Characterization of nanoparticles based on block copolymer micelles

Three-layer nanoparticles were prepared by gamma -radiation-induced polymer ization of methyl methacrylate (MMA) in polystyrene-block-poly(methaerylic acid) aqueous micellar solution, and their structure was studied by small-a ngle neutron scattering (SANS). The scattering data were fitted using the b are-core approximation for a two-component core to elucidate the distributi on of MMA before polymerization and the structure of nanoparticles with pol ymerized MMA The newly formed polymer (poly(methyl methacrylate), PMMA) is deposited on the surface of polystyrene cores of the original micelles. The thickness of the PMMA layer (8-139 Angstrom for the presented series of sa mples) depends on the monomer concentration. The SANS results indicate that the PMMA layer is penetrated by the poly(methacrylic acid) corona chains f orming channels accessible to water.