Multiscale Orientation Armoring Strategy to Heat-Resistant and High-Selectivity Nanofiber Membranes for Fireground Emergency

High-temperature fire scenarios are typically characterized by high concentrations of particulate matter (PMs) and asphyxiating harmful gases (e.g., CO₂ and SO₂), seriously threatening the respiratory safety of rescue personnel. Here, we propose a multiscale orientation armoring strategy to engender heat-resistant nanofiber membranes for long-term efficient coremoval of gases and PMs. Exploiting the synergistic effect of high-voltage E-field and high-speed stretching, stereocomplex crystals serve as physical cross-linking points to facilitate multiscale orientation of poly(lactic acid) (PLA) nanofibers, chains, and diploes. Furthermore, in situ metal-organic framework (MOF) armoring was employed to assemble high-selectivity MOFs onto the nanofiber surface, while interface polarization between nanofibers and charged water molecules was exploited to intensify charge accumulation. The multiscale orientation armored PLA (MSOA-PLA) membranes exhibited a specific surface area of 194.5 m²/g and a surface potential of ∼8 kV, leading to adsorption capacities of 1.87 mmol/g for CO₂ and 8.20 mmol/g for SO₂, along with PM_0.3 and PM_2.5 filtration efficiencies of 99.12 and 99.95% at 32 L/min, respectively. Notably, the MSOA-PLA membranes maintain structural integrity and a PM_0.3 filtration efficiency of 99.15% (32 L/min) even when exposed to elevated temperatures of up to 120 °C, showing enormous potential in high-temperature applications. This work provides a viable strategy for fabricating highly protective membrane filters for harsh working environments.