Chiral Photomechanical Behavior of Azobenzene-based Molecular Glass Particles Observed in Hydroxypropyl Cellulose Hydrogel

We have previously reported the chiral photomechanical behavior of azobenzene-based photochromic molecular glass particles fixed in agar gel. That is, when their particles were irradiated with polarized 488 nm laser beam, they elongated in the direction parallel to the polarization direction of the incident laser beam accompanied with undulatory motion. And the resulting photo-elongated particles took on a left-handed rather than right-handed helical structure at the ends of the particles. In the present study, such chiral photomechanical behavior was also found in hydroxypropyl cellulose hydrogel, suggesting that the chiral photomechanical behaviors were the general phenomena of the azobenzene-based molecular glasses observed in chiral natural polymer-based hydrogels. Asymmetric viscoelasticity of the surrounding chiral hydrogels seems to play a role in causing such chiral photomechanical behaviors.