摘要:

AbstractLinear organic chains and their architectural derivatives such as branched and crosslinked macromolecules have been the main focus of polymer science for many decades. A new direction which should be pursued in the field is the exploration of polymers as “nanostructures”. This exploration would study synthetic polymers as shape invariant objects with nanoscale dimensions which resemble the folded proteins of nature. Such synthetic macromolecules would have well defined shapes which may even include topographical features. Ideally, the definition of shape could include well defined dimensions as well, but molecular objects of common shape but varying dimensions could also exhibit interesting properties. One could for example envision polymers as flat plates (two‐dimensional polymers), discs, ellipsoids, spheres with cavities, parallelepipeds, among many other possible shapes. Such objects must have fairly high molar masses, possibly in the range of hundreds to thousands of kilodaltons, and would therefore not be accessible as chemical compounds synthesized by conventional methods. At the same time, the prospects of learning “folding rules” for synthetic chemical sequences in a biomimetic approach to molecular nanostructures seems to be an extremely difficult goal at the present time. This is suggested given our contemporary difficulties in understanding the protein foldin

ISSN:1022-1360    

DOI:10.1002/masy.19971170104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe influence of uniaxial mechanical stress applied parallel or perpendicular to the director axis (optical axis) of nematic and smectic‐A elastomers having a permanent macroscopically ordered monodomain structure is investigated. Due to the different phase structures applying an external mechanical stress leads to completely different responses with respect to the young moduli and reorientation processes of the director. Nematic elastomers exhibit a weak anisotropy of the moduli parallel (μ11and perpendicular (μ) to the optical axis with μ11/ μ = 1.5. The moduli are mainly determined by the rubber elasticity of the poly(siloxane) network. Applying the mechanical stress perpendicular to the initial director axis causes a rotation of the director axis that is connected with a periodic pattern formation and a ‘soft elastic’ response. For smectic‐A elastomers μ11/μ is in the order of 102. While μ reflects a rubber elastic response similar to that of the nematic system, μ11indicates an enthalpy‐elastic behaviour of the one‐dimensional long range order of the smectic layers. In this direction reorientation of the phase structure with a deformation of the smectic layers occurs above a threshold elongation. In contrast to the nematic networks, a deformation perpendicular to the optical axis causes no director reorientation, displaying the liquid‐like properties with

ISSN:1022-1360    

DOI:10.1002/masy.19971170105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe polymer backbone of a side‐chain liquid crystal polymer exhibits an anisotropic shape due to the coupling of the liquid crystal orientational order of the mesogenic side‐chains to the backbone. The magnitude and sign of this coupling may be controlled by chemical design. The introduction of chemical cross‐links in to such a system provides both a memory of the anisotropic organisation and a mechanism by which the microscopic anisotropy can be realised at a macroscopic level. We show how this anisotropic network structure yields new phenomena when electric or mechanical fields are ap

ISSN:1022-1360    

DOI:10.1002/masy.19971170106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractDiffusion enforced photo‐assembling during polymerization of a chiralnematic monomer blend yields a cholesteric network in which the helical pitch gradually changes over the cross‐section of the film. The polarization selective reflection band of cholesterics can be made much wider than those of single pitch materials and may expand over the whole visible wavelength. The paper discusses the photo‐controlled diffusion process in thin films, the important process parameters and some of the properties of the molecular architectures obt

ISSN:1022-1360    

DOI:10.1002/masy.19971170107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFive linear mesogenic polyesters, containing terephthalic groups, and bearing different amounts of unsaturated substituents were prepared and their phase behaviour characterised by calorimetric and X‐ray diffraction means. Networks based on these polymers were obtained by thermally activated radical polymerisation. Some optical and structural features of these networks were investigated both in the bulk and in the swollen stat

ISSN:1022-1360    

DOI:10.1002/masy.19971170108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFerroelectric liquid crystalline elastomers combine the rubber elasticity of polymer networks with liquid crystalline phases and ferroelectric ordering. Ferroelectric switching leads therefore to a deformation of the polymer network and an elastic stress. The coupling between both effects can be varied by changing the topology of the netpoints.

ISSN:1022-1360    

DOI:10.1002/masy.19971170109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis contribution from a non‐theorist aims to give some introduction to the following theoretical papers as well as some of the points brought out in the oral discussio

ISSN:1022-1360    

DOI:10.1002/masy.19971170110

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe outline the simplest principles which, taking advantage of tandem interaction, can give rise to long range motion with the use only short range forces.

ISSN:1022-1360    

DOI:10.1002/masy.19971170111

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis article focuses on the continuum aspects of liquid crystal elastomer structure. There are two opposing tendencies, the lack of thermal fluctuations that enhances the order in the system, and the random quenched disorder that leads to a highly frustrated polydomain state in equilibrium. Imposing an external field (mechanical stress) changes the balance between order and disorder, this process being monitored by a polarised light scattering.

ISSN:1022-1360    

DOI:10.1002/masy.19971170112

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe describe the results of theoretical and experimental studies of the regular heterogeneities on a nanometer scale which are formed in the systems containing weakly charged polyelectrolytes due to the competition of ionic and hydrophobic interactions. In particular, we consider the effect of microphase separation in poor solvent polyelectrolyte solutions and gels and nano‐self‐assemblies emerging in the complexes of polyelectrolyte gels with oppositely charged surfactants. The practically important application connected with metal nanoparticles formation in regular microstructures in polyelectrolyte systems is considered as w

ISSN:1022-1360    

DOI:10.1002/masy.19971170113

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY