Micelle formation by sodium perfluorooctanoate and decyltrimethylammonium bromide in 18-crown-6+β-cyclodextrin plus water systems

The conductances of sodium perfluorooctanoate (SPFO) and decyltrimethylammonium bromide (DeTAB) have been determined in 18-crown-6 + water (CR + W), beta-cyclodextrin + water (CD + TN) and in CR + CD + W mixtures with a fixed 0.0151 mol dm(-3) concentration of CR and varying amounts of CD with overall change in the mole fraction range of CD from 0.0 to 0.5 in CR + CD + W mixtures at 30 degrees C. From the conductivity data, the critical micellar concentration (cmc), the degree of counter-ion association (alpha), the free energy of transfer of the surfactant hydrocarbon chain from the medium to the micelle (Delta G(HP)(0)), and the free energy of transfer of surface contributions (Delta G(S)(0)) of SPFO and DeTAB have been computed. It has been found that the micelles of SPFO are stabilized in CR + W mixtures in comparison to pure water, whereas micelles of DeTAB remain comparatively unaffected upon addition of CR in water. On the other hand, micelles of SPFO and DeTAB are denatured upon addition of CD in CR + CD + W mixtures. The denaturation effect is stronger on the micelles of SPFO in comparison to that of DeTAB.