Asymmetric Polystyrene/PNIPAM-Gold Composite Particles Via One-Step Pickering Emulsion Polymerization

Core-shell structured polystyrene-gold composite particles are synthesized from one-step Pickering emulsion polymerization. The core-shell particle’s surface coverage of the gold nanoparticles (AuNPs) is improved with increasing AuNP hydrophobicity and concentration. At high surface coverage, the AuNPs exhibit an ordered hexagonal pattern likely due to electrostatic repulsion during the emulsion polymerization process. In addition to core-shell structured polystyrene-gold composite particles, an intriguing observation is that under low AuNP concentrations, asymmetric polystyrene-gold nanocomposite particles are simultaneously formed, where a single gold nanoparticle is attached onto each polystyrene particle. It is found that these asymmetric particles are formed via a “seeded-growth” mechanism.  The core-shell and asymmetric polystyrene-gold composite particles prove to be efficient catalysts as they successfully catalyze the Rhodamine B reduction reaction with stable performance and show high recyclability as catalysts.