摘要:

AbstractPolyurethane and polyurethane cationomers were synthesized using 2,3‐dihydroxypyridine and 2,3‐dihydroxypyridine hydrochloride as chain extenders. Poly(butyl methacrylate‐co‐methacrylic acid) was synthesized by free radical solution polymerization and was converted into its sodium salt. The polyurethane cationomer and the acrylic anionomer were blended in different proportions inN,N‐dimethylformamide. Simple blends without ionic groups were also prepared. Miscibility enhancement in these systems was studied by means of differential scanning calorimetry and scanning electron m

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170201

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe decrease of the droplet radii of silicone oil dispersed in a polystyrene matrix at a temperature of 140°C with increasing time was measured by NMR dynamic imaging. From this time dependence the diffusion coefficient of the silicone oil into the matrix was calculated to be 7 · 10−18m2· s−1. The uptake of the silicone oil in the polystyrene matrix was confirmed by broad line NMR measur

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170202

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA new optically active medium for lasers — a polyelectrolyte hydrogen swollen in a mixture of water + alcohol + dye — is presented. An anomalous dependence of the absorbance on the composition of the mixture is observed. It shows a maximum which corresponds to the composition when the hydrogel starts to swell as a hydrophilic netw

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170203

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractLiquid crystalline (LC) polymers with monosubstituted ferrocenyl units in the side chain were prepared by radical polymerizations of the corresponding LC and non‐LC acrylates. It was demonstrated that polymerization is useful for the LC orientation and expands the LC temperature range. In addition, these mesogenic ferrocenes form a complex with tetracyanoethylene (TCNE) to give spin labeled molecules simply by mixing the ferrocenyl compounds with TCNE in the solid state at ambient temperatur

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170204

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe anionic grafting of methyl methacrylate onto several lithium diisopropylamide (LDA) — treated polymers of methyl α‐substituted acrylates containing an active methylene or methine group was investigated. The grafting was carried out using a mole ratio of LDA/acrylate unit of 0.75 in the feed polymer. The anionic graft copolymerizability of these acrylate polymers largely depends upon the surrounding of the active α‐hydrogen atom adjoining a carbonyl group or of the carbanion produced by the LDA treatment in the feed

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170205

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe peptide catalyst having the amino acid sequence (Z‐L‐Leu (or Phe)‐L‐His) was found to be the most stereoselective among theL‐histidyl group‐containing di‐, tri‐, or tetrapeptide catalysts in the hydrolysis of enantiomeric amino acid substrates in vesicular membranes. The role of the membrane‐assisted hydrophobic interaction between the peptide catalyst and enantiomeric substrates for the improvement of the hydrolysis stereoselectivity was demonstrated by means of direct measurements ofnuclearOverhausereffectspectroscopy (NOESY) spectra of the interaction system and by the extremely high stereoselectivity itself obtained by intensifying the membrane‐promoted hydrophobic interaction between the catalyst

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170206

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractStructures of poly(ether ether ketone ketone)‐poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X‐ray scattering and the one‐dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (nb). Whennb= 0.35, invariantQ, long periodL, average thickness of crystal lamellae d̄, electron density difference ηc− ηaand degree of crystallinityWc, xassume mini

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170207

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractTo induce degradabilities in polymers in response to environmental conditions, endm odification reactions of poly(α‐methylstyrene) (PMS) derivatives were carried out. 2‐Phenylallyl halide derivatives such as 2‐phenylallyl bromide, 2‐(p‐tolyl)allyl bromide, and α‐trifluoromethylstyrene were found to be suitable end‐modification agents. For example, the ω‐2‐phenylallyl‐PMS derivative was prepared with almost quantitative functionality by the reaction of the living PMS derivative with 2‐phenylallyl bromide. In a similar way, ω‐3,3‐difluoro‐2‐phenylallyl‐ and ω‐2‐(4‐toly)allyl‐PMS derivatives were synthesized. Based on thermogravimetric analysis, the onset of the degradation temperature of the endmodified PMS derivatives decreased in the following order: ω‐hydrogen‐>ω‐3,3‐difluoro‐2‐phenylallyl‐>ω‐2‐phenylallyl‐>ω‐2‐(p‐tolyl)allyl‐PMS. Actually, the onset temperature of ω‐2‐(p‐tolyl)allyl‐PMS derivatives was 50°C lower than that of ω‐H‐PMS derivatives. These results indicate that the active species is produced effectively at the endunsaturated bond, which initiates depolymerization of the polymer at rather low temperatures. Therefore, it is concluded that a 2‐phenylallyl subs

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170208

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractGlycol chitosan (GC) and methyl glycol chitosan (MGC) were separately reacted with poly(potassium vinyl sulfate) (PVSK) in the presence of iron(III) hydroxide sulfate (IHS) to form water‐insoluble macromolecular complexes (MC's). The chemical compositions and properties of MC's obtained were compared with each other. The solubility of MC in the MGC‐IHS‐PVSK system was lower than that in the GC‐IHS‐PVSK system, and it was suggested that MGC contributes to the propert

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170209

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractPolystyrene macromonomers, fitted with a norbornenyl unsaturation in α position, have been obtained from a norbornene based carbanionic initiator that has been purposely designed to this end. The advantages of this synthetic scheme over that based on the deactivation of living PS chains are emphasized. One of the macromonomers prepared has been subsequently polymerized by ring‐opening metathesis, using a Schrock complex as initiator. The characterization of the resulting polymacromonomers showed that the metathesis process occurred under “living” cond

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170210

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY