I. Surface Forces Surface Forces and Physicochemistry of Surface Phenomena

The results of modern theoretical and experimental The results of modern theoretical and experimental studies of components of the long-range surface forces which studies of components of the long-range surface forces which determine the properties of dispersions and wetting liquid films determine the properties of dispersions and wetting liquid films are generalised. The bibliography includes 113 references are generalised. The bibliography includes 113 references.. During the last 10 ± 15 years, numerous studies dealing with the interactions of interfaces through thin liquid films have been carried out as applied to colloids including nanoparticles and asymmetrical systems, i.e., wetting films. This line of research forms the basis for solving a number of engineering problems such as control of the properties of dispersions, wetting, flotation and water treatment and the problems of environmental protection. The physicochemistry of the surface phenomena considers the components of the surface forces and their change upon modification of the interfaces due to the adsorption of ions, surfactants and polymers including polyelectrolytes. We shall start the discussion of the state-of-the-art of this field of physicochemical science with consideration of the results of fundamental studies of the surface forces which play the key role when the distances between the interacting particles or surfaces are comparable with the radius of action of these forces. Attractive or repulsive forces whose radius of action is much greater than the length of chemical bonds arise between condensed phases separated by a thin gas or liquid interlayer. The physical nature of such long-range forces can be different. They may be due to the electric fields of charged surfaces, fluctuating electromagnetic fields related to the movement of electrons in atoms and molecules, and structural forces arising upon the overlap of the boundary layers of the liquids with a changed structure. 1 The radius of action of these forces has the same order of magnitude as the correlation length in the liquid bulk (usually, this makes several nanometres). For solutions of polymers or surfactants, it is necessary, in addition, to take into account the steric forces which appear when the adsorption layers approach each other and overlap. 2 The surface forces and the thermodynamic properties of thin liquid interlayers between two planar surfaces of solids are described conventionally by the disjoining pressure (P), which was introduced by Derjaguin. 3 This value is equal to the difference between the pressure P acting on a planar liquid interlayer …