摘要:

AbstractThe influence of the number of oxyethylene repeating units in the oligomeric derivatives of ethylene bis(4‐chlorocarbonylbenzoate) (1,n= 3, 6,4, 13, 22,3, 45 and 68) on the reactivity of the chlorocarbonyl end groups in the acceptor‐catalytic esterification was determined by means of thermodynamic and kinetic investigations in diluted solutions. The violation of the principle of equal reactivity was found to be caused by the far‐order effect, when with increasing chain length the effective local concentration of oxyethylene repeating units increases in the environment of the end group whose reactivity is determined by the ratio between the “solvating ability” of the repeating units and the solvent. The far‐order effect influences not only the kinetics, but also the reactio

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890501

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractPoly(dimethylsiloxane) (poly(DMS))/poly(N‐tert‐butylaziridine) (poly(TBA)) block copolymer was synthesized by two different techniques; (1) the coupling reaction of poly(DMS) having a dimethylaminopropyl end‐group (1) with living poly(TBA) (2) which was prepared with methyl trifluoromethanesulfonate as an initiator, and (2) the polymerization ofN‐tert‐butylaziridine (5) using poly(DMS) having ap‐toluenesulfonyl ester end‐group (4) as macromolecular initiator,

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890502

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe thermal expansivity of semicrystalline polymers is interpreted within the framework of the composite model which has already been found useful in describing mechanical and optical properties as well as the thermal conductivity of a large number of polymers. The model assumes the polymers to be an aggregate of units composed of crystalline and amorphous phases. The thermal expansivities of the unit are calculated in terms of those of the constituents. In the undrawn state the units are distributed randomly, and the isotropic thermal expansivity of the bulk results. The development of strong anisotropy in thermal expansivity on drawing is explained in terms of preferred orientation of the units. The orientational changes on drawing have been directly calculated from the birefringence versus draw ratio data. The results of these investigations indicate that the present model is quite successful in interpreting thermal expansivity data for poly(oxymethylene) and poly(propylene) over the entire draw ratio and temperature range.

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890503

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractWater‐soluble polymers6–17containing covalently bound moieties of porphyrin derivatives were prepared by reaction of poly(methacrylic acid) (4) and poly(N‐vinylpyrrolidone‐co‐methacrylic acid) (5) with the low‐molecular‐weight substituted tetraphenylporphyrin1 b, phthalocyanines2 band2 dand naphthocyanine3 c. Besides binding of one porphyrin derivative, also combined binding of two or three different porphyrin derivatives to the polymers could be achieved. The resulting polymers are negatively charged (polymers6–11) or uncharged

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890504

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractPositively charged polymers6–13containing covalently bound moieties of tetraphenylporphyrin (1), phthalocyanine2and naphthocyanine3were obtained by reaction of poly(chloromethylstyrene) with low‐molecular weight substituted porphyrins (1 b,2 b,2 d,3 c) in the presence of triethylamine. The water‐soluble polymers contain moieties of one or of two or three different porphyrin deriva

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890505

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractBy ring‐opening copolymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐octadecyl‐β‐D‐glucopyranose (1) with 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose (2) using phosphorus pentafluoride as initiator in dichloromethane at 0°C, stereoregular copolymers3, withM̄n= 6 · 103to 24 · 103were obtained. For debenzylation of copolymers3, either the reduction with sodium in liquid ammonia or radical bromination‐hydrolysis was applied, depending on solubility and copolymer composition. Poly[2,3,4‐tri‐O‐octadecyl‐α‐D‐glucopyranosyl‐(1→6)‐stat‐α‐D‐glucopyranosyl‐(1→6)] (4,) exhibits characteristic solution properties arising from its amphiphilic structure. Polysaccharide4, with mole fractions of trioctadecylated unit (x) below 0,03, are water‐soluble and interact with magnesium 1‐anilino‐8‐naphthalenesulfonate (ANS) in water. The polysaccharide4(x= 0,29), which is soluble in chloroform, was found to solubilize an aqueous methyl orange solution in chloroform.

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890506

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractCrosslinked polymers containing pendant tris(bipyridyl)ruthenium(II) complexes [Ru(bipy) 32+] were synthesized and examined as sensitizers for the light‐induced formation of hydrogen in the heterogeneous system H2O/immobilized Ru(bipy) 32+/ethylenediamine‐tetraacetic acid/platinum. Hydrogen generation rates of 0,037 ml/h were obtained with Ru(bipy) 32+‐complexes immobilized with spacer groups onto hydrophilic carriers based on sucrose‐methacrylates as well as hydrophobic carriers based on crosslinked poly(4‐aminostyrene), whereas carrier bound complexes without spacer gave lower efficiencies in hydrogen production. The hydrogen generation rates were linear for m

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890507

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe reactive species (radicals, ions, etc.) or the UV‐visible radiation emitted by the excitated species initiate the cold plasma induced polymerization of a monomer in the liquid or solid state. The residual CC double bond concentration of an acrylic monomer depends on the plasma characteristics (gas nature, pressure, discharge power, etc.), but also on the polymerization conditions. The UV‐visible radiation emitted in a cold plasma has more influence on the thickness of the film than the reactive species bombardment. Two simple mathematic laws describe these phenom

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890508

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractComplementary experiments confirm the recent findings that the rate of propene polymerization is temporary enhanced if a small amount of ethylene is introduced during the polymerization, normalizing after consumption of ethylene by copolymerization. In addition, the study of the sequence distribution of propene monomeric units in the copolymerization carried out under various conditions revealed that the activation by ethylene does not involve the propagation steps, but the re‐initiation after deactivation. A similar temporary activation effect was observed after the addition of small amounts of hydrogen. In this case, however, hydrogen is not consumed. Thus, the deactivation observed after the initial rate enhancement is due to another reason. The deactivation could be shown to be reversible after removal of the adsorbed hydrogen when either ethylene or hydrogen was added again to allow re‐initiation of the polymerization. One of the important reasons of the continuous decrease of the propene homopolymerization rate may be due to the fact, that, after a transfer step, the re‐initiation of polymerization does not take place spontaneously. Small amounts of ethylene or hydrogen allow the reinitiation to take place, at least for some kind of active

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890509

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractA new method for the synthesis of compact, multifunctional star‐shaped polystyrenes was designed. A plurifunctional metalorganic initiator is obtained upon reaction of potassium naphthalene with commercial divinylbenzene. The resulting polymeric “core” exhibits a number of metalorganic sites. In a subsequent step, these sites initiate the polymerization of styrene to yield a star‐shaped polymer. High numbers of branches can be obtained, thus rendering these molecules extremely compact. However, the major advantage of the “core first” method is that it allows functionalization of the branches at their outer end, thus providing the possibility of further reaction or selective adsorption. This “core first” method was also applied to the preparation of star‐block copolymers formed of a polystyrene block and a poly(ethy

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890510

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY