By reactions of p-hydroxybenzoic acid with the chlorides of adipic acid

suberic acid

sebacic acid and 1

10-decanedicarboxylic acid respectively four new diacids

and then their dich-lorides

were obtained. The four diacids were found to be thermotropic.Twelve regular copolyesters were synthesized by solution polycondensations of the four monomers with hydroquinone

chlorohydroquinone

4

4'-dihydroxy biphenyl. The copolyesters were characterized by polarized microscope with hot stage

DSC and X-ray diffraction. It was found that all copolyesters are thermotropic nematic liquid crystals with wide mesomorphic temperature range. The melting temperature of copolyesters vary from 150℃ to 300℃ with the change in molecular structure of the polymers.