Containing polymer liquid crystals, elastic

ELASTIC MODULI OF IN SITU COMPOSITES CONTAINING POLYMER LIQUID CRYSTALS... 

The three elastic constants of a liquid crystal are important physical parameters which depend on the interaction between the molecules in the liquid crystalline state. While a large number of theoretical and experimental investigations on the elastic constants are contained in the literature for thermotropic liquid crystals, very little is known about them in the case of lyotropic polymer liquid crystals such as those formed by poly-Y-benzyl-L-glutamate (PBLG) in various organic solvents. Some theoretical investigations have been carried out 3 the experimental data is limited largely to measurements of the twist elastic constant and a few recent measurements of the bend and splay constants. ... 

In general, in comparison with low molecular weight nematics, polymeric nematics show higher elastic constants. Solutions of low molecular weight fractions of polymers in monomeric nematic liquid crystals are of practical interest, because viscoelastic coefficients can be tailored in this way. Investigations of the viscoelastic characteristics have been reported, e.g. for side-chain [99] and main-chain polymers [100-102, 160]. In the side-chain mixtures, A, has been found to remain constant in mixtures containing up to 20% of added polymer. For main-chain additives, the bend and splay constants both increase moderately with polymer concentration (measurements up to 5% [102]). The twist constant seems to be uninfluenced [160]. 

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