摘要:

AbstractPoly(p‐hydroxycinnamic acid) was synthesized by thionyl chloride activated polycondensation ofp‐hydroxycinnamic acid at ambient temperatures and by polycondensation of its various monomeric esters at elevated temperatures. The thionyl chloride activated polycondensation proceeds as a 2‐stage process, yielding reduced viscosities of up to 102 mL/g. 360 MHz proton NMR spectra indicate an all‐trans structure and the absence of side reactions. The polymer with a melting temperature of 313°C can be pressed in

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860501

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe reaction between the MgTiCl6·4CH3COOC2H5complex and alkylaluminium compounds was studied. The solid samples, recovered after increasing reaction times, were analysed. Elemental analyses, X‐ray diffraction patterns, and IR spectra clearly indicated the formation ofactivated, high‐surface MgCl2. Polymerizations of ethylene were carried out employing, as the solid component of the catalyst system, both MgTiCl6·4CH3COOC2H5and the recovered samples. The lower induction time in the latter case was related to the extent of MgCl2formation and its degree of activ

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860502

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractPoly(oxythiocarbonyloxy‐1,4‐phenyleneisopropylidene‐1,4‐phenylene) (1) was obtained from 4,4′‐isopropylidenediphenol (Bisphenol A) and thiophosgene under phase transfer conditions, using quaternary ammonium and phosphonium salts and crown ethers as catalysts. The polymer was identified by IR and1H NMR spectroscopy, and the molecular weights were estimated from inherent viscosity measurements. The influence of catalysts, solvent and thiophosgene addition was studied in order to find the best conditions. It was found that tetrabutylammonium bromide, dichloromethane and the addition of thiophosgene at once gives the highest yields and inherent viscosities. Other catalysts and solvents were less efficient or unefficient for th

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860503

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDialkyldiallylammonium salts1a–cwere prepared by quaternization of diallylamine with alkyl bromides and their polymerizability as oriented molecular assemblies in aqueous solution is discussed. Thin films of those ammonium salts on the glass wall were incubated by adding a phosphate buffer solution to yield giant spherical vesicles with diameters ranging from 10 to 100 μm. When large amounts of the ammonium salt were applied, it was necessary to add more than 5 mol‐% of cholesterol in order to stabilize the resulting giant vesicles. By ultrasonication of the film‐aqueous solution system, much smaller vesicles with diameters ranging from 0,03 to 0,2 μm were obtained. The stabilizing effect of cholesterol addition to the system of the small vesicles is similar to that observed for the giant vesicles. Under an inert atmosphere, the vesicles in aqueous solution were polymerized by ultraviolet irradiation. From the results of TEM and NMR spectroscopy, it was concluded that the molecules were polymerized in the vesicles without changing the profile of molecular assembly during an irradiation of 6 h. However, when the ammonium salts were dissolved homogeneously in degassed benzene, the ultraviolet irradiation polymerization did not proceed beyond a conversion of 5% under the same con

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860504

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA macromolecular prodrug of quinidine was synthesized by linking the amino ester ofL‐phenylalanine with quinidine to carboxymethylcellulose via an amide bond. The release of the drug results from the hydrolysis of the ester linkage which occurs only in the presence of α‐chymotrypsin at pH 8. This specificity is relative to the nature of the ester derivative whose carboxylic moiety is an aromatic amino acid residue withL‐configuration. This prodrug contains 160 mg of quinidine per g of dry powder and allows a prolonged release (5–7 h) of the drug in an intestina

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860505

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractHigh‐molecular‐weight polyamides based on the natural amino acid lysine were synthesized by condensation ofNα,Nε‐bis(trimethylsilyl)lysine alkyl esters (1a–c) with derivatives of aromatic dicarboxylic acids (2a–c). The best results were obtained with diacyl dichlorides. However, in the case of aliphatic dicarboxylic acid derivatives, preference should be given to their active diesters. The properties of the resulting polyamides were shown to be determined, to a considerable degree, by the nature of the reaction medium. Polyamides with free carboxyl groups, capable of further polymeranalogous conversions, were obtained by means of saponification of the side chain alkyl ester groups. The substituted phenols, resulting from the polycondensation of1a–cwith active diesters, could be used for the synthesis of polyamides with active ester groups in th

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860506

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractNumerous copolymerizations of glycolide with β‐propiolactone, γ‐butyrolactone or δ‐valerolactone were conducted either in bulk or in nitrobenzene solution at temperatures in the range of 20 to 150°C. Three classes of catalysts were used, namely acidic catalysts initiating cationic polymerizations, complexing catalysts initiating insertion mechanisms, and anionic catalysts. The molar composition of the copolyesters was determined from1H NMR spectra and the sequence distribution of the comonomers from13C NMR spectra. No reasonable copolymerization of glycolide and βhyphen;propiolactone was obtained at 20°C in nitrobenzene, whereas all catalysts yielded copolyesters at 100°C. In the case of glycolide/γ‐butyrolactone only bulk copolymerizations at 60°C with acidic initiators were successful. Under other conditions only homopolymerization of glycolide was observed. Copolymerizations of glycolide and γ‐valerolactone were performed in bulk and in nitrobenzene with both acidic and complexing initiators, whereas anionic initiators only caused homopolymerization of glycolide. Acidic initiators favored the incorporation of δ‐valerolactone, whereas the complexing initiators favored the incorporation of glycolide. The crystallinity of the glycolide/δ‐valerolactone copolymers was characterized by means of differential scanning calorimetry, and a good agreement with the expectations from both molar composition and sequen

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860507

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractFour series of new poly(β‐aminoester)s based on different mesogenic units and amino spacers were prepared and their properties examined. The polymers were obtained by a Michael‐type polyaddition reaction of the diamines piperazine (5a), 2‐methylpiperazine (5b),N,N′‐dimethylhexamethylenediamine (5c), and 4,4′‐trimethylenedipiperidine (5d) to diacrylates containing the anisotropic group,trans‐4,4′‐vinylenedi‐p‐phenylene diacrylate (1), 4‐(4‐acryloyloxybenzylideneamino)phenyl acrylate (2), 4,4′‐diphenylylene diacrylate (3), and 4,4′‐azoxydi‐p‐phenylene diacrylate (4). The mesophase behaviour of the resulting polymers6–9was strongly influenced by the nature of both the anisotropic and spacer groups. The 4,4′‐azoxydi‐p‐phenylene unit appeared to be the most efficient in promoting liquid crystal properties, whereas no mesophases could be observed in polymers incorporating the 4,4′‐biphenylylene unit. Doping of poly(β‐aminoester)s, based on 4,4′‐azoxydi‐p‐phenylene units, with a low‐molar‐mass cholesterogen allowed to obtain cholesteric structures extending over wide ranges of temperature. The molecular weight of the polymers was found to play a role in determining thermotropic mesomorphism by affecting the melting temperature of the polymer. In this context, some non‐macromolecu

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860508

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860509

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractValues of the mean number of chain scissions per macromolecule and the quantum efficiency of chain scission processes are presented for systems studied in our previous works, in which the photodegradation of polystyrene in solutions irradiated with mercury light (λ ≧ 270 nm) was investigated and changes of the weight‐average molecular weightM̄wwere considered to be a measure for chain scission. The presented values of the number of scissions were obtained as follows: the molar mass distributions were determined for the investigated polystyrene samples by dynamic (quasielastic) light scattering experiments, before and after irradiation, the number‐average molecular weight valuesM̄nwere calculated from these distributions and the mean number of scissions was obtained from the changes of theM

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860510

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY