Directional Deformations in Photosensitive Azopolymers


Azobenzene polymers have been extensively explored in the last decade as photo-deformable smart materials. They have a number of technical applications as data storage media, aligning layers in display and semiconductor technology, light-controllable artificial muscles, etc. We develop a theory of light-induced deformation of azobenzene polymers both for glassy polymers and for crosslinked azobenzene elastomers. The reorientation of azo-chromophores perpendicular to the polarization of light is found to be a self-sufficient explanation for the photo-mechanics of azo-polymers. The theory demonstrates that the light-induced stress caused by azo-reorientation is enough to deform glassy polymers irreversibly and the sign of deformation (expansion/contraction) depends on the chemical structure of the molecules. The results of the theory are in agreement with molecular dynamic simulations performed by us to study light-induced deformation of azobenzene polymers with different chemical architecture. Presently we study the effects of orientation interactions between chromophores on the light-induced deformation and the kinetics of this deformation.


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