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

This study investigated the effects of polydopamine 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.

Automated summary

This study explored the effects of polydopamine formation on catalytic activity. Different molecular weights of PEI or PEG were mixed with dopamine at varying concentrations to obtain different PDA/PEI or PDA/PEG codepositions. AgNPs were observed on the surface of these codepositions after soaking in silver nitrate solution, and their catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol was examined. Results showed that AgNPs on PDA/PEI or PDA/PEG codepositions were smaller and more dispersed compared to those on PDA coatings. The catalytic activity of AgNPs on all codepositions was better than that on PDA, and it was related to the size of AgNPs.