Polydopamine as reinforcement in the coating of nano-silver on polyurethane surface: Performance and mechanisms

•A facile, mild and green method was proposed for fabricating AgNPs on the polyurethane by using the polydopamine.•PDA was eff ;ectively reinforce the coating of nano-silver on polyurethane surface.•More nanosilvers were loaded onto the polyurethane at the DA concentration of 12 g/L.•Catechol groups of PDA chelated with [Ag(NH3)2]+ and reduced [Ag(NH3)2]+ to Ag0. Polyurethane (PU) is a popular medical polymer material and plays a vital role in many artificial organs and medical devices. The antibacterial properties of medical polyurethanes have always been a research hotspot for scientists. We studied the effect of polydopamine (PDA) modification and dopamine (DA) concentration on the coating of nano-silver on polyurethane surface, and investigated the bonding mechanism between nano-silver layer and modified polyurethane. We found that the polydopamine-modified polyurethane has a better nano-silver coating on the surface and a uniform distribution.We also found that the catechol groups in the PDA film could chelate with Ag+ or [Ag(NH3)2]+ and in situ reduce the Ag+ or [Ag(NH3)2]+ to Ag0 without extra reducing agent.