Some Peculiarities of Silica Modification under High Reagent Pressure. II. Influence of Chemical Nature of Modifying Reagent

Abstract

The modes of interaction between organic substances and aerosilogel at high pressures and high temperatures were considered. The analysis was performed on the basis of data from IR spectroscopy and differential thermal analysis, and the porous structure characteristics of the modified aerosilogel. The following types of substances were used as modifiers of the silica surface: (a) substances which did not interact chemically with the silica surface; (b) substances capable of polymerization or polycondensation; and (c) substances capable of chemical reaction with the surface.

From an analysis of data obtained for 26 adsorbents, it results that depending on the nature of the substance used for modification such substances can promote the process of silica mass transfer. During this process, the possibility occurs of the occlusion of the substances inside silica globules, changes in the parameters of the porous structure, physical or chemical bonding of the modifier molecules with the aerosilogel surface, destruction of the reaction products, etc. The mechanism of the reaction was discussed.