Adsorption and self-assembly in methyl ester sulfonate surfactants, their eutectic mixtures and the role of electrolyte

作者：Xu Hui; Li Peixun; Ma Kun; Welbourn Rebecca J L; Doutch James; Penfold Jeffrey^*; Thomas Robert K; Roberts David W; Petkov Jordan T; Choo Ken Loon; Khoo Soo Yee

来源：Journal of Colloid and Interface Science, 2018, 516: 456-465.

DOI：10.1016/j.jcis.2018.01.086

• Methyl ester sulfonate surfactants
• Adsorption at air-water interface
• Self-assembly
• Eutectic mixture
• Surface multilayers
• Surface and micelle mixing

The alpha-methyl ester sulfonate, MES, anionic surfactants are a potentially important class of sustainable surfactants for a wide range of applications. The eutectic-like Kraft point minimum in the C-16 and C-18-MES mixtures is an important feature of that potential. Understanding their individual adsorption properties and the surface mixing of the eutectic mixtures are key to their wider exploitation.
Neutron reflectivity has been used to investigate the adsorption at the air water interface of the C-16 and C-18-MES surfactants and the eutectic mixture of C-16 and C-18-MES, in aqueous solution and in electrolyte.
The micelle mixing of the eutectic mixture is investigated using small angle neutron scattering. The adsorption isotherms for C-14 to C-18-MES are found to scale with their critical micelle concentration value. The surface and micelle compositions of the C-16 and C-18-MES eutectic mixture differ from the eutectic composition; with compositions in the limit of high concentrations richer in C-16-MES. The mixing properties are described by the pseudo phase approximation with a repulsive interaction between the two surfactants. The impact of the multivalent ions Al3+ on the adsorption at the air water interface results in a transition from monolayer to multilayer adsorption.

• 出版日期2018-4-15