The large and stable photomechanical effect in the glassy guest-host azopolymers

We demonstrate a photomechanical response of a series of amorphous guest-host azopolyimides and azopolystyrenes. The maximum bending angle close to 120° was reached within 1–2 min of exposure to 405 nm linear polarized light with intensity 150 mW/cm2. No relaxation of cantilevers bent upon visible light within three month was observed. We postulate a twofold nature of the bent stability. It can be connected to stable both trans-chromophore reorientation and polymer backbone migration. On the other hand, when the laser beam was turned on and off during the bending process, turning off the light caused the relaxation of the bent in the range of 2–10°. It may be related to fast cis-trans isomerization and/or reorientation of trans-azomolecules.