摘要:

AbstractA series of new poly(bismaleimide‐diamine)s (3a–c) with crown‐ether groups in the main chain were synthesized from bismaleimides (1a–c) and a diamino‐functional dibenzo‐18‐crown‐6 (2). The polymerization occurred in solution through the addition of the NH2groups of2to the CC double bonds of the maleimide rings of1. The optimum polymerization conditions were established. The polymers3were obtained in good yields and fairly high molecular weights (ηred= 0,15–0,35 dL/g). The polymeric crown eithers show high capacity for the binding of alkali metal ions and may be used a

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941001

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA novel polymerizable phospholipid with conjugated diene groups at the hydrocarbon chain ends, 1,2‐bis(11,13‐tetradecadienoyl)‐sn‐glycero‐3‐phosphocholine (7), was synthesized. This phospholipid gives liposomes which can be readily polymerized upon γ‐and UV‐irradiation. The conversion is up to 95% within 10 h at 60°C or within 3 days at room temperature. According to light scattering,31P NMR and electron microscopy, the polymerized liposomes are detergent‐resistent and maintain their structure under ultrasonic treatment and in or

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941002

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe biodegradability of solution‐cast films of poly(D(–)‐3‐hydroxybutyrate) (PHB) blended with the melt‐compatible component atactic poly(epichlorohydrin) (aPECH) was investigated. A bacterium which produced extracellular enzymes that degraded PHB even when blended with aPECH was isolated, and tentatively designated asAureobacterium saperdae. The growth rate ofA. saperdaedecreased with increasing aPECH content in the blend, up to films containing 60 wt.‐% aPECH, at which composition growth was completely inhibited. The decrease in the bacterial growth rate could be due to the dilution of PHB molecules on the blend film surface caused by the presence of aPECH molecules. At the stationary phase of bacterial growth the percentage of weight loss of blend films decreased with increasing aPECH fraction, which was probably due to the lower accessibility of PHB when blended with aPECH. During the bacterial growth only PHB was metabolized, whereas neither degradation nor abiotic release of aPECH was detected for

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941003

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA large number of new liquid‐crystalline 1‐alkenes with various mesogenic groups based on substituted phenyl benzoate or biphenyl and with different spacer lengths (2‐10 methylene groups) were synthesized and copolymerized with sulfur dioxide by free‐radical initiation to produce alternating polysulfones with liquid‐crystalline side chains. The phase transition temperatures of the 1‐alkenes and polysulfones were determined; their clearing temperatures lie in the ranges 43–138°C and 89–194°C, respectively. The liquid‐crystalline phases of the polysulfones, as determined by means of X‐ray diffraction, show a great variation, i.e. cholesteric and nematic as well as various smectic

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941004

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe phase behaviour and the related morphology of the system high‐density polyethylene/diphenyl ether was investigated. A liquid‐liquid demixing precedes the crystallization in solutions with polymer weight fractions lower than 0,30. A three‐phase equilibrium is installed, in which two liquid phases with different polymer concentrations and a crystalline phase coexist. This does not lead to an invariant situation, as would be predicted from the phase rule for a strictly binary system. The crystallization and melting temperature decrease in this concentration region with increasing polymer concentration. Transmission electron microscopy observations were carried out on samples with a polymer concentration in the demixing region. A morphology, characteristic of a liquid‐liquid demixing, preceding crystallization, is observed. Globular particles with a variety of surface structures and internal organization are obtained at very low polymer concentration. Solutions with a polymer weight fraction higher than 0,10 are transformed into porous, crystalline structures. An important shrinkage of the concentrated domains takes place. It results in a pronounced solvent synersis. This change in the physical aspect of the samples is ascribed to the nature of the three‐phase eq

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941005

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe conformational transition expanded coil to compact globule for linear and crosslinked poly(4‐but‐3‐en‐1‐ynyl‐1‐methylpiperidin‐4‐ol), poly{1‐[2‐(4‐hydroxy‐1‐methyl‐4‐piperidyl)ethynyl]ethylene}, (1) in aqueous and aqueous‐salt solutions was investigated. The free energy of the conformational transition for linear1.nHCl was calculated. It was shown that in aqueous solution1is characterized by a lower critical solution temperature (LCST). The collapse of crosslinked1on changing the ionization state (aqueous salt solution) and temperature was observed and

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941006

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractPolymerization of vinyl monomers such as styrene, methyl methacrylate, and vinyl acetate was carried out in the presence of the captodative substituted dimers1–6at 50 to 110°C. It was found that the dimer initiates the radical polymerization of these monomers, even of vinyl acetate. The initiation ability of the dimers depends on the nature of both captive and dative groups as well as the substituent at a remote position. The kinetic study suggests that in the polymerization initiated by the dimers primary‐radical termination and chain transfer play a minor

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941007

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe galvanostatic electropolymerization of thiophene (1), 3‐methylthiophene (2) and 2,2′‐bithiophene (3) in acetonitrile, containing 0,002 to 20 mol/L water, was studied in detail. The current efficiency γ for the polymer film formation decreased rapidly for1, but much slower for2and3with increasing water concentrationc H 2O. Forc H 2O= 0,1 mol/L, γ was found to be 10, 82 and 95% for1–3. It was possible to describe the experimental γ vs.c H 2Oplots quantitatively by a model where the electrogenerated radical cations (rc) of the thiophene (derivative) are consumed by two competing second‐order follow up reactions, the nucleophilic attack of the rc by water (i) and the rate‐determining dimerization of two rc's (ii). Their rates are given by: (i)v1=k1crcc H 2Oand (ii)v2=k2c2rc. The side reaction (i) leads to soluble products, while reaction (ii) contributes to the polymer film growth. The ratiok1/k2was found to be 3 · 10−7, 2 · 10−8and 4 · 10−9for1, 2and3, respectively, and this shows that the electropolymerization of 2,2′‐bithiophene is by a factor of about 100 less sensitive toward the present water than thiophene. The steady state concentrationcrcis in the order of 10−9mol/L in all three cases. The relative insensitivity of doping/undoping cycles with respect to the presence of water is discussed in terms of a lessened reactivity of the polarons and a low solu

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941008

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractBlock copolymers were synthesized composed of an isotropic, crystallizable poly(oxy‐1,4‐phenylene) block and a thermotropic liquid‐crystalline (LC) polyester block. Crystalline as well as amorphous LC polyesters were used, derived from substituted poly(1,4‐phenylene terephthalate). The block of poly(oxy‐1,4‐phenylene) was introduced via telechelic1.1was prepared with a functionality of 2 in a Cu‐catalyzed reaction of 4‐bromophenolate4with 4,4′‐isopropylidenediphenol (bisphenol A). The molecular weight of the telechelic is given by the ratio4/bisphenol A. The increase in molecular weight during formation of the block copolymer is shown by viscosity and gel‐permeation chromatography measurements. The maximum weight loss of the block copolymer as obtained by thermogravimetry is in the range of 450–500°C. Both segments in the block copolymers have a strong influence on their mutual crystallization behaviour. Short segments of poly(oxy‐1,4‐phenylene) suppress the crystallization of both blocks. When using longer segments of poly(oxy‐1,4‐phenylene) the melting endotherms of both blocks are observed, but the degree of crystallinity is lower than that of the homopolymers. The fracture behaviour of the liquid‐crystalline polyester2ais changed by modification with 20 wt.‐% of poly(oxy‐1,4‐phenyle

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941009

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe laser‐induced photoisomerization of various α‐thiocyanatoketones in a polymer matrix (polystyrene,cis‐1,4‐polybutadiene, butadiene‐styrene copolymer) was studied by means of FT‐IR spectroscopy. Phenacyl thiocyanate was converted to phenacyl isothiocyanate under UV irradiation. The degree of isomerization increased with the styrene content of the matrix polymer. Aromatic sensitizers such as chrysene and anthracene enhanced the isomerization reaction, but also led to the decomposition of already formed isothiocyanate. After comparison of the photoreactivity of different α‐thiocyanatoketones, a linear correlation was established between the amount of isothiocyanate formed after a certain pulse number and the absorption coefficient at the laser wavelength. Polystyrene containing thiocyanatoacetyl groups was prepared via reaction with acetyl chloride, subsequent bromination at the acetyl group and reaction with potassium thiocyanate. The photoisomerization was similar to that of the low‐molecular‐weight α‐thiocyanatoketones. This photoisomerization increased, and the degree of crosslinking decreased, when a magnetic field

ISSN:0025-116X    

DOI:10.1002/macp.1993.021941010

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY