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 (AgNO3) in formamide solutions containing poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers at similar to 100 degrees 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.