Nanostructured silver-boron nitride hybrid materials: Toward high-performance antibacterial hydrogels with enhanced mechanical and thermal properties

Silver nanoparticles (AgNPs) are grown uniformly on the surface of white porous boron nitride nanofibers (BNNFs) via a thermal reduction method to overcome the issue of nanoparticle aggregation. The optical characteristics of the AgNPs are retained, with different colors present depending on reduction temperature. This mainly depends on the white appearance of BNNFs. In addition, compared to boron nitride (BN) nanosheets and nanospheres, abundant pore structure and high specific surface area of the BNNFs enable superior AgNPs loading without agglomeration. The prepared AgNPs-loaded BNNFs (Ag-BNNFs) are then incorporated into poly (vinyl alcohol) (PVA) hydrogels fabricated through cyclic freeze-thaw techniques to develop antibacterial Ag-BNNFs/PVA composite hydrogels. The addition of 3 wt% Ag-BNNFs increases the tensile strength by 73.1% and compressive strength by 92.8% relative to the unmodified PVA hydrogels. Thermal stability also improves considerably, with the maximum PVA decomposition rate shifting from 280.9°C to 323.6°C in the composite hydrogels. Importantly, a potent bactericidal effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are achieved, with 99.5% and 100% inhibition after 24 h exposure to the Ag-BNNFs/PVA composite hydrogels, respectively. This work demonstrates a new method of dispersing AgNPs with BNNFs, and the resulting Ag-BNNFs effectively enhance the mechanical properties, thermal stability and antibacterial activity of PVA hydrogels.