Multivalent counterion induced multilayer adsorption at the air-water interface in dilute Aerosol-OT solutions

The formation of surface multilayer structures, induced by the addition multivalent counterions in dilute surfactant solutions, has been widely observed a range anionic surfactants. phenomenon is associated with ability to manipulate properties, especially promotion enhanced wetting, and presence an extensive near reservoir for rapid delivery other active components. Hypothesis. In single alkyl chain surfactants, such as sodium dodecysulfate, SDS, alkylethoxylsulfate, SAES, alkylestersulfonate, AES, promoted trivalent Al 3+ , generally not divalent counterions, Ca 2+ or monovalent counterions. di-alkyl surfactant, dodecylbenzenesulfonate, LAS, now occurs It attributed closer proximity bulk lamellar phase, resulting greater tendency formation, hence should occur Experiments. Aerosol-OT, AOT, one most commonly used extensively emulsifying, wetting dispersing agent. This paper reports on predominantly neutron reflectivity, NR, measurements which explore nature salt AOT at air-solution interface separate Findings. concentration 0.5 2.0 mM Although evolution structure counterion broadly similar those reported SAES some notable differences occur. particular thresholds are higher than . encountered reflect affinity how packing controlled part headgroup binding affinity.