Advanced Functional Materials, Vol.21, No.15, 2913-2918, 2011
Photodriven, Flexural-Torsional Oscillation of Glassy Azobenzene Liquid Crystal Polymer Networks
Cantilevers composed of glassy, photoresponsive liquid crystalline polymer networks (LCNs) are shown to oscillate at high frequency (similar to 50 Hz) and large amplitude when exposed to light from a 442 nm coherent wave (CW) laser. Added dimensionality to previously reported in-plane oscillations is enabled by adjusting the orientation of the nematic director to the long axis of the cantilever yielding in-plane bending accompanied by out-of-plane twisting (flexural-torsional oscillation). The fundamental photoresponse of this class of glassy azobenzene liquid crystal polymer networks (azo-LCN) is further probed by examining the influence of cantilever aspect ratio, laser intensity, and temperature. The frequency of photodirected oscillations is strongly correlated to the length of the cantilever while the amplitude and threshold laser intensity for oscillation is strongly correlated to temperature.