Preparation and characterization of super-hydrophilic porous TiO2 coating films

In this study, the super-hydrophilic TiO2 coating films are prepared from alkoxide solutions containing polyethylene glycol (PEG) by the sol–gel method on soda lime glass. The effects of PEG addition to the precursor solution on the super-hydrophilic property and microstructure of the resultant coating films are studied. The larger the amount and molecular weight of PEG, the larger are the size and numbers of pores produced in the resultant coating films on the decomposition of PEG during heat treatment. The adsorbed hydroxyl content of such porous coating films is found to increase due to the larger size and number of pores in the coating films. However, the transmittance of the coating film decreases due to the scattering by the larger size and number of pores. The contact angle for water of porous TiO2 coating film decreases with the increase of the adsorbed hydroxyl content, capillary force and roughness of the resultant coating films.