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

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.