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

¹ Complex Fluids Laboratory, CNRS-Cranbury Research Center Rhodia Inc. 259 Prospect Plains Road CN 7500, Cranbury, NJ 08512, USA
² Rhodia, Centre de Recherches d'Aubervilliers - 52 rue de la Haie Coq F-93308 Aubervilliers Cedex, France
³ IPNS Division, Argonne National Labs 9700 South Cass Avenue, Argonne IL 60439, USA
⁴ Laboratoire Léon-Brillouin, CEA Saclay - F-91191 Gif-sur-Yvette, France
⁵ Institute Laue-Langevin - BP 156, F-38042 Grenoble cedex 9, France

Corresponding author: jeanfrancois.berret@us.rhodia.com

Received: 21 November 2001
Accepted: 20 March 2002

Abstract

Using neutron and light scattering experiments, we show that neutral/poly- electrolyte 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.