Conductance and NMR studies of cetyltrimethylammonium bromide and chloride micelles in the presence of several additives

Abstract

Conductance and NMR studies of aqueous solutions of cetyltrimethylammonium bromide (CTAB) and chloride (CTAC) in the postmicellar region have been investigated in the absence and presence of the additives 2,6-di-tert-butyl-4-methylphenol (BHT) and 2- or 3-tert-butyl-4-methoxyphenol (BHA). The results show that these additives enhance counterion binding to the micelles in both surfactant systems. While the additives do not appear to induce any shape change in CTAC micelles, they increase the concentration of CTAB at which a shape change is known to occur in the absence of any additive. NMR results suggest, qualitatively, that the additives are solubilized in the headgroup region of the micelles.