Synthesis and thermotropic liquid‐crystalline properties of polyurethane‐polystyrene graft copolymers

Abstract

Abstract New polyurethane‐ graft ‐polystyrenes (4) of well‐defined structures and compositions were synthesized by macromonomer technique and the structure‐liquid‐crystalline (LC) property relationship is discussed. The expected graft copolymers with polystyrene grafts were prepared by melt polycondensation of a mixture of a dihydroxy derivative of biphenyl as a mesogenic moiety (1) and a dihydroxy‐terminated styrene macromonomer (2) with diphenyl N , N ′‐hexamethylenedi‐carbamate (3) . Of the resulting polymers mesogenic unit‐rich graft copolymers retain the LC mesophases in spite of introduction of the polystyrene segments onto the polyurethane backbones and possess microphase‐separated structures. Polystyrene‐rich copolymers reveal no well‐defined LC mesophases and analogous thermal properties to the polystyrene segments.