Mutual solubilities study for binary mixtures of dipropylene glycol dimethyl ether and water via molecular dynamics simulation and AMOEBA polarizable force field

It is a challenging task to accurately compute the structures and physicochemical properties of partially soluble liquid mixtures using classical force field simulation methods due to the limitations of both sampling and intermolecular potential. In the present study, we employed replica exchange molecular dynamics in combination with the AMOEBA polarizable force field to simulate partially miscible liquid mixtures of dipropylene glycol dimethyl ether and water. We demonstrated that our strategy is promising in studying such complicated binary mixture systems without involving empirical fitting of any available experimental data of mixtures. We correctly predicted the trend of liquid concentration distribution as the function of temperature, and the concentration drifts found in the simulations are consistent with the concentration difference between experimental values and initial configurations. Based on self-diffusion coefficient analysis, the lower critical solution temperature of the system was identified at about 290 K, which is in satisfactory agreement with experimental evidence. Although accurate concentration prediction of such a partially miscible system using direct molecular dynamics method remains an intractable task, we expect that such atomistic simulations will play a more important role in future studies of liquid mixtures.