Fluorocarbon vapors slow down coalescence in foams: influence of surfactant concentration

• Published in: Colloid and polymer science Vol. 301; no. 7; pp. 685 - 695
• Main Authors: Steck, Katja, Dijoux, Jonathan, Preisig, Natalie, Bouylout, Victor, Stubenrauch, Cosima, Drenckhan, Wiebke
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2023; Springer Nature B.V; Springer Verlag
• Subjects: Alkanes; Aqueous solutions; Characterization and Evaluation of Materials; Chemical Sciences; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Condensed Matter; Foams; Food Science; Gas exchange; Nanotechnology and Microengineering; or physical chemistry; Original Contribution; Physical Chemistry; Physics; Polymer Sciences; Soft and Granular Matter; Soft Condensed Matter; Stability; Surface tension; Surfactants; Theoretical and; Vapor phases; Thin films; Foam; Adsorption; Foam coalescence; Surface tension; Fluorocarbons; Surfactants
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-023-05129-7

Even though it has been known for a long time that traces of perfluorinated vapors suppress gas exchange (coarsening) between the bubbles of aqueous foams, its stabilizing impact on foam coalescence has been evidenced only recently. While previous work has demonstrated this effect for different surfactant types, we investigate here the influence of the surfactant concentration. We compared the foam properties of aqueous solutions of the non-ionic surfactant dodecyldimethylphospine oxide (C 12 DMPO) in the absence and presence of perfluorohexane (PFH) in the gas phase. In order to decouple foam coarsening and coalescence, we accompany the foam stability experiments with (a) lifetime statistics of individual, vertical foam films pulled from the same solutions and (b) surface tension measurements in controlled gas environments. All measurements show a clear increase of foam and film stability in the presence of PFH, its effect being most pronounced above the cmc of the surfactant. The surface tension measurements show a clear co-adsorption of the PFH up to the formation of macroscopic films at saturation. We complete the analysis by showing that alkane vapors also have a stabilizing effect for the same surfactant solutions, yet much less pronounced than that of PFH. The precise origin of the stabilizing action of these hydrophobic vapors remains to be elucidated. Graphical Abstract