Preparation and structural characterization of mesoporous silicas.

Abstract

The tri-block copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic P123) is an interesting class of structure controller agent in the polymerization process of silica species because the micelle structuring can determine the formation of organized templates for the precipitation or phase separation, or yet gelification in the hydrolysis and condensation of silicon alcoxides, TEOS for instance, yielding interesting mesoporous silica structures. These materials present structural characteristics with high specific surface area and very uniform pore size distribution that become them of great scientific and technological interest in several areas of knowing, as catalysis, separation, adsorption, enzyme immobilization, driving and controlled drug delivery, and nanotechnology, working in the last case as proper medium for the preparation of nanoparticles of advanced materials. In this work, the effects of the variation of the concentration of the tri-block copolymer Pluronic P123 on the properties of gelification and/or precipitation of the system, after the TEOS hydrolysis and condensation, and the structural characteristics as a function of the drying conditions of the final products are studied. The structural characteristics are studied by means of density measurements, thermal analysis (TG and DSC), nitrogen adsorption, DSC termoporometry, and small-angle x-ray scattering (SAXS). The candidate is IC student supported by CNPq since 2007 (2 renovations) with the same orientation of the responsible for the present proposition to FAPESP. The results of the candidate research contributed for a recent publication of an article in the Journal of Non-Crystalline Solids (doi: 10.1016/j.jnoncrysol.2009.06.011).