Diffuse Reflectance Fourier Transform Infrared Spectroscopic Study of Chemical Bonding and Hydrothermal Stability of an Aminosilane on Metal Oxide Surfaces

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Abstract
Fourier transform infrared spectroscopy was used to study the metal oxide/silane interface. Structures of γ-aminopropyldimethylethoxysilane (γ-APDMES) coupling agent on the surface of metal oxide powders are proposed. The structures depend on the surface characteristics of the substrate. The amine group of the silane molecule forms a hydrogen bond with the silica surface. The enhanced intensity of the amine band around 1600 cm−1 indicates that the amine group forms a complex on the titanium dioxide and aluminum oxide surfaces, as well as a hydrogen bond. By using the diffuse reflectance infrared technique, the Al-O-Si and Ti-O-Si antisymmetric frequencies are detected at 963 and 950 cm−1, respectively, which agree favorably with the calculated frequencies. When the treated metal oxide powders are immersed in 80°C water, the rate of silane desorption increased in the following order of substrate; SiO2, TiO2 and Al2O3.