Bulk Concentration Effects on the Structure and Orientation of Adsorbed Silane on the Surface of Nanosized SiO2 Particles

Abstract

In this study, the concentration effects of 3‐methacryloxypropyltrimethoxysilane (MEMO) on the surface coverage extent, orientation, and structures of MEMO silane grafted onto the surface of SiO2 particles are investigated using Fourier transform infrared (FTIR) and 29Si‐NMR spectroscopy. The MEMO silane concentration effects on the rheological behaviors of the SiO2 particles–1,6‐hexanedioldiacrylate (HDDA) suspensions are discussed in terms of the surface coverage extent and the MEMO silane structures grafted onto the surface of SiO2 particles. At low MEMO concentrations, many free silanol SiOH groups were observed for the MEMO grafted onto the SiO2 surface and the adsorbed MEMO molecules tended to orient parallel to the SiO2 surface due to the hydrogen bonding of the MEMO‐carbonyl and the hydroxyl group of the oxides. At high MEMO concentrations, the condensation reactions between neighboring grafted MEMO molecules result in the predominance of a T2 and T3 silicon atom structure and complete coverage of the SiO2 surface by the grafted MEMO. The enhanced steric hindrance and compatibility between the MEMO‐modified SiO2 particles and HDDA monomer, which originate from the complete coverage of the SiO2 surface by MEMO silane and a higher proportion of free carbonyl groups on the grafted MEMO, may improve the dispersibility of nanosized SiO2 in acrylate suspensions.