Interactions between polyanions and cationic surfactants with two unequal alkyl chains or of the dimeric type

The interaction between two polyelectrolytes (PS1 and PS4, copolymers of disodium maleate and methyl or butyl vinyl ether, respectively) and quaternary ammonium bromide surfactants (3-dodecyldimethyl(alkyl)ammonium bromides and two dimeric surfactants of the polymethylene-α,ω- bis(dodecyldimethylammonium bromide) type) has been investigated by means of surfactant ion-specific electrode (surfactant-binding isotherms) and spectrofluorometry using pyrene as a fluorescent probe (onset of binding). As in a previous study, the results show that the surfactant binding to the polyanion is less cooperative when the polyanion is more hydrophobic, irrespective of the surfactant nature. They also show that the interaction of a given polyanion with a dimeric surfactant is stronger than with the corresponding alkyltrimethylammonium bromide or dodecyldimethyl(alkyl)ammonium bromide. (C) 2000 Academic Press.