Fluorine-free bronopol-functionalized waterborne polyurethane with durable antifouling and antibacterial properties for multisubstrate coating applications

Developing durable antibacterial and antifouling fluorine-free waterborne polyurethane (WPU) coatings for diverse substrates remains challenging. In this study, a prepolymer synthesis strategy was developed to prepare WPU (GWSiPU) with tailored contents of polydimethylsiloxane (PDMS) and glycerol monostearate (GMS), while incorporating bronopol as an antibacterial component. The GWSiPUs containing 4 wt% PDMS and 20 wt% GMS exhibited persistent antifouling behavior and superior antibacterial ability, achieving 99.9% antibacterial efficiency against E. coli and S. aureus . When applied to cotton fabrics, the coating rendered the fabric surface highly hydrophobic with a water contact angle (WCA) above 145° while maintaining favorable breathability. Various aqueous liquids cannot completely penetrate the coating within 10 min. After 50 cycles of abrasion and repeated washing, the WCA of GWSiPU coated cotton fabric remained above 140°, endowing the fabric with resistance to bacterial adhesion. In addition, the GWSiPU coating also enabled rapid droplet shedding on wood and prevented corrosion of metal after 30 days of immersion in a 3.5 wt% NaCl solution. This work demonstrates a fluorine-free strategy for constructing multifunctional WPU coatings that integrate antibacterial activity, antifouling performance, and long-term durability across diverse substrates.