Aerosol-OT forms oil-in-water spherical micelles in the presence of the ionic liquid bmimBF4.
The phase diagram sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT)/water/1-butyl-3-methylimidazolium tetrafluoborate (bmimBF(4)), 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 bmim(+) cation is strongly adsorbed at the interface. Data are accounted for by Hill's model for cooperative binding. The overall process is described as a comicellization 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 micelles having positive curvature is inferred from the analysis of the self-diffusion coefficients. The analysis of the water diffusion data in the L(1) phase (according to the effective cell model) allows one to exclude the presence of oblate and/or discoid micelles. Finally, the study of the oil diffusion in samples doped with p-xylene permits one to assess furthermore not only the formation of AOT aggregates of the oil-in-water type but also the occurrence of dynamic percolation phenomena.
Murgia
Sergio
S
Dipartimento di Scienze Chimiche, Universita di Cagliari and CSGI, ss 554 bivio Sestu I-09042 Monserrato (CA), Italy. murgias@unica.it
Palazzo
Gerardo
G
Mamusa
Marianna
M
Lampis
Sandrina
S
Monduzzi
Maura
M