Main-chain ordering and stability of the light-induced anisotropy in the films of comb-like azo-polymer

Induction of optical anisotropy in azo-polymer films under the action of polarized UV light and its relaxation in a wide temperature range are investigated by polarization UV and IR spectroscopy methods as well as by light-induced birefringence measurements. The dependence of anisotropy relaxation on the exposure conditions is established. The results are explained proceeding from the partial ordering of main-chain fragments in irradiated films. A theoretical model explaining experimental results is developed.