An experimental investigation of polymolecular solvate (adsorbed) films as applied to the development of a mathematical theory of the stability of colloids

Abstract

After a critical discussion of the current concepts of solvation of surfaces and colloid particles, as well as of the methods of studying solvation, a new quantitative definition of solvation is advanced. This definition connects solvation with the disjoining action of thin layers of liquids, discovered and studied in earlier experiments described in the preceding papers of this series.The present paper describes a new, more convenient method of measuring both the thickness and disjoining action of thin layers for cases when they separate gas bubbles from solids (wetting films).Observations of non-equilibrium states of such wetting films are described.Experimental data are quoted, which are used in establishing an equation of state of a solvate layer. This equation expresses the equilibrium pressure (disjoining action) of a solvate layer for aqueous and non-aqueous media as a function of the thickness of the layer.The effect of electrolytes on the thickness of aqueous solvate films. as well as the influence of surface-active substances upon vaseline-oil films on steel surfaces, has been investigated.A theory of interaction of micelles, taking into account the disjoining action of thin layers of dispersion medium between the micelle surfaces, is advanced.In conclusion, the computations used in the latter theory are employed to elaborate a theory of slow coagulation and stability of colloids and disperse systems.