PHASE-TRANSITIONS OF HYDROXY-TELECHELIC SIDE-CHAIN LIQUID-CRYSTALLINEPOLYETHERS AND POLYURETHANE NETWORKS DERIVED THEREOF

Hydroxy-telechelic polymers with side-chain mesogenic groups have been prepared from epoxy monomers using a BF3/1,6-hexanediol initiating sy stem. Homopolymers showed either nematic or smectic A and C phases, de pending on the length of the alkoxy substituent on the aromatic mesoge nic group. In copolymers both nematic and smectic phases could be obse rved, depending on composition. Liquid crystallinity was found to be r etained after crosslinking with a triisocyanate at temperatures below the clearing temperature of the mixture. On the other hand, the mesoph ase was found to disappear on rapid cooling after a certain degree of crosslinking above the clearing temperature, only to reappear after a period of heating above the glass transition temperature.