Novel core-shell structure for colloids made of neutral/polyelectrolyte diblock copolymers and oppositely charged surfactants

Using neutron and light scattering experiments, we show that neutral/polyelectrolyte diblock copolymers and oppositely charged surfactants in dilute aqueous solutions associate into colloidal aggregates which have an original core-shell microstructure. We have found that the core is constituted of densely packed surfactant micelles, most likely connected between them by the polyelectrolyte blocks. The outer part of the colloid is a corona and is made of the neutral chains. We suggest that the mechanism of formation of these colloids is identical to that of the associative transition reported in homopolyelectrolyte/ surfactant solutions. However, here, the macroscopic phase separation is hindered by the presence of the neutral chains.