Synthesis and dual alignment of liquid crystalline polymethacrylate bearing 4-styrylpyridine and biphenylene moieties

Abstract

A new methacrylate monomer,2 with 4-styrylpyridine unit as a photocyclodimerizable group, biphenylene unit as a mesogenic group, and two hexylene groups as flexible spacers, was synthesized. Radical polymerization of2 provided the corresponding polymer,1. The intrinsic viscosity of1 in TFA at 25 °C was 0.25 dL/g. The polymer showed a smectic texture with a layer period of 34.48 A at 240 °C. Also, it was found that the biphenylene unit of the polymer gave rise to an in-plane alignment after LPUV light irradiation at room temperature and subsequent annealing at the LC temperature of 250 °C while the 4-styrylpyridine unit in the same side chain of the polymer resulted in a high out-ofplane order by the same treatment, being due to the separating ability of the flexible hexylene group between the two mesogenic units.