(400f) Predicting Emulsions Stability Using Coarse-Grained Simulations

Understanding the molecular mechanisms and processes that control the stability of emulsions is of great interest for many practical applications, ranging from foodstuff to oilfields. Both surfactants and particles have been developed and optimised to control the emulsions stability. Yet, several open fundamental questions remain, and technological progress is often achieved via trial and error processes. Molecular dynamics simulations are useful to identify some of the molecular mechanisms responsible for emulsions stability, but are limited by assumptions and the time scale accessible to the studies, even when state-of-the-art approaches and devices are used.

We present here recent advances obtained via the implementation of the coarse-grained Dissipative Particle Dynamic simulation framework, DPD. First, we document a robust workflow useful for determining the parameters to describe immiscible liquids containing surfactants. Starting from the Hansen theory of solutions, we obtained a model able to reproduce experimental water/oil interfacial tension as well as the micellar properties of aqueous non-ionic surfactants representative of the octyl polyethylene oxide family. Then we demonstrate how DPD can be used to describe the Ostwald ripening phenomenon in an emulsion. The DPD simulation results are consistent with theoretical expectations, as well as with experimental observations. Finally, investigate the competition between surfactants and particles for adsorption at a water/oil interface. The results are compared against recent experimental observations.