Effect of branching and molecular ''kinks'' on the properties of main chain thermotropic liquid crystalline polymers containing flexible spacers

An A-B type of self-condensation route permits the generation of main chain liquid crystalline polymers with better control on the degree of branching. The synthesis of branched liquid crystalline polyesters by copolymerization of a biphenyl containing A-B type monomer, ethyl 4-[4-(ω-hydroxydiethyleneoxy)phenyl]benzoate (BEO2), and an AB2 monomer, ethyl 3,5-bis(ω-hydroxydiethyleneoxy)benzoate (EBHDB) was studied. For branched copolyesters, the mesophase disappears at a much lower branching monomer composition and exhibited fluid birefringence in the expected temperature regions. Furthermore, some of the copolymers exhibited very high melt viscosity.