Adsorption of oppositely charged polyelectrolyte/surfactant complexes at the air/water interface: formation of interfacial gels.
The adsorption and complexation of polystyrene sulfonate (a highly charged anionic polyelectrolyte) and dodecyltrimethylammonium bromide (a cationic surfactant) at the air-water interface can lead to interfacial gels that strongly influence foam-film drainage and stability. The formation and characteristics of these gels have been studied by combining surface tension, ellipsometry, and foam-film drainage experiments. Simultaneously, the solution electromotive force is measured and used to track the polymer-surfactant interactions in the bulk solution. We find that surface gelation occurs above the critical aggregation concentration in solution but before bulk precipitation of the polymer-surfactant complexes. Furthermore, we reveal that strong readsorption of polymer-surfactant complexes occurs during the resolubilization of the precipitated complexes at high surfactant concentrations (i.e., >>critical micelle concentration). Seemingly overlooked in the past, this readsorption significantly influences the surface rheological properties and foam-film drainage of these systems.
Monteux
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Laboratoire de Physique Statistique, UMR 8550, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France.
Williams
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CE
Meunier
J
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Anthony
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Bergeron
V
V
D000327:Adsorption; D000388:Air; D004573:Electrolytes; D005782:Gels / Q000138:chemical synthesis* / Q000737:chemistry; D008567:Membranes, Artificial; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D004573:Electrolytes; D005782:Gels; D008567:Membranes, Artificial; D011137:Polystyrenes; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D014867:Water; C003321:polystyrene sulfonic acid; C022806:dodecyltrimethylammonium