Small-angle neutron scattering from tetradecyltrimethylammonium bromide in NaBr aqueous solutions

Small angle neutron scattering was used to characterise quantitatively the micelles of tetradecyltrimethylammonium bromide at a concentration of about 50 mM in aqueous (D2O) solutions with added salt NaBr. It is shown that the shape of the micelles changes from spheres to rod-like particles with increasing electrolyte concentration. The interparticle interaction becomes effectively screened if the salt concentration exceeds 0.1 M leading to a remarkable growth of the cylindrical micelles. Moreover, it is demonstrated that there is a gradual dehydration of the micelles due to the addition of NaBr.