Single-step generation of double emulsions in aqueous two-phase systems

Abstract

This communication presents a simple yet straightforward method for preparing water-in-water-in-water particle-stabilized double emulsions, also known as Pickering double emulsions. The approach involves using oppositely charged nanoparticles (OCNPs) in two distinct fluid phases, promoting self-assembly and the formation of aggregates with varying sizes and compositions. By enhancing the interfacial area through the adsorption of aggregates at the interface, this method increases the Gibbs detachment energy of particles between the two aqueous phases, forming stable double emulsions. Furthermore, we investigated the impact of the molecular weight of polyethylene oxide and dextran in the respective fluid phases and the mass ratio (M) of the OCNPs on double emulsion formation. The results demonstrate that the molecular weight of the polymers used in the aqueous phase is a critical parameter influencing the structural formation of the emulsion and the generation of double emulsions. Consequently, double emulsions are formed when equal molecular weight polymer mixtures are employed at an appropriate M, with the dispersed phase placed in the highly viscous continuous phase. The proposed method offers a one-step synthesis process, enabling easy preparation, and exhibits excellent stability for at least 30 days. This study represents the first reported approach for the one-step synthesis of multiple emulsions in an aqueous two-phase system utilizing a Pickering emulsion template.

Single-Step Formation of Pickering Double Emulsions by Exploiting Differential Wettability of Particles

“…In the single-step emulsification method, two or more immiscible liquids and one or more emulsifiers are mixed under appropriate conditions to produce DEs. To this end, different types of stabilizers, such as brush-coated hybrid nanoparticles, 31 silica particles of varying wettability, 32 surfacesegregated micelles with adaptive wettability, 33 amphiphilic diblock copolymers, 34 poly(dodecyl acrylate-co-acrylic acid) nanoparticles, 35 supra-amphiphile-based soft polymers, 36 plantbased particles, 37 plant latex, 38 microbowls, 39 polyethylene oxide, 40 and dextran 41 have been used. Recently, Sun et al 42 used a mixture of oppositely charged silica particles in different proportions and identified the formation of Pickering DE near the phase inversion point.…”