ISSN:1022-1360    

DOI:10.1002/masy.19971130103

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPolysoaps are linear hydrophilic chains that incorporate, at intervals, covalently bound amphiphilic monomers. In water, the amphiphilic monomers self assemble into intrachain micelles thus endowing the chain with a secondary structure. The relaxation of the secondary structure upon deformation qualitatively modifies the elastic behaviour of polysoaps in accordance with the LeChatelier principle. For long polysoaps a regime in which the tension in the chain,f, is independent of the end to end distanceR, f ˜ R°is predicted. The extension of long polysoaps is analysed for the particularly simple case when the backbone obeys Gaussian statistics and excluded volume interactions are neglecte

ISSN:1022-1360    

DOI:10.1002/masy.19971130104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractDifferent morphologies and phase transitions of ternary triblock copolymers with different block sequences (ABC and BAC) are discussed qualitatively. The interplay between interfacial energies and elastic energies of the different blocks leads to various morphologies and enhances or prevents mixing of different blocks, depending on composition and topology.

ISSN:1022-1360    

DOI:10.1002/masy.19971130105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractElectrooptical characteristics of mesogenic chain molecules in solution and in mesophase can be described in terms of intra‐ and intermolecular orientational orders. The value and sign of electric birefringence δn in a solution of kinetically rigid chain molecules are determined by the combination of two factors: intramolecular orientational order which depends on the dipolar and anisotropic architecture of the molecule and intermolecular orientational order caused by the action of the external electric field E. The value and sign of the dielectric anisotropy δε of the polymer nematic phase are also determined by the combination of intra‐ and intermolecular orders. However, in this case the latter is not maintained by the external field but by the nematic potential of the mesophase. Therefore, comparative investigations of electrooptical properties of polymers in solutions and in nematic melts make it possible to obtain information about the intra‐ and intermolecular orientational orders of the molecules under investigation in these two states. These investigations were carried out using the method of electric birefringence in solutions and the method of orientational deformations of nematic textures in an electric field. The objects being investigated were nematogenic dimers and trimers. Experimental data obtained for these compounds showed the presence of intramolecular order in their molecules, which is manifested in the odd‐even oscillations of the value and sign of Kerr constant K≈δn/E2in solution and δε in the nematic phase when the number of C‐C bonds in the methylene spacers of these molecules is varied. This effect is particularly dramatic in the mesophase where it is enhanced by intermolecular

ISSN:1022-1360    

DOI:10.1002/masy.19971130106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractMechano‐chemical conversion through the swelling of polymer gels suffers from several limitations, as far as the artificial muscles applications are concerned: mechanical response is too slow and strong local stress damages the sample. We propose a different approach to bypass these difficulties: artificial muscles based on nematic gels. When the temperature is lowered below the nematic clearing point, strong uniaxial deformations occur. The estimated shape relaxation time is well within actual muscle contraction time

ISSN:1022-1360    

DOI:10.1002/masy.19971130107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractMesophases are briefly summarized and defined on a uniform basis, making use of order and mobility parameters. A schematic one‐component phase diagram is then reviewed that includes equilibrium as well as nonequilibrium phases. Assuming only five condensed phases (crystal, melt, glass, mesophase, and mesophase glass), fifteen different phase areas exist with simultaneous presence of up to three phases. Examples of all phase areas are documented with results from our laboratory. This scheme can be extended to more components and more than these five phases and produces then many more possible phase areas than can be handled experimentally at the presen

ISSN:1022-1360    

DOI:10.1002/masy.19971130108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractConformational transitions in thermotropic main‐chain polymers of complex chemical structure including homopolymers with possibility of conformational transformations in mesogens and random copolymers (CPLs) containing mesogens of the same type and spacers of different lengths were investigated. It was demonstrated that liquid crystalline (LC) state influences conformational transformations in fragments of chain restraining them in comparison with an isotropic melt. It was found that CPLs studied form LC order of smectic type. Peculiarities in spacers behaviour during transition to LC state ensure formation of such type of LC order. Conclusion about dependence of mechanism of smectic LC order formation on chemical structure of rigid components of CPLs is mad

ISSN:1022-1360    

DOI:10.1002/masy.19971130109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe conformon model of liquids postulates a heterogeneous dynamic superstructure in liquids. The model predicts a universal reduced energy‐ and entropy‐density distribution (Planck distribution) which typify together the thermodynamics of fluctuations. The mean reduced energy‐ and entropy density distributions are identical and invariant at all temperatures, independently of the type of molecules the liquid is comprised of. The model predicts therefore a unique superstructure at the quasi‐static glass‐transition temperature. Tapping‐mode atomic force experiments on monolayers of bottle‐brush molecules reveal a type of a superstructure which is, in fact, in good accord with the conformon model. Relaxation experiments can be described as superposition of a broad set of intra‐conformon Debye‐processes which is consequently related to the heterogeneous equilibrium structure. Principal aspects of the results are refle

ISSN:1022-1360    

DOI:10.1002/masy.19971130110

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

Abstract1H and19F spin‐lattice relaxation times and nuclear Overhauser enhancement factors are reported for solutions of poly(fluoromethylene) in DMSO, and for poly(vinyl fluoride) in DMF. These results, together with literature values for other fluorinated ethylene polymers, show that substitutions of F for H on the chain backbone produce only mild changes in segmental mobilit

ISSN:1022-1360    

DOI:10.1002/masy.19971130111

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe influence of different annealing treatments has been investigated on the stability of the Electro‐Optic coefficient in a poled DANS (4‐dimethylamino‐4′‐nitrostilbene) sidechain polymer, which was poled near its Tg‐onset of 140°C. The annealing treatments and the EO relaxation experiments were performed at 120°C. The EO stability can be significantly increased both by an annealing treatmentafterpoling and by annealingbeforepoling. This latter effect is concluded from the reduction of the EO relaxation rates in successive relaxation cycles performed in the same polymer sample ‐ completely depoled and repoled in between the cycles. The effect from the different annealing treatments on the time‐dependence of the EO relaxation process is different and is analyzed in terms of a Debye‐like model with a single, time‐dependent Debye relaxation time r(t)=ri+C. t3. The time‐dependence ofrand the observed effects from annealing are attributed to the parallel relaxation pro

ISSN:1022-1360    

DOI:10.1002/masy.19971130112

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY