Photoinduced Orientation of Hydrogen Bonding Liquid Crystalline Polymers / Pyridine Derivatives Composite Films

Abstract

This paper describes the photoalignment behavior of composite thin films comprised of polymethacrylate with cinnamic acid side groups (pM6CA) and pyridine derivatives. Linearly polarized (LP) UV irradiation to composite films undergoes the photoreaction of cinnamic acid side groups, and the axis-selection is observed regardless of the content of pyridine derivatives. The negative dichroism is generated in all conditions and the photoinduced anisotropy is amplified when the exposed films are annealed. The photoinduced anisotropy and the exposure dose margin for the effective amplification of the molecular orientation improves when specific pyridine derivatives are doped with pM6CA. Using the reoriented pM6CA/pyridine derivatives composite films for the LC alignment layer, anti-parallel LC cell is prepared, where the LC alignment uniformity is related to the in-plane orientation order of the composite films.

Keywords:

• Photoalignment
• photoreactive polymer
• pyridine-caroboxylic acid interaction