CO₂-Responsive Worm-like Micelle Based on Double-Tailed Surfactant

Area of Science:

• Materials Science
• Colloid and Surface Chemistry
• Supramolecular Chemistry

Background:

• Carbon dioxide (CO2)-responsive worm-like micelles (WLMs) are valuable for smart materials due to tunable properties.
• Applications include enhanced oil recovery and drug delivery systems.

Purpose of the Study:

• To develop a novel system of CO2-responsive WLMs using a double-tailed surfactant (DTS).
• To characterize the viscosity, thermal stability, and responsiveness of the DTS-CO2 system.

Main Methods:

• Self-assembly of double-tailed surfactants (DTS) in response to CO2 exposure.
• Rheological measurements to determine zero-shear viscosity and temperature dependence.
• Cyclic testing to assess responsiveness and stability.

Main Results:

• Protonation of DTS in CO2 forms ultra-long cationic surfactants self-assembling into WLMs.
• Zero-shear viscosity increased from 2 mPa·s (DTS-air) to ~300,000 mPa·s (DTS-CO2).
• High viscosity (>100,000 mPa·s) was maintained from 25-120 °C under CO2, with reversible transitions observed over multiple cycles.

Conclusions:

• The DTS-CO2 system demonstrates significant, reversible viscosity changes in response to CO2.
• This research provides insights for developing advanced CO2-responsive surfactants for functional materials.