Influence of methyl group in a quinoline moiety on optical and light-induced properties of side-chain azo-polymers

We present the optical and photochromic properties as well as surface quality of thin films of the methacrylic copolymers containing 2-methylquinoline and quinoline azo-dyes in side chain. The extinction coefficient and refractive index were determined using spectroscopic ellipsometry combined with transmittance measurements. Photo-responsive behavior was investigated by determination of trans – cis photoisomerization rates under irradiation with unpolarized 365 nm light. We found that optical properties as well as photoisomerization rates of investigated polymers are dependent on the presence of a methyl substituent in the 2nd position of the quinoline moiety. The quality of the thin films was examined using Atomic Force Microscopy measurements.