Sol-gel synthesis of silica-based mesoporous powders

Mesoporous silica powders have been synthesized starting from aqueous solutions of Si(OCH2CH3)4 (TEOS) under acidic conditions, using non-ionic alkyl poly(ethylene oxide) oli- gomer (Brij76) as a structure-directing agent. Template removal was performed by thermal treatment in air as well as by ethanol extraction. The annealing process (400 - 600°C) resulted in more efficient elimination of the organic molecules, thus yielding hexagonal (p6mm) mesopor- ous materials with pore volume and specific surface area ranging between 0.58 - 0.41 cm3/g and 900 - 700 m2/g, respectively. The systems were characterized by X-Ray Diffraction (XRD), N2 BET adsorption, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Particular attention was focused on the evolution of the system mesostructural and po- rous features as a function of the template removal procedure. The obtained mesoporous net- works are suitable as matrices for the development of nanocomposite systems in which the dis- persion or the growth of various guest species (clusters, molecules...) can be addressed into the host mesopores.