Studies On Preparation And Properties Of Super-hydrophilic Nanometer TiO₂ Composite Thin Films

The nanometer inorganic composite film of TiO₂, SiO₂/TiO₂,Fe₂O₃/TiO₂, Fe₂O₃/SiO₂/TiO₂, the nanometer polymer-inorganic composite films of PEG-TiO₂, PVA-TiO₂, PAM-TiO₂, MC-TiO₂, and the nanometer polyethylene glycol-multiple inorganic composite film of PEG-Fe₂O₃/TiO₂, PEG-SiO₂/TiO₂, PEG-Fe₂O₃/SiO₂/TiO₂ were prepared by the sol-gel method and dip-coating way in this master dissertation. The morphology and structure of the thin film was characterized by X-ray powder diffraction (XRD), Scanning Electronic Diffraction (SEM), thermal analysis (DSC) and UV-vis spectra of transmittance (UV-vis). The hydrophilic activity, the photocatalytic activity to the low concentration methylene blue solution, the adhesion to the substrate glass, the transmittance and the chemical stability of film were studied,. The ultraviolet-visible spectrop hotometer from the wavelength 300 run to 900 nm was measured and analyzed.Results indicated that the hydrophilic activity and photocatalytic activity of SiO₂/TiO₂,Fe₂O₃/TiO₂ composite thin films were superior to the pure TiO₂ film.The hydrophilic activity and photocatalytic activity of thin films increased with the increasing of heating temperature.When heat treatment temperature was 500℃and sintering time was 2 h, the hydrophilic activity and photocatalytic activity of thin films were optimal. XRD patterns showed that the crystal form of TiO₂ was anatase after adding SiO₂, Fe₂O₃, and the average diameter was diminished. The UV-vis spectra of transmittance showed that Fe₂O₃ caused the absorption wavelength to move to long wavelength.Effects of the stuff prescription and the process parameters on the hydrophilic activity and photocatalytic activity of ternary inorganic composite thin films were studied. The optimal prescription was that the content of Fe₂O₃ was 0.25 %, and SiO₂ was 20 %, The optimal process parameter was that the treatment temperature was 500℃and sintering time was 2 h. Under these optimal conditions, the ternary inorganic composite thin films of Fe₂O₃/SiO₂/TiO₂ had best hydrophilic activity and the photocatalytic activity.Polyacryamide, polyvinyl alcohol, polyethylene glycol and methocel were added to improve the hydrophilic activity and the photocatalytic activity of TiO₂ film and inorganic composite film. The polymer-inorganic composite film of PEG-TiO₂, PVA-TiO₂, PAM-TiO₂ and MC-TiO₂ were prepared. The effects of the stuff prescription and the process parameter were researched. The results showed that the PEG-TiO₂ film had the best hydrophilic activity and photocatalytic activity under the condition of the PEG molecular weight 1000 and the dosage of PEG 2.5 g. L^-1.SEM image also showed that the added PEG had produced uniform hole in the surface of TiO₂ film, and the number and the size of holes increased with the increasing of the molecular weight and quantity.Meanwhile, the polymer-inorganic composite films of PEG-Fe₂O₃/TiO₂, PEG-SiO₂/TiO₂ and PEG-Fe₂O₃/SiO₂/TiO₂ were prepared too, and these films had the better hydrophilic activity and photocatalytic activity than those of above. For the PEG-Fe₂O₃/SiO₂/TiO₂ composite thin film prepared, the average diameter of TiO₂ particles was 5.3 nm and the content of rutile phase was 0. The performance parameters studied showed that the adhesion to the substrate glass, the transmittance, the chemical stability of film of the polymer-inorganic composite film were good to meet the demand.