Effect of polyelectrolyte/surfactant combinations on the stability of foam films

What happens if polymers are added to a macroscopic foam or to foam films? This is an important question for many technical applications, but it is also important for materials and life science. This paper reviews the effect of the surface composition on the thickness and stability of aqueous foam films containing surfactants and polymers. The surfactant concentration is below the critical micellisation concentration (cmc) and the critical aggregation concentration (cac). The addition of polymers to foam films leads to the formation of surface active polymer/surfactant complexes or to depletion of polymers close to the interfaces, which has a strong effect on the film stability. The review mainly concentrates on the dilute polymer regime (below the overlap concentration c*), and results at the semi-dilute regime (above c*) are briefly reviewed. A principle concept for the relation between the surfactant/polymer combination and the film thickness and stability is developed. It allows the prediction, of whether an unstable Newton black film (NBF) or a stable common black film (CBF) will be formed.