Complex wetting phenomena in liquid mixtures: frustrated-complete wetting and competing intermolecular forces

We give a phenomenological overview of recently discovered complex wetting states in simple liquid mixtures relevant to both fundamental research and industrial applications such as oil recovery, Alkanes on water show a seque nce of two wetting transitions, from partial wetting to 'frustrated-complet e wetting', and finally to complete wetting: a first-order thin-thick trans ition between a microscopic and a mesoscopic adsorbed alkane film is follow ed by a long-range critical wetting transition to a macroscopic wetting lay er. The existence of the new 'frustrated-complete wetting' state follows fr om a competition between short-range and long-range components of the inter molecular forces, the latter opposing wetting. The effective long-range for ces between interfaces consist of Debye dipolar and London dispersion contr ibutions, which can also be in mutual competition. The London component is ultimately responsible for the frustration preventing complete wetting at a mbient temperatures and pressures.