On the Analogy between Lateral Capillary Interactions and Electrostatic Interactions in Colloid Systems

Abstract

A formal analogy between the linear theories of the lateral capillary interaction between solid bodies at a liquid−fluid interface and the electrostatic interaction between charged surfaces in electrolyte solution (linear DLVO theory) has been recognized. Thanks to that analogy, the well-developed methods for calculation of electrostatic interactions in DLVO theory can be utilized to explore the less well-studied lateral capillary interactions between particles adsorbed at a liquid−fluid interface. A few examples of the usefulness of such approach to capillary interactions in different geometries are given. A complete electrostatic analogy is found for the lateral capillary interaction between plates or rods, but not in the case of spherical particles. It is demonstrated how the approximations used in the nonlinear theory of electrostatic interaction work for the case of lateral capillary forces in colloid systems. The analogy between electrostatic image forces and capillary image forces is also discussed. The author believes that this study will be helpful for better understanding of the complex phenomena accompanying the capillary interactions between colloid particles attached to a liquid−fluid interface, the formation two-dimensional ordered aggregates of colloid particles in wetting films, etc.