Adsorption component of the disjoining pressure in thin liquid films

The disjoining pressure isotherm in foam films is theoretically studied and an important contribution of adsorption is discovered. On the basis of the interfacial thermodynamics an adsorption disjoining pressure component is derived, which is repulsive and exponentially decaying by the film thickness. Expressions for its magnitude and decay length are derived in terms of well-known thermodynamic characteristics such as the partial Gibbs elasticity and adsorption length. Several adsorption isotherms are considered and the corresponding adsorption disjoining pressure components are calculated. An important coupling between the interfacial layer phases and wetting transitions is discussed as well.