Liquid Crystalline Polyurethane Containing Biphenyl Units

Abstract

Polyurethanes were synthesized by the reaction of 4, 4′-di (2-hydroxymethyloxy) biphenyl with diisocyanates such as hexamethylene diisocyanate (HDI), dicyclohexylmethane 4, 4′-diisocyanate (H₁₂MDI), cyclohexane 1, 3-di (methylisocyanate) (H₆XDI), 2, 4-tolylene diisocyanate (TDI), and 4, 4′-diphenylmethane dissocyanate in DMF for 1.5hr at 100-140°C in the absence of catalysts. The polyurethanes obtained from HDI, H₁₂MDI, H₆XDI and TDI exhibited mesomorphic phase at 188-203°C, 147-172°C, 135-193°C and 151-193°C, respectively.