LAYER STRUCTURES .7. THERMOTROPIC POLY(ESTER-IMIDE)S BASED ON TRIMELLITIC ANHYDRIDE AND BRANCHED DIAMINO ALKANE SPACERS

Two new dicarboxylic acids were synthesized from trimellitic anhydride and 1,5-diamino-2-methylpentane or from a mixture of isomeric 1,6-dia mino-trimethyl hexanes. These dicarboxylic acids were polycondensed ei ther with the bisacetate of 2,6-dihydroxynaphthalene or with the bisac etate of 4,4'-dihydroxybiphenyl. D.s.c. measurements, WAXD powder patt erns and optical microscopy revealed that all four poly(esterimide)s d erived from 1,5-diamino-2-methylpentane still form a highly ordered, q uasi crystalline smectic layer structure in the solid state, but a nem atic phase in the molten state. The poly(ester-imide)s derived from th e trimethyl substituted spacers only form a smectic glass in the solid state. This smectic glass is a frozen smectic-A phase in the case of 4a but may be a mixture of frozen smectic-C and smectic-A phases in th e case of 4b (derived from 4,4'dihydroxybiphenyl). Upon heating above the glass-transition the layer structures gradually disappear with for mation of a nematic phase. Due to this gradual change revealed by sync hrotron radiation measurements no endothermic phase transition is dete ctable in the d.s.c. traces. (C) 1997 Elsevier Science Ltd.