Langmuir, Vol.12, No.3, 699-705, 1996
H-1 and C-13 NMR-Studies of Mixed Counterion, Cetyltrimethylammonium Bromide Cetyltrimethylammonium Dichlorobenzoate, Surfactant Solutions - The Intercalation of Aromatic Counterions
One- and two-dimensional H-1 NMR studies of mixed counterion CTAB/CTA3,5 and CTAB/CTA2,6 surfactant systems indicate that, in their respective micelles, the dichlorobenzoate counterions intercalate among the surfactants’ trimethylammonium headgroups. Shielding effects observed in 1D H-1 NMR studies of the N-CH3 and the alpha-CH2 through epsilon-CH2 protons suggest that, on average, the 3,5-dichlorobenzoate counterions insert further into the interface of their rodlike micelles than the 2,6-dichlorobenzoate counterions insert into the interface of their spherical micelles. C-13 chemical shifts for the carbonyl carbons of the dichlorobenzoate counterions in their respective micellar systems also support this assertion.
Keywords:ANGLE NEUTRON-SCATTERING;ORIENTATIONAL BINDING;MICELLAR SOLUTIONS;WATER-CONTENT;VISCOELASTICITY;HYDROXYBENZOATES;INTERFACE;ORIGIN