The effect mechanisms of pH, complexant and calcination temperature on the hydrophilicity of TiO2 films prepared by the sol-gel method

Nano TiO2 sols are prepared by the sol-gel method, and hydrophilic TiO2 films are deposited on stainless steel sheets by spin-coating technology. The effects of pH, complexant and calcination temperature on the hydrophilicity of TiO2 films are studied in this paper. In summary, they all affect the hydrophilicity of films by changing the hydroxyl content on the films surface. pH has a decisive influence on the size of holes in the film surfaces and also has a marked impact on the hydrolysis rate of Ti(OBu)4. When pH = 6, the film surfaces are covered with micro-Nano holes. The complexant is the critical factor of the hydrolysis rate of Ti(OBu)4. Double-complexants makes TiO2 sols more stability and films more hydrophilic. The calcination temperature determines the size, arrangement and crystal structure of TiO2 particles. When the temperature is 500 °C, the hydrophilicity of TiO2 films is the best. It is concluded from mechanism analysis that super hydrophilicity of TiO2 films is the combination of TiO2 particles and the surface morphology that work together.