Dual-responsive pickering emulsions triggered by CO2 and magnetism

We reported the dual-responsive Pickering emulsion systems with a reversible transition between the oil-in-water emulsified form and separated oil/water phase. The Pickering emulsions were prepared using negatively charged Fe 3 O 4 nanoparticles in combination with 1-dodecyl-1H-imidazole (abbreviated as C 12 mim) as stabilizers. By blowing CO 2 , C 12 mim was protonated to be [C 12 mim] + , inducing the modification of negatively charged Fe 3 O 4 nanoparticles through electrostatic attraction and further the generation of emulsions. Moreover, the emulsions exhibited excellent stability at different oil/water ratios and high ionic strength. The reversible process, demulsification, could be realized by bubbling N 2 to remove CO 2 . Being ascribed to the magnetism of the Fe 3 O 4 nanoparticles, the complete demulsification process could also be triggered in several minutes under an external magnetic field. In addition, due to the avoidance of the extra additives in response, the emulsions can maintain their initial performance in theory after the transition between emulsification and demulsification, and can be adequately recycled after removing the original oil and adding fresh oil, being conformed to the principle of green and energy-saving processing.