Synthesis and Characterization of Biphenylnate Liquid Crystalline Polyurethanes
A series of novel biphenylnate liquid crystalline polyurethanes (BLCPs) were synthesized by polyaddition reaction of 4,4’-dihydroxybiphenyl with 2,4-TDI(2,4-toluenediisocyanate) and diethylene glycol through changing the molar ratio of diphenol and diol. The thermotropic properties, the melting point (Tm) and the isotropization temperature (Ti) of the synthesized polyurethanes were characterized by FT-IR, DSC, POM and WXRD. The results of experiments showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 130°C and 230°C. The transition temperature (Tm and Ti) decreased with an increase in the length of the flexible chain.
Yuan Ming Huang
J. F. Ban et al., "Synthesis and Characterization of Biphenylnate Liquid Crystalline Polyurethanes", Key Engineering Materials, Vols. 428-429, pp. 158-161, 2010