New environmental friendly dicephalic amine dichlorides: Nonequivalent adsorption and interactions with model polyelectrolyte

The physicochemical behavior of new dicephalic surfactants, derivatives of tertiary amines, N,N-bis[3,3′-(dimethylamine)propyl]alkylamide dichlorides Cn(DAPACl)2, was analyzed in terms of the advanced model of multicharge cationic surfactant adsorption, taking into account counterion specificity and the formation of surfactant ion-counterion associates. Interactions of the studied compounds in mixtures with model anionic polyelectrolyte, sodium poly(styrene sulfonate) (PSS) were also examined. Surface tension data indicate binding of surfactant to polyions occurring above a concentration threshold lying much below the critical micelle concentration (cmc) of the pure surfactant in an aqueous solution. Above this threshold very surface active surfactant/polyion complexes are formed and that leads to an abrupt drop of surface tension. The obtained results are compared with those previously reported for N,N-bis[3,3′-(trimethylammonio)propyl]alkylamide dibromides C12(TAPABr)2 and N,N-bis[3,3′-(trimethylammonio)propyl]alkylamide dimethylsulfates C12(TAPAMS)2.