Formation of Catalytic Silver Nanoparticles Supported on Branched Polyethyleneimine Derivatives

A new and straightforward method for screening highly catalytically active silver nanoparticle−polymer composites derived from branched polyethyleneimine (PEI) is reported. The one-step systematic derivatization of the PEI scaffold with alkyl (butyl or octyl) and ethanolic groups led to a structural diversity correlated to the stabilization of silver nanoparticles and catalysis. Analysis of PEI derivative libraries identified a silver nanoparticle−polymer composite that was able to efficiently catalyze the p-nitrophenol reduction by NaBH4 in water with a rate constant normalized to the surface area of the nanoparticles per unit volume (k1) of 0.57 s−1 m−2 L. Carried out in the presence of excess NaBH4, the catalytic reaction was observed to follow pseudo-first-order kinetics and the apparent rate constant was linearly dependent on the total surface area of the silver nanoparticles (Ag-NPs), indicating that catalysis takes place on the surface of the nanoparticles. All reaction kinetics presented induction...