Bioinspired aldehyde-free and durable coatings for antibacterial, UV-resistant and flame-retardant cotton fabrics by the covalent bonding and in-situ coprecipitation

The development of functional and durable coatings is an effective solution for obtaining the satisfactory properties of cotton fabrics. Herein, the aldehyde-free and durable cotton fabrics (CZIF-8@CF) with well anti-bacteria, UV-resistance and flame retardancy had been obtained via an interfacial reaction strategy, where the well-organized zeolitic imidazolate framework-8 (ZIF-8) was in-situ grew on cotton fabrics pre-modified with chitosan (CS) and Zn ion. CZIF-8@CF displayed excellent antibacterial performances with 99.99 % antibacterial rates for both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Besides, the resulted cotton fabrics exhibited less than 5 % UV transmittance. Flame behaviors tests proved that the multifunctional coatings acted as "physical barrier" to reduce the heat produce coming from the synergistic effect of catalytic charring and high residual protection under high temperature of CZIF-8, and "vacuum cleaner" to decrease the smoke release resulting from the self-porous structure of ZIF-8. Even after 50 washing cycles, the CZIF-8@CF still showed less than 5 % UV transmittance, 99.99 % and 93.67 % antibacterial rates of S. aureus and E. coli, respectively. It was demonstrated that the covalent bonding between CS and part of Zn2+ in ZIF-8 could promote the durable antibacteria, UV-resistance and flame retardancy of cotton fabrics.