Limpet-Inspired Multifunctional Composite Fibers with Exceptional Mechanical Performance From Self-Assembled Aramid Nanofibers.

Aramid nanofibers (ANFs) have emerged as promising building blocks for bioinspired materials due to their exceptional mechanical strength and chemical stability. However, their widespread application has been hindered by the limitations of conventional top-down synthesis from Kevlar, which is costly, inefficient, and offers limited control over molecular structure. Addressing this challenge, a cost-effective, bottom-up strategy is reported to fabricate limpet-inspired composite fibers by combining the self-assembly of ANFs from poly(paraphenylene terephthalamide) polyanions with in situ iron oxide mineralization. This approach enables spontaneous co-alignment of ANFs and β-FeOOH nanowhiskers, emulating the hierarchical architecture of limpet teeth. Guided by hydrogen bonding and π-π stacking, self-assembly regulates nanoscale ordering, crystallinity, and interfacial interactions-critical for enhancing mechanical performance. The resulting fibers exhibit an ultimate strength of 1.8 GPa, modulus of 42.7 GPa, and toughness of 336 MJ m , surpassing spider silk and many high-performance synthetic fibers. Multiscale toughening mechanisms, including crystallographic slip, melt-recrystallization, and micro-crazing, are enabled by the semicrystalline structure of the ANFs. Beyond mechanical properties, the fibers display paramagnetic behavior and UV resistance. This work introduces a scalable platform for multifunctional composite fibers, integrating molecular-level control with structural biomimicry and advanced functionality.