摘要:

AbstractIn the first part new monoaminodiacetylenes with different numbers of CH2‐groups, the formation of Perowskit‐type Mn complexes and their polymerizability are described. Symmetrical diaminodiacetylenes and some derivatives therefrom have also been prepared. The second part deals with different types of polymers with diacetylene units in the backbone. Under irradiation color formation and crosslinking take place. Well‐defined low molecular weight model compounds of polydiacetylenes is the subject of the third part. Finally rod‐like but soluble polymers with alternating p‐phenylene and acetylene units are

ISSN:0258-0322    

DOI:10.1002/masy.19910440102

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractLow‐molar‐mass and polymeric liquid crystals exhibit large nonlinear optical responses, due to a combination of orientational order and fluidity. Polymeric liquid crystals have the disadvantage of longer response times but offer the advantage that the liquid‐crystalline state and any modulation imposed on it can be frozen‐in in the anisotropic glassy state. This holds in particular for light‐induced reorientations of the director and thus of the optical axes based on a photoselection process of photostationary

ISSN:0258-0322    

DOI:10.1002/masy.19910440103

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractMolecular dynamics calculations are used to explore the structure of dense monolayers of long‐chain molecules supported on a planar surface. As a model we consider ensembles of flexible chains consisting of N segments (N=32, 64 and 128) in a box with lateral (x, y) periodicity conditions. The effect of surface coverage on the conformational properties of chains is studied. At high coverages, the results of the simulations show that each chain is strongly stretched along the normal to the surface and the mean layer thickness is linear in N. The segment density distribution along the normal is found to be an universal function A2/3f (zA1/3N), where A is the surface area per chain. The high‐coverage distribution has a well defined broad plateau, in agreement with the so‐called blob model. In contrast to the predictions of this model, however, we observe that the chains are strongly stretched at all space scales. Differences between the results of simulations and those predicted by the mean‐field theory are also di

ISSN:0258-0322    

DOI:10.1002/masy.19910440104

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

Abstract1H and2H NMR methods were used to investigate the effect of fillers on the molecular motions in filled poly(dimethylsiloxane). Molecular mobility at the polymer filler interface is strongly different from that outside the adsorption layer. The influence of concentration and type of filler on molecular motions and concentration of the adsorption layer was determined.

ISSN:0258-0322    

DOI:10.1002/masy.19910440105

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractMany polymer products are heterogeneous. Examples of heterogeneities are the chemical composition, distributions of mechanical stress, and variations in flexibility or molecular orientation. Applications of NMR imaging to polymers are summarized and investigations of the aging of rubber are reported as well as novel deuteron NMR techniques to image molecular order and mobility of polymers below the glass transition temperature.

ISSN:0258-0322    

DOI:10.1002/masy.19910440106

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe majority of compatible polymer mixtures known so far has been rationalized by assuming special interactions between the different polymers or by specific repellent forces within certain types of copolymers. Thus, the compatibility of PMMA with special copolymers of styrene and acrylonitrile is explained by an intramolecular repulsion within the copolymer between the two comonomers styrene and acrylonitrile. In our opinion this phenomenon is not limited to copolymers, but also holds for explaining the compatibility of various homopolymers such as PVDF/PMMA. To this end we simply regard the homopolymer PVDF (‐CH2‐CF2‐) as a copolymer of ‐CH2‐ and ‐CF2‐ “monomers”. By the same token it is possible to assume repellent forces within the PMMA monomer units (i.e. repulsion between the CH2‐C(CH3) and the polar carbonyl group). Those strong repellent forces within the PVDF and PMMA homopolymers can be reduced by mixing the two species. This concept of repulsive forces within monomers as a driving force for polymer‐polymer compatibility can be used to search for new classes of compatible polymers. This will be demonstrated with the polystyrene/polyalkylmethacrylate blends. Thus, with comparable geometry in the side chains, polystyrene and polymethacrylic esters will form compatible blends, as born out in the systems polystyrene/polycyclohexyl methacrylate or poly‐tert‐butyl styrene/poly‐3,3,5‐trimethylcyclohexylmethacrylate which are compatible in all proportions. Taking into account certain steric prerequisites, one can even obtain compatible blends l

ISSN:0258-0322    

DOI:10.1002/masy.19910440107

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe coupling and the competition of two phase transitions (demixing and crystallization) and the coupling of both demixing and vitrification are investigated during phase transformations under far‐from‐equilibrium conditions. The coupling leads to formation of the different non‐equilibrium morphologies and to kinetic pecularities of phase transforma

ISSN:0258-0322    

DOI:10.1002/masy.19910440108

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractMicroporous membranes were prepared from poly(vinyl methyl ether ‐ crosslinked‐polystyrene) (PVME‐cross‐PS) semi‐IPN's by extraction of poly(vinyl methyl ether) (PVME) with water. Membrane morphology and properties are fixed during the process of swelling, phase separation, PVME extraction and vitrification which occurs upon immersing the samples in water. The membranes are characterized by swelling (water uptake), the relative amounts of free and bound water, and their permselectivity towards KCI

ISSN:0258-0322    

DOI:10.1002/masy.19910440109

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractSynthesis and photoconductivity measurements are presented for two different types of photoconductors: i) polymers with pendant carbazolyl groups and ii) conjugated polymers. The temperature‐ and field dependence of the effective carrier mobility has been measured in a series of polymethacrylates with pendant carbazolyl groups and is discussed in relation to theoretical models. Time‐of‐flight measurements show that conjugated polymers like poly(methylphenylsilane) and poly(1,4‐phenylenevinylene) exhibit extremely high carrier mob

ISSN:0258-0322    

DOI:10.1002/masy.19910440110

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe synthesis, reactions and structure of linear polydiorganosilanes, including crystalline polydialkylsilane polymers and polydiphenylsilane olygomers with various terminal functional groups are discussed in terms of the equilibrium chemical and structural processes.

ISSN:0258-0322    

DOI:10.1002/masy.19910440111

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY