Effect of interface modification on forces in foam films and wetting films

The paper reviews the effect of the surface composition on forces within aqueous foam and wetting films. In both types of films the charge of the air/water interface is varied by different surfactants. In wetting films the charge and the hydrophobicity of the solid substrate is changed by polymer coatings. The addition of polymers to foam films leads to the formation of surface active polymer/surfactant complexes or to depletion near the interfaces. The dissolution of polyelectrolytes within the film bulk can lead to structural forces. The selection of studies is made with respect to two questions: (1) What is the reason for charges at the air/water interface and (2) what is the mechanism of long-range hydrophobic interaction?