Durable flame-retardant cotton fabrics with tannic acid complexed by various metal ions

In this paper, a variety of metal ions (Ca2+, Fe2+, Co2+, Ni2+, and Zn2+) were used to coordinate biomass tannin (TA) and tartar emetic (TE) to prepare durable flame-retardant cotton fabrics. All the obtained TATEMe systems endowed cotton fabrics with highly durable flame retardancy, while different metal ions in the system contributed to different flame retardant effects. The Ca2+ and Zn2+ flame-retardant systems showed much better smoldering performances in comparison with Fe2+, Co2+, and Ni2+-containing coatings. Further, the catalytic carbonization process of different metal ions on biomass TA was tracked, the material pyrolysis process was revealed, and the durable flame-retardant mechanism of biomass TA-metal complexes was clarified. The Ca2+ flame-retardant system promoted the release of CO2 and the formation of graphitized carbon in both the gas phase and the condensed phase. And Zn2+ showed a better promotion effect on graphitized carbon in the condensed phase than those of Fe2+, Co2+, and Ni2+. This work provides a reference for the research of metal ion catalyzed carbonization flame retardancy.