摘要:

AbstractBased on our differential scanning calorimetry observations, a polyether1synthesized from 4′‐[2‐(4‐hydroxyphenyl)propyl]‐4‐biphenylol and 1,9‐dibromononane shows multiple transition behavior during cooling and heating. Furthermore, these transition temperatures do not exhibit significant supercooling dependence. Detailed analyses of the wide‐angle X‐ray diffraction powder and fiber patterns at different temperatures have indicated that highly ordered smectic F and G phases exist in this polyether and are differentiated from traditional c

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160801

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractA new route of synthesis of block copolymers was investigated. It involves the polymerization of a side‐chain liquid‐crystalline acrylate and poly(propylene glycol), modified by an esterification reaction with mercaptoacetic acid used as macrotransfer agent, in the presence of 2,2′‐azoisobutyronitrile as initiator. The molecular weight of the liquid‐crystalline blocks is determined by the molar ratio between the

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160802

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractUnique effects of π‐conjugated polypyridine (PPy) blocks on fluorescence from the following macromolecular systems have been examined: (A) poly(2,2′‐bipyridine‐5,5′‐diyl) (PBpy)‐Ru(bpy)2, (b) block‐type copolymer of pyridine and selenophene, and (c) a system containing poly(6‐hexylpyridine‐2,5‐diyl) (6HexPy) and poly(2‐methylanthraquinone‐1,4‐diyl) (P2MeAQ). The PPy blocks in the systems serve as good molecular antennas and transfer the photoactivated energy to other molecular parts of the systems connected to the PPy blocks, thus causing emission of light fr

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160803

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractADMET depolymerization is a viable route in the formation of tailored‐molecular‐weight polybutadiene telechelics. The bulk depolymerization requirement is met by initially forming macrocyclic butadiene, thereby decreasing the amount of macrocyclic formation. This synthetic scheme is capable of generating well‐defined, tailored‐molecular‐weight polybutadiene telechelics (M

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160804

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractHomo‐ and copolymerization of butadiene and styrene in the presence of the catalyst system Nd(octanoate)3/CCl4/Al(iBu)3(iBu: isobutyl) were investigated at 60°C in heptane as solvent. The initiating catalyst system is very effective in the polymerization of butadiene. However, the presented copolymerization of butadiene and styrene is only practicable when using a special addition order of the catalyst components and a prescribed ageing phase. Copolymers obtained from various monomer feed ratios were characterized by1H and13C NMR spectroscopy and gel‐permeation chromatography (GPC). The copolymer characteristics especially microstructure, molar mass and molar‐mass distribution (MMD) are strongly dependent on the composition of the monomer m

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160805

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe synthesis and the optical properties of the novel aryleneethynylenes (7,8) and arylenebutadiynylenes (10,11) using either a Heck‐type or a Hay‐type coupling are reported. The route reported here also makesmeta‐linked arylene‐alkynylenes accessible. The number‐average degree of polymerization of the obtained polymers is between 13 and 60. Some of the materials show promising optical properties (photolumi

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160806

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractPropylene was polymerized in the presence of the isospecific Et(Ind)2ZrCl2(Et: ethylene, Ind: indenyl) and the aspecific (Ind)2ZrCl2complexes in solution and anchored to SiO2and SiO2/MAO (MAO: methylaluminoxane) supports. From the stereochemical analysis of the polypropene samples obtained it can be deduced that (i) the same active species is formed when a metallocene is in solution and when it is anchored to the SiO2/MAO support and (ii) a completely different active species is formed when the metallocene is anchored to the silica. The fact that both systems Et(Ind)2ZrCl2SiO2and (Ind)2ZrCl2SiO2produce the same prevailingly isospecific polymer suggests that only isospecific centers are formed in this case, independently of the metallocene stereochemical struct

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160807

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractHeteroarm star copolymers with polystyrene and poly(tert‐butyl acrylate) arms are studied in dilute solutions by means of viscometry and static light scattering. In a weakly selective solvent a segregated‐nonsegregated conformational transition is observed induced by temperature change. In a strongly selective solvent association phenomena take place and the heteroarm star molecules form multimolecular micel

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160808

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo types of polyazomethines containing repetitive pairs of a tridentated ligand and an oligodimethylsiloxane in the backbone were synthesized and complexed with cobalt ion. The resulting polymer complex membranes showed very good oxygen permselectivity at 1 atm pressure difference, which is very close to the upper boundary line in an α vs.Po2plot of data reported in the literature. The complexes are thought to function as oxygen carrier

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160809

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe existence of micelles of polystyrene‐block‐poly(ethylene/propene) in solutions of polystyrene in toluene was investigated. Toluene is a good solvent of both copolymer blocks whereas polystyrene and poly(ethylene/propene) are immiscible polymers. The presence of homopolystyrene at high enough concentration can induce the micellization of polystyrene‐block‐poly(ethylene/propene) in solution of a good solvent such as toluene. The thermodynamics of this new micelle system at a given polystyrene concentration was studied. Light scattering measurements were carried out in order to determine the critical micelle temperature (CMT) of different micellar solutions. Standard Gibbs energy, enthalpy and entropy of micellization were estimated from CMT and concentration data. The numerical values found were less negative than those found for micelle systems consisting in a block copolymer dissolved in a single selective

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160810

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY