New thermotropic polyesters from distyrylbenzene bisphenols

New main-chain thermotropic liquid crystalline (lc) polymers based on four derivatives of 4,4′- (p-phenylenedi-1,2-ethenediyl)bisphenol have heen prepared by Schotten-Baumen polymerization. Fusibility and solubility were achieved through the incorporation of side groups and flexible methylene spacers. Both a model ester and polymers based on the unsubstituted bisphenol were thermotropic, but had melting points in the vicinity of decomposition. Methyl, methoxy, and ethoxy side groups were used to lower the melting transition. The liquid-crystallinity was investigated with polarized light microscopy, differential scanning calorimetry, and X-ray diffraction. Methyl substitution provided the model compound and polymers with the greatest number of mesophases. Chemical structure was analyzed by infrared and UV/visible spectroscopy, ¹H NMR, and elemental analysis of monomers and model compounds. Intrinsic viscosities were measured in N-methylpyrrolidone (nmp) solution.