Photomechanical Rolling Motions of Azobenzene-based Molecular Glass Microspheres on a Substrate upon Grazing-angle Irradiation

Grazing-angle irradiation of azobenzene-based molecular glass microspheres with an s-polarized laser beam induced drastic shape changes to form peculiar shapes with curved horns. In contrast, grazing-angle irradiation with a p-polarized laser beam induced transport of the microspheres away from the light source. Observation of the behaviors from the side indicated that microspheres exhibited rolling motion to locomote on the substrate. Locomotion speeds were suggested to depend on the size of the microspheres and Tg of the material. Azobenzene-based molecular glass microspheres exhibited rolling motion to move on the substrate away from the light source upon grazing-angle irradiation with p-polarized laser beam. The phenomena could be explained by considering that the molecules tend to move and/or vibrate parallel to the polarization direction of the incident beam. Higher glass-transition temperature was suggested to be desirable for such photomechanical behavior.