L-arginine and quaternary ammonium salt-synergistically modified waterborne polyurethane for efficient antibacterial performance

Antibacterial waterborne polyurethane (WPU) is attracting increasing interest in a wide range of industrial applications due to its versatility and eco-friendliness. However, single system antimicrobial WPU often does not meet the requirements of highly antimicrobial coating fields. Therefore, WPU was synergistically modified by L-arginine (L-Arg) and quaternary ammonium salts (QAs) in this study. They were introduced into the molecular structure of WPU by in-situ emulsion polymerization to form the composite antibacterial system (WRPUs). The results showed that the composite systems had excellent antibacterial activity against both Escherichia coli and Staphylococcus aureus compared to single system. When the content of both L-Arg and QAs was 7%, the antibacterial effect of WRPU7 was optimal, from the sum (E. coli: 8.3 mm + 8.3 mm = 16.6 mm and S. aureus: 9.8 mm + 9.5 mm = 19.3 mm) of the inhibition circles of L-Arg and QAs to 21.4 and 22.6 mm, respectively, net effi-ciency increase of 29% and 17%, fully reflecting the synergistic effect of "1+1 > 2. "Taken together, the results presented in this study confirm the sig-nificance of L-Arg and QAs as synergistic antimicrobial building blocks. In this way, the antimicrobial performance of WPU can be significantly improved and better biocompatibility can be exhibited, thus broadening the application of WPU in highly antibacterial fields.