To synthesize antibacterial polyurethane (PU) films, a novel chain extender, bis(3-pyridinemethanol) silver (BPDS), and a PU prepolymer were also synthesized through coordination and covalent reactions. The effects of incorporating different amounts of BPDS were investigated by characterizing the BPDS/PU films using various instruments: FTIR, TGA, DSC, DMA, XRD, EDX, universal testing machine, contact angle goniometer, and positron annihilation spectroscopy (PALS). With a higher BPDS content, the glass transition temperature, final degradation temperature, and Young's modulus were all enhanced; however, the tensile strength and elongation at break were both reduced. PALS analysis revealed that the more rigid and randomly packed structure of the BPDS/PU films at a higher BPDS content was characterized by a broader free volume size distribution that consisted largely of much smaller free volume holes. Quantitative tests with Staphylococcus aureus and Escherichia coli indicated excellent antibacterial properties, suggesting that the PU films could be used repeatedly. (C) 2016 Elsevier Ltd. All rights reserved.