Molecular dynamics simulation of the adsorption of sodium dodecyl benzene sulfonate at the decane-water interface

Molecular dynamics method was employed to explore the micro-characteristic of decane-water interface with the adsorption of sodium dodecyl benzene sulfonate (SDBS). We analyzed the effect of interfacial molecular arrangement on the micro-structure and properties of oil-water interface from concentration distribution and molecular conformation insights. The results show that the thickness of decane-water interface is 0.378 nm. Both decane molecules and the dipole moment of water molecules tend to be parallel to the interface. The aggregation of surfactants at the interface increases the thickness of oil-water interface, therefore weakening the oil-water interaction and disrupting the directional alignment of water and decane molecules. Meanwhile, we found that there are some cavities at the decane-water interface, combining with the strong electrostatic interaction between hydrophilic groups and water molecules, can aggravate the diffusion of water molecules at the interface, thus enhancing the deformation ability of the interface.