Oppositely charged ionic surfactants can self-assemble into hollow structures, called catanionic vesicles,
where the anionic-cationic surfactant pair assumes a double-tailed zwitterionic attitude. In the present
work, multilamellar-to-unilamellar thermal transition of a mixed aqueous system of sodium dodecyl
sulphate (SDS) and cetyl trimethyl ammonium bromide (CTAB), with a slight excess of the anionic one,
has been investigated by 1H, 2H, 14N NMR spectra and 23Na transverse relaxation measurements. It has
been inferred that an increase of the temperature enhances the SDS counterion dissociation, which can be
considered as one of the driving forces of the mentioned transition. Moreover, interesting 23Na T2 changes
with temperature have been detected for unilamellar aggregates.
