Highly effective emulsification/demulsification with a CO2-switchable superamphiphile.

This article reports a systematic study on a highly CO2-responsive superamphiphile (D-OA) in preparation of CO2-switchable oil-in-water emulsions. The D-OA was assembled with Jeffamine D 230 and oleic acid (HOA) via electrostatic interaction, which was characterized using FT-IR, (1)HNMR, surface tension, and interfacial tension techniques. The assembled gemini-like superamphiphile D-OA was shown to have a low cmc value and adsorb quickly at the paraffin oil/water interface, decreasing the interfacial tension effectively. Highly stable O/W emulsions were obtained by mixing D-OA aqueous solution and paraffin oil. After bubbling CO2 through the stable emulsions for just 20s, quick phase separation was observed; while upon removal of CO2 by bubbling N2 at 60°C, stable emulsions were recreated. The reversible assembly and disassembly of the D-OA superamphiphile by adding or removing CO2 were considered as the cause of demulsification and re-emulsification processes. The rapid and complete demulsification of the system in response to CO2 addition and removal may have potential applications in emulsion-based fabrication/separation and enhanced oil recovery processes.