Enhancement of the Excellent Properties of an Intrinsically Antimicrobial Poly(Oxime‐Urethane) Coating with a Bio‐Based Furan Chain Extender

Polyurethane coatings that exhibit excellent mechanical, weathering, and antimicrobial properties are highly valuable for developing new marine antifouling coatings. In this study, poly(oxime-urethane) were synthesized using the bio-based furan chain extender, 2,5-diformylfuran dioxime (DFFD), and a top coating (DPUC_x) was then prepared with titanium dioxide (TiO₂) fillers and additives. After application to the surface of the epoxy primer, DPUC_x exhibited excellent mechanical properties, including crosshatch adhesion of 5B, pull-off adhesion of 3.85 MPa, flexibility of 2 mm, pencil hardness of H, and impact strength of 120 cm·kg. Following 20 consecutive days of salt spray corrosion and xenon lamp accelerated ageing testing, samples with a high DFFD content exhibited no discernible changes in appearance, with a color difference value (ΔE^*) of just 0.53, demonstrating superior weathering performance. Furthermore, DPUC_x exhibits outstanding intrinsic antimicrobial activity, achieving a 100% inhibition rate against both Escherichia coli (G^-) and Staphylococcus aureus (G⁺). This study provides a feasible design strategy for developing high-performance, sustainable antibacterial protective coatings.