Synthesis of a polysilazane layer on silica gel by chemical surface coating

Abstract

Thermally pretreated silica gel has been modified with SiCl₄ and NH₃. Repeating this treatment gives rise to a polysilazane layer, chemically bonded to the silica gel surface. Using FTIR, N and Cl determinations and gravimetric analysis, a total characterization of the polysilazane layer was obtained, together with quantification of the different reactions occurring. The parameters of the reaction cycles have been optimized in such a way, that a high density of silazanes (Si—NH—Si) is reached at the silica surface. The influence of the modification process upon the porosity of the silica gel was also studied.