Thermotropic polyesters, 2. Synthesis of regular polyesters from aromatic dicarboxylic acids and phenols or aliphatic diols,and study of their mesomorphic properties

Several series of thermotropic liquid-crystalline polyesters, based on 4-chlorocarbonyl phenyl esters of aromatic dicarboxylic acids ( 1–4 ) and phenols or aliphatic diols, were synthesized and studied by polarizing microscopy and differential scanning calorimetry (DSC). A relationship between geometry of mesogenic moiety and stability of mesophase formed by the polymers was established. The effect of both the length and chemical structure of the flexible fragments on the mesomorphic properties was revealed for polyesters obtained from aliphatic diols. Several polymers were obtained whose temperatures of transition into the liquid crystalline state were found to be below 100°C. Two series of low-molecular-weight liquid-crystalline compounds were synthesized to compare their properties with those of the polymers of similar structure. Most of the low-molecular-weight analogs have not been described so far. They predominantly form a smectic type mesophase.