Nanostructured mesoporous materials obtained by template synthesis and controlled shape replica

Mesoporous nanostructured materials are useful for a widespread field of applications, such as gas storage; selective molecular adsorption; confined chemical reactions and catalysis. In this work, periodic mesoporous silica and organosilica materials, thanks to their high surface area, narrow pore size distribution and high regular structure, have been exploited to obtain nanostructured porous materials with different chemical nature, such as polymer or carbon. Periodic mesoporous silica objects with defined micrometric shape have been obtained by template synthesis in aqueous medium. A change in synthesis condition of temperature, time and acidity leads to the generation of different shapes such as gyroids, spheres and hollow tubes. Mesoporous silica particles have been exploited for confined polymerization of different monomers (styrene, methylmethacrylate and acrylonitrile) to obtain morphological polymeric nanocomposites. The nanocomposite with polyacrylonitrile has been then heated at high temperature in non-oxidative atmosphere to induce polymer carbonization until the formation of a graphitic-like carbon structure. The silica matrix has been then removed by chemical etching to obtain nanostructured porous materials in polymer and graphitic-like carbon with high surface area and the same micrometric morphology of starting silica matrix (shape replica effect). Afterwards, a periodic mesoporous organosilica system, with phenylene groups directly linked in the wall structure and organized on the molecular scale, has been synthesised, exploited as selective gas adsorption system and heated in non-oxidative atmosphere to obtain a new mesoporous carbon material with high surface area, very regular mesoporous structure and graphitic-like pore walls. Characterization of these materials has been conduced with X-ray diffraction, calorimetric techniques (DSC and TGA), adsorption of gases and vapours and advanced mono- and bi-dimensional NMR experiments to investigate the interaction between the organic and the inorganic moieties. Thermal evolutions of polyacrylonitrile and phenylene-organosilica have been studied with spectroscopic techniques of ATR and Raman, while the shape replica effect and the high regular pore structure have been directly seen with SEM and TEM microscopies.