Formation of W/O emulsion using hydrophilic nanoparticles by three-phase emulsification and its energetic analysis

In this study, we investigated the characteristics of water-in-oil (W/O) emulsions formed by hydrophilic nanoparticles in three-phase emulsification and discussed their stability by performing an energy analysis. W/O emulsions prepared using the three-phase emulsification method are stable in several systems, even in those with a high internal-phase ratio of water up to 85 wt%. Hydrophilic nanoparticles can exist in the internal water phase independently, and the emulsifying action does not depend on the concentration of nanoparticles or the state of the internal water phase. The energy analysis of the model, in which nanoparticles partially penetrate from the aqueous phase to the oil phase, suggests that hydrophilic nanoparticles can form W/O emulsions. It was also found that the entropy change based on the hydrophobic hydration around the nanoparticles was the main driving force for the nanoparticles to partially penetrate the oil phase.