POLYMERS FROM MULTIFUNCTIONAL ISOCYANATES .7. SYNTHESIS AND PHASE-BEHAVIOR OF LIQUID-CRYSTALLINE TRIAD ESTER-GROUP-CONTAINING DIISOCYANATES

A number of novel triaromatic diisocyanates based on para-linked ester mesogens (1,4-phenylene dibenzoate, diphenyl terephthalate, diphenyl trans-1,4-cyclohexanedicarboxylate and trans-dicyclohexyl trans-1,4-cyclohexanedicarboxylate) are described. One series was synthesized by reaction of 4-trimethylsiloxyphenyl or cyclohexyl isocyanate with terephthaloyl chloride or trans-1,4-cyclohexanedicarbonyl chloride, and the other from a 4-isocyanatobenzoyl chloride with a 1,4-bis(trimethylsiloxy)benzene (trimethylsilyl-protected hydroquinone). Acidic and basic catalysts were used in this reaction. The influence of substituents in various positions of the mesogenic cores on the phase transitions was also investigated. All liquid-crystalline diisocyanates have a nematic mesophase.