In the surface treatment of silica with alkylsilanes, the formation of a covalent bond with the surface is recognized as being important in obtaining highly robust films. In this paper, we show that the presence of a covalent bond is also important in defining the behavior and properties imparted to the silica by the silane layer. Specifically, it is shown that a chemically bonded alkylsilane is a necessary condition to alter the triboelectric properties of the silica. The triboelectric charge is sensitive to the distribution and level of absorbed water and this is altered by the presence of the surface bonds.