Aramid Nanofiber Aerogels: Versatile High Complexity Components for Multifunctional Composites

Aramid nanofibers (ANFs) have emerged as versatile and readily accessible building blocks for multifunctional, complex nanostructures. A key motivation for studying and utilizing ANFs lies in their potential to directly recycle commercial macro-aramid plastics, such as poly(p-phenylene terephthalamide), for diverse applications. Retaining the advantageous properties of parent aramid fibers and fabrics, ANFs enable the creation of a variety of nanostructured solids, both independently and in combination with polymeric and nanoscale components. A wide spectrum of ANF-based aerogels is developed, many of which exhibit property sets previously unattainable in other materials-properties critical for advancing sustainable development. These biomimetic composites replicating complex organization of cartilage, combine high toughness, thermal resilience, nanoscale porosity, and low density with the capability for roll-to-roll manufacturing. The transformative advancements in materials for energy storage, electromagnetic interference shielding, thermal management, biomedical implants, water purification, and other applications are spurred by ANF-based aerogels and related composites. This review summarizes recent progress in the engineering, fabrication, characterization, modification, and implementation of ANF aerogels. It also highlights future research directions, potential applications, and key challenges including the development of structural descriptors for ANF solids, that must be addressed to fully realize the potential of ANF-based technologies.