Dielectric Spectroscopy into Co-Ion Effects on Microemulsion Dynamics
and Phase Behavior
Wolfgang Wachter and Richard Buchner,
Acta Chim. Slov. (J. Barthel Festschrift) 56 (2009) 53-57
The effect of added cationic co-ions (Li+, Na+, Cs+, (CH3)4N+)
on the dielectric spectra of didode-cyldimethylammonium bromide / water / n-dodecane microemulsions is reported.
At high water/surfactant mole ratios (W ≈100-120) small amounts of co-ions drastically change the shape of the
dielectric spectra in the 5-500 MHz region whereas for W ≈ 20 almost no effect is observed. It is shown that the
sensitivity of the dielectric spectra towards co-ion addition correlates with the percolation transition of the
microemulsion structure from reverse micelles at high W to a bicontinuous phase at low W.