Synergistic modification of waterborne polyurethane by l-phenylalanine and quaternary ammonium salt: Synthesis and antibacterial properties

For an extended period, the proliferation and propagation of microorganisms on material surfaces have posed an inevitable challenge, leading to potential surface deterioration and infection risks, resulting in substantial economic ramifications. To address this issue, the application of coatings on material surfaces has consistently proven to be a viable strategy. Waterborne polyurethane (WPU) stands out due to its cost-effectiveness, safety profile, environmental sustainability, and widespread applicability across various domains. However, owing to its limited antibacterial properties, it is seldom utilized as an antibacterial coating. This study delves into the antibacterial attributes of water-based polyurethane modified by L-Phe and QAs. The modified WPU exhibits exceptional antibacterial activity with effective inhibition of bacterial growth. The prepared emulsions demonstrate uniform dispersion in water with average particle sizes ranging from 46.63 nm to 153.95 nm. Zeta potential and centrifugal tests confirm the stability of the emulsion. Introduction of L-Phe increases the contact angle to 98.8°, a marked increase compared to pure quaternary ammonium based waterborne polyurethane-indicating heightened crosslinking density and film hydrophobicity post modification with L-Phe. The antibacterial test reveals that the aqueous polyurethane emulsion modified by quaternary ammonium salt and phenylalanine displays significant antibacterial activity against Escherichia coli and Staphylococcus aureus with maximum zone diameters reaching 15.6 mm and 15.8 mm respectively–significantly surpassing those observed for pure quaternary ammonium based aqueous polyurethanes. This suggests that introducing hydrophobic amino acid functional groups into quaternary ammonium based waterborne polyurethane systems can enhance both hydrophobicity and antibacterial activity, providing valuable insights for developing high-performance biocompatible antibacterial waterborne polyurethanes.