Recyclable Supramolecular Nanofibrous Composite Membranes for Efficient Air Filtration

Developing high-performance, low-resistance, and recyclable air filtration materials remains a formidable challenge. Herein, silica nanoparticles (SiO2 NPs) and supramolecular complexes consisting of melamine (MA) and trimesic acid (TMA) are constructed as SiO2@MA<middle dot>TMA supramolecular nanofibrous composite membrane via a thermally induced precursor process (TIPC) for efficient particulate matter (PM) removal. Hydrophilic SiO2 NPs as additional nucleation mediators can not only promote the growth of MA<middle dot>TMA nanocrystalline fibers by shortening the interfacial free energy and thus reducing the nucleation barrier, but also increase fiber surface roughness thus constructing hierarchical structure of membrane. Under the synergy of MA<middle dot>TMA nanocrystalline fibers and SiO2 NPs, the membranes possess high filtration efficiency of 99.82% for PM1, 99.96% for PM2.5, and 99.98% for PM10 with low air resistance (153 Pa, <0.15% of standard atmospheric pressure). Taking advantage of the thermally reversible property of supramolecular complexes, the closed-loop recycling of MA<middle dot>TMA nanocrystalline fibers and SiO2 NPs are realized. Only green solvents (water and ethanol) are involved in the TIPC process, making this strategy environmentally-friendly and cost-effective. This work not only provides an innovative strategy for the preparation of supramolecular nanofibrous composite materials, but opens an avenue for the development of recyclable high-performance air filters.