Morphology-wettability relations in artificially structured superhydrophilic TiO2-SiO2 composite films

Naturally superhydrophilic TiO2-SiO2 composite films were deposited through a sol-gel route and the morphology of these films was artificially modified by nanosphere lithography using polystyrene spheres. Morphology changes induced by this structuration were studied by optical, scanning electron, and atomic force microscopy. The water wettability of the so-obtained films over aging under ambient atmosphere was then studied with respect to the sol composition and morphological features. This study i/confirms the assumption of a natural superhydrophilicity of composite films intrinsically induced by TiO2-SiO2 granular interfaces and ii/shows that this property can be greatly improved by artificially induced morphology features. Such features are discussed on the basis of well-established surface thermodynamic models.