Protsak I. Chemical modification of silica surface with polyorganosiloxanes in presence of alkyl carbonates

The thesis is devoted to the development of methods for chemical modification of silica surface with organosiloxanes based on using the effective initiators of heterolytic cleavage of siloxane bond for obtaining highly disperse materials characterized by the enhanced content of the organic groups in the surface grafted layer and the absence of potential electrolytes in the modifying layer. Chemical interaction of dimethyl carbonate with sites of the dehydrated silica surface was shown to occur at temperature of 200 °C, chemisorption processes take place involving both structural silanol groups and siloxane bridges on the surface. Chemical modification of pyrogenic silica surface with organosiloxanes in the presence of alkyl carbonates has been done. It has been shown that the use of mixtures of organosiloxanes with dimethyl carbonate for surface modification increases the concentration of grafted organic groups in the surface layer and provides full participation of free silanol groups in chemisorption processes at the moderate temperatures (220 °С). The obtained hydrophobic products are characterized of high uniformity of nanoparticles.