Tuning of Foam Film Thickness by Different (Poly)electrolyte/Surfactant Combinations

Abstract

Disjoining pressure isotherms of free-standing liquid films (foam films) consisting of different polyelectrolyte/ surfactant combinations are measured in a thin film pressure balance (TFPB). In dependence of the charge of polyelectrolyte and surfactant, a transition from an electrostatically stabilized common black film (CBF) to a sterically stabilized Newton black film (NBF) can be induced in some cases while for other polyelectrolyte/ surfactant combinations the film is a CBF up to several thousands of pascals. The thinner NBF is less stable, and the film breaks after a few minutes. An exchange of the polymers by monomers leads to the same kind of film as that for the respective polymer, while the addition of, for example, simple salt leads always to a transition from CBF to NBF. The typical stratification of polyelectrolyte/surfactant films is not observed in monomer/surfactant films.

Polyelectrolyte-mediated surface interactions

“…The very limited influence of the polyelectrolyte molecular weight is supported by experiments [61]. Further, the prediction that the nature of the surface, similar charged, uncharged or oppositely charged to the polyelectrolyte, has a limited effect on the nature of the oscillating forces is also confirmed by experiments [62][63][64][65]. Since the organization of the polyelectrolyte solution is caused by the repulsion between polyelectrolyte chains any variation that will reduce this repulsion, e.g.…”

Effect of polyelectrolytes on (de)stability of liquid foam films

“…[36][37][38] On one hand, the addition of PDADMAC to one of the surfactants has no signicant inuence on the surface tension isotherms (Fig. 8).…”

“…33,38 Fig. 15 displays disjoining pressure isotherms for solutions containing 3.8 Â 10 À3 (mono)mol l À1 carboxyMC and 10 À4 mol l À1 surfactant varying in chain length from 12 to 16 carbon atoms.…”

Surface adsorption of sulfonated poly(phenylene sulfone)/C14TAB mixtures and its correlation with foam film stability

“…6,7 Depending on the charge combination of the used polyelectrolytes and surfactants, either a Common Black Film (CBF) with a thickness of 10-100 nm, or a Newton Black Film (NBF) with a thickness below 10 nm is formed as the final state before film rupture. 5,8 CBFs are electrostatically stabilized due to the presence of surface charges, while NBFs are stabilized by steric repulsions of the adsorbed complexes. CBFs contain two surface layers with differing amounts of water between them, while NBFs consist of only two layers of adsorbed molecules and their respective hydration shells.…”

“…[9][10][11][12] This oscillation is induced by a transient network of the polyelectrolyte chains in the film core and/or by the layering of micelles, respectively. For polyelectrolyte/surfactant mixtures the influence of different parameters such as polyelectrolyte/surfactant type, 8 polyelectrolyte/ surfactant ratio, 13 polyelectrolyte/surfactant hydrophobicity, 14 pH and surfactant head group 15 and ion specific effects 16 on the air/water interface and foam film properties were extensively investigated. However, for most of the investigated polyelectrolyte/surfactant mixtures the polyelectrolyte backbones were quite flexible, e.g.…”