Liquid crystals elastomeric networks

The field of thermoset polymers is an area of polymer science that has not yet been widely integrated with liquid crystal polymer research. It is interesting to note that Finkelmann et al. (5) reported on the formation of crosslinked elastomeric liquid crystalline networks in 1981. Although the general concept of a... 

In the phrase liquid-crystalline, the crystalline adjective refers to the faa that these materials are sufSdentiy ordered to diffract an X-ray beam in a way analogous to that of normal crystalline materials. On the other hand, the liquid part specifies that there is frequently sufSdent disorder for the material to flow like a liquid. liquid crystals can be divided into thermotropic, that exhibit a phase transition with change of temperature, and lyotropic, that exhibit phase transition as a function of both temperature and concentration of the LC molecules in a solvent. Both low molecular wdght materials and polymers " can show liquid crystallinity. In the case of polymers, it frequently occurs in very stiff chains such as the Kevlars and other aromatic polyamides. It can also occur with flexible chains, however, and it is these flexible chains in the elastomeric state that are the focus of the present discussion. LC networks of flexible chains have the following three properties (1) they can be extensively deformed (as described for elastomers throughout this book), (2) the deformation produces alignment of the chains, and (3) alignment of the chains is central to the formation of LC phases. Elastomers of this type have been the subject of numerous studies, as described in several detailed reviews. ... 

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