Modelling of the reaction-phase interaction of γ-aminopropyltriethoxysilane with silica

The coating formed in the reaction phase of the modification of silica with γ-aminopropyltriethoxysilane was modelled using the freeze sampling method with a classical N-determination. The formation of a monolayer coating in the reaction phase is confirmed. Within the selected region of silane : silica ratio, the monolayer capacity value was determined to be 1.02 mmol g–1 on dehydrated silica gel and 0.63 mmol g–1 on the dehydroxylated substrate. The obtained monolayer structure is described and related to the specific surface area of the substrate used. APTS molecules are distributed over the silica surface with each molecule covering 64 Å2.