In situ formation of photoalignable N-benzylideneaniline side groups and control of photoinduced reorientation in polymethacrylate with 4-oxybenzaldehyde side groups and 4-methoxyanilline composite films

Abstract

We investigate control of the photoinduced orientation of photoalignable polymeric films from polymethacrylate with 4-oxybenzaldehyde side groups (1) and monomeric 4-methoxyanilline (2) composites, where both 1 and 2 have no photoreactivity. Annealing the 1/2 composite film with various 1/2 ratio generates N-benzylideneaniline (NBA) side groups, which exhibit photoreactivity and photoinduced molecular reorientation when irradiated with linearly polarized (LP) 365 nm light. Adjusting the 1/2 mixture ratio controls the amount of NBA side group's formation, as well as the photoinduced orientation performance of the film. Analyses of the three-dimensional refractive indices reveal biaxial photoinduced reorientation for a 1/2 film saturated with NBA side groups (∼96%), while in-plane motion plays a major role for 1/2 films containing unreacted 4-oxybenzaldehyde side groups. Furthermore, a post-annealing procedure after exposure greatly amplifies the in-plane reorientation structure for film consisting of more than 75% NBA side groups, which exhibits LC characteristics.