Experimental Studies of the Mechanisms of Photomechanical Effects in a Nematic Liquid Crystal Elastomer in a Photomechanical Optical Device Geometry

摘要

Azo-dye-doped liquid crystal elastomers (LCEs) are known to show a strongphotomechanical response. We report on experiments that suggest thatphotothermal heating is the underlying mechanism in surface-constrainedgeometry. In particular, we use optical interferometry to probe the lengthchange of the material and direct temperature measurements to determineheating. LCEs with various dopants and optical density were used to study theindividual mechanisms. In the high dye-doped limit, most of the light isabsorbed near the entry surface, which causes a local strain from photothermalheating and a nonlocal strain from thermal diffusion. The results of ourresearch on the microscopic mechanisms of the photomechanical response can beapplied to designing photomechanical materials for actuating/sensing devices,the potential basis of smart structures.