Surface Properties and Mixed Micellization of Cationic Gemini Surfactants with Ethyleneamines

Herein, we report the surface properties and mixed micellization of cationic gemini surfactants (butanediyl-1,4-bis(dimethylcetylammonium bromide), pentanediyl-1,5-bis(dimethylcetylammonium bromide), and hexanediyl-1,6-bis(dimethylcetylammonium bromide), respectively referred to as 16-4-16, 16-5-16, and 16-6-16) in the presence of different mole fractions of ethyleneamines (ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine) at 303 K. The surface properties (critical micelle concentration (CMC), C 20 (surfactant concentration required to reduce the surface tension of the solvent by 20 mN·m −1 ), Γ max (maximum surface excess), A min (minimum surface area per molecule), and interaction parameter β (for mixed monolayer formation at the aqueous solution/air interface (β σ ) and for mixed micelle formation in aqueous medium (β m )) are reported. A synergistic effect has been observed in all instances that were found to be correlated with the chain length of ethyleneamines. The CMC values of 16- s -16 decreased with increasing amine concentrations, and the extent of the effect followed the sequence: tetraethylenepentamine > triethylenetetramine > diethylenetriamine > ethylenediamine and 16-6-16 > 16-5-16 > 16-4-16. The standard Gibbs energies of adsorption (Δ G ads 0 ) and the excess free energies of micellization (Δ G ex ) of 16- s -16 with the amines were also evaluated.