Influence of the AOT counterion chemical structure in the generation of organized systems

LÉPORI, CRISTIAN M.O.*; CORREA, N. MARIANO; SILBER, JUANA J.; FALCONE, R. DARIO; LÓPEZ-LÓPEZ, MANUEL; MOYÁ, MARÍA LUISA

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2020 vol. 36 p. 10785 - 10793

0743-7463

The impact of the imidazolium counterions structure on the organized systems formed by the surfactant 1,4-bis-2-ethylhexylsulfosuccinate, AOT, both in aqueous solutions and in non-polar solvents is investigated. With this in mind, we investigated if the ionic liquid-like (IL-like) surfactant 1-ethyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, emim-AOT, forms direct micelles or vesicles in water. Dynamic Light Scattering (DLS), zeta potential, conductivity, fluorescence and UV-Visible spectroscopy measurements were performed to characterize the organized systems in aqueous solution. We also studied the self-aggregation of emim-AOT, 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, bmim-AOT, and of 1-hexyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, hmim-AOT, in non-polar solvents.The results obtained showed that the IL-like surfactant emim-AOT forms direct micelles in water, as Na-AOT does. However, emim-AOT aggregates are larger, have a lower surface charge, are more stable, and have a more polar and less fluid micellar interface than Na-AOT micelles. It was also observed that emim-AOT and hmim-AOT form reverse micelles in non-polar solvents. The size of the imidazolium cations dramatically influences on the size of the reverse micelles as well as on their ability to solubilize water.