title: Coalescence In Draining Foams Made of Very Small Bubbles.
abstract: We studied the stability of foams containing small bubbles (radius ≲ 50  μm). The foams are made from aqueous surfactant solutions containing various amounts of glycerol. The foams start breaking at their top, when the liquid volume fraction has decreased sufficiently during liquid drainage. Unlike in foams with larger bubbles, the liquid fraction at which the foam destabilizes is surprisingly high. In order to interpret this observation we propose that film rupture occurs during reorganization events (T1) induced by bubble coarsening, which is particularly rapid in the case of small bubbles. New films are therefore formed rapidly and if their thickness is too small, they cannot be sufficiently covered by surfactant and they break. Using literature data for the duration of T1 events and the thickness of the new films, we show that this mechanism is consistent with the behavior of the foams studied.
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris Saclay, Bâtiment 510, 91400 Orsay Cedex, France.|Departamento de Investigación en Polímeros y Materiales de la Universidad de Sonora Blvd. Luis Encinas y Rosales s/n, 83000 Hermosillo, Sonora, Mexico.
authors.forename: Zenaida
authors.initials: Z
authors.lastname: Briceño-Ahumada
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris Saclay, Bâtiment 510, 91400 Orsay Cedex, France.
authors.forename: Wiebke
authors.initials: W
authors.lastname: Drenckhan
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris Saclay, Bâtiment 510, 91400 Orsay Cedex, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Langevin