ABSTRACT
Chemical surface modification of silica powders renders new opportunities for their effective use as fillers of polymers, thickeners of dispersion media, adsorbents, silica-based bonded phases for different kinds of chromatographic separation, supports of catalysts, and active compounds. Among the modifying reagents, organosilanes with amino-, methacryl-, epoxy- or vinyl group have found widespread application and their fiber/polymeric matrix interface structures have been widely studied. Improvement of the physicomechanical properties of polypropylene can be also executed by chemical modification of glass fibers with 3-methacryloxypropyltrimethoxysilane. The majority of the reactions involving the silica surface sites concerns to the heterolytic processes of substitution, addition, elimination, and rearrangement. Chemisorption of methylchlorosilanes on the hydrated silica surface proceeds in mild conditions, beginning with room temperature. Interaction of trimethylhalosilanes with the silica surface may be realized in several ways, namely according to the mechanism of electrophilic proton substitution in the isolated silanol groups by the trimethylsilyl ones, or by addition of organosilanes to the siloxane bonds.
