Micellization and Surface Properties of Alkanediyl-1,4-bis(tetradecyldimethylammonium Bromide) Gemini Surfactants with Dodecylethyldimethylammonium Bromide

Mixed micellization and surface properties of three cationic gemini surfactants, viz., (butanediyl-), (pentanediyl-), (hexanediyl-)-1,4-bis(tetradecyldimethylammonium bromide) (14-s-14; s = 4-6) with dodecylethyldimethylammonium bromide have been studied by conductometric, tensiometric, and fluorimetric techniques at 298 K. Values of cmc, ideal cmc(cmc*), degree of counter ion dissociation (g), micellar mole fractions of the components, and interaction parameters have been determined. Further, activity coefficients of the components, surface excess concentration (Gamma(max)), minimum surface area per molecule (A(min)), surface pressure at the cmc (pi(cmc)), average aggregation numbers of the micelles (N-agg), excess Gibbs free energy (Delta G(Ex)(m)), and Gibbs free energy of micellization (Delta G(m)(0)) were also calculated and discussed. The compositions of the mixed systems were varied between 0 and 1. It is observed that the values of cmc, g, X-1(sigma), X-1(m), and Gamma(max) decreases whereas A(min) increases with augmentation of 14-s-14 (s=4-6) mole fraction in the mixed systems. The negative values of interaction parameters (beta(sigma) and beta(m)) obtained for mixed micelle formation indicate attractive interaction between the components leading to nonideality. The nonideal behavior has been theoretically treated by Clint's and Rubingh's model in light of regular solution theory.