A time-resolved small angle neutron scattering study of the micelle-to-vesicle transition

Amphiphilic molecules spontaneously self-assemble in solution to form a variety of aggregates. While significant progress has been made in the understanding or equilibrium properties such as the sequence of structures as a function of the solution composition, limited information is available about the existence of non-equilibrium or metastable states and the pathway and kinetics associated with the structural transitions observed. Aqueous mixtures of lecithin and bile salt exhibit a transition from polymer-like mixed micelles to vesicles upon dilution. Here we present a time-resolved study of this transition using light and small angle neutron scattering experiments. We demonstrate that it is possible to follow the temporal evolution of the aggregate structure and obtain detailed information even on molecular length scales.