Abstract: Self-cleaning TiO2 films were prepared by hydrothermally treating a microemulsion followed by dip-coating. Effect of the amount of surfactant dodecylbenzenesulfonic acid(DBS) in the microemulsion on the surface morphology and microstructure of TiO2 film was investigated. Photocatalytic activity, photo-induced hydrophilicity and self-cleaning efficiency of the synthesized TiO2 films were evaluated. With the amount of DBS increases, the size of the dispersed TiO2 particle decreases, but the particles tend to agglomerate after hydrothermal treatment. When the amount of DBS is in the range of 0 and 58 mg/L, the resultant TiO2 films consisted of particles with 15~20 nm in diameter are quite smooth. The water contact angles of those films kept in dark increase slowly and their superhydrophilicity can be quickly recovered after irradiation by UV light. The surfaces maintain clean when the films are exposed to outdoor atmosphere for 25 days with their contact angles increasing from 0° to 14°~18°. When the amount of DBS is increased to beyond 580 mg/L, the surfaces of the films become rough and show poor hydrophilicity. The contact angles of the surfaces exposed to outdoor atmosphere for 25 days increase from 0 to 46°~48°.

Key words: Microemulsion, TiO2 film, Self-cleaning, Dodecylbenzenesulfonic acid