PHOTOCHEMICAL MODIFICATION OF AMPHOTROPIC POLYMERS IN DIFFERENTLY ORDERED FILMS

Amphotropic 2-hydroxyethyl polyacrylates with azobenzene side groups c ombine amphiphilic and thermotropic liquid crystalline behaviour. Upon UV irradiation the initial double layer structure of LB multilayer is irreversibly destroyed by the E-Z photoisomerization of the azobenzen e moieties. New ordered structures with modified spacing but without i n-plane anisotropy are established by subsequent Vis irradiation. The irradiation with linearly polarized Vis light causes a reorientation o f the tilted azobenzene side groups perpendicular with respect to the electric field vector. In this way optical anisotropy is induced in th e plane. The photoorientation process depends on the supramolecular or der of spin-coated and LB films, the aggregation of the azobenzene moi eties and the irradiation conditions.