SYNTHESIS AND CHARACTERIZATION OF EXTENDED ROD THERMOTROPIC POLYESTERS WITH POLYOXYETHYLENE PENDANT SUBSTITUENTS

The liquid crystalline properties of a series of aromatic polyesters prepared from alkoxy and alkoxyethyleneoxy-substituted hydroquinone monomers and either terephthaloyl chloride or diphenyl terephthalate were studied by optical and thermal methods. The melting temperatures of these polymers were considerably less than the corresponding polymers with n-alkyl substituents with the same number of atoms in the pendant substituent group on the hydroquinone ring. The melting temperature decreased in an exponential manner with the increase in the number of atoms in the alkoxy substituents, and at some temperature above their melting transition, a transition from a highly threaded liquid crystalline texture to a highly birefringent schlieren liquid crystalline texture was observed to occur for all polymers. All polymers except one were also observed to become homeotropic at elevated temperatures. When cooled from the homeotropic melts, a nematic glass was observed to form for the majority of polymers. Two polymers, on cooling from homeotropic melts to room temperature, showed optical textures representative of Williams domains which formed without the application of any electrical field.