Photoresponsive behavior of crosslinked liquid-crystalline polymer films with a different content of an azobenzene moiety

Crosslinked liquid-crystalline polymer films with a different content of an azobenzene moiety were prepared by in-situ photopolymerization, and their photoresponsive behavior was investigated. Observation of the films by polarized absorption spectroscopy and polarizing optical microscopy has revealed that the azobenzene moieties are aligned along the rubbing direction in the films. Upon irradiation with UV light, a film with 5mol% of the azobenzene bent toward an actinic light source along the rubbing direction. The bent film reverted completely to the initial state upon irradiation with visible light. On the other hand, films with 3 and 1mol% of the azobenzene showed no obvious bending by continuous irradiation with UV light. The bent film also reverted to the flat state upon continuous irradiation with UV light.