In‐situ reduction method to build <scp>Chitosan@silver</scp> nanoparticles and its application for bis(2‐hydroxyethyl) terephthalate‐based polyurethane composite films with excellent antibacterial and mechanical properties

Abstract Herein, an efficient and rapid one‐step approach to construct CS@Ag nanohybrids through in‐situ reduction of AgNO 3 with L‐ascorbic acid using chitosan (CS) as carrier only at room temperature was presented. Novel polyurethane/CS@Ag composite films with remarkable properties were fabricated via the reaction of CS@Ag nanohybrid as an antibacterial and reinforcing agent with bis(2‐hydroxyethyl) terephthalate (BHET)‐based polyurethane. With the increase of CS@Ag content, the antibacterial rate for polyurethane against Staphylococcus aureus and Escherichia coli increases. The antibacterial rate of polyurethane with 20 phr CS@Ag against S. aureus is 85.5%, and that containing 30 phr CS@Ag against E. coli is 94.9%. Thereby, the synergistic effect of CS and Ag can effectively improve the antibacterial rate of polyurethane. Meanwhile, the bond strength and tensile strength of polyurethane containing 20 phr CS@Ag are up to 8.72 MPa (improved by 74.3%) and 20.1 MPa (enhanced by 130.5%), respectively. Indeed, this work may unlock new possibilities for developing antibacterial and enhanced polyurethanes, which are expected to applied in the medical devices, food packaging, and automotive industries. Highlights CS@Ag was efficiently fabricated by in‐situ reduction via a one‐step approach. BHET is used as a novel chain extender for PU. CS@Ag is able to fully exert the synergistic effect of CS and Ag. CS@Ag endows PU with high strength and excellent antimicrobial properties.