摘要:

AbstractCopolyimides, their microstructure being determined by the method of synthesis, were prepared by copolycondensation of 4,4′‐oxydiphthalic anhydride(1a), 4,4′‐carbonyldipthalic anhydride(1b), or 1,8:4,5‐naphthalenetetracarboxylic anhydride with a mixture of two diamines, hexa‐, octa‐, or dodecamethylene diamine(5a, 6a, 7a)and cardo‐diamines 9,9‐bis(4′‐aminophenyl)fluorene(3a)and 3,3‐bis(4′‐aminophenyl)phthalide(4)or two aromatic diamines, 4,4′‐oxydianiline(9)and 2,2‐bis(4‐aminophenyl)hexafluoropropane(8), at various mole ratios of the comonomers. Blockcopolyimides with five‐membered imide cycles were formed by catalytic imidization of the intermediate polymers prepared by addition of the solid dianhydride to a solution of the mixture of the two diamines, whereas the thermal cyclization of such polymers and the one‐step high‐temperature synthesis led to random copolyimides. The thermal and mechanical properties of the copolyimides with various microstructure and their sol

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840201

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe synthesis and the phase behaviour of liquid crystalline main chain polymers are described. In these poly‐ and copolyesters the mesogenic units are linked by highly flexible oligodimethylsiloxane spacers. The comparison of their phase behaviour with that of polyesters known from the literature shows that dimethylsiloxane spacers as a replacement for alkyl spacers are leading to a drastic decrease of the transition temperatures. Depending on the length of the spacer glass transitions as low as −111°C can be achieved. The widths of the liquid crystalline phases thereby are retained up to a spacerlength of 13 oxydimethylsilanediyl (dimethylsiloxane) units. The homopolyesters mainly show smectic phases. In contrast to this nematic phases are found for copolyesters in which either the spacerlength or the mesogenic unit was varied. In one case a nematic phase was found over a temperature range of 3

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840202

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractSulfuryl chloride was used as chlorination agent of poly(dimethylsiloxane)s(1)in order to obtain poly(dimethylsiloxane‐co‐chloromethylmethylsiloxane) and it was found to be more specific than molecular chlorine. Identification of chlorinated and chlorosulfonated units was shown to be possible by comparison of the results of1H NMR spectroscopy with those obtained by GLC analysis of the mixtures obtained from octamethylcyclotetrasiloxane(2). After having shown that the distribution of the various types of methyl groups in1and2, modified in this way, fits correctly a binomial law and that chlorosulfonated units can be hydrolysed, copolymers containing 20 to 25% of chloromethylated units and less than 2% of unwanted dichloromethylated units are accessible by use of this chlorination ag

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840203

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractAs an approach to the programmed release of drugs a polymeric carrier(1)from which the drug would be liberated by the degradation of definite covalent chemical bonds by means of specific enzymes, was synthesized by coupling pholcodine(2), an antitussive drug, with an insoluble, physiologically inert polymer, cellulose, using L‐phenylalanine as a spacer arm. As chemical bond between drug and amino acid an ester function was chosen linking the hydroxyl group of2and the carboxylic end of L‐phenylalanine. This linkage is not hydrolyzed in simulated digestive fluids containing pepsin or trypsin; it is only broken in the presence of α‐chymotrypsin to release slowly the paren

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840204

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractMethyl methacrylate, benzyl methacrylate, butyl methacrylate, and methacrylic acid can be polymerized by 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane and 1,1,2,2‐tetraphenyl‐1,2‐dicyanoethane. In the first period of the polymerization with both initiators oligomers are formed which can initiate the polymerization of other vinyl monomers yielding block‐copolymers besides the resp.

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840205

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractAccurate measurements of the sedimentation coefficients at unit pressure and zero‐concentration s 00, the diffusion coefficients at zero concentration D0, and the intrinsic viscosities [η] were conducted at theta‐conditions (cyclohexane, 34,5°C) on 11 polystryrene standard samples with narrow molar mass distribution. These samples with nominal mass‐average molar masses (5 · 104

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840206

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractExperimental data from hydrodynamic measurements on eleven standard polystyrene samples in a poor and a good solvent (cyclohexane at theta‐temperature 34,5°C, toluene at 25°C) are analyzed in terms of the two‐parameter theory of the hydrodynamic properties of random coils. The discussion is focussed on the expansion factors of hydrodynamic radii αfand αμ, evaluated from the translation friction coefficients and the intrinsic viscosity, and on the hydrodynamic‐interaction parametersPandΦ. The expansion factors αfand αηare shown to assume nearly equal values (at 1,15 ≤αη≤ 1,5). That implies that the dependences on coil expansion must be very similar forPand Φ1/3. The value of thePparameter in the unperturbed state (i.e.P0) is shown to be close to that recently calculated by Zimm and to be significantly higher than the results of previous the

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840207

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe kind of molecular weight averageMVPOresulting from vapour pressure osmometry (VPO) measurements on solutions of paucimolecular polymer mixtures of different compositions is studied with a Hewlett Packard Model 302 B. Recent theoretical calculations which predicted thatMVPO>Mnare confirmed. The experimentally found quotientMVPOMnis between 1,04 and 1,26, being the greater, the greater is the polydispersity of the mixture, which is agreement with the former mathematical derivations.

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840208

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractDue to its importance in the field of block‐polycondensation and of chemical modification, we carried out an extensive study of the epoxy‐carboxy reaction on models. This papier is related to the reaction of benzoic acid with 1‐phenoxy‐2,3‐epoxypropane in the presence of a basic catalyst,N,N‐dimethyldodecylamine. It is carried out in low polar solvents (xylene, chlorobenzene, ando‐dichlorobenzene); essential kinetic parameters are reported. From studies carried out under stoichiometric or non‐stoichiometric conditions a general rate equation (υ =k[acid]0.5[epoxy] [amine]) is obtained. Kinetic relations are the same, no matter what the catalyst is: dimethyldodecylammonium benzoate or free amine. From these kinetic data it results that the overall mechanism in

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840209

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractIn the first part of this series devoted to epoxy‐carboxy polycondensation, we showed that the overall mechanism of the amine catalyzed epoxy‐carboxy reaction is complex. The present article studies the reaction of benzoic acid with 1‐phenoxy‐2,3‐epoxypropane carried out in nitrobenzene and in the presence ofN,N‐dimethyldodecylamine as catalyst. In contrast to the results obtained in low polar solvents, where two equivalent reactions take place, the studies carried out in nitrobenzene show that, in this solvent, one of these two reactions is largely predominant. Its rate equation is: υ =k[epoxy][amine]. However, in the last steps of the reaction (conversion above 75% ), the system behaves as in low polar solvents. These results were obtained from studies carried out under stoichiometric and non‐stoichiometric conditions. The overall rate constant depends only very slightly on the stoichiometric balance. This is in agreement with a major contribution of one of two competi

ISSN:0025-116X    

DOI:10.1002/macp.1983.021840210

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY