Switchable Pickering Emulsions Stabilized via Synergistic Nanoparticles-Superamphiphiles Effects and Rapid Response...

A CO₂/N₂-responsive emulsion provides milder reaction conditions, nontoxicity, and economic feasibility compared to other switchable surfactants. In this study, CO₂/N₂-responsive pickering emulsions were fabricated by using a compounded dispersion containing SiO₂ nanoparticles (NPs) and superamphiphiles as the emulsifying agents. The synergistic effects of the SiO₂ NPs and superamphiphiles significantly stabilized the emulsion at all of the tested concentrations and prevented complete phase separation of oil and water. The electrostatic interaction between the SiO₂ NPs and superamphiphiles was disrupted after bubbling with CO₂ for 30 s, resulting in the breaking of the emulsion. However, the dispersion recovered its interfacial activity after the introduction of N₂ and again emulsified the emulsion. This reversible switching behavior was validated through three consecutive cycles of bubbling CO₂/N₂. The protonation and deprotonation of the SiO₂ NPs and superamphiphiles in response to CO₂/N₂ facilitated reversible assembly and disassembly, which enabled the switching of the emulsions between inactive and active forms. The novel highly stable Pickering emulsions demonstrated rapid demulsification and emulsification in response to CO₂/N₂ and are promising for a wide range of applications.