Wettability study of modified silicon dioxide surface using environmental scanning electron microscopy

The wettability analysis is often used to characterize a surface in micro and nanometer scale. At these small scales, effects of the contact line tension are also expected to play a significant role. Wettability effect is studied using environmental scanning electron microscopy on silicon dioxide surface modified by a low-energy electron irradiation method. Electron-induced wettability variation and patterning at micrometer scale on silicon dioxide substrate allow investigating the contact angle dependence on the water droplet line curvature and calculating values of the line tension of a three-phase system (solid-liquid-vapor) of about 10-9 J/m that is consistent with theoretical estimations. It is found that the sign of the line tension alters from positive for hydrophilic surface to negative for hydrophobic one.