Photo-alignment behavior of mesoporous silica thin films synthesized on a photo-cross-linkable polymer film

Two-dimensional-hexagonal mesoporous silica thin films with aligned mesochannels in one direction at large scales will be favorably applied in optics, electronics, separation technologies, and so forth. We propose herein a new photo-aligning and micropatterning technique for mesochannels of a silica thin film using a photo-cross-linkable polymer film with a cinnamoyl group. The polymer film was uniaxially photo-oriented by exposure to the linearly polarized UV (LPUV) light. On this film, the mesoporous silica thin film was synthesized by various preparation methods. The orientation of the mesochannels was evaluated by in-plane X-ray diffraction (XRD) measurements. It was shown that the mesochannels were aligned perpendicular to the polarized direction of the irradiated LPUV light. In-plane XRD measurements and transmission electron microscopic and optical microscopic observations of the silica films revealed that photo-orientation of the mesochannels is controlled over the whole surface area of the film. In addition, micropatterning of the photo-aligned mesoporous silica films was readily attained by exposure to the LPUV light passed through a photomask.