Synthesis of Liquid Crystalline Polyurethanes consisting of Two Mesogenic Groups and The Smectic Liquid Crystal Formation

Abstract

In this study, polyurethans were synthesized from diisocyanate and two different mesogenic diols. Asymmetric mesogenic diol (MD2-6) and symmetric mesogenic diol (MD-66) were used for the mesogenic diol. 2,4-Tolylene diisocyanate (TDI) was used as the diisocyanate. Composition ratio of the two mesogenic diols was changed, and the effect on liquid crystal behavior was investigated by FT-IR measurement ,DSC measurement and X-ray diffraction measurement. As a result, all copolyurethanes (PU(2-6_n)，n = molar ratio of MD2-6) showed liquid crystallinity. Except for composition ratio of MD2-6 around 0.1 to PU(2-6_0), only the nematic phase was formed. Composition ratio of MD2-6 around 0.1 to PU(2-6_0) was only formed smectic A phase in a relatively wide temperature range compared to the others.