CO2-switchable oil-in-dispersion emulsions stabilized by tertiary amine surfactant and alumina particles

A CO2/N2-switchable oil-in-dispersion emulsion was developed by using a tertiary amine surfactant (PKO-CO2) and alumina particles at concentrations as low as 0.06 mM and 0.1 wt%, respectively. In contrast to the Pickering emulsions, PKO-CO2 adsorbs at the oil-water interface, while alumina particles almost remain in the aqueous phase. Reversible demulsification/stabilization of the oil-in-dispersion emulsion can be achieved by CO2/N2 trigger at room temperature. The sensitive of the tertiary amine group in PKO-CO2 to CO2/N2 trigger at room temperature endows the emulsion with CO2-responsiveness under mild conditions. Such a strategy needs much less amount of the surfactant and particles than that of the conventional emulsions or Pickering emulsions, and it avoids rigorous switching conditions, which is environmentally and economically attractive for various applications. [Display omitted]