Banded texture of photo-aligned azobenzene-containing side-chain liquid crystalline polymers

Poly(6-[4-(4-cyanophenylazo)phenoxy]x-methylene methacrylate) (Px, x is 2 or 6) were synthesized and used to study the texture of side-chain liquid crystalline polymers (SCLCPs) after photoinduced orientation. With increasing temperature of irradiated P2 film up to 125 °C, just above its Tg, 123 °C, a banded texture was observed for SCLCPs under polarized optical microscope (POM). There is no banded texture of irradiated P6 (Tg, 72 °C) film when heating to 75 °C. The formation of the banded texture is considered to be due to co-existing of in-plane and out-of-plane orientation mesogens in P2 film, which is explained in terms of a molecular model. Based on our experimental results, factors of irradiation light intensity, film thickness, and heating rate on the formation of the banded texture were studied in this work.