On the Relation between Surface Forces and Wetting

Structural forces play a dominant role in the range of contact angles θ < 15° (hydrophilic repulsion) and θ > 40° (hydrophobic attraction); the intermediate region corresponds to the field of application of the DLVO (Derjaguin–Landau–Verwey–Overbeek) theory. The short-range hydrophobic forces in the wetting films of water seem to be the same as in colloids; this can be explained by assuming an unstable wetting film to be disposed between two hydrophobic surfaces: the hydrophobic solid substrate and the water–air interface.