Mesoscopic simulation study on the orientation of surfactants adsorbed at the liquid/liquid interface

With a simple coarse-grained model, the orientation of sodium dodecylsulfonate (DDS) and sodium dodecylsulfate (SDS) adsorbed at the water/CCl4 interface, has been investigated on a mesoscopic level by considering the variation of root mean square (RMS) end-to-end distances of surfactants using dissipative particle dynamics (DPD) simulation. An increase in the interfacial concentration of surfactants results in the increase in the orientation of surfactants before reaching a full monolayer. Strong hydrophilic head groups are beneficial to form a well-ordered configuration, and appropriate salts make surfactant molecules more stretched and ordered. These conclusions are consistent with the experimental and theoretical results.