Antibacterial anionic waterborne polyurethanes/Ag nanocomposites with enhanced mechanical properties

Antibacterial properties of anionic waterborne polyurethane (WPU) were obtained by the incorporation of silver nanoparticles via in situ reduction of silver ions. Formation of Ag nanoparticles in WPU was revealed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). TEM results indicated that Ag nanoparticles had a spherical shape with particle size ranging from 5 - 30 nm depending on the AgNO3 concentration. XRD patterns exhibited face-centered cubic structure of Ag nanoparticles in WPU, whereas XPS result showed Ag0 oxidation state as a major component of the Ag 3d peak. The WPU/Ag nanocomposites could release silver ions and exhibited antibacterial property. The antibacterial activity tests of the nanocomposites showed the bacterial reduction of 99.99% for Escherichia coli and 53.97% for Staphylococcus aureus. Incorporation of Ag nanoparticles into WPU not only provided antibacterial properties but also enhanced mechanical properties. Tensile strength of the WPU/Ag nanocomposites was twice that of the control, whereas the Young's modulus of the nanocomposite was three times higher than that of the pure WPU. This WPU/Ag nanocomposite has potential to be used as a coating for antimicrobial products with enhanced mechanical properties.