Photoinduced molecular reorientation in liquid crystalline polymer film via an axis-selective photoreaction of benzaldehyde moieties in its side chain

Abstract

Photoinduced molecular reorientation of a liquid crystalline polymethacrylate bearing 4-formylphenyl benzoate (BPA) side groups was investigated using linearly polarized 313-nm light followed by annealing. Axis-selective photo-cross-linking induced thermally stimulated molecular reorientation exclusively in the direction parallel to the electric-field vector, producing dichroism greater than 0.6. The reorientation was restored after THF immersion by reannealing, and additional irradiation improved thermal stability, demonstrating the potential of benzaldehyde-containing side group as a new photoreactive unit for photoalignment technology.