Liquid crystalline polymers, theoretical aspects

Theoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers... 

Thermotropic liquid crystal polymers (LCI ) are of considerable current interest, because of their theoretical and technological aspects [1-3]. Evidently, a new class of polymers has been developed, combining anisotropic physical properties of the liquid crystalline state with diaracteristic polymer features. This unique combination promises new and interesting material properties with potential ai lications, for example in the field of high modulus fibers [4], storage technology, or non-linear optics [5]. 

The linkage of low molar mass liquid crystals as side groups to a polymer main chain leads to a new class of substances which are important with respect to theoretical aspects as well as future technological application. They combine the liquid crystalline (LC) behavior with specific polymer properties To get... 

The phenomenological aspects of LCP rheology has been reviewed by the author [2]. More recently [14, 15], further data were obtained to compare the viscosity of the same polymer in the isotropic and liquid crystalline states. As with small molecule LC s, the viscosity of nematic LCP s was found to be lower than that of the isotropic forms. There are other aspects of the LCP rheology which require discussion, but first the evidence from theoretical considerations Is described. 

The coupling between the properties of conventional polymer networks and the properties of chiral liquid crystalline phases results in interesting, new opto- and electromechanical effects of the chiral liquid crystalline elastomers, as demonstrated by theoretical considerations and experiments. Knowledge about these new materials is still in its infancy. But the properties analyzed so far for these elastomers indicate promising aspects for application and are the basis for the new syntheses of optimized chiral liquid crystal networks. 

Polymers can be either amorphous or semicrystalline in structure. The structure of amorphous materials cannot be described in terms of repeating unit cells such as that of crystalline materials because of nonperiodicity, the unit cell of an amorphous material would comprise all atoms. The physics and chemistry of the amorphous state remain poorly understood in many aspects. Although numerous experiments and theoretical studies have been performed, many of the amorphous-state features remain unexplained and others are controversial. One such controversial problem is the nature of glass-liquid transition. 

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