Sol-Gel Synthesis of Silica–Based Mesoporous Powders.

Mesoporous silica powders have been synthesized starting from aqueous solutions of Si(OCH(2)CH(3))(4) (TEOS) under acidic conditions, using non-ionic alkyl poly(ethylene oxide) oligomer (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 degrees C) resulted in more efficient elimination of the organic molecules, thus yielding hexagonal (p6mm) mesoporous materials with pore volume and specific surface area ranging between 0.58-0.41 cm(3)/g and 900-700 m(2)/g, respectively. The systems were characterized by X-Ray Diffraction (XRD), N(2) BET adsorption, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Particular attention was focused on the evolution of the system mesostructural and porous features as a function of the template removal procedure. The obtained mesoporous networks are suitable as matrices for the development of nanocomposite systems in which the dispersion or the growth of various guest species (clusters, molecules...) can be addressed into the host mesopores.