ROLE OF THE SOFT-SPACER IN THE MAIN-CHAIN TYPE LIQUID-CRYSTALLINE POLYMERS

The role of the soft-spacer incorporated in the main-chain type liquid crystalline polymers has been studied via a conformational analysis of the chain. The angle theta defined by unit vectors attached to two successive rigid cores has been evaluated for each conformation of the intervening flexible segments. The analysis has been extended to systems such as polyethers XO(CH//2)//nOX, polycarbonates XOC(O)O(CH//2)//nOC(O)OX, and polyethers of the type X(OCH//2CH//2)//xOX. These polymers are all known to exhibit thermotropic nematic liquid crystals. The observed even-odd oscillation in various thermodynamic quantities such as T//N//I, DELTA H//N//I and DELTA S//N//I with the chain length n (or x) was found to be explicable in terms of the geometrical characteristics of the chain.