Orientation of Liquid Crystalline N-Substituted Polypyrroles

Abstract

Liquid crystalline polypyrroles having a mesogenic substituent with oxobiphenyl and cyanobiphenyl mesogenic cores at the N-position were synthesized by Ni(cod)2 method. The polymers showing stable enantiotropic smectic phases with large domains and good reproducibility were macroscopically oriented by mechanical alignment techniques of rubbing and friction-transfer, respectively. The ordered structure was characterized from dichroic ratio of polarizing IR and PL spectra. In case of orientation by the rubbing method, arranged mesogenic side chains on the rubbed substrate induced a vertical alignment of polymer backbone to the rubbing direction. In contrast, the friction-transfer method selectively aligned rigid polymer backbone parallel to the friction direction, which successively induced a vertical arrangement of mesogenic side chains.