Ultra-tough poly(vinyl alcohol)/polydopamine/nanosilver nanocomposite films with enhanced antibacterial and antioxidant properties

The fabrication of ultra-tough biodegradable nanocomposite films with antibacterial activity and antioxidant properties remains a huge challenge. Herein, we developed a super-tough antibacterial biodegradable poly(vinyl alcohol) (PVA) nanocomposite film by simply introducing highly effective antibacterial agent PDA@LS-Ag into PVA matrix. The antibacterial agent PDA@LS-Ag was synthesized from the mussel-inspired polydopamine (PDA) and green biomass sodium lignosulfonate (LS) via a facile microwave-assisted reduction strategy, in which PDA played the role of reducing agent and LS performed as the dispersant. The tensile strength of the PVA nanocomposite film with 5 wt% addition of PDA@LS-Ag reached up to 131.7 MPa, which was far higher than most of engineering plastics. The excellent mechanical performance was resulted from the synergistic effect of the unique nanoscale phase-separation structure and the dense hydrogen bonds between the PDA@LS-Ag nanoparticles and PVA matrix. Owing to the existence of silver nanoparticles and rich phenolic hydroxyl groups, the PDA@LS-Ag nanoparticles also endued the composite film with good antibacterial activity, outstanding antioxidant activity, and UV-shielding properties. As the biomass LS, PDA, and the PVA matrix are all biodegradable, this work provides a feasible way for preparing highly strong and super-tough biodegradable nanocomposite films with antibacterial and antioxidant properties.