Liquid crystalline polyurethanes, 1. Polyurethanes based on 4,4′‐[1,4‐phenylenebis(methylidynenitrilo)]diphenylethanol

Abstract Polyurethanes were synthesized from 4,4′‐[1,4‐phenylenebis(methylidynenitrilo)]diphenylethanol ( 3 ) with diisocyanates such as hexamethylene diisocyanate ( 4a ), 4,4′‐methylenedicyclohexyl isocyanate ( 4b ), 1,3‐cyclohexylenedimethyl isocyanate ( 4c ), 2,4‐toluylene diisocyanate ( 4d ) and 4,4′‐methylenediphenyl isocyanate ( 4e ), and their thermal properties were investigated. The resulting polymers show a liquid crystalline state at 206–230, 160–216, 186–226 and 144–204°C, respectively, and the polymer obtained from 4e has a melting point at 272°C, determined by DSC and polarizing microscopy.