Thermotropic polyesters. 1: Synthesis, characterization and thermal transition of poly[4,4′-bis(ω-alkoxy)biphenyl isophthalate]

A new homologous series of thermotropic polyesters has been synthesized by polycondensation reaction between isophthaloyl chloride and mesogenic diols 4,4′-bis(ω-hydroxyalkoxy)biphenyl in which the spacer length is varied from 3 to 6 methylene units. The thermal behavior of the polymers has been characterized using polarized light microscopy and differential scanning calorimetry (DSC). The odd members exhibit a smectic C (SC) phase in a narrow temperature interval, while the even members form a smectic A (SA) phase in a broader temperature range. All of the obtained compounds were characterized by conventional spectroscopic methods.