Disjoining pressure in thin liquid foam and emulsion films—new concepts and perspectives

The present review is a topical survey of the disjoining pressure in thin liquid foam and emulsion films from both the experimental and the theoretical points of view. Section 2 deals with the latest research work on experimental techniques with which the disjoining pressure Π in foam, emulsion, and pseudo-emulsion films can be measured. Although a lot of techniques are available, the question of the origin of the charges at the water/air and the water/oil interfaces of films, which are stabilized by non-ionic surfactants, has not yet been answered. We address this question in section 3, reviewing the latest relevant literature. The relevance of structural forces for the disjoining pressure is outlined in section 4, which focuses on films which are stabilized by surfactant/polyelectrolyte mixtures.