Synthesis and characterization of random semi-flexible thermotropic liquid crystalline poly(ester-imide)s

A series of novel poly(ester‐imide)s were prepared by the reaction of meta‐ and para‐substituted trimellitimide dicarboxylic diacid chlorides with various diols containing four, five, six, seven, eight, nine, 10, and 12 methylene groups by a solution polymerization technique utilizing refluxing 1,2,4‐trichlorobenzene as a solvent. The poly(ester‐imide)s were characterized by dilute solution viscosity, infrared spectroscopy, differential scanning calorimetry, and polarized light microscopy. The inherent viscosities of the meta‐substituted poly(ester‐imide)s ranged from 0.06 to 0.25 dL/g while those of the para‐substituted poly(ester‐imide)s ranged from 0.10 to 0.65 dL/g and were obviously of higher molecular weight. The meta series were amorphous and showed no mesophase formation. All para‐substituted poly(ester‐imide)s exhibited monotropic mesophase identified as smectic A order. © 1994 John Wiley & Sons, Inc.