摘要:

AbstractThe synthesis and NMR‐spectroscopical characterization of the topological arrangements of new side‐chain polyrotaxanes(3a)bearing about 80% of peracetylated cyclodextrins in the side‐chains of a functionalized poly(ether sulfone) is described. The characterizations have been conducted in relation to a similar model compound bearing no cyclodextrins(3b). The results strongly indicate that the cyclodextrins are uniformly located on the side chains, with the bigger opening over the aromatic anilide components of the barrier group. The glass transition temperature (Tg) of the polyrotaxane3ais in the region of 143°C, which is significantly higher than that of the model polymer3bhaving a value of

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170401

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractFilms of polymers bearing pendant acyloxyimino (AOI) groups become insoluble when irradiated by ultraviolet light in the presence ofp‐benzoquinone. Post‐heating of these films after irradiation also induces further the insolubilization. In the photocrosslinking, it is deduced thatp‐benzoquinone serves not only as sensitizer for the decomposition of AOI groups but also as crosslinker during the photo‐irradiation and heating after irra

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170402

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe asymmetric lactone (3S, 4R)‐3‐methyl‐4‐benzyloxycarbonyl‐2‐oxetanone (6) was anionically polymerized to give an insoluble, crystalline, highly isotactic polymer with (2S, 3S)‐benzyl β‐3‐methylmalate repeating units. Solubility was achieved by copolymerization of6with the recemic (R,S)‐butyl malolactonate (7). The semicrystalline copolymer was characterized (M̄n= 107 000,Tg= 29,6°C,Tm= 161°C, [α] = 1,5 deg · dm−1· g−1· cm3) and its stereo

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170403

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDilute solutions of unimodal high‐molecular‐weight poly(butyl cyanoacrylate) (“parent” polymer) in tetrahydrofuran (THF) at 21°C underwent rapid depolymerization accompanied by simultaneous repolymerization of the unzipped monomer to yield lower‐molecular‐weight “daughter” polymer following addition of tetrabutylammonium hydroxide (TBAOH), a slow initiator of butyl cyanoacrylate (BCA) monomer. The rate‐determining step for the reaction was tentatively identified as abstraction of the terminal chain proton. Similarly, addition of TBAOH to a THF solution of BCA monomer resulted in initial formation of high‐molecular‐weight (MW) polymer that subsequently rapidly depolymerized with simultaneous formation of TBAOH initiated, low‐MW daughter polymer. The depolymerization‐repolymerization reaction is the relaxation process that occurs following perturbation of the monomer/high‐MW parent polymer equilibrium by low‐MW daughter polymer and proceeds at least 100°C below the ceiling te

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170404

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSugar‐derived surfactants bearing a polymerizable acryloyl moiety on one of the branches of the double‐chain hydrophobic tail were prepared. The non–ionic hydrophilic head and the biantennary hydrophobic tail were built on, respectively, an aspartic acid and a tris(hydroxymethyl)aminomethane core. Ultraviolet irradiation of aqueous dispersions of these surfactants above their transition phase temperature (Tc) was achieved. The morphology of self‐assemblies produced in such a way were investigated by transmission electron microscopy. TEM photographs revealed that irradiation leads to the formation of unilamellar vesicles. Neither fibers nor tubules were detected in contrast to what was observed before polymer

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170405

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe synthesis and properties of soluble, conjugated polymers consisting of oligo(p‐phenylene) sequences linked by ethylene, vinylene, or ethylene, units are reported. Benzene‐, stilbene‐, diphenylacetylene‐ and 1,2‐diphenylethane derivatives serve as monomers and are connected by the Suzuki‐coupling method. A wide range of poly‐(p‐phenylene)‐related polymers are available by the combination of different AA/BB‐type monomers in various concentrations. The optical properties of the resulting polymers can therefore be tailored. Number‐average degrees of polymerization of up to X̄n= 137 were reached under optimized conditions. Photoluminescence quantum yields of these materials in s

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170406

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA supported magnesium‐vanadium‐aluminium catalyst was prepared by depositing –with the use of a milling technique–VOCl3on the MgCl2(THF)2support and subsequent activation with diethylaluminium chloride. Catalytic activity of the obtained system for ethylene polymerization was evaluated as a function of Mg/V and Al/V ratios as well as catalyst ageing time and polymerization temperature. High concentrations of THF in the catalytic system and considerable excess of an organoaluminium co‐catalyst were found to have no deactivating action on vanadium active sites. The catalyst obtained is stable and its activity for ethylene polymerization is high. It yields polyethylene with higher molecular weight and higher melting point than offered by the materials produced with the use of a corresponding unsupported vanadium catalyst or a titanium‐based system on the same magnesium support. Kinetic investigations confirmed stability of this catalyst irrespective of its concentration in the polymerization medium or of monomer concentration. Moreover, analysis of the kinetic findings revealed that over 80% of vanadium employed forms active polymeriz

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170407

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractNovel block copolymers of poly(ethylene glycol) (PEG) with acrylamide (AAm) and methacrylic acid (MAA) were synthesized using a redox system consisting of ceric ions and PEG in aqueous acidic medium. The molecular weight of PEG in the redox system was varied to obtain a series of block copolymers with differing molecular weights of PEG segment. The polymerization proceededviamacroradical generation, which was substantiated by ESR spectroscopy. This macroradical acted as a redox macroinitiator for the block copolymerization of the vinyl monomers. The formation of the block copolymers was confirmed by fractional precipitation technique.

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170408

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe peptide‐containing block copolymer poly(N‐acetyliminoethylene)‐block‐poly(L‐phenylalanine)(1)formed large water‐soluble aggregates in water due to the hydrophobic and hydrogen‐bonding character of the poly(L‐phenylalanine) block. The solution properties of1were compared with those of the block copolymer poly(N‐acetyliminoethylene)‐block‐poly(N‐benzoyliminoethylene)(2)with an analogous structure.1formed aggregates even though the poly(phenylalanine) segment was short as compared with2in which hydrophobic interaction may be the only driving force to form aggregates. The aggregates have strong capability of incorporating Lipase P and largely increase the hydrolysis activity againstp‐nitrophenyl propionate as compared w

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170409

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY