SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYETHERS BY CHEMICAL MODIFICATION OF POLYEPICHLOROHYDRIN

Copolymers derived from polyepichlorohydrin (PECH), bearing pendant mesogenic units are obtained by chemical modification of atactic samples of PECH with sodium 4-cyano-4'-biphenoxide. Rate and yield of substitution are strongly dependent on the molecular weight of the used PECH. A substantial rise (DELTA-T approximately 110-degrees-C) of glass transition temperature with the percentage of incorporated cyanobiphenyl groups is observed. Copolymers with an amount of substitution higher than 60% present thermotropic liquid-crystalline behaviour and form nematic phases. Chemical modification of PECH offers a simple method for the synthesis of new liquid-crystalline polyethers whose transition temperatures can be adjusted by varying the amount of substitution.