Structural Transitions of CTAB Micelles in the Presence of n-Octylamine: A Small Angle Neutron Scattering Study

Small angle neutron scattering (SANS) was used to characterize the micelles of cetyltrimethylammonium bromide (CTAB) in D 2O solutions, with or without added n-octylamine. SANS data have been analyzed using various models. Micellar parameters, such as mean aggregation numbers, micelle dimensions, and fractional charge on the micelles, are reported from the analysis of SANS spectra for the CTAB/ n-octylamine system as a function of octylamine concentration and temperature. Results are interpreted in terms of micellar sphere-to-rod transition prompted by amine concentration in CTAB micellar solution. The size of the micelle decreases as the temperature increases.