Reversibly Damping Protein Fibers with High Strength and Self-Recovery Capacity Enabled by Dual Dynamic Bonding...

Spider silk exhibits a unique combination of high strength and self-recoil capability through supercontraction, crucial for cyclic loading applications. However, reproducing these properties in synthetic polymer or recombinant protein fibers remains challenging, primarily due to their rigid molecular structures or monotonous cross-linking networks that limit molecular mobility and hinder structural recovery. Here, reversibly damping protein fibers are engineered by developing a dual-dynamic network fiber chemistry (DNFC) strategy. The resulting fibers integrate high-density hydrogen bonds and dynamic imine cross-links with entropy-driven elasticity, overcoming the limitations of static networks. The DNF exhibits high mechanical strength and up to 88.95% damping efficiency during cyclic loading, the latter surpassing that of regenerated silk and polymer fibers. This reversible energy dissipation arises from a unique humidity-responsive structural recovery mechanism. The process involves hydration-triggered chain recoil and reversible β-sheet rezipping through inter-domain hydrogen bond rearrangement, followed by dehydration-driven imine bond reformation. The approach establishes a versatile platform for engineering dynamically adaptive materials, pioneering an innovative paradigm in biomimetic protein fiber technology through modular chemical cross-linking strategies.