TRANSESTERIFICATION IN NEMATIC POLYMERS

Polydisperse melts of nematic polymer liquid crystals (PLC's) display a biphase region at the nematic-isotropic transition. We describe this phase separation for a melt of transesterifying chains. Transesterification, a process where chains exchange material at fixed overall chain number, results in an annealed rather than quenched polydispersity. The PLC is modeled as a wormlike chain with a Maier-Saupe nematic mean field. The phase diagram and length distribution are calculated. The biphasic gaps reported in experiments on transesterifying melts are discussed.