CO₂-Responsive wormlike micelles based on sodium oleate and hydrophobic tertiary amines

ABSTRACT

We reported two simple and novel CO₂-responsive surfactant wormlike micellar systems consisting of commercial anionic surfactant sodium oleate (NaOA) and common hydrophobic tertiary amine N,N-dimethylcyclohexylamine (DMCHA), N,N-dimethylbenzylamine (DMBA). The conductivity, pH, and rheological measurements demonstrated the CO₂-sensitive flowing behavior and property, which were attributed to the spherical-wormlike micelles transition, verified by cryogenic transmission electron microscopy (Cryo-TEM) and dynamic laser light scattering (DLS) measurements. Moreover, the transition can be easily cycled more than three times without deterioration of viscosity. Combined with the species distribution curve and ¹H NMR spectra, a mechanism of the intermolecular electrostatic interaction and hydrophobic effects was proposed.

GRAPHICAL ABSTRACT

KEYWORDS:

• CO₂-responsive surfactant wormlike micellar system
• electrostatic interaction
• hydrophobic effects
• hydrophobic tertiary amine
• spherical-wormlike micelles transition