Preparation and antibacterial study of waterborne polyurethane modified with lysine and quaternary ammonium salt

Bacterial surface contamination can lead to the formation of biofilms, infection by pathogens and damage the surface of materials, which can seriously endanger health and even life. However, single-system antibacterial waterborne polyurethane (WPU) cannot meet its application in the field of high antibacterial activity. Therefore, in this study, WPU was synergistically modified by lysine (Lys) and quaternary ammonium salts (QAS), and they were introduced into the WPU molecular framework by chemical bonding to form a composite system, named WKPU. The results showed that WKPU had excellent antibacterial activity against both E. coli and S. aureus compared to a single system (Lys or QAS). When the contents of both Lys and QAS were 7%, the antibacterial activity of WKPU7 was optimal, from the sum (E. coli: 8.4 mm + 8.3 mm = 16.7 mm and S. aureus: 9.7 mm + 9.5 mm = 19.2 mm) of the inhibition circles of Lys and QAS to 19.2 mm and 20.0 mm, respectively, demonstrating the net efficiency increase of 15% and 4.2%, which fully reflects the effect of “1 + 1 > 2”. This highlights their great potential as antibacterial materials that could be used in highly antibacterial fields, such as medical apparatus and food packaging.