CO2/N2-switchable high internal phase Pickering emulsion stabilized by silica nanoparticles and low-cost commercial N,N-dimethyl-N-dodecylamine

Herein, we reported a CO2-triggered oil-in-water high internal phase Pickering emulsion based on silica nanoparticles functionalized in situ by a trace amount of low-cost commercial CO2-switchable surfactant, N,N-dimethyl-N-dodecyl amine (C12A). Upon alternately bubbling CO2 and N2 at a moderate conditions (35 °C, 40 mL·min−1), C12A could be reversibly switched between cationic and nonionic forms, and then adsorbed on or desorbed from the surface of particles. As a consequent, interfacial active particles were formed, stabilizing the emulsion (CO2), or disrupted, breaking the emulsion (N2). Above a critical concentration, the Pickering emulsion can be formed over the whole concentration scope without interruption, even as zeta potential equals to zero, because of the unusual adsorption of the protonated C12A. Such a stabilizer composed of silica and the protonated C12A can be used to producing high internal phase Pickering emulsion for different oil, showing significant application value.