Synthesis and properties of liquid crystal copolyurethanes containing biphenyl type diols and diisocyanates

In this study, a series of liquid crystal copolyurethanes based on mesogenic biphenyl diol and two aromatic biphenyl diisocyanate were synthesized via polyaddition method. Chemical structure of the polyurethanes was characterized by FTIR and 1HNMR measurements. The crystal to crystal, melting and isotropization transitions were confirmed by DSC and POM results. WAXD results showed that the polyurethanes had layered and semicrystalline structure. The obtained copolyurethanes had enough thermal stability to be melt processed considering its relatively low melting temperature (149–204 °C). In addition, the resulted polyurethanes had good fiber formation ability as verified by rheology measurement.