Emulsification mechanism of surfactants in different oil phases: A dissipative particle dynamics study

The type of oil component affects the emulsification behaviors of surfactants while the underlying mechanism remains vague. In this work, the dissipative particle dynamics (DPD) method is conducted to analyze the behaviors of polyoxyethylated alcohols non-ionic surfactant at different water/oil (W/O) interfaces. Towards this end, the benzene and dodecane molecules are chosen as representatives of aromatic and alkane, respectively. The density distribution of surfactants, the radial distribution functions between different pairs of components, and the diffusion coefficient of surfactants are investigated, along with the morphological analysis. The phenomenon of similarity and intermiscibility is observed at the nanoscale between the hydrophobic chain of the surfactant and the oil phase, and in addition, it is found that the diffusion constant of surfactant molecules in water/benzene systems is nearly three times larger than that in water/dodecane systems, and a local maximum value of diffusion coefficient appears near the critical micelle concentration. This work provides a theoretical guidance for the screening and use of surfactants under different external environments.