Self-assembly of Anionic Surfactant and Its Effect on Oil-Water Interface: Implications for Enhanced Oil Recovery

Surfactant micellization is a self-assembly process governed by complex interplay of solvent-mediated in-teractions. However, quantitative modeling of micelle formation and its effect on oil-water interface are not yet completely understood. In this work, dissipative particle dynamics simulations were used to investigate the self -assembly behavior of anionic surfactants of alcohol alkoxy sulfate (AAS) and its structural influence on the interfacial properties of oil-water at the mesoscopic scale. Our results indicate that with the increase of sur-factant concentration, the morphology of surfactant aggregates varied from spherical micelles to rod-shaped micelles, and finally formed worm-like micelles. The larger the number of propylene oxide (PO) groups, the easier the formation of large micelles and the more tightness of formed micelles. On the oil-water interface, the interfacial tension of solutions decreased with increasing surfactant concentration below the critical micelle concentration, whereas a positive correlation was found for the tightness of surfactant arrangement. When surfactants formed micelles, the overall coverage area of AAS decreased and a lower root mean square end distance of individual PO group directly affected interfacial properties of AAS. The obtained results could provide a solid theoretical basis for the rational design of efficient surfactants in oil recovery and soft matter applications.