Adsorption of alkoxysilanes on aluminum surface from aqueous solutions

Adsorption of vinyltriethoxysilane and γ-aminopropyltriethoxysilane on the surface of aluminum from an aqueous solution is studied with the use of a quartz-crystal microbalance. Upon adsorption of silanes, adsorbed water is found to be displaced from the surface. For the interpretation of adsorption data, Langmuir, Brunauer-Emmett-Teller, Flory-Huggins, multisite Langmuir, Temkin, Frumkin, and Freundlich adsorption isotherms were used. The surface orientation of adsorbed molecules is determined. The heat of adsorption of silanes is calculated in different ways. Silanes are found to be chemisorbed on the surface of aluminum.