Interaction of ionic liquid type cationic surfactants with triton X-100 nonionic micelles

The aggregation behaviour of alkyl triphenylphosphonium bromide (C_nTPPBr, n=10,12,14,16) in presence of non-ionic Triton X-100 in aqueous solutions is investigated by different analytical techniques viz. surface tensiometry (ST), dye solubilization (DS), cloud point (CP), dynamic light scattering (DLS), zeta potential, small-angle neutron scattering (SANS), contact angle, wettability and foamability measurements. The calculated critical micelle concentration (CMC) for aqueous solutions of mixed surfactants is lower than the individual pure surfactants, which confirms the synergistic interactions among the monomers in the formed mixed micelles. On gradual addition of C_nTPPBr, the cloud points of TX-100 are shifted to higher temperatures and size of the formed mixed micelles decreases as observed by CP and DLS, respectively. Zeta potential of mixed micelles increases with corresponding increase in the concentration of C_nTPPBr. Morphological and clouding behaviour of mixed micelles is found to be independent of chainlength for added cationic surfactant, but initial ellipsoidal shape micelles transform to extended ellipsoids in presence of sodium bromide depicting significant increase in the axial ratio.