Ostwald ripening in nano/miniemulsions in the presence of two costabilizers as revealed by molecular dynamics simulations

Abstract

The stability of mini and nanoemulsions is affected by Ostwald ripening, i. e. the growth of large droplets at expense of the disappearance of the small ones because of chemical potential gradient. A way to decrease Ostwald ripening is by the addition of a costabilizer or a mixture of them. Mixtures of costabilizers (short and long chain ones) has shown to be efficient in preventing mini and nanoemulsion degradation. Molecular dynamics simulations are used to show the mechanism under which the use of a mixture of costabilizers can enhance droplet stability in mini and nanoemulsions, providing complementary information to the available experimental and simulations results. Molecular dynamics simulations allow the study of Ostwald ripening under diverse conditions using a limited number of parameters. The proposed molecular dynamics simulation approaches are able to reproduce the behavior observed experimentally and by other simulations, and reveal that this enhancement is due to the retaining of the small costabilizer by the larger one. The effect of chain length of the long costabilizer on the degradation mechanism is studied.