摘要:

AbstractThe direct syntheses of poly(p‐phenyleneterephthalamide) in presence of poly(vinylpyrrolidone) and poly(4‐vinylpyridine) as matrices have been carried out following the so‐called Yamazaki's and Higashi's methods. The intrinsic viscosity data of the resulting polyamide were found to be strongly dependent on the matrix used as well as on its molecular w

ISSN:1022-1360    

DOI:10.1002/masy.19971220103

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe ways of the preparing of high performance polymers (HPP) having tailored properties are considered. Common two and one step methods of such polymers synthesis are compared. Some peculiarities of one step polycyclization including the catalytic processes are discussed. Matrix polycondensation leading to the formation of HPP and their blends is analysed. The synthesis of some functional polymers (polyamides and polyamides) having quinuclidine moieties is described.

ISSN:1022-1360    

DOI:10.1002/masy.19971220104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIn contrast to a‐a/b‐b type monomers, the a‐b monomers(e.g. hydroxy‐ or amino carboxylic acids) possess a much greater synthetic potential. Using 3‐ or 4‐hydroxy‐benzoic acid and 4‐hydroxyphenylpropionic acid (phloretic acid) starshaped polyesters with controlled molecular weight were prepared. Analogously, starshaped liquid‐crystalline copolyesters were synthesized, and the influence of star‐centers on the stability of the nematic phase was studied. Three polycondensation methods were elaborated and compared for the synthesis of hyperbranched homo‐ and copolyesters. Both the degree of branching and the nature of the endgroups were varied and their influence on the solubility, crystallinity and melt rheology was investigated. Furthermore, A‐B‐A triblock co‐polymers with hyperbranched A‐blocks, and hyperbranched poly(ester‐amide)s wer

ISSN:1022-1360    

DOI:10.1002/masy.19971220105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractHigh temperature chain‐coupling reactions in the bulk between amino‐, hydroxy‐ or carboxy‐terminated polymers and various coupling agents have been studied and applied to the synthesis of copolymers with aliphatic polyester, polyether or polyamide blocks. Thus, carboxy‐terminated oligomers can be coupled by bisoxazolines or bisimidazolines, while 4‐substituted and 4, 4‐disubstituted bis(5‐oxazolinones) are efficient coupling agents for amino‐ or hydroxy‐terminated oligomers. In the latter case, the use of a catalyst is necessary. The reaction has been optimized using a series of bisoxazolinones deriving from α‐amino‐acids and 1‐dodecanol and α, ω‐dihydroxy‐poly(ϵ‐caprolactone) as model compounds. High molar mass poly‐ϵ‐caprolactone containing α‐aminoacid moieties has been obtained in the pr

ISSN:1022-1360    

DOI:10.1002/masy.19971220106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA novel class of organo‐soluble polyimides has been developed based on monomers containing twisted‐biphenyl structures. Thus, 2, 2'‐disubstituted‐4, 4'‐diaminobiphenyls and 2, 2'‐disubstituted‐4, 4', 5, 5'‐biphenyltetracarboxylic dianhydrides have been prepared and polymerized in refluxing phenolic solvents. The polyimides, some of which are soluble in ketone and ether solvents, can be readily solution cast into colorless thin films. The rigid polymer chains align parallel to the substrate surface (in‐plane orientation) during the casting process, which results in anisotropy in the film properties. The anisotropy in the refractive index has been used in the development of compensation layers for liquid crystal displays. The polymers have also been dry jet‐wet spun from phenolic solutions to afford fibers that display tensile strengths of 3.5 GPa an

ISSN:1022-1360    

DOI:10.1002/masy.19971220107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractLipases in organic solvents catalyse lactonisation or polymerisation of ω‐hydroxyesters. Under these conditions the enzymes exhibit both enantioselectivity and prochiral selectivity. This approach was used to develop the synthesis of chiral γ‐lactones and A‐B type polyesters from racemic or prochiral hydroxyester su

ISSN:1022-1360    

DOI:10.1002/masy.19971220108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe chemistry and the reaction rates have been related to the phase transitions and transformations occuring during different polymer syntheses. Early cristallization of chain segments disturbs the synthesis of linear segmented polyureas or polyurethanes. The gelation process occuring during the epoxy‐amine network formation does not affect the reaction rate, but after vitrification, this reaction becomes diffusion‐controlled. In the case of modified thermoset a liquid‐liquid transition may induce a fractionation phenomenon which modifies the average functionality of the molecules and the appearance of the gel

ISSN:1022-1360    

DOI:10.1002/masy.19971220109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper reviews our current studies on the high pressure synthesis of polyimides and related condensation polymers. After a brief introduction of the solid‐state thermal synthesis of polyimides starting from nylon‐salt‐type monomers, the paper deals with the high pressure synthesis of polyimides, the preparation of polyimide‐silica hybrid materials by the combination of the above synthetic method for polyimides and the sol‐gel reaction for silica synthesis, and the high pressure synthesis of polybenzoxazoles and addition‐type pol

ISSN:1022-1360    

DOI:10.1002/masy.19971220110

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis lecture deals with some problems connected to the synthesis and the characterization of tailored polycondensates. They will be illustrated by examples mainly from our laboratory and bearing on block‐copolycondensates, macrocycles and some structures obtained by enzymatic catalysis. We will particularly emphasize the analysis of the structures and of the eventual side reaction

ISSN:1022-1360    

DOI:10.1002/masy.19971220111

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractBy using organometallic reactions like Pd‐catalyzed C‐C coupling, metal‐carbon bond formation and silicon‐carbon bond cleavage, novel carbon‐rich organometallic monomers HC≡C‐C6H4‐C≡C‐[M]‐C≡C‐C6H4‐C≡CH ( [M] = ‐Ru(dppe)2‐ and (η5‐C5H4)2Fe) and organic monomers H‐(C≡C‐C6H4)X‐C≡CH (x = 1 to 3) have been obtained. They have been used for the design of novel homo and hetero metal‐containing polymersviaorganometallic polycondensation reactions b

ISSN:1022-1360    

DOI:10.1002/masy.19971220112

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY