Ultrasonic dispersion of a silica hydrosol is compared with the effects of mechanical activation through the combined action of high shear stresses, ultrasound and cavitation. This action leads to breaking the siloxane bonds and increasing the content of silanol groups. The mechanical activation of binary silica system with acrylate dispersion promotes a chemisorption of oligoacrylate with the formation of Si – O – C and Si – C bonds. The effect of modification of oligoacrylate on the formation of a graft-copolymer and the stiffness of a composite material was evaluated.