Multifunctional Biomass-Derived Composite Coatings for Flame-Retardant, Antibacterial, and Durable Hydrophobic Textiles

Abstract Multifunctional textiles with integrated protective properties and long-term durability are highly desirable for practical applications. Here, a facile and scalable coating strategy is developed to fabricate biomass-derived composite coatings on cotton and polylactic acid (PLA) nonwoven fabrics, enabling simultaneous flame retardancy, antibacterial activity, and water repellency. The coating, composed of phosphorylated chitosan (PCS), polydopamine-modified copper nanoparticles (PDA-CuNPs), and PDMS-SiO2, forms a hierarchical micro/nanostructure that contributes to the multifunctional performance. The coated textiles exhibit significantly improved flame retardancy, as evidenced by increased limiting oxygen index and reduced total heat release, which can be attributed to synergistic condensed-phase charring and catalytic effects. In addition, the hierarchical structure imparts excellent water repellency. The textiles demonstrate strong antibacterial activity against Escherichia coli and Staphylococcus aureus (>99%). Notably, PDA modification may contribute to prolonged antibacterial durability by stabilizing copper species, extending antibacterial durability from 2 to 14 days before the activity decreases below 70%. Furthermore, flame retardancy and antibacterial efficacy are well retained after 20 washing cycles. Repeated laundering eliminates the initial superhydrophobicity, reducing the water contact angle to ∼130°, though favorable hydrophobic performance is still preserved. This work provides a sustainable and effective strategy for constructing durable multifunctional textile coatings for protective and wearable applications.