FORMATION OF WORMLIKE MICELLES OF TETRADECYLTRIMETHYLAMMONIUM P-BENZOATES: A CONDUCTOMETRIC STUDY

It has recently been established that ionic surfactants with aromatic rings can form wormlike micelles instead of spherical micelles.¹This study aims to investigate the formation of aggregates of the cationic surfactant tetradecyltrimethylammonium (TTA⁺) and to monitor the thermodynamic consequences of substituting the atom at the para-position of benzoate derivatives used as counterions, specifically -H, -F, -Cl, -Br, and -I, using electrical conductivity measurements and Cryo-TEM at 298.2 K. Our results indicate that the hydrophobicity of these benzoate-derived counterions significantly influences the critical micelle concentration (CMC) in the order -pHBZ > -pFBZ > -pClBZ ≈ -pBrBZ > -pIBZ, making the aggregation process increasingly thermodynamically favorable (ΔG⁰>0) in the same sequence. Interestingly, the degree of dissociation (α) values suggest that there is no significant difference in mobility and confinement between the pre-micellar and post-micellar regions for all complex salts. Additionally, Cryo-TEM measurements confirmed the formation of wormlike micelles.²