Effects of UV irradiation treated polycarbonate substrates on properties of nanocrystalline TiO2 sol-gel derived thin films

In this study, in order to achieve effective coating of the homogeneous titanium dioxide (TiO2) thin film, UV irradiation pre-treatment was carried out to activate PC surfaces before coating. Sol-gel-based nanocrystalline TiO2 thin films were prepared by employing tetrabutyl-titanate as a precursor. Nanocrystalline TiO2 thin films were deposited by sol-gel spin coating on the treated substrates. Some characterization techniques such as UV/Visible, FTIR spectroscopy and contact angle measurement were used to study the induced changes on the properties of the treated substrates. FTIR and UV spectra obtained from substrates before and after UV irradiation treatment, showed that UV irradiation has induced some chemical and physical changes in surface properties. The initial contact angle of PC surface was 94°, which decreased substantially after treatment. The XRD pattern reveals that TiO2 thin film has a crystalline structure, and it has been observed in two phases: (1) anatase and (2) rutile. According to UV/Vis spectra of samples the prepared films have high transmission. AFM has been applied for morphology characterization of the films surface. The surface morphology results indicate that UV exposure time lead to alter in the roughness of the nanoTiO2 thin films.