Effect of surface hydroxyl concentration on the bonding and morphology of aminopropylsilane thin films on austenitic stainless steel

Abstract

Abstract The adsorption of 3‐aminopropyltrimethoxysilane thin films on Fe18Cr7Mn3Ni (austenitic stainless steel) was investigated by X‐ray photoelectron spectroscopy (XPS) and inelastic electron background analysis. The bonding and morphology of the films were strongly dependent on the surface hydroxyl concentration, which was controlled by the oxidation pretreatment of the substrate. In particular, an aminopropylsilane (APS) monolayer with high degree of bonding to the substrate was obtained on an electrochemically passivated surface with very high hydroxyl concentration. On the other hand, the deposition of weakly bound APS clusters was observed on substrates having relatively low hydroxyl concentrations. The adsorption occurred initially via hydrogen bonding, whereas heating to 373 K resulted in the formation of covalent SiOM bonds at the silane/metal oxide interface. The results of this study provide insight into the interaction between silanes and stainless steels surfaces, and can be applied for functionalization of stainless steel materials in an extensive range of applications. Copyright © 2010 John Wiley & Sons, Ltd.