摘要:

AbstractThe aqueous emulsion copolymerization ofN,N′‐methylenebis(acrylamide) (MBA) and an unsaturated polyester (UP) initiated with potassium peroxodisulfate was kinetically investigated at 50°C as a function of comonomer feed compositions. The reaction order with respect to the monomer concentration was found to be proportional to the UP monomer concentration at medium conversions and independent of the UP monomer concentration at low conversions. The high reaction order obtained from the dependence of the particle concentration on UP monomer concentration was attributed to the multifunctionality of UP monomer. At low conversions, an enrichment of the copolymer in UP structural units is observed. The polymerization was suggested to proceed in the aqueous phase, in the UP micelles and in the shell of the polymer parti

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930801

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractCationic cyclopolymerization of divinyl ethers, which were derived from (R)‐ or (S)‐1, 1′‐bi‐2‐naphthol with methyl, phenyl, and bromo groups in the 3,3′‐positions, yielded polymers with changing optical rotation according to the reaction conditions. Model compounds, therefore, corresponding to the three stereoisomeric forms of the constitutional units, i. e., two racemo (R,R‐andS,S‐) forms and one meso form, were synthesized to confirm the origin of changing optical rotation in the polymers.1H NMR analysis showed that the polymers change their optical rotation due to the configuration, which has a tendency to be preferentially a racemo‐diisotactic structure at higher monomer concentrations and in less polar solvents. The chiral twist of the (R)‐or (S)‐binaphthyl template induces the main chain to form an asymmetricR,R‐ orS,S‐racemo sequence, respectivel

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930802

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA set of novel zwitterionic side‐chain polyacrylates and polymethacrylates is studied by X‐ray scattering. The structural order both in the short‐range and long‐range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are a

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930803

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe molecular packing and spatial correlations of two isomeric zwitterionic polymethacrylates and one polyacrylate analog are studied by means of X‐ray analysis and conformational calculations. The analysis of the correlation functions and density distribution profiles suggest a double‐layered molecular packing which is discussed for the three polymers investigated, with respect to their different chemical structures. Whereas the zwitterionic polymethacrylates studied exhibit liquid‐like short‐range order, the polyacrylate analog exhibits an ordered double‐layered super

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930804

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIn order to elucidate the dependence of electrical conductivity on conjugation length, polyketones built up of short conjugated aromatic blocks and methylene chains of different length were studied. As obtained, the polymer exhibit very low electrical conductivities of about 10−15S/cm. Upon doping with iodine the conductivity increases up to 10 orders of magnitude and samples become paramagnetic. The colour turns from yellow to black, and a new absorption maximum appears in UV spectrum at 365 nm characteristic of I3−. The monomers and a model compound do not absorb iodine. In the polymers we assume some ordering of the aromatic moieties, which enables enhanced π‐π interaction. The result could be considered as an extension of the conjugation, thus allowing partial oxidation (doping) and therefrom enhanced conductivity. We explain the doping and the conductivity of polydienes in a simillar way. The conclusion is that extended conjugation along the chain is not a prerequisite for higher condu

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930805

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA new synthetic approach to soluble, rigid‐rod, aromatic polymides is described. The polycondensation is done by a Pd‐catalyzed aryl‐aryl coupling ofN,N′‐bis(4‐bromo‐2,5‐didodecyl‐phenyl)‐1,2:4,5‐pyromellitic diimide (2) and 2,5‐didodecyl‐1,4‐benzenediboronic acid (3). Here, the imide structure is already preformed in monomer2. A structurally identical polymer is synthesized by the classical procedure condensing 1,2:4,5‐pyromellitic dianhydride (PMDA) (4) and 4,4″‐diamino‐2,5,2′,5′,2″,5″‐hexadodecyl‐p‐terphenyl (5). Both polymers are characterized in detail by1H and13C NMR spectroscopy, membrane osmometry and size exclusion chromatography. The average degree of polycondensation is of the order of 15. The thermal behaviour of the polymers is studied by differential scan

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930806

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe microstructure of aromatic copolyesters prepared by bulk polymerization was investigated by means of1H NMR spectroscopy. The aromatic region of the spectra appears to be sensitive to the sequence distribution of aromatic rings. Line shape simulation and resolution enhancement of the time domain spectra with a Gaussian window function allow a quantitative evaluation of the relative intensities. Sequence distribution in terms of triads and diads formed by aromatic rings was then derived and compared with the one calculated on the basis of a random distribution. The results show that the distribution, as expected for this class of copolymers, is random.

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930807

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe synthesis of high‐molecular‐weight polyethers and copolyethers based on 4‐hydroxyacetophenone azine and α,ω‐dibromoalkanes was carried out inN‐methyl‐2‐pyrrolidone via Williamson etherification using the caesium salt of the diol. Polyethers were composed of a homologous series of flexible methylene spacers withm= 5−12, while the copolyethers contained a 1:1 mole ratio of two different spacers withm= 5/7, 6/8, 7/9, 8/10, 9/11 and 10/12. Polymers with relatively short spacers (m= 5−8 methylene groups) exhibit enantiotropic mesomorphism, whereas those havingm= 8−11 are tentatively identified to be monotropic. The polyether withm= 12 is crystalline. Copolyethers are enantiotropic and their mesophase ranges are considerably wider than those of the homopolyethers. The mesophases were identified to be nematic by polarised light microscopy. The transition temperatures of both the homopolymers and copolymers show classical even‐odd variations as a functi

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930808

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly(α‐malic acid) is of interest for the application as a biodegradable and bioadsorbable drug carrier, which has pendent reactive carboxylic acid groups. In order to provide a biodegradable macromolecular prodrug of doxorubicin (adriamycin, ADR), reducing the side‐effects of ADR and exhibiting effective antitumor activity, ADR residues were covalently attched to poly(α‐malic acid) via ester or amide bonds to give poly(α‐malic acid)/ester/ADR conjugate1or poly(α‐malic acid)/amide/ADR conjugate2, respectively. The release rate of ADR from the poly(α‐malic acid)/ester/ADR conjugate1was faster than that from the poly(α‐malic acid)/amide/ADR conjugate2in buffer solution (pH 7,4) at 37°C. While the cytotoxic activity of poly(α‐malic acid)/ester/ADR conjugate1is as strong as that of free ADR against p388D1lymphocytic leukemiacells in vitro, the cytotoxic activity of poly(α‐malic acid)/amide/A

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930809

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe preparation of a highly active Ti‐Mg catalyst in two steps is reported. the first step is a Grignard reaction conducted in hexane with an under‐stoichiometric amount of tetrahydrofuran. In the second step the Grignard suspension is treated with a TiCl4/CCl4mixture. Owing to optimized synthesis conditions after a thermal activation the catalyst suspension is ready for use in combination with an alkylaluminium cocatalyst without further separation and drying operations. Because of its high response to H2the catalyst may preferably be used for the production of polyethylene (PE) for injection moulding. Depending on the Ti content the catalyst shows an activity of between 184 and 250 kg PE per g Ti per h and per bar for a PE with melt flow index between 20 and 30 g/10 min. The content of Ti4+in the catalyst is high (up to 72 wt.‐%). The catalyst suspension shows a marked resistance against reduction by the cocatalyst. The catalytic activity not only depends on the mole ratio of the individual catalyst components but even more on their actual concentration in the reaction m

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930810

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY