Patchy and Multiregion Janus Particles with Tunable Optical Properties

Multiregion and patchy optically active Janus particles were synthesized via a hierarchical self-assembly process. Gold nanoparticles were assembled on the top surfaces of nano- and submicrometer silica particles, which were selectively protected on their bottom surfaces by covalent attachment to a copolymer film. The morphologies of the gold particle layer, and the resulting optical properties of the Janus particles, were tuned by changing the surface energy between the silica and gold particles, followed by annealing.