Photosensitivity of titania-doped hybrid polymer prepared by an anhydrous sol-gel process

Methacrylate-modified hybrid polymer with varied TiO2 concentrations was prepared by an anhydrous sol-gel process, and the effects of TiO2 on the photosensitivity of the hybrid polymer in the forms of wet films (before the polymerisation of the unsaturated CC bonds of methacrylate groups) and hard films (after the polymerisation of the unsaturated CC bonds with a pre-UV cross-linking and thermo-curing process) were studied. TiO2 doping was found useful for enhancing the photosensitive response to UV light irradiation in both wet and hard films. In wet films, TiO2 has a similar effect as a photo-initiator on accelerating the polymerisation of the unsaturated CC bonds of methacrylate groups, therefore TiO2 doping favours UV-patterning with photolithographic process for planar optical waveguides fabrication. In the fully polymerised TiO2-doped hard films, photosensitivity with a refractive index increase as large as 0.01 was firstly observed. The structural changes of the hybrid polymer upon UV irradiation were investigated by FT-IR and energy dispersive X-ray spectroscopic (EDXS) techniques, and the mechanisms for the photosensitivity in hard films were proposed.