PREDICTION OF MICROSTRUCTURE IN LIQUID-CRYSTALLINE POLYMERS

This paper focuses on the importance of distinctly different principal elastic constants in determining the microstructure of main-chain the rmotropic liquid-crystalline polymers. A brief survey of microstructur es seen in these materials is followed by an outline of established me thods of calculating vector fields around defects of predefined topolo gy. The strategy for modelling liquid-crystalline polymers depends on modelling at a molecular level to obtain estimates of the values of th e splay, twist and bend constants (the splay is invariably the greates t for main-chain polymers). These parameters then form the input to a lattice model of the microstructure. New developments of the central a lgorithm of this model enable the splay and bend components to be succ essfully partitioned in three dimensions, and splay-splay compensated structures to be handled properly. Modelling using the new algorithm f or the case where the splay constant is dominant leads to the generati on of structures in which twist escaped +1 line singularities are a pr edominant feature, simulating the experimental surfaces.