Synthesis of nanometer scale oxide-based titania films by a two-dimensional sol-gel process at the air-liquid interface

The present study focuses upon the synthesis of nanometer scale oxide-based titania films from tetrabutoxy titanium according to a two-dimensional sol-gel process at the air-liquid interface. First, surface pressure-area isotherms of the tetrabutoxy titanium were measured at 22.0 +/- 0.5 degrees C on various subphases: pure water (pH = 5.5), aqueous acetylacetone (0.01 M, pH = 4,6), aqueous acetic acid (0.01 M, pH = 3.3) and glycerol. At the same time, UV-vis absorption spectra were directly recorded at the interface at variable surface pressures. Brewster angle microscopy served to observe the film topology on the different subphases. The results are interpreted in terms of the formation of a macroscopic network interconnecting the titania atoms. On the aqueous acetic acid and the glycerol subphases, the film showed to be more complex and stronger interconnected, i.e. involving two networks made of oxide and ligand bridges. In the case of the aqueous acetylacetone subphase, the resulting coating appears much less interconnected. (C) 1999 Elsevier Science B.V. All rights reserved.