Surface energy of oxides and silicates

Published data and the author’s own data on the surface energy of hydrophilic oxides, silicates, and hydrophobic adsorbents based on them are reviewed. The prospects of using the combined Gibbs-Helmholtz-Young equation to obtain data on the surface pressure, heat of wetting, and wetting contact angle of hydrophilic and hydrophobic adsorbents are demonstrated. These data are used to estimate the thermodynamic characteristics of the surface and interfacial regions at the boundary between the materials and water. It is shown that the boundary layers of water close to the hydrophobic surfaces are more ordered while those close to the hydrophobic surfaces are less ordered than with liquid water. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 133–149, May–June, 2006.