Surface modification of fine colloidal silica with copolymer silane-coupling agents composed of maleic anhydride

Abstract

The reactivity of copolymer silane composed of maleic anhydride in the modification of fine colloidal silica was studied. The reaction of colloidal silica of 10 and 45-nm diameter with trimethoxysilyl-terminated poly(maleic anhydride-co-styrene) [P(MA-ST)] and poly(MA-co-methyl methacrylate) in tetrahydrofuran resulted in effective surface modification without particle aggregation. From the results that the reaction using the polystyrene silane of low molecular weight led to partial aggregation, it was suggested that the steric interaction between relatively rigid copolymer chains having a maleic anhydride moiety adsorbed on the silica prevented the aggregation in the reaction. The ²⁹Si cross-polarization magic-angle-spinning NMR spectra of P(MA-ST)-modified silica showed that the polymer silane was bound to the silica surface by the direct reaction with silica hydroxyl groups and via the polymerization.