LC‐Polyimides. XIX. Chiral and thermotropic poly(esterimide)s based on N‐(4′‐caboxyphenyl)trimellitimide and novel chiral spacers

Starting from commercial S‐ or R‐3‐bromo‐2‐methylpropanol, several new spacer diols were prepared. These spacers were polycondensed with the acid chloride of N‐(4′‐carboxyphenyl)trimellitimide. The resulting poly(ester‐imide)s were characterized by elemental analyses, viscosity measurements, 1H‐NMR spectroscopy, DSC‐ and WAXD‐measurements and optical microscopy. The poly(ester‐imide)s derived from chiral, aliphatic spacers form layer structures in the solid state, but no liquid crystalline phase. With nonsymmetrical, nonchiral semialiphatic spacers, poly(ester‐imide)s were obtained, which form a smectic E or H phase in the solid state, a smectic‐A or ‐C phase in the melt, and a nematic phase, when the spacer possesses an odd number of CH2 groups. The polycondensation of a chiral semialiphatic spacer yielded thermotropic poly(ester‐imide)s with either S‐ or R‐configuration. WAXD patterns measured with synchrotron radiation at various temperatures proved that a layer structure exists in the solid state (smectic‐E* or H*) and a chiral smectic‐A* or ‐C* phase plus a cholesteric phase in the melt. A 1 : 1 blend of the S‐ and R‐polyesters was also studied, but did not show unusual features.