Effect of Codeposition of Polydopamine with Polyethylenimine or Poly(ethylene glycol) Coatings on Silver Nanoparticle Synthesis

This study investigated the effects of polydopamine (PDA), PDA/polyethylenimine (PEI), and PDA/poly(ethylene glycol) (PEG) deposition on silver nanoparticle (AgNP) formation. PEI or PEG with different molecular weights was mixed with dopamine at different concentrations to obtain various PDA/PEI or PDA/PEG codepositions. These codepositions were soaked in silver nitrate solution to observe AgNPs generated on the surface and then to examine the catalytic activity of AgNPs for the reduction of 4-nitrophenol to 4-aminophenol. Results revealed that AgNPs on PDA/PEI or PDA/PEG codepositions were smaller and more dispersed than those on PDA coatings. Codeposition with 0.5 mg/mL polymer and 2 mg/mL dopamine generated the smallest AgNPs in each codeposition system. The content of AgNPs on PDA/PEI codeposition first increased and then decreased with an increase in the PEI concentration. PEI with a molecular weight of 600 (PEI600) generated a higher AgNP content than did PEI with a molecular weight of 10000. The AgNP content did not change with the concentration and molecular weight of PEG. Except for the codeposition with 0.5 mg/mL PEI600, codepositions produced less silver than did the PDA coating. The catalytic activity of AgNPs on all codepositions was better than that on PDA. The catalytic activity of AgNPs on all codepositions was related to the size of AgNPs. Smaller AgNPs exhibited more satisfactory catalytic activity. The codeposition with 0.5 mg/mL PEI600 had the highest rate constant (1.64 min–1). The systematic study provides insight into the relationship between various codepositions and AgNP generation and demonstrates that the composition of these codepositions can be tuned to increase their applicability.