Preparation And Forming Mechanism Of Super-hydrophilic Porous TiO₂ Surface

With the development of science and technology, the superhydrophilic surfaces were paid attention to for their high properties. Although a lot of methods were used for preparation of superhydrophilic surfaces, they were not used widely owing to their complicated processes.According to superhydrophilic mechanics, the superhydrophilic porous films based on TiO2 surface with the light catalyst property were prepared using methods of template agents and double complexing agentsThe nanopores and micropores TiO2 films were prepared using tetrabutyl titanate as titanium precursor, polyethylene glycol (PEG) as a templating reagent by sol gel method.With the increasing of the PEG, the pores of film became larger and deeper, and the specific surface area increased also. When the amount of PEG was lower than the critical value 0.002 0.0025 M, the numerous small cracks disappeared on the surface. PEG molecules would not contribute to a complete enlargement of aperture, and the shape of holes would become irregular and fluctuating when the content of PEG was above 0.02 M. The experimental results showed that the surface of TiO2 films was rough and the contact angle with water was lower 5o under the natural light condition.When acac or DEA as the complexing agent, the film was compact and flat, and the contact angle with water was about 200 and 230 respectively.When the acac and DEA were used as complexing agents together, the phase separated for oligomers formation. With the increasing of the PEG, the time of the phase separated decreased. The surface roughness of the films increased for the carbon dioxide produced by the solvent when the films were calcined. The contact angle with water of the TiO2 films was about 6.50 under the no light condition.The superhydrophilic behavior was explained by the Wenzel and Cassie wetting impregnating model. The transition between these two wetting regimes was investigated. The criteria contact angle with water of the porous TiO2 films was got. And the superhydrophilic mechanics of the TiO2 films was also analyzed.