Nylon 6 was reacted with trimellitic anhydride (TMA) at 230 degrees C so that a complete degradation to N-(5-carboxy-pentamethylene) trimellitimide was obtained. The crude imide dicarboxylic acid was reacted in situ with 4,4'-bisacetoxy biphenyl whereby an enantiotropic smectic polyesterimide was obtained. Analogous degradation and polycondensation reactions were also performed with nylon 11 and nylon 12. Parallel syntheses were conducted with isolated imide dicarboxylic acids. Furthermore, the crude imide dicarboxylic acid obtained from nylons 6, 11, and 12 were polycondensed in situ with diacetates of hydroquinone or substituted hydroquinone in combination with various amounts of acetoxy benzoic acid or 6-acetoxy-2-naphthoic acid. In this way enantiotropic nematic copoly(ester-imide)s were prepared. The phase transition of all LC-poly(ester-imide)s were characterized by DSC measurement and optical microscopy. In addition, a series of isotropic poly(ester-imides)s was prepared using nonmesogenic bisphenols, such as bisphenol A, as comonomers.