Polarization-controlled, photodriven bending in monodomain liquid crystal elastomer cantilevers

We report on the fast and optically controlled angular bending of cantilevers made from liquid crystal polymer networks functionalized with azobenzene moieties (azo-LCN). For potential applications such as adaptive optics, photoresponsive cantilevers should rapidly deform to controlled angles while maintaining a modulus that can accomplish appreciable mechanical work. This work demonstrates cantilevers made of monodomain azo-LCN containing pendant (side chain) azobenzene mesogens with a storage modulus of 1.4 GPa bend 85° in less than 300 ms upon exposure to 442 nm irradiation. Moreover, the bending angle of these monodomain azo-LCN cantilevers can be controlled by the polarization angle of the source relative to the long-axis of the cantilever. The bending performance (deformation angle and speed) of this monodomain system is compared to a polydomain analogue. The impact of azobenzene concentration, laser intensity, and thickness on these parameters is also presented.