A new way to improve the fire safety of polyurethane composites with the assistance of metal-organic frameworks

Polyurethane (PU) is extensively utilized for its outstanding properties. However, its flammability and the substantial release of toxic smoke and harmful gases during combustion pose significant safety concerns in practical applications. Consequently, the development of efficient flame-retardant PU materials has become a critical priority. In recent years, metal-organic frameworks (MOFs) have attracted considerable interest as innovative flame retardants. Thanks to their structural diversity, large specific surface area, tunable porosity, and multifunctional properties, MOF materials show significant promise in improving the flame retardancy of PU. MOFs not only catalyze the formation of stable char layers during PU combustion but also adsorb and trap smoke and toxic gases, all while avoiding the release of corrosive or toxic gases at high temperatures, unlike conventional flame retardants. This review systematically compiles the latest progress in using MOFs to enhance PU flame retardancy, with an emphasis on their applications in polyurethane elastomers (PUE), thermoplastic polyurethanes (TPU), and polyurethane foams (PUF). This paper offers a comprehensive evaluation of the flame-retardant effects of various MOF structures and investigates the synergistic interactions between MOFs and other flame retardants. Additionally, this work identifies current challenges and future development paths, offering theoretical guidance and research avenues for advancing efficient and safe flame-retardant PU materials. This is crucial for enhancing the safety of PU materials and broadening their application areas.