Surfactant binding of polycations carrying charges on the chain backbone: Cooperativity, stoichiometry and crystallinity

Studies on the interaction between polycations carrying charges on the chain backbone [x,y-ionene bromides (x = 3, 6, 12; y = 3, 4, 6, 12)] and anionic surfactants (sodium alkyl sulfates and sodium alkanesulfonates) have been made in water. It was found that there are two categories of surfactant binding: one is the formation of insoluble complex with one-to-one composition and the other is that of soluble complex with nonstoichiometric composition. Some of these complexes have ordered structure on a molecular and a supramolecular level, wherein the charge density and the alkyl size separating the charges on the chain backbone play an important role. The mechanism and process of the complex formation have been discussed.