Some Properties of Liquid-Crystal Polymer Networks

Finally, there were established several correlations between certain chain transition temperatures and the extent of network formation. Accordingly, transition temperatures such as Tg [760-762] or heat distortion temperature [763] show linear dependence on the level of network perfection, the less defective the network the higher the respective transition temperature within a range characteristic of the particular network composition. Based on our current level of understanding of the relationship between transition temperatures and concentration of network flaws [764], a significant amount of additional experimental, computer modeling and theoretical work remains to be done before a theory will evolve with predictive powers describing these relationships. 

3 Some Properties of Liquid-Crystal Polymer Networks 

Elastomeric LCP networks with the potential to show piezoelectric behavior were described by Zentel and co-workers [109, 110, 125, 773]. More recently, Meier and Finkelmann [774, 775] created piezoelectric cholesteric elastomers and described some of their properties. Polymers [776] and networks [126,777] with nonlinear optical responses were recently synthesized. Some of these polymers are liquid crystalline [776], We see no reason why mesogenic monomers and NLO responsive monomers may not soon be combined to form permanently crosslinked NLO LCP networks. 

There have been several mechanical studies performed on gelled networks of stiff LCPs, some where the liquid crystallinity of the precursors was retained in the gels [278,780] and others where stiff mesogenic segments were connected by rigid branchpoints, leading to loss of mesomorphicity [277, 311, 312, 393, 400, 409]. Thus far, the results are limited to reported stress-strain curves [278, 393] and to values of static shear modulus obtained by linear compression ex- 

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