Fire-safe polymer composites enabled by a nature-inspired MOF-derived single atom catalysis strategy for thermal management with recyclability

Driven by global carbon neutrality and sustainable development goals, advanced polymer materials with fire safety and environmental compatibility are crucial. In view of the environmental and performance limitations of traditional flame retardants, a metal-organic framework (MOF) template strategy was proposed to design hexagonal boron nitride (h-BN) nanosheets and atomically dispersed cobalt (Co⁰) sites through boron/nitrogen co-doping and pyrolysis of ZIF-67. Inspired by the hierarchical architecture of pine cones in nature, the designed nanoarchitecture features a biomimetic three-dimensional (3D) flower-like structure. The confinement effect of MOFs inhibits the re-stacking of h-BN, thereby enhancing the interfacial adhesion to thermoplastic polyurethane (TPU). The peak heat release rate and smoke release rate of TPU/h-BNNSs@Co composites decreased by 47.5% and 44.5%, respectively. The h-BN nanosheets form a ceramic barrier, while the Co⁰ single-atom site catalyzes the conversion of CO to CO₂. Simultaneously, the composite material exhibits a 42.8% increase in thermal conductivity while maintaining satisfactory mechanical properties even after ultraviolet aging. This work not only highlights the potential of MOF-derived strategies for multifunctional flame-retardant systems but also provides a new paradigm for the development of recyclable composites with efficient fire protection and thermal management properties.