Block copolymer micelles in solutions of a homopolymer: Dynamic light scattering and viscosity studies

Solutions of polystyrene-b-poly(ethylene/propylene) block copolymer and homopolystyrene in toluene (a good solvent of both copolymer blocks) were studied by dynamic light scattering and viscometry. The presence of homopolystyrene in the solution induces the formation of micelles with a core which consists of poly(ethylene/propylene) blocks. The dynamic light scattering measurements showed that these micelles have a narrow size distribution. The influence of the polystyrene concentration on the structural parameters of the micelles was analysed. The hydrodynamic radius and molar mass remained constant in the polystyrene concentration range studied. However, the diffusion of the micelles was very influenced by the increment of the solution viscosity caused by the polystyrene chains. Copyright (C) 1996 Elsevier Science Ltd.