Biomimetic Interface Engineering Approach for Universal Toughening of Rigid Fibers

Abstract The development of a straightforward, universally applicable methodology for transforming short, rigid fibers into ultra‐long, high‐toughness fibers is of significant theoretical and practical importance, presenting considerable challenges in its execution. Inspired by the intricate structure of natural silk, a biomimetic interface engineering technique is developed to fabricate extensive, high‐toughness bamboo filaments. These filaments feature a unique design with alternating layers of soft silk fibroin acting as a flexible sheath between rigid bamboo microfibers, markedly enhancing the strain and toughness of the resulting bamboo‐silk filaments (BSFs). Consequently, the BSFs exhibit an extraordinary toughness of 115 ± 17 MJ m⁻³, ≈12 times greater than that of pristine bamboo microfibers. By leveraging the tunable mechanical properties of silk fibroin, the approach offers a versatile strategy to bolster the toughness of various materials, including biopolymers (e.g., cellulose), synthetic polymers (e.g., aromatic polyamide), and inorganics (e.g., fiberglass). This enhancement is achieved by precisely modulating the interactions between the soft protein matrix and rigid inclusions, providing a novel approach for fabricating high‐toughness fibers and significantly expanding the potential applicability of biomass, inorganic, or petrochemical‐based fibers.