Pickering Emulsions Responsive to CO2/N2 and Light Dual Stimuli at Ambient Temperature.
A dual stimuli responsive n octane in water Pickering emulsion with CO2/N2 and light triggers is prepared using negatively charged silica nanoparticles in combination with a trace amount of dual switchable surfactant, 4 butyl 4 (4 N,N dimethylbutoxyamine) azobenzene bicarbonate (AZO B4) as stabilizers. On one hand, the emulsion can be transformed between stable and unstable at ambient temperature rapidly via the N2/CO2 trigger, and on the other hand, a change in droplet size of the emulsion can occur upon light irradiation/rehomogenization cycles without changing the particle/surfactant concentration. The dual responsiveness thus allows for a precise control of emulsion properties. Compared with emulsions stabilized by specially synthesized stimuli responsive particles or by stimuli responsive surfactants, the method reported here is much easier and requires a relatively low concentration of surfactant (1/10 cmc) which is important for potential applications.
Langmuir the ACS journal of surfaces and colloids