The impact of electrolyte on the adsorption of the anionic surfactant methyl ester sulfonate at the air-solution interface: Surface multilayer formation

摘要

Graphical abstractDisplay OmittedAbstractThe methyl ester sulfonates represent a promising group of anionic surfactants which have the potential for improved performance and biocompatibility in a range of applications. Their solution properties, in particular their tolerance to hard water, suggests that surface ordering may occur in the presence of multi-valent counterion. Understanding their adsorption properties in a range of different circumstances is key to the exploitation of their potential.Neutron reflectivity and surface tension have been used to characterise the adsorption at the air-aqueous solution interface of the anionic surfactant sodium tetradecanoic 2-sulfo 1-methyl ester, C14MES, in the absence of electrolyte and in the presence of mono, di, and tri-valent counterions, Na+, Ca2+, and Al3+. In particular the emphasis has been on exploring the tendency to form layered structures at the interface.In the absence of electrolyte and in the presence of NaCl and CaCl2and AlCl3at low concentrations monolayer adsorption is observed, and the addition of electrolyte results in enhanced adsorpti