Hydrodynamics of thin liquid films: Retrospective and perspectives

This review presents a summary of the results in the domain of microscopic liquid film hydrodynamics for several decades of experimental and theoretical research. It mainly focuses on the validation, application and further development of the Stefan-Reynolds theory on the liquid drainage, based on the accumulated knowledge of surface forces, surface tension caused by the surfactant adsorption, and diffusion of surfactants. Liquid films are of primary significance for colloidal disperse systems, and diverse industrial processes. The transient stability of the froth phase and the froth drainage is a function of the drainage and rupture of liquid films between air bubbles. In flotation, the bubble-particle attachment is controlled by the thinning and rupture of the intervening liquid film between an air bubble and a mineral particle. Both the experimental and theoretical results are mostly related to the foam liquid films between two bubbles, but can be principally generalized for emulsion films, formed in another liquid, as well as wetting films between a bubble and a solid surface.