Ag and Au Monometallic and Bimetallic Colloids: Morphogenesis in Amphiphilic Block Copolymer Solutions

We report here a facile synthesis of Ag colloids with various morphologies (e.g., spherical nanoparticles, plates, wires) through autoreduction of silver nitrate (AgNO 3 ) in formamide solutions containing poly(ethylene oxide)−poly(propylene oxide) (PEO−PPO) block copolymers at ∼100 °C. The PEO−PPO amphiphilic block copolymers act in tandem as reducing, stabilizing, and morphogenic agents. Judicious selection of conditions leads to spherical Au−Ag core−shell nanoparticles or Ag−Au bimetallic nanonetworks (e.g., spherical Au or Ag nanoparticles connected by Ag or Au nanowires, respectively) that are generated in the same solution (“one pot”) without additional agents and/or energy input.