Shape transition in Micelles of undecylammonium chloride in the presence of sodium chloride and n-butanol: A study by dynamic light scattering

Dynamic light scattering measurements have been performed on micellar solutions of undecylammonium chloride in the presence of 0 to 0.5 mol dm-3 n-butanol and 0 to 0.2 mol dm-3 sodium chloride. The results support opposing effects of these additives on micellar growth, with the n-butanol causing a reduction of micelle size. The dependence of the aggregation number on the hydrodynamic radius suggests a transition from sphere to prolate ellipsoid when the aggregation number approximates that predicted for the maximum aggregation number of a spherical micelle. Micelle dimensions calculated from the aggregation number, conformational considerations, and packing criteria of the monomers in the micelle are compared with those from dynamic light scattering data. © 2001 Academic Press.