Light-driven self-healing polyurethane based on PDA@Ag nanoparticles with improved mechanical and antibacterial properties.

To endow the polyurethane (PU) coating with antimicrobial and self-healing ability, a PU composite film (PUDA@Ag) based on furfuryl functional polydopamine nanoparticles (FPDA NPs) and Diels-Alder (DA) reaction was prepared successfully. Herein, FPDA NPs were added to maleimide-terminated PU by DA reaction as cross-linking agents and photothermal fillers. Owing to the excellent photothermal effect of PDA NPs and the existence of DA bonds, the PUDA@Ag film had superior self-healing performance (90%). Importantly, with the existence of FPDA@Ag, the PU composite films showed comprehensive mechanical properties (tensile strength up to 50 MPa, toughness of 153.9 MJ m -3 , and elongation at break of 895%). Silver nanoparticles (AgNPs) as antibacterial agents and nanofillers endowed the PUDA@Ag with excellent antibacterial and long-term antibacterial properties against Gram-negative E. coli and Gram-positive S. aureus . This work provides a reasonable method to prepare multi-responsive self-healing PU composite films with super-high strength and antimicrobial properties that have great potential in the fields of biomedicine, coating, and thermal management.