Emulsion inversion induced by CO2

Abstract

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.