Particles with coordinated patches or windows from oil-in-water emulsions

In this paper, we demonstrated a unique and simple method for fabricating colloidal particles of complex structures using oil-in-water emulsion droplets as confined geometries. A variety of structural motifs were produced using binary colloids of microspheres of polystyrene (PS) or silica and nanosized particles as the second component. When PS or silica microspheres and PS macromolecules were dispersed in oil-in-water emulsion droplets, particles with well-coordinated patches were obtained because the PS macromolecules partially covered the microsphere clusters. When silica or gold nanoparticles were dispersed together with the PS microspheres in oil-in-water emulsion droplets instead of PS macromolecules, composite particles with patches were obtained. In this case, silica or gold shell structures with well-coordinated windows were produced by selectively removing the large PS microspheres from the organic-inorganic composite clusters.