3D Orientational Order in the Photoaligning Polymer Films and its Correlation with LC Alignment

摘要

In this work we study correlation between spatial molecular distributions in the contacting anisotropic polymer films and LC layers. Two kinds of side-chain azopolymers were employed: with he azochromophores containing hydrophobic OC_4H_9 alkyl chain (P1) and strongly polar NO_2 group (P2) as the end substituences, respectively. The tilt orientation of azochromophores was induced by the oblique irradiation of the polymer films with non-polarized UV light. The tilt angle was controlled by the change of the angle of the UV light incidence. The uniform alignment of several LC with the quasilinear dependence of the LC pretilt angle on the inclination angle of azochromophores was observed for the films of P1. In contrast, the alignment of LCs on the films of P2 strongly depended on the structure of LC molecules and did not depend on the inclination of azochromophores in the polymer bulk. Possible reasons of the difference in results obtained for P1 and P2 are discussed.