Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Vol.297, 489-496, 1997
Interdependence of Photoorientation and Thermotropic Self-Organization in Photochromic Liquid-Crystalline Polymers
By irradiation with linearly polarized light optical anisotropy is generated in isotropic films of photochromic LCP’s due to a photoorientation process. Generally, the efficiency is much higher in films of polymers with a high content of azobenzene moieties. On the other hand, the photochemically induced orientation of the photochromic side groups affects also the distribution of non-photochromic but mesogenic moieties. Furthermore, in initially isotropic firms it acts as initializing force, governing the direction of thermotropic self-organization. The combination of both ordering principles causes a significant amplification of the light-induced optical anisotropy. Investigating several polymers of the same general structure but with a different content of azobenzene side groups an interdependent behaviour was found for the photoorientation of the photochromic and the co-operative orientation of non-photochromic side groups.
Keywords:SIDE-CHAIN