Photomechanical Response of Glassy Azobenzene Polyimide Networks

We report the synthesis of amorphous, heat-resistant (T-g ranging from 220 to 246 degrees C) polyimides cross-linked with a novel tris(azobenzeneamine) cross-linker and. examine the photodirected bending of cantilevers composed of these materials to exposure to linearly polarized, 442 nm light. Increasing the cross-linker concentration from 5 to 20 mol % in the network not only serves to increase the T-g and modulus but also results in a considerable increase in photomechanical response observed as an increase in bending angle from 5 degrees to 20 degrees. Adjustment of the orientation of the electric field of the light polarization to the cantilever axis is shown to generate forward and backward (bidirectional) bending. Upon removal of the incident light, the cantilevers exhibit photoelastic behavior by restoring to the original vertical position.