The CO2-responsive Pickering emulsions employed
have
garnered considerable attention across enhanced oil recovery agents,
delivery of crude, and oilfield-produced fluid treatment. This study
focuses on the design of an innovative type of Janus nanoparticle
(JNP) and its application in the construction of CO2 stimuli-responsive
Pickering emulsions. The emulsion stabilized by JNPs demonstrates
swift phase separation subsequent to the injection of CO2. Furthermore, the mechanism of the CO2-stimulated responsiveness
enabled by the JNPs was proposed. Based on the Schiff reaction, the
synthesis of JNPs was achieved successfully via the Pickering emulsion
template method. The properties of the JNPs were studied using various
analytical techniques such as Fourier transform infrared, thermogravimetric
analysis, scanning electron microscopy, transmission electron microscopy,
etc. The developed responsive system, composed of JNPs and sodium
oleate surfactant, showed high interfacial activity at the oil/water
interface. The study revealed that the responsive system-stabilized
Pickering emulsions could remain stable at 70 °C and room temperature
for 24 and 120 h, respectively. Furthermore, the introduction of CO2 for 1.5 min resulted in phase separation because the nanoparticles
lost the amphiphilic nature, triggering a significant decrease in
interfacial activity and the protonation of sodium oleate surfactant
inactivation. Then, the particles started to desorb from the interface.
This study proposes a convenient, simple, and cost-effective approach
for preparing fast CO2-responsive Pickering emulsions.
It provides novel insights into the advancement of oilfield-produced
fluid treatment, transportation of crude oil, and enhanced oil recovery.