Hierarchically structured colloids of diblock copolymers and Au nanoparticles

A simple route for fabrication of hierarchically structured multi-layer composite spheres, which were produced by introducing polymer-coated gold nanoparticles into spherically confined phases of block copolymers, was demonstrated. The block copolymer and nanoparticles were dissolved in toluene, which was then emulsified in water using a high-speed mechanical homogenizer. Particles were formed by slow evaporation of the toluene by heating. Spherically confined layered onionlike structures were produced, with the gold nanoparticles encapsulated inside, because a symmetric poly(styrene-b-butadiene) (PS-b- PB) diblock copolymer was used as the matrix for the composite particles. The cross-sectional TEM images show that PS-Au nanoparticles were confined within the polystyrene layers. It was observed that as the areal chain density increased, the location of PS-Au nanoparticle in PS domain with the same degree of polymerization was shifted from the interface to the center.