Liquid Crystal Photoalignment Using Soluble Photosensitive Polyimide

Abstract

A novel soluble fluorinated polyimide containing a photosensitive chalcone unit in the main chain was investigated as a thermally stable photoalignment material for liquid crystals. A defect-free homogeneous alignment of liquid crystals was induced on the surface of a polymer film after exposure to linearly polarized UV light at an exposure energy of 7200 mJ/cm2. Spectroscopic analyses revealed that [2+2] cycloadditon between the chalcone moieties generated the surface anisotropy needed to induce an efficient alignment of liquid crystals.