Influence of Surfactants, Polymers and Proteins on Foam Film Drainage*

Foams can be described as colloidal dispersions containing large gas cells separated by thin liquid films, whose junctions are called Plateau borders. Drainage of individual ultrathin foam films (thickness < 100 nm) into Plateau borders is governed by the interplay of capillarity, disjoining pressure, viscosity, and interfacial rheology.  It is well-established that confinement-induced structuring and layering of supramolecular structures like micelles, liquid crystals, colloidal particles, or polyelectrolytes within foam films results in drainage via stratification. Only few examples show the possibility of stratification in foam films containing polymers or proteins. In this contribution, we visualize and analyze drainage in foam formulated with surfactants, proteins, polymers and their mixtures, and describe the specific connection to foam stability and applications in diverse areas in foods, cosmetics, environmental remediation, oil recovery, and healthcare.