Binary micellar schemes of cationic gemini and conventional surfactants: chain length effect

Abstract

Binary micellar schemes have been appropriated to ascertain the effect of chain length on micellization and interfacial properties. Mixed micellar systems of cationic gemini surfactant, bis-N,N-tetradecyldimethyl-m-phenylenediammonium dibromide (14-m-ɸ-14), and conventional cationic surfactants, viz., dodecyltrimethylammonium bromide (C12TAB), tetradecyltrimethylammonium bromide (C14TAB) and hexadecyltrimethylammonium bromide (C16TAB), in aqueous media were investigated by conductometric, tensiometric, fluorimetric and dynamic light scattering (DLS) techniques at 25 °C. The behavior of the binary mixtures under regular solution theory have been explained in light of Clint’s and Rubingh’s models. A non-ideal behavior was indicated. This was further confirmed by interaction parameter (β) values and activity coefficients. The synergism, an attractive interaction, between the surfactant molecules was ascertained. The average aggregation number () was evaluated by steady-state fluorescence quenching method. The increased with increase in mole fraction of CnTAB (n = 12, 14, 16). The size of the aggregates varied with length of conventional surfactants as exhibited by DLS. The zeta potential values of the mixed micelles increase with increase in mole fractions of CnTAB.