News Coatings Technologies

Bronopol-functionalised WPU repels dirt, water and bacteria

A newly developed fluorine-free water-borne polyurethane coating combines durable antibacterial and antifouling properties across a wide range of substrates. Functionalised with bronopol and modified with polydimethylsiloxane and glycerol monostearate, the coating achieves 99.9 % antibacterial efficacy against E. coli and S. aureus while providing hydrophobicity, breathability and corrosion protection.

PFAS
The fluorine-free water-borne polyurethane coating provides high hydrophobicity, breathability and long-term antibacterial performance on textiles, wood and metal. Source: luchschenF - stock.adobe.com

Developing durable antibacterial and antifouling fluorine-free water-borne polyurethane (WPU) coatings that can be applied to a wide range of substrates remains a considerable challenge. In this study, researchers developed a prepolymer synthesis strategy to prepare a WPU system (GWSiPU) with tailored contents of polydimethylsiloxane (PDMS) and glycerol monostearate (GMS), while incorporating bronopol as an antibacterial component. The synergy between PDMS and GMS significantly reduced the surface energy of the coating, enabling multifunctional performance without the use of fluorinated compounds.

The optimised GWSiPU formulation, containing 4 wt.-% PDMS and 20 wt.-% GMS, exhibited persistent antifouling behaviour and superior antibacterial activity, achieving 99.9 % antibacterial efficiency against Escherichia coli and Staphylococcus aureus. This combination positions the coating as a promising fluorine-free alternative for hygiene-sensitive applications.

Event tip:

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Multi-substrate performance and long-term durability

When applied to cotton fabrics, the coating rendered the surface highly hydrophobic with a water contact angle (WCA) above 145°, while maintaining favourable breathability. Various aqueous liquids were unable to fully penetrate the coating within 10 min. After 50 cycles of abrasion and repeated washing, the WCA of the coated cotton fabric remained above 140°, providing sustained resistance to bacterial adhesion.

The versatility of the system was further demonstrated on other substrates: the GWSiPU coating enabled rapid droplet shedding on wood and prevented corrosion of metal after 30 days of immersion in a 3.5 wt.-% NaCl solution. Overall, the work demonstrates a viable fluorine-free strategy for constructing multifunctional WPU coatings that integrate antibacterial activity, antifouling performance and long-term durability across textiles, wood and metal.

Source: Yang, R. et al., Fluorine-free bronopol-functionalized waterborne polyurethane with durable antifouling and antibacterial properties for multisubstrate coating applications. Progress in Organic Coatings, 110169 (2026).