Ultraviolet/visible and Fourier transform infrared spectroscopic investigations of organic-inorganic hybrid layers for UV protection

A study of vacuum-deposited organic-inorganic hybrid coatings for ultraviolet (UV) protection of polycarbonate is presented. For this purpose, UV-absorbing organic molecules were embedded in a silica matrix by thermal co-evaporation. Typical UV absorbers, namely a benzotriazole, a hydroxyphenyltriazine, and a cyanoacrylate, were used as organic materials. The hybrid layers were investigated by means of ultraviolet/visible (UV/VIS) and Fourier transform infrared spectroscopy (FTIR) concerning their UV/VIS absorption properties and the influence of the silica network on the organic molecules. The porosity and silica-organic interactions are discussed with reference to the infrared spectra. UV irradiation experiments were carried out to demonstrate the UV protection ability of the hybrid layers. Hybrid layers containing the hydroxyphenyltriazine compound showed the best results.