Examination of dispersive properties of alumina treated with silane coupling agents, by using inverse gas chromatography

This study applied inverse gas chromatography (IGC) to examine the surface properties of an untreated alumina and alumina treated with four types of silane coupling agents. The carbon content of the silane coupling agents adsorbed on the surfaces of the alumina was analyzed to examine the number of adsorption layer. The results suggested that multilayers are generally adsorbed onto the alumina surfaces based on the assumption that a molecule of each silane coupling agent occupies an area of 0.5–1 nm2. This paper presents and discusses the dispersive properties expressed by γSD, which is the dispersive component of the surface free energy, as determined at various temperatures. The γSD values of the alumina treated with γ-methacryloxy propyl trimethoxy silane (MTMS) were the highest, while those of the alumina treated with γ-amino propyl triethoxy silane (AES) were the lowest at the same measuring temperature. The alumina treated with γ-glycidoxy propyl trimethoxy silane (GMS) and γ-mercapto propyl trimethoxy silane (MCMS) showed γSD values in close agreement to those of most resins (approximately 30 mJ m− 2 at 160 °C).