Orientational Behavior and Thermomechanical Properties of Poly(aminourethane)s with Mesogenic groups

Abstract

Novel liquid crystalline polyaminourethanes and their ionic families were synthesized by polyaddition of mesogenic diols and diisocyanates. In the case of the liquid crystalline homopolyurethanes, which were synthesized from mesogenic diols with a tertiary amino group and diisocyanates, the repeating unit consists of a mesogenic group, tertiary amino group and diurethane core. On the other hand, the liquid crystalline copolyurethanes were synthesized by the reaction of mesogenic diol and diethanol amine with diisocyanate. The liquid crystalline polyurethanes exhibited a nematic phase on heating and cooling. The ionic family of the liquid crystalline homopolyurethanes formed a smectic A phase. However, the ionic family of the liquid crystalline copolyurethanes showed a nematic phase and did not form a smectic A phase. The ionic families revealed higher phase transition temperatures when compared to the liquid crystalline polyurethanes. Mechanical properties were examined for the liquid crystalline polyurethanes and their ionic families.