A. Pappalouisi et al., PHASE-TRANSFORMATIONS AT THE HG AQUEOUS SOLUTION INTERFACE IN THE PRESENCE OF CETYLTRIMETHYLAMMONIUM CATIONS/, Electrochimica acta, 39(3), 1994, pp. 375-383
Differential capacity measurements at a mercury electrode in contact w
ith aqueous solutions containing cetyltrimethylammonium cations, CTA() and supporting electrolytes of different types have been carried out
. The results obtained are interpreted within the frames of the theore
tical treatments presented in J. Phys. Chem. 96, 8453 (1992) and J. el
ectroanal. Chem. 348, 59 (1993). It is shown that a surface film of ag
gregates starts to develop at positive polarizations. At pre-micellar
concentrations this film is likely to be monolayer, whereas at concent
rations around and above the cmc, the aggregation phenomena extend at
least to two successive layers along the interface. The micellar film
developed in this region covers the electrode surface throughout the n
egative polarization region. Depending on the potential this film unde
rgoes a number of phase transformations. These transformations and mor
e generally the properties of the film are affected by the presence of
oxygen in the bulk solution and the nature of the supporting electrol
yte. The desolved oxygen may affect the structure of bulk micelles and
through them the structure of the adsorbed micellar film, whereas the
possible role of counterions in the absorption process of CTA(+) is e
ither direct, in the region where they are specifically adsorbed, or i
ndirect, through the structure of the bulk micelles in the negative re
gion where they are desorbed from the interface.