Amorphous and Crystalline Mesoporous Materials Prepared Via Evaporation

Abstract

Because of the increasing interest in nanoscale technologies, many groups have taken part in the recent development of nanostructured materials that may be preserved in a robust form for designed applications. Amongst the various possible synthesis paths, the Evaporation Induced Self Assembly (EISA), leading to surfactant templated materials in the shape of thin films (liquid deposition), spheres (spray-drying) or monolith (slowevaporation), is one of the most promising since it enables to control morphologies and allows keeping the stoichiometry in non-volatile species homogeneously distributed in the final materials. The elaboration of the desired mesoporous materials passes by the control of the three steps involved in such a process: The control on the precursor chemical reactivity in the initial solution, the control of all processing parameters during evaporation and the control during consolidation by thermal decomposition of the organic phase and the potential crystallisation of the inorganic network.

Through the use of complementary in-situ experiments and conventional characterisation techniques (NMR, 2D-SAXS, interferometry, TEM, ellipsometry, N₂-BET), the present paper recalls the top-to-bottom studies of the EISA process applied to two different systems (SiO₂ and TiO₂) as thin films and spherical sub-micronic particles. In addition, the preparation of ordered mesoporous pure anatase thin films stable up to 700°C will be presented in details at the end of this work.