Surface-mediated photoalignment of organic/inorganic nanohybrids

Light irradiation provides significant tools for material structuring and processing. In this article, the photo-orientation processes of the organic/inorganic hybrid materials recently achieved in our laboratory are briefly introduced. Irradiation of linearly polarized light to a polymer film containing a photoisomerizabke azobenzene or photocrosslinkable cinnamoyl unit leads to the induction of anisotropic molecular orientations on the surface. This molecular anisotropic surface structure can be transferred to a controlled orientation of nanostructures of organic/inorganic hybrid films at macroscopic scales. Two classes of lyotropic/silica systems have been applied to the photo-orientation procedures, i.e., ordinary surfactant systems and chromonic ones. These processes can be regarded as the extended applications of the so-called command surface systems, which photochemically regulate the molecular orientations of liquid crystals.