摘要:

AbstractThis lecture summarize some recent results of our current research. The first part describes the homopolymerization and copolymerization of a monocyclic and two bicyclic unsaturated acetals. In this way polyacetals with 1,4‐cis‐butadiene units and cyclohexene units respectively are obtained. Secondly, the N‐substitution of polyamides is described. By N‐metalation and subsequent alkylation comb‐like polyamides are available. Longer branches cause a side‐chain crystallinity. The anionic “grafting‐from” technique forms irregular branched polyamides. By termination reaction between living ends of poly(2‐isopropenylnaphthalene) and suitable electrophiles new macromonomers are available. The last part describes their copolymerization with

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985102

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThis paper describes our recent developments of block and graft copolymers prepared by the cationic ringopening polymerization of 2‐oxazolines. First, the mechanistic aspects of polymerization are mentioned, in which terms of “electrophilic and nucleophilic polymerizations” are proposed. Then, preparations and properties of poly(N‐acylethylenimine) chains from 2‐oxazoline monomers are described. They are (i) AB and BAB type block copolymers of 2‐oxazolines for nonionic polymer surfactants, (ii) poly[(N‐acetylethylenimine)‐b‐(oxyethylene)] for anti‐electrostatic agents, (iii) cellulose diacetate having poly(N‐acylethylenimine) graft chain for “compatibilizer” with commodity polymers, and (iv) polyethylene/vinyl acetate copolymer having poly(N‐acylethylenimine) graft chain for blood‐c

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985103

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, δ‐valerolactone and ϵ‐caprolactone were conducted either in bulk or in nitrobenzene solution at temperatures in the range of 20–150°C. Three classes of catalysts were used, namely acidic catalysts initiating cationic polymerizations, complexing catalysts operating via an insertion mechanism and true anionic catalysts. A summary of these already previously described results is presented in this work along with a detailed report on the copolymerization of glycolide and L, L‐lactide. These two monomers were copolymerized in bulk at 100 or 150°C and twenty different catalysts were used in both series. The molar compositions of the resulting copolyesters were used in both series. The molar compositions of the resulting copolyesters were determined by1H NMR spectroscopy. The possibility of13C NMR sequence analyses is discussed for all afore‐mentioned copoly(lactone)s and also for L,L‐lactide/ϵ‐caprolactone copoly(ester)s. DSC measurements of the glycolide/L,L‐lactide copolymers are discussed in connection with the NMR spectroscopic results. Furthermore, optical rotation measurements were conducted and it was found that the optical rotation of glycolide/L,L‐lactide copolyme

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985104

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA new block copolymer composed of hydrophilic polyamide as outer segments and polyoxyethylene as an inner segment was obtained by anionic polymerization of a bicyclic oxalactam, 8‐oxa‐6‐azabicyclo[3.2.1]octan‐7‐one, using the isocyanate‐terminated polyoxyethylene as an activator. A novel polyamide macromer having a vinylbenzyl end group was prepared by anionic polymerization of the bicyclic oxalactam followed by the reaction withp‐vinylbenzylamine. Its radical copolymerization with styrene was conducted to obtain a graft copolymer consisting of a nonpolar hydrophobic polystyrene stock and hydrophilic polya

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985105

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractIf low molar mass mesogenic molecules, which are able to form a liquid crystalline phase, are linked as side groups to a polymer main chain, a new class of polymeric substances with liquid crystalline behaviour is obtained. Nematic, smectic and cholesteric elastomers have been synthesized. The new material is marked by a new combination of liquid crystalline and elastomer specific properties. Above the glass temperature, Tg, the substances are rubber‐elastic. Starting from the elastomer in the optical isotropic state, a first order phase transformation into the liquid crystalline state is obtained by decreasing the temperature. By further cooling the liquid crystalline elastomer is converted into an anisotropic liquid crystalline glass.The thermoelastic and optoelastic properties of the networks have been investigated by uniaxial deformation (compression, elongation) and birefringence measurements. Above the transformation point nematic‐isotropic, Tn‐i, the thermoelastic behaviour is the same as for usual elastomers. However, when the transformation temperature is reached, the nominal stress decreases rapidly. If one passes to temperatures below the transformation temperature by maintaining the deformation of the network, the liquid crystalline order is built up in a sample having a preferential direction. This is the reason for the unusual stress‐temperature behaviour observed.Stress optical measurements above Tn‐ishow a considerable temperature dependence, which is untypical for common rubbers. The steep increase of the stress optical coefficient, some 20 k above Tn‐i, indicates that there are marked pretransformational effects. The sign of the birefringence indicates the orientation of the mesogenic side groups with respect to the axis of deformation or to the direction of the polymer backbone, respectively.In the LC state the investigations of the LC elastomers by X‐ray diffraction‐ and polarizing microscopic measurements lead to same results with respect to the orientation of the mesogenic side groups in the deformed networks. It is remarkable that the results depend on the length of the flexible spacer between the mesogenic side groups and the p

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985106

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractWell‐defined graft copolymers composed of a hydrophilic clyceryl methacrylate backbone and hydrophobic monodisperse molecular weight polystyrene branches were prepared by the macromonomer technique. The swelling behaviour and the oxygen permeability of hydrogels prepared from these graft copolymers were studied. It was found that equilibrium water content of these hydrogels was considerably high and depended on both the graft copolymer structure and the microphase separated structure of the prepared hydrogel. Oxygen permeability of the hydrogels was directly related to their water content. Hydrogel membranes prepared from the graft copolymers have also well‐defined structures which can be easily controlled by the graft copolymer struct

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985107

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe solid state polymerization of disubstituted diacetylene single crystals can lead to polymer single crystals of macroscopic dimensions. Polymer single crystals with a volume of half a cubic centimeter can be produced by thermal or by γ‐ray polymerization. Details of the reaction are revealed if it is initiated by UV‐light. ‐ Recent spectroscopic and holographic experiments during the photoinitiated reaction of the by far most investigated diacetylene TS are reviewed (TS =P‐toluene‐sulfonyl‐oxymethylene substituted diacetylene). ‐ Electron Spin Resonance (ESR) and Electron Nuclear Double Resonance (ENDOR) spectra at 4.2 K identify bicarbene oligomers and their detailed structures as intermediate states during the reaction. Bicarbene oligomers consisting of up to thirteen monomer units are analyzed and specified spectroscopically. ‐ Laser flash photolysis is able to analyze the kinetics of the first reaction steps separately and within a large temperature range up to room temperature. The UV‐flash initiates the reaction which subsequently proceeds exothermic and thermally activated. The activation energies are measured to be almost equal for each step following the photoinitiation: ΔE = 0.25 eV/monomer. The relevant rate constants for the first steps are of the order of 1 vs at room temperature and 1 ms at 180 K, respectively. Single crystal polymer gratings produced by two interfering UV‐laser beams at the surface of the monomer single crystal show that holograms with both, high spatial resolution of more than 1600 lines per mm and high efficiency of up to more than 30 % can be stored and read out without any

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985108

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractSeveral new polyetherurethane (urea)s were synthesized and their morphologies and biomedical properties such as the antithrombogenicity, the oxygen permeabilities and the permeation of uremic toxins were investigated.

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985109

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractCertain polymerization reactions show the formation of medium molecular weights at the beginning of the reaction, althoughthey can be considered to be polycondensations. The principle of equal reactivity of the end groups is not given in thiscase. Intermediates more reactive than the monomer are formed during the reaction. Poly(oxy‐2,6‐dimethyl‐l,4‐phenylene),poly(l,4‐phenylene sulfide) and poly(l,4‐phenylene) are examples of this type of reaction. The formation of radical ions in these reactions is discussed and they are compared toBunnett's SRN

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985110

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe velocity of free‐radical copolymerization is as yet not comprehensively understood in terms of the elementary processes of propagation and termination. A prevailing view of this classical subject may be that the propagation process is, in most cases, correctly described by the simple mechanism embodied by the “terminal model”, whereas the termination process involves complexity, still remaining to be interpreted. However, very recent experiments on styrene/methyl methacrylate and p‐chloro‐styrene/methyl acrylate copolymerizations, in which both the steady‐ and nonsteady‐state polymerizations were observed to examine the two processes separately, indicate that the fact may be just the reverse: it is the propagation step that need be re‐interpreted, while the termination step is well described by simple models such as the North

ISSN:0025-116X    

DOI:10.1002/macp.1985.020121985111

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY