Antibacterial waterborne polyurethane coatings impregnated with in-situ formed and capped silver nanoparticles via p-sulfonatocalix[4]arene

The development of antibacterial nanocomposite coatings has been well studied in response to antibiotic resistance concerns. In this regard, silver nanoparticles incorporated waterborne polyurethanes (WPUs) are among the most attractive area due to their unique properties such as biocompatibility, reduced use of volatile organic compounds (VOC), easy construction, low viscosity, high adhesion to various surfaces, and rapid film formation. In this project, silver nanoparticles (AgNPs) were in-situ formed and simultaneously stabilized in the presence of sodium p-sulfonatocalix [4]arene (p-SC4A) as both reducing and stabilizing agents. Subsequently, the p-SC4A-stabilized AgNPs (p-SC4A/Ag) were incorporated into waterborne polyurethane, which was synthesized by the prepolymer mixing method. Examination of the structure and morphology of p-SC4A/Ag nanostructures using FT-IR, XRD, UV, SEM, and TEM analyses confirmed the synthesis of p-SC4A/Ag NPs with a smaller size than 50 nm. In addition, the various properties of WPU films with and without SC4A/Ag were evaluated by ATR-FTIR, XRD, SEM, ICP, TGA, and contact angle tests. The results showed that using p-SC4A macrocycles not only solves the agglomeration problem of silver nanostructures in waterborne polyurethane dispersions but also significantly improves bacteria-killing efficiency against the gram-positive S. aureus and gram-negative E. coli bacteria relative to pure WPU. The biocompatibility of WPU films was also evaluated, and the results showed that samples containing SC4A/Ag NPs have good biocompatibility in contact with L929 fibroblast cells.