Micellar morphologies of charged diblock-copolymers

Using scaling arguments, we consider dilute solutions of diblock-copolymers consisting of a strongly hydrophobic block and a charged block in an aqueous salt solution. At low salt, the electrostatic repulsion of the charged block dominates and we find a transition from spherical to cylindrical micelles as the salt concentration increases. At high salt, the elastic energy of the hydrophobic core dominates and bilayers are favored. At intermediate salt concentrations cylindrical, spherical. and bilayer morphologies coexist, suggesting the formation of degenerate, multiply connected structures. The endcap energy of cylindrical micelles is high, suggesting the formation of long or toroidal cylindrical micelles.