Adsorption and interaction of organosilanes on TiO2 nanoparticles

Organosilanes with different organic functional groups are precursors of corresponding organosilanol which can be attached to the surface of oxide nanoparticles by silyation. In this work, surface of commercial TiO2 nanoparticles was modified by 3-aminopropyltrimethoxysilane (APS) and phenyltrimethoxysilane (PTMS) through an aqueous process. The amount of adsorbed organosilane was evaluated by energy dispersive X-ray spectroscopy and was found to be 3 times higher on PTMS treated sample than on APS treated sample. The orientation and bonding of the molecules on particle surface was analyzed using Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectrometry. The obtained data confirmed that bonding of organosilanols on particle surface was realized through Si-O-Ti bonds and organic functional groups were extended away from particle surface on both APS and PTMS modified particles. It was found that phenylsilanol molecules are cross-linked to each other through Si-O-Si bonds, while such bonds are very little to none between aminosilanol molecules. A model of adsorption is proposed to explain these observations. (C) 2010 Elsevier B.V. All rights reserved.