Torr; 'H NMR 6, (200 MHz, CDCl,): 1.31 (3 H, s, CH,), 1.38 (3 H, s, CH,), 2.54 (1 H, s, broad, OH), 3.44-4.40 (13 H, m, CH20,CH-0).100 cl 024 6 8 100 8, ,I,, 0 2 4 6 8 10 0 2 4 6 8 10 eldegrees Fig. 4 Schematic plot of the interferences: (a) S, phase of compound 5 at 162 "C; (b)SB phase of compound 3.5 at 185"C; (c) SB phase of compound 9.2 at 185"C Fig. 5 Polarized optical microscopic texture observed at the [ransition from the smectic A phase (homeotropically oriented sample) to the low-temperature mesophase (S,) of compound 3.4 at 187"( Table 4 Structural parameters of the SB phase of compountls 3.5 and 9.2 (L was estimated using CPK-models) compound alnm dfnm Llnm dlL 3.5 0.5424 2.75 2.80 0.982 9.2 0.521 2.26 2.33 0.969 4,4'-Bis( 9,10-dihydroxy-1,4,7-trioxadecyl)biphenyl, 4.2 This compound was synthesized according to the procedures given for 2.1 via 12.1, from 4,4'-dihydroxybiphenyi (0.24 g, 1.5 mmol) and 16.2 (0.88 g, 4 mmol). The crude product, obtained after having worked up the etherification 'reaction, was used for the deprotection procedure.Overall yield: 0.32 g (42%); mp 127 "C; 'H NMR 8, (200 MHz, C2H6] DMSO): 3.25-3.58 (18 H, m, CH,O, CH-0), 3.75 (4 H, t, CH,O), 4.11 1556 Table 5 Structural parameters of the S, phase of 5" reflection no. O,,,/degrees O,,,,/degrees A0 hkl indices 1 1.234 --001 2 2.467 2.468 0.001 002 3 3.705 3.704 0.001 003 4 7.41 7.424 0.014 005 5 8.475 8.484 0.009 112 6 8.675 8.695 0.02 112 7 9.087 9.074 0.013 111 8 9.605 110 --0209 9.806 10 10.26 10.253 0.007 111 11 12.50 12.478 0.022 121 12 12.90 12.872 0.028 120 13 13.40 13.374 0.026 121 a Calculated lattice parameters: a =0.645 nm; b=0.904 nm; c = 4.293 nm; and p= 123.5".(4H, t, CH,O-arom), 4.46 (2H, t, CH,OH), 4.61 (2H,d, CH-OH), 6.99 (4H,d, CH-arom), 7.52 (4H,d, CH-arom). 11,12-Isopropylidenedioxy-3,6,9-trioxadodecan-l-ol,l6.3 This compound was synthesized according to the procedure given for 16.2 from l-chloro-10-phenyl-3,6,9-trioxadecane (14.3; 25.9 g, 0.1 mol). Overall yield: 9.8 g (37%); 1H NMR dH (200 MHz, CDC1,): 1.30 (3 H, s, CH,), 1.37 (3 H, s, CH,), 3.0 (1 H, s, broad, OH), 3.44-4.40 (17 H, m, CH,O, CH-0); 13C NMR dC (CDC1,): 25.2 (CH,), 26.6 (CH,), 61.5, 66.3, 70.2, 70.4, 70.5, 70.7, 72.2, 72.4, 74.5(CH), 109.2 (quart.C) 4,4'-Bis(12,13-dihydroxy-1,4,7,1O-tetraoxatridecyl)biphenyl, 4.3 This compound was synthesized according to the procedures given for 2.1 via 12.1, from 4,4'-dihydroxybiphenyl (0.24 g, 1.5 mmol) and 16.3 (1.06g, 4.0mmol). The crude product, obtained after work up of the etherification reaction, was used J. MATER. CHEM., 1994, VOL. 4 for the deprotection procedure. Overall yield: 0.53 g (59%); mp 89 "C; 'H NMR BH (200 MHz, C2H6]DMSO): 3.25-3.58 (26H,m, CH,O, CH-0), 3.74 (4 H, t, CH,O), 4.13 (4H, t CH,O-arom), 4.45 (2 H, t, CH,OH), 4.59(2 H, d, CH-OH), 6.98 (4 H, d, CH-arom), 7.52 (4 H, d, CH-arom). 4-[ 2,3-( Isopropylidenedioxy) propoxy] phenyl Benzyl Ether, 21 4-Allyloxyphenol (35 g, 0.175 mol) was added to a sodium methanolate solution, obtained by dissolving sodium (0.4 g, 17.5 mmol) in dry methanol (200 ml).After all the allyloxy- phenol had been dissolved, a solution of freshly distilled 2,3-epoxypropan-l-o1 (13 g, 0.175 mol) in dry methanol (80 ml) was added dropwise to the stirred mixture at room temperature and the mixture was refluxed for a further 8 h. Afterwards the solvent was evaporated and the residue dis- solved in ethyl acetate (150ml). After washing with dilute hydrochloric acid (50 ml), water (100 ml) and drying over Na,SO,, the solvent was distilled off using a rotatory evapor- ator. The crude product obtained was dissolved in dry acetone (100 ml).2,2-Dimethoxypropane (62.5 g, 0.6 mol) and pyridin- ium toluene-p-sulfonate (100 mg) were added and the resulting mixture was stirred at room temperature overnight. Afterwards, the solvent was evaporated off and the residue dissolved in diethyl ether (150 mlj. The solution was washed twice with NaHCO, solution (5%, 100 ml), with water (50 ml) and brine (50ml) and was dried over Na,SO,. The residue, obtained after evaporation of the solvent, was crystallized from methanol to give 21 as white crystals. Yield: 24 g (76%); mp 82°C. 4-[ 2,3-(Isopropylidenedioxy)propoxy]phenol, 22 Lithium (1.0g, 0.15 mol) was dissolved in liquid ammonia (150 ml). A solution of 21 (24 g, 0.076 mol) in dry tetrahydro- furan (50 ml) was added dropwise with stirring within 10 min at -33 "C.Stirring was continued for a further 10 min and any excess of lithium was destroyed by addition of ammonium chloride (15 g). The ammonia was allowed to evaporate off overnight and the residue was then suspended in diethyl ether 194 160 R = -O(CH2),-:HCHzOH -O(CHZ),-OH -0(CHZ),-COOEt -CN -C6H13 OH cornpound: 3.4 9.2 32 35 34 Fig. 6 Comparison of the thermotropic properties of the bolaamphiphilic compounds 3.4, 9.2, 32, 3516 and the amphiphilic diol 3414 (black areas indicate the crystalline state) J. MATER. CHEM., 1994, VOL. 4 (150 ml). Solids were filtered off and the ethereal solution was evaporated in uucuo. The oily residue was shaken three times with n-hexane (3 x 50 ml) to remove diphenylethane.The residue crystallized slowly and was used without further purification for the etherification. Yield: 15.8 g (93%); mp 67°C; 'H NMR 6, (200 MHz, CDC1,): 1.38 (3 H, S, CH,), 1.44(3 H, ~,CH3),3.81-4.18(4H,CH,O),4.44(1H,CH-0), 4.59 (1 H, s, OH), 6.75 (4 H, m, C-H arom). I3C NMR 6, (20 MHz, CDC1,): 24.4 (CH,), 26.8 (CH,), 66.8 (CH,O), 69.6 (CH,O-arom), 74.2 (CH-0), 110.0 (quart. C), 115.9 (CH-arom), 116.2 (CH-arom), 150.3 (C-0, arom), 152.5 (C-OH, arom). m/z 224 (M', 84%), 149 (43), 115 (loo), 110(48), 57 (58). 1,6-Bis(4-[ 2,3-( isopropylidenedioxy) propoxy ]phenoxy) hexane Compound 22 (1.04 g, 5 mmol) was dissolved in methanol (5 ml). A solution of potassium hydroxide (0.34 g, 6 mmol) in water (2 ml) and 1,6-dibromohexane (0.49 g, 2 mmol) was added.The solution obtained was refluxed for 5 h and after cooling to room temperature the solvent was distilled off. The residue was dissolved in diethyl ether (50 ml) and washed with water (50ml) and brine (50ml). After drying over Na,SO, the solvent was evaporated off and the residue crystallized from methanol. Yield: 0.74 g (70%); mp 122-130 "C (Found: C, 67.87; H, 8.08%. C30H4208 requires C, 67.89; H, 7.98%); 'H NMR 6, (200 MHz, CDCl,): 1.38 (6 H, s, CH,), 1.44 (6H, s, CH,), 1.50 (4 H, m, CH,), 1.77 (4 H, m, CH,), 3.82-4.18 (10 H, m, CH,O), 4.44 (4 H, quint. CH-0), 6.80 (8 H, s, CH-arom); m/z 530 (M+, 90"/0), 416 (33), 115 (loo), 83 (97), 55 (83), 43 (42). 1,6-Bis[44 2,3-dihydroxypropoxy) phenoxy] hexane, 7.2 The cleavage of the isopropylidene protective groups of 23.2 (0.53 g, 1 mmol) was achieved according to the procedure given for 2.1.Yield: 0.34 g (76%); mp 187 "C (Found: C, 63.85; H, 7.53%. C24H3408 requires C, 63.98; H, 7.61%); 'H NMR 6, (200 MHz, [2H6]DMSO): 1.43 (4 H, m, CH,), 1.65-1.71 (4 H, m, CH,), 3.42 (4 H, dd, CH,OH), 3.74-3.98 (10 H, m, CHZO, CH-OH), 4.62 (2 H, t, CHZOH), 4.88 (2 H, d, CH-OH), 6.82 (8 H, s, CH-arom); m/z 450 (M', 58%), 110 (loo), 83 (69), 55 (63), 44 (85). trans-4-Allyloxy-4-(2-isopropyl-l,3-dioxan-5-ylmethoxy) biphenyl, 26 4-Allyloxy-4-hydroxybiphenyl(24;0.68 g, 3.0 mmol) was eth- erified with 2-isopropyl- 1,3-dioxan-5-ylmethanol (25) (0.72 g, 4.5 mmol) according to the procedure given for 2.1. The crude product was recrystallized from methanol to leave white crystals.Yield: 0.86 g (78%); transition temperatures ( OC): Cr 145 SA 180 I (Found: C, 74.60; H, 7.58%. C23H2804 requires C, 74.96; H, 7.67%); 'H NMR 6H (200 MHz, CDCI,): 0.94 (6 H, d, CH,), 1.81 [l H, m, CH(CH,),], 2.52 (1 H, m, H-5 dioxane), 3.61 (2 H, dd, H-4,,, H-6,, dioxane), 3.76 (2 H, d, CH,O), 4.21 (2 H, d, H-4,,, H-6,, dioxane), 4.27 (1H, d, H-2 dioxane), 4.56 (2 H, m, CH, =CH-CH,O), 5.29 (1 H, dd, cis-CH2=CH), 5.40 ( 1H, dd, trans-CH, =CH), 6.03 (1H, m, CH2=CH), 6.88 (2 H, d, CH-arom), 6.95 (2 H, d, CH-arom), 7.45 (4 H, d, CH-arom); m/z 368 (M', loo%),327 (28), 279 (36), 185 (31), 169 (38), 71 (58), 41 (90). trans-442,3-Dihydroxypropoxy)-4'-(2-isopropyl-l,3-dioxan-5-ylmethoxy) biphenyl 27 Compound 26 (1.84 g, 5.0 mmol) was added to a solution of N-methylmorpholine N-oxide (0.75 g, 7.0 mmol) in acetone 1557 (20 ml).To this solution water (0.1ml) and osmium tetraoxide solution (0.05ml of 1% solution in toluene) were added. The resulting mixture was stirred for 24 h at room temperature. After this time starting materials could no longer be detected and the mixture was worked up as follows: sodium hydro- gensulfite (saturated solution, 5 ml) was added and the resulting slurry was vigorously stirred for 30 min nt room temperature. Afterwards the solids were filtered off through a pad of Celite, the residue was washed twice with ethyl acetate (2 x 50 ml) and the solvents distilled off using a rotarq evapor- ator.The residue was dissolved in diethyl ether (50 ml) and the solution was washed three times with water (3 x 25 ml) and brine and was finally dried over Na,S04. After evapor- ation of the solvent the residue was crystallized from n-hexane+thyl acetate (lo+ 1).Yield: 1.61 g (80%); mp 221 "C (Found: C, 67.95; H, 7.40%. C23H3006 requires (:, 68.63; H, 7.51%); 'H NMR 6, (200 MHz, [2H,]DMSB): 0.88 (6 H, d, CH,), 1.74 [l H, m, CH(CH,),], 2.32 (1 H, m, C-5 dioxane), 3.45 (2 H, dd, CH,OH), 3.53 (2 H, dd, H-4,,,, H-6,, dioxane), 3.80 (2 H, d, CH,O), 3.76-4.23 (6 H, m, H-4,,, H-6,, dioxane, CH,O, CH-OH, H-2 dioxane), 4.27 (1 H, d, H-2 dioxane), 4.67 (1 H, t, CH,OH), 4.95 (1 H, d, C€t-OH), 6.96 (2 H, d, CH-arom), 6.97 (2 H, d, CH-aroim), 7.51 (4 H, d, CH-arom); m/z 402 (M', loo%), 185 (34), 57 (33), 43 (45).442,3-Dihydroxypropoxy)-4'-[3-hydroxy-2-(hydroxymethyl )propoxy] biphenyl, 8.1 The cleavage of the 1,3-dioxane ring of 27 (1.21 g, 3 mmol) was achieved according to the procedure given for 2.1 using toluene-p-sulfonic acid ( 100 mg) instead of pyridinium tolu- ene-p-sulfonate. The crude product was repeatedly crystallized from chloroform. Yield: 0.74 g (71 YO);transition temperatures ( OC): Cr 210 SA 260 I (Found: C, 64.97; H, 6.72%. C'19H2406 requires C, 65.50; H, 6.94%); 'H NMR 8, (200 MHz, [2H6]DMSO): 1.97 [1H, quint., CH(CH,OH),], 3 42 (2 H, dd, CHZOH-l,2-diol), 3.50 (4 H, dd, CH,OH- l,3-diol), 2.7-4.08 (5 H, m, CH,O, CH-OH), 4.55 (2 H, t, <'H,OH), 4.70 (1H, t, CH20H), 4.97 (1 H, d, CH-OH), 6.96 (4 H, d, CH-arom), 7.50 (4 H, d, CH-arom).4-Allyloxy-4-( 3-hydroxypropoxy) biphenyl, 29.1 4-Allyloxy-4'-hydroxybiphenyl24 (3.54 g, 15 mmol) was dis- solved in dry acetone (50 ml). Potassium carbonatrr (12.4 g, 0.90mol) and potassium iodide (0.5 g) were added to the solution, followed by addition of 3-bromopropan-l-ol(2.78 g, 20 mmol). The mixture was then stirred under reflux for 16 h. After cooling to room temperature diethyl ether (1001ml) was added and the suspension was filtered. The solid residue was washed twice with diethyl ether (2 x 50 ml), the solutions were combined and the solvent was distilled off using a rotatory evaporator. The residue was dissolved in ethyl acetate (100 ml). The solution was washed with water (50 ml) and then dried over Na,S04.Evaporation of the solverit gave a solid residue, which was recrystallized from methanol. Yield: 3.28 g (77%), mp 165°C (Found: C, 75.65; H, 7.06%. C18H2003 requires C, 76.03; H, 7.09%); 'H NMR 6, (200 MHz, [2H6]DMSO): 1.86 (2 H, quint., CH,), 3.56 (2 H, q, CH,OH), 4.05 (2 H, t, CH,O), 4.55 (1 H, t, OH), 4.59 (2 H, m, CH,=CH-CCH,O), 5.26 (1 H, dd, cis-CH', =CH), 5.39 (1 H, dd, trans-CH, =CH), 5.95-6.14 (1 H, m, CH,=CH), 6.94-7.01 (4 H, 2d, CH-arom), 7.51 (4 H, d, CH-arom); m/z 284 (M+, 46%), 243 (73), 185 (loo), 57 (41). 442,3-Dihydroxypropoxy)-4-( 3-h ydrox ypropox y)biphenyl 9.1 The bishydroxylation of the double bond of 29.1 (1.42g, 5 mmol) was carried out according to the procedure given for 1558 the synthesis of 27.The crude product was crystallized from chloroform. Yield: 1.38 g (87%); transition temperatures ( "C): Cr 227 SA 242 I (Found: C, 67.56; H, 6.93%. C18H220, requires C, 67.94; H, 6.92%); 'H NMR hH (200 MHz, [2H6]DMSO): 1.86 (2 H, quint, CH,), 3.42 (2 H, dd CH20H- 1,2-diol), 3.55 (2 H, t, CH,OH), 3.3-4.1 (5 H, m, CH20, CH-OH), 4.57 (1H, t, CH2-OH), 4.7 (1 H, t, CH,OH), 4.97 (1 H, d, CH-OH), 6.97 (4 H, d, CH-arom), 7.51 (4 H, d, CH -arom) Ethyl 64 4'-allyloxybiphenyl-4-yl) hexanoate, 30 4-Allyloxy-4'-hydroxybiphenyl24 (6.8 g, 30.0 mmol) was eth- erified with ethyl 6-bromohexanoate (10.0 g, 45 mmol) accord- ing to the procedure given for 29.1. The crude product was sufficiently pure to be used without further purification for the next step.Yield: 9.5 g (86%); thin-layer chromatography (silica gel, Rf= 0.56, eluent light petroleum-ethyl acetate, 10+6); 'H NMR dH (500 MHz, CDCl,): 1.25 (3 H, t, CH,), 1.51 (2H, quint, CH,), 1.70 (2 H, quint., CH,), 1.81 (2H, quint., CH,), 2.33 (2 H, t, CH,COO), 3.98 (2 H, t, CH,O), 4.12 (2 H, 9, COOCH,), 4.56 (2 H, d, CH,=CH-CH,O), 5.28 ( 1 H, dd, cis-CH=CH,), 5.42 (1 H, dd, trans-CH=CH,), 6.02-6.11 (2H,m, CH2=CH-), 6.92 (2H,d, CH-arom), 6.95 (2 H, d, CH-arom), 7.43-7.46 (4 H, 2d, CH-arom). 4-Allyl-4'-( 6-hydroxyhexyloxy) biphenyl, 31 A solution of 30 (2.95 g, 8.0 mmol) in dry tetrahydrofuran (25 ml) was added dropwise to a stirred solution of lithium aluminium hydride (0.20 g, 4.5 mmol) in dry tetrahydrofuran (10 ml). The mixture was stirred overnight at room tempera- ture and afterwards was carefully hydrolysed with water (5 ml).The precipitate was filtered off and was carefully washed twice with tetrahydrofuran (2 x 30 ml). The residue, obtained after evaporation of the solvent, was dissolved in ethyl acetate (100 ml), washed with brine (20 ml) and dried over Na,SO,. The solvent was evaporated in uucuo and 31 was obtained, it was then repeatedly crystallized from ethanol. Yield: 1.8 g (69%); mp 142 "C; (Found: C, 77.33; H, 8.09%. C21H2603 requires C, 77.27; H, 8.03%); 'H NMR 6, (200 MHz, [2H,]DMSO): 1.45-1.80 (8 H, m, CH,); 3.56 (2H,t, CH20H), 4.01 (2H,d, CH,O); 4.56 (2H,d, H,C=CH-CH,O); 5.28 (1H,dd, cis-CH=CH,), 5.41 (1 H, dd, trans-CH=CH,), 5.97-6.16 (2 H, m, CH,=CH-), 6.90-6.97 (4 H, 2d, CH-arom); 7.44 (4 H, d, CH-arom).4-(3,4-Di hydroxypropyl)-4-( 6-hydroxyhexyloxy) biphenyl, 9.2 Compound 31 (0.65 g, 2 mmol) was bishydroxylated accord- ing to the procedure given for 27. Yield: 0.62 g (86%); trans- ition temperatures ( cC): Cr 172 SB 191 SA 209 I; (Found: C, 69.76; H, 7.78%. C2,H2,05 requires C, 69.97; H, 7.83%). Ethyl 6-[ 4-(2,3-dihydroxypropoxy) biphenyl-4- yloxy] hexanoate, 32 Bishydroxylation of 30 (1.48 g 4.0 mmol) according to the procedure described for the synthesis of 27 gave 32. Yield: 1.32g (82%); mp 154°C; (Found: C, 68.56; H, 7.56%. C23H3006 requires C, 68.63; H, 7.51%); TR (KBr): 1180, 1250, 1380, 1460, 1610, 1740, 3310cm-'.6-[ 4'4 2,3-Dihydropropoxy) biphenyl-4-yloxy ]hexanoic acid, 33 Saponification of the ester 32 (0.80 g, 2mmol) gave the carboxylic acid 33. Yield: 0.70 g (93%); transition tempera- tures ( "C): Cr 177 SA 231 I; (Found: C, 67.13; H, 7.36%. J. MATER. CHEM., 1994, VOL. 4 C2'HZ6O6 requires C, 67.36; H, 6.99%); 'H NMR hH (200 MHz, C2H6]DMSO): 1.32- 1.80 (6 H, m, CH,); 2.22 (2 H, t, CH,COO), 3.45 (2 H, d, CH,OH); 3.73-4.08 (5 H, m, CH,O, CH-0); 6.97 (4 H, d, C-H arom); 7.52 (4 H, d, C-H arom); IR (KBr): 1040, 1180, 1250, 1380, 1460, 1610, 1720, 3310 cm-'. Support of this work by the Deutscho Forschungs-gemeinschaft, the Fond der Chemischen Industrie and the Dr. Otto Rohm Gedachtnistiftung, Darmstadt is gratefully acknowledged. References 1 C.Tschierske, G. Brezesinski, F. Kuschel and H. Zaschke, Mol. Cryst. Liq. Cryst. Lett., 1989,6, 139. 2 H. Van Doren, 1989, Theses, Groningen. 3 G. A. Jeffrey and L. A. Wingert, Liq. Cryst.. 1993, 14. 179, and references cited therein. 4 H. A. van Doren, R. van der Geest, C. A. Keuning, R. M. Kellogg and H. Wynberg, Liq. Cryst., 1989,5,265. 5 B. Pfannemuller, W. Welte, E. Chin and J. W. Goodby, Liq. Cryst., 1986,4, 357. 6 V. Vill, T. Bocker, J. Thiem and F. Fischer. Liq. Cryst., 1989, 6, 349. 7 K. Praefcke, B. Kohne, A. Eckert and J. Hempel. Z. Narurforsch., 1990,45b, 1084. 8 W. V. Dahlhoff, Z. Naturforsch., 1987,42b, 661. 9 G. Lattermann and G. Staufer, Liq. Cryst., 1989.4, 347. 10 K. Praefcke and D. Blunk, Liq.Cryst., 1993,14. 1181. 11 S. Diele, E. GeiBler, H-M. Vorbrodt and H. Zaschke, Mol. Cryst. Liq. Cryst. Lett., 1984, 102, 181. 12 J. D. Bunning, J. E. Eabon, P. M. Jackson, J. W. Goodby and G. W. Gray, J. Chem. Soc., Faraday Trans. I, 1982,78,713. 13 C. Tschierske, F. Hentrich. D. Joachimi, 0.Agert and H. Zaschke, Liq. Cryst., 1991,9, 571. 14 C. Tschierske, A. Lunow, D. Joachimi, F. Hentrich, D. Girdziunaite, H. Zaschke, A. Madicke, G. Brezesinski and F. Kuschel, Liq. Cryst., 1991,9,821. 15 N. Pietschmann, A. Lunow, G. Brezesinski. C. Tschierske, F. Kuschel and H. Zaschke, Colloid Polym. Sci., 1991, 269, 636. 16 D. Joachimi, C. Tschierske, H. Miiller, J.-H. Wendorff, L. Schneider and R. Kleppinger, Angew. Cheni., Int. Ed. Engl., 1993,32,1165.17 J-H. Fuhrhop, H-H. David, J. Mathieu, U. Liman, H-J Winter and E. Boekema, J. Am. Chem. SOC.,1986,108,1785. 18 B. A. Gulik and V. Luzzati, J. Mol. Biol., 1985, 182, 131. 19 C. Tschierske and H. Zaschke, J. Chem. SOC., Chem. Commun., 1990,1990,1013. 20 F. Hentrich, C. Tschierske and H. Zaschke, Angew. Chem., Int. Ed. Engl., 1991,30, 440. 21 F. Hentrich, S. Diele and C. Tschierske, Liq. Crj st., 1994, submit-ted for publication. 22 0.Mitsunobu, Synthesis, 1981, 1. 23 E. Cordova, R. A. Bissell,N. Spencer, P. R. Ashton, J. F. Stoddart and A. E. Kaifer, J. Org. Chem., 1994,58, 6550. 24 M. Caron and K. B. Sharpless, J. Org. Chem., 1985,50, 1557, 25 C. M. McCloskey, Adv. Carbohydr. Chem., 1957.12, 137, 26 V. van Rheenen, R. C. Kelley and D. Y. Cha, Tetrahedron Lett., 1976,1973. 27 C. F. H. Allen and J. W. Gates, Org. Synth., 1955, coll. vol. 111, p. 140. 28 C. Tschierske, unpublished results. 29 G. W. Gray and J. W. Goodby, in Smectic Liquid Crystals, ed. G. W. Gray and J. W. Goodby, Leonard Hill, Glasgow, 1984, p. 152. 30 N. Pietschmann, G. Brezesinski, C. Tschierske, H. Zaschke and F. Kuschel, Liq. Cryst., 1989,5, 1697. 31 G. Brezesinski, A. Madicke, C. Tschierske, H. Zaschke and F. Kuschel, Mol. Cryst. Liq. Cryst., Lett., 1988,5. 155. 32 N. Pietschmann, G. Brezesinski, F. Kuschel, C. Tschierske and H. Zaschke, Mol. Cryst. Liq. Cryst. Lett., 1990,7. 39. 33 E. Klarmann, L. W. Gatyas and V. A. Shternov, J. Am. Chem. Soc., 1993,54, 298. 34 A. N. Wrigley, A. J. Stirton and E. Howard, JI-., J. Org. Chem., 1960,25,439. 35 C. J. Pederson, J. Am. Chern. Soc., 1967,89, 7017 36 E. L. Eliel and H. D. Banks, J. Am. Chem. Soc., 1972,94, 171. Paper 4/01690D; Received 21st March, 1994

ISSN:0959-9428    

DOI:10.1039/JM9940401547

出版商:RSC    

年代:1994

数据来源: RSC