2026 Volume 26 Issue 8 Pages 309-316
Three-phase emulsification stabilizes emulsions through the irreversible adhesion of soft hydrophilic nanoparticles to the oil-water interface by the van der Waals forces. Unlike conventional surfactant emulsification relying on reversible molecule adsorption, this fundamental difference endows three-phase emulsions with unique physicochemical properties. This review outlines the theoretical background and characteristics of three-phase emulsification based on interparticle interactions. Operating as an independent phase insoluble in water and oil, the irreversible interfacial adhesion mechanism is categorized as an “extensive variable type” governed by the amount of substance, fundamentally distinct from conventional methods (intensive variable types) regulated by interfacial tension lowering. This unique mechanism enables the emulsification of diverse oils, even those difficult to emulsify conventionally. Furthermore, the resulting emulsions exhibit exceptional stability against severe environmental changes, including oil phase transitions, salt/acid addition, and the mixing of different emulsions. They also possess distinctive properties, such as adhering to solid substrates while maintaining their emulsion structure. Finally, future application outlooks in foods, cosmetics, pharmaceuticals, and industrial materials are discussed, including the functional design of the nanoparticles themselves.
