Supramolecular Nonwoven Materials via Thermally Induced Precursor Crystallization of Nanocrystalline Fibers/Belts for Recyclable Air Filters

Abstract

Functional micro-/nanofibrous nonwovens have been widely used in both civil and military fields. However, traditional nonwoven materials preparation methods generally require special equipment and are often plagued by high-energy consumption or toxic solvent contamination. Here, a thermally induced precursor crystallization (TIPC) approach is reported for preparing macroscopic free-standing supramolecular nonwoven materials, which stemmed from the self-assembly of cocrystals of melamine and aromatic carboxylic acids. Green solvents are involved in the entire preparation process without the use of costly specialized equipment, making this strategy cost-efficient, environmentally benign, and scalable in size and quantity. Distinct nanocrystalline fibers/belts formed by hydrogen bonds and π–π interactions in thus-obtained nonwovens are tightly connected in a 3D network, constructing diverse porous fabrics with outstanding mechanical flexibility and advantageous thermal stability. These supramolecular nonwovens display selective optical transmittance and, remarkably, can be utilized as recyclable air filters. Taking advantage of the thermally reversible property of supramolecular complexes, a proof-of-concept on the closed-loop recycling of supramolecular nonwovens is realized. This work for assembling common small molecules into structurally complex architectures not only opens up promising avenues for multifunctional supramolecular materials based on synthetically facile procedures but also provides a versatile and cost-effective bottom-up approach to preparing micro-/nanofibrous nonwovens for emergent applications.