CO₂-Responsive Imidazoline-Based Surfactants for Tunable Interfacial Activity and Controllable Emulsification

Area of Science:

• Materials Science
• Physical Chemistry
• Green Chemistry

Background:

• Switchable surfactants offer tunable interfacial properties via external stimuli.
• Environmentally friendly surfactants are crucial for sustainable chemical processes.

Purpose of the Study:

• Synthesize and characterize novel imidazoline-based carbon dioxide-switchable surfactants.
• Investigate their surface activity, micellization, and switching behavior.
• Evaluate their performance in emulsion stabilization and destabilization.

Main Methods:

• Fourier transform infrared (FTIR) and 1H NMR spectroscopy for structural confirmation.
• Surface tension and interfacial tension measurements to determine surface activity and CMC.
• Conductivity and NMR analyses for reversible CO2/N2 switching studies.
• Emulsification and demulsification cycle testing.

Main Results:

• Successful synthesis of long-chain alkyl imidazolines confirmed.
• Demonstrated strong adsorption and efficient micellization with tunable CMC.
• Confirmed robust and repeatable switching between neutral and ionic forms using CO2/N2.
• Showcased stable oil/water emulsion stabilization by salt forms and rapid demulsification by neutral forms.

Conclusions:

• Established fundamental interfacial behavior of imidazoline-based CO2-switchable surfactants.
• Highlighted potential applications in enhanced oil recovery, chemical separation, and drug delivery.
• Underscored the utility of these surfactants in sustainable process design.