Interaction of polystyrene-block-poly(ethylene oxide) micelles with cationic surfactant in aqueous solutions. Metal colloid formation in hybrid systems

The interaction of the amphiphilic block copolymer, polystyrene-block-poly( edhylcne oxide) (PS-b-PEO), with cationic surfactant, cetylpyridinium chlor ide (CPC), in aqueous media was studied by static Light, scattering and ana lytical ultracentrifugation. Three well-defined populations of hybrid struc tures corresponding to micelles, micellar clusters, and supermicellar aggre gates were found to Exist in the PS-b-PEO/CPG aqueous solutions at a block copolymer concentration of 10 g/L. The relative ratio of each type of struc ture and their parameters strongly depend on the CPC concentration, mobilit y of the polystyrene micellar core, and chemical composition of the dispers ingmedia. Ion exchange of the surfactant counterions in the hybrid PS-b-PEO /CPC system by PtCl62- and PdCl42- ions resulted in saturation of the micel lar structures with noble metal ions. The subsequent reduction of the metal -containing PS-b-PEO/CPC/MXn species with NaBH4 and molecular hydrogen resu lted in the formation of metal nanoparticles mainly located in the black co polymer micelles.