Abstract:

A novel method was developed to produce a TiO2 film with circular pores on its surface. Macrospore structure can be obtained in the presence of two complexing agents of acetylacetone(acac) and diethanolamine(DEA) under a template-free condition. Notwithstanding, it has been found that irrespective of the kind of complexing agents, whether it is acac, or DEA, a common flat surface-formation process has been confirmed. In this account, acac or DEA added in the sols serve as stabilizers that impedes the hydrosis and polymerization among constituents during gel-forming reactions. But the situation has entirely changed when both acac and DEA were used as complexing agents. The hydrolysis is conducted under acidic conditions where a relatively narrow distribution of growing oligomers can be obtained. And the phase separation is driven by the reduction of miscibility between the polar solvent and polycondensed inorganic species. The phase-formation time would decline according the adding amount of DEA which triggers the process of hydrolysis under acidic conditions. The fluid phase of solvent mixture could oxidize and decompose to carbon dioxide which leaves numerous pores on the surface. The results show that the TiO2 film doped with two stabilizers exhibits superhydrophilic characteristic(6.5°) although it is not exposed to ultraviolet irradiation, comparing with flat ones(20° and 23°). Finally, the formation mechanism and the property structure relationship were discussed in details.

Key words: porous film, acetylacetone, diethanolamine, complexing agent,, superhydrophilicity