Photo-Durable Molecularly Oriented Liquid Crystalline Copolymer Film based on Photoalignment of <i>N</i>-benzylideneaniline

Abstract

Copolymer films of photoalignable liquid crystalline (LC) copolymethacrylates comprised of a phenyl benzoate mesogen connected with N-benzylideneaniline end moiety (NBA2) and benzoic acid (BA) side groups exhibit a photoinduced reorientation behavior. Significant thermally stimulated molecular reorientation attains a dichroism (D) greater than 0.7 for all copolymer films and a birefringence of 0.113–0.181. In situ thermal hydrolysis of the oriented NBA2 groups decreases the birefringence to 0.111–0.128. However, the oriented structures of the film are maintained, demonstrating a photo-durability, even though the NBA2 side groups photo-react. The hydrolyzed oriented films show higher photo-durability without changing their optical properties.

Keywords

• liquid crystalline polymer
• photoalignment
• photoinduced reorientation
• birefringent film
• <i>N</i>-benzylideneaniline