Abstract
Rational design of thin films for improving their functional properties can result in complex architectures. This issue will be here illustrated in the case of sol-gel derived hierarchically porous and multifunctional silica-based membranes. Thin silica layers with isolated and randomly distributed macropores, isolated and ordered mesopores and an interconnected microporosity in the silica walls are thus obtained by combining different synthesis strategies. The impact of the overall porosity and of the pore size distribution on the mechanical properties of these layers is investigated coupling experimental measurements and numerical simulation. The extra porosity is used for providing a catalytic functionality by inserting Pt nanoparticles at predefined locations. Two methods are implemented to control the spatial distribution of the catalytic nanoparticles either in the mesopores or in the macropores. The catalytic performance of the resulting materials is tested. Organosilica thin films with isolated and ordered mesopores and an interconnected microporosity in the walls are also prepared and characterized in terms of adsorption and gas permeation. Numerical simulation of adsorption appears as a promising tool for understanding and predicting the properties of such films.