ABSTRACT
This chapter explains the thermodynamic properties of a single fluid interface. It deals with the case of two interfaces interacting across a liquid phase and talks about the surface forces, which in fact determine the properties of the liquid films in both equilibrium and dynamic conditions. A great development was achieved in the field of surface forces during the last decade: in addition to the classical DLVO forces the importance of many new forces of different physical origin, called “non-DLVO forces,” were recognized. If the forces acting in the thin film are known, one can predict the equilibrium properties of the film as well as the dynamic properties. The chapter presents a review of the thermodynamic and hydrodynamic theories of thin liquid films. The physical importance of the hydration force is that it stabilizes some dispersions, preventing coagulation in the primary minimum.
