Aggregation behavior and intermolecular interaction of binary surfactant mixtures based on cationic Geminis and nonionic surfactants

The Gemini surfactants of type alkylediyl-α-ω-bis(alkyldimethylammonium) dibromide with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred as “m-2-m” [C m H2m + 1(CH2)2 N+(CH2)2 N+(CH2)2 C m H2m + 1, 2Br−] (m = 12 and 16), have been synthesized, purified, and characterized in our laboratory. The interactions between cationic Geminis and nonionic surfactants polyoxyethylene (23) lauryl ether (Brij35) and polyoxyethyleneoctyl phenyl ether (TX-100) have been studied by conductivity and steady-state fluorescence quenching techniques at a certain micellar concentration range and certain temperature. Rubingh’s theory is used to evaluate the micellar interaction parameters (β) for the mixed systems. It has been observed that mixed micelle formation in all the binary mixtures exhibited negative synergism (antagonism) or ideal behavior due to positive β values. It was observed that contribution of conventional surfactants was always more than that of the Geminis. By using the ratio of peak intensities, micro-polarity, dielectric constant (D), and binding constant (K sv) of mixed systems have been found.