Structural and Mechanical Evolution of Mesoporous Films with Thermal Treatment: The Case of Brij 58 Templated Titania

Abstract

Mesoporous titania thin films (MTTFs) with well ordered cubic array of mesopores were synthesized on glass and silicon substrates using Brij 58 as a template. The effect of the thermal treatment and the substrate on the structural parameters (thickness, porosity, pore order, and crystallinity) and the mechanical properties of MTTFs were determined by electron microscopy, X-ray diffraction, Raman spectroscopy, 2D-small angle X-ray scattering, ellipsometric porosimetry, and nanoindentation. Clear differences in the mesostructural order evolution and crystallization behavior were observed as a function of the substrate and the thermal treatment. In particular, the anatase crystallization process occurs at lower temperatures for samples prepared on silicon when compared with samples prepared on glass, due to the balance between nanocrystals formation, mass diffusion, and Na+ migration from the substrate. As a consequence of such phenomena, the MTTFs mechanical properties are also dependent on the substrate. F...