Surface OH group governing wettability of commercial glasses

Abstract

X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurements are applied to investigate the relationship between the wettability and the surface OH group density of various commercial glasses. The contact angle of water droplets has been measured for the glass as a function of elapsed time. The hydrophobicity, resulting from the adsorption of organic substances in the atmosphere, is different among the glasses and is dependent on the surface OH group density of the glass. These facts indicate that the surface OH group density is a major factor governing the wettability of the glass surface. Furthermore, there is a linear correlation between the OH group density and silicon concentration at the surface except for the bottom face of float glass. This fact indicates that the formation ability of the surface OH group depends on the surface silicon concentration, and the majority of the surface OH groups consist of SiOH groups. For the bottom face of float glass, the formation ability of the surface OH group is affected by the tin which penetrates into the surface as a result of direct contact with the molten tin bath.