Effect of Annealing on Morphology of Thermotropic Liquid Crystalline Polyesters

Liquid crystal polymers with semiflexible polymer backbone exhibit crystalline order despite of some defects in crystal packing. Isothermal heat treatment of the polymers below and above their liquid crystalline temperatures is expected to provide the necessary energy and time for the molecular chains to overcome the defects in crystal packing and to be arranged in a more perfect crystal lattice. A number of liquid crystalline polyesters, possessing both rigid mesogenic groups and flexible aliphatic spacers in the polymer backbone, have been considered for this experiment and were annealed at different temperatures. An improvement in molecular and crystal structure of the polyesters has been observed and the results of such experiment using FTIR spectroscopy, optical microscopy and wide angle X-ray diffraction of the sample before and after annealing are presented here.