Rheology of Mixed Complex Salt Wormlike Micelles

Wormlike micelles (WLM) are supramolecular aggregates with rheological behavior similar to that of polymer solutions, but they possess a transient macromolecular structure due to dynamic breakage and recombination phenomena.[1] This study investigates the rheology and electrical conductivity of WLMs formed by mixed complex salts composed of the cationic surfactant monomer hexadecyltrimethylammonium (CTA+ ) and the aromatic anions trans-o-hydroxycinnamate (OHC- ) and trans-o-methoxycinnamate (OMC- ), with the general formula CTA(OHC)x(OMC)y, at 298.2 K. The rheological results indicate that (OHC- ) exhibits a strong interaction with the cationic monomer, promoting WLM formation, whereas (OMC- ) shows an intermediate interaction strength.[2] The combination of these aromatic counterions allowed us to define the stoichiometric limits of the synergistic and antagonistic effects in the CTA(OHC)x(OMC)y system, as reflected in the properties of individual micelle chains and the internal structure of the gel. Additionally, in the dilute regime, critical parameters for micelle formation, such as the critical micelle concentration (CMC) and the degree of dissociation (α) characteristic of each complex salt, provided correlations with our rheological results.