Emulsion inversion induced by CO2

Herein it was found that CO2 could trigger an O/W to W/O emulsion inversion via a W/O/W nanoemulsion. In comparison with the conventionally used liquid or solid additives, the unusual advantage of this method is that the emulsion morphologies can be switched reversibly by the control of CO2 pressure. Besides, CO2 can be easily removed by depressurization and thus no extra separation process is needed, and CO2 can be recycled. Furthermore, other lipophilic gases of ethylene, propylene and isobutane can also induce the O/W to W/O emulsion inversion. A possible mechanism for the gas-triggered emulsion inversion was proposed.