In situ and controllable synthesis of Ag NPs in tannic acid-based hyperbranched waterborne polyurethanes to prepare antibacterial polyurethanes/Ag NPs composites

In this research, a simple and facile method was developed for preparation of antibacterial polyurethanes/Ag NPs composites, where tannic acid-based hyperbranched waterborne polyurethanes (THWPU) was employed as both reductant and stabilizer to in situ and controllably synthesize Ag NPs at mild room temperature. The resultant Ag NPs in THWPU was confirmed by UV spectrophotometer, SEM and EDX. The effects of reaction temperature on the properties of the formed Ag NPs were investigated, and the results showed that the formed Ag NPs under room temperature and 80 °C were both spherical, whereas increasing the reaction temperature benefits for promoting the formation of Ag NPs and narrowing the size distribution of the formed Ag NPs. Furthermore, triangular Ag NPs were in situ synthesized in THWPU via adding strong reductant (NaBH(4)) during the formation of Ag NPs. Both spherical and triangular Ag NPs enhanced the mechanical property, thermal stability and antibacterial performance of THWPU. More importantly, our results demonstrated that formation of spherical Ag NPs in THWPU were beneficial for improving the mechanical property and thermal stability of THWPU, while the formation of triangular Ag NPs enabled THWPU better antibacterial performance against E. coli and S. aureus. Given these advantages, our obtained Ag NPs nanocomposites could be suitable for a broad range of commercial applications, such as medical products, children's products.