The ternary diagram sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT)/water/1-butyl-3-methylimidazolium tetrafluoborate (bmimBF4), a polar room temperature ionic liquid, is explored through optical microscopy in polarized light, SAXRD and NMR PGSTE techniques. The analysis of SAXRD and self-diffusion data reveals that the ionic liquid is strongly adsorbed at the interface. Data are accounted for by the Hill’s model for cooperative binding. The overall processes is described as a co-micellization of AOT- and bmim+ involving roughly two cations for AOT- ion. The bmim+ is severely involved in the structural arrangement of the interface. Indeed, a huge modification of the interfacial geometry resulting in the occurrence of a micellar phase having positive curvature is inferred from the analysis of the self-diffusion coefficients. The analysis of the water diffusion data in the L1 phase (according to the Effective Cell Model) allows to exclude the presence of oblate and/or discoid micelles. Finally, the study of the oil diffusion in samples doped with p-xylene permits to asses furthermore not only the formation of AOT aggregates of the oil-in-water type but also the occurrence of dynamic percolation phenomena.
Aerosol-OT Forms Oil-in-Water Spherical Micelles in the Presence of the Ionic Liquid bmimBF4
PALAZZO, Gerardo;
2009-01-01
Abstract
The ternary diagram sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT)/water/1-butyl-3-methylimidazolium tetrafluoborate (bmimBF4), a polar room temperature ionic liquid, is explored through optical microscopy in polarized light, SAXRD and NMR PGSTE techniques. The analysis of SAXRD and self-diffusion data reveals that the ionic liquid is strongly adsorbed at the interface. Data are accounted for by the Hill’s model for cooperative binding. The overall processes is described as a co-micellization of AOT- and bmim+ involving roughly two cations for AOT- ion. The bmim+ is severely involved in the structural arrangement of the interface. Indeed, a huge modification of the interfacial geometry resulting in the occurrence of a micellar phase having positive curvature is inferred from the analysis of the self-diffusion coefficients. The analysis of the water diffusion data in the L1 phase (according to the Effective Cell Model) allows to exclude the presence of oblate and/or discoid micelles. Finally, the study of the oil diffusion in samples doped with p-xylene permits to asses furthermore not only the formation of AOT aggregates of the oil-in-water type but also the occurrence of dynamic percolation phenomena.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
