Surface Properties and Mixed Micellization of Cationic Gemini Surfactants with Ethyleneamines

Abstract

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), C20 (surfactant concentration required to reduce the surface tension of the solvent by 20 mN·m−1), Γmax (maximum surface excess), Amin (minimum surface area per molecule), and interaction parameter β (for mixed monolayer formation at the aqueous solution/air interface (βσ) and for mixed micelle formation in aqueous medium (βm)) 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 (ΔGads0) and the excess free energies of micellization (ΔGex) of 16-s-16 with the amines were also evaluated.