Liquid‐crystalline polyimides, 1. Thermotropic poly(ester‐imide)s derived from 4‐hydroxyphthalic acid, 4‐aminophenol and various aliphatic α,ω‐diacids

Poly(ester‐imide)s with a regular sequence of aliphatic spacers and aromatic imide mesogens were prepared in two ways. Either aliphatic α,ω‐diacids were condensed with an acetylated diphenol derived from 4‐hydroxyphthalic acid and 4‐aminophenol, or aliphatic α,ω‐diacid dichlorides were condensed with the silylated diphenol. The resulting poly(ester‐imide)s were characterized by elemental analyses, viscosity measurements, microscopy under polarized light, DSC‐ and WAXS measurements. All poly(ester‐imide)s are crystalline materials with a layered supermolecular structure in the solid state. Above the melting point a nematic mesophase exists over a broad temperature range. A pronounced odd‐even effect was found for the temperature of isotropization, but not for the melting points.