Robust Artificial Spider Silk via Synergistic Cross-Linking of Slide-Ring and Covalent Bonds

Abstract

Inspired by the structure of spider silk, the introduction of slide-ring molecules into covalent networks to construct double cross-linked networks (DCNs) has become an effective strategy for preparing robust polymer artificial spider silk. However, the complex interplay between the two cross-linking modes poses significant challenges for elucidating the molecular mechanisms underlying mechanical enhancement and hinders the precise design and fabrication of robust artificial silks. Here, we engineered robust artificial spider silk fibers based on DCNs and employed coarse-grained molecular dynamics (CGMD) simulations to establish quantitative models linking the network architecture to macroscopic mechanical properties. The models reveal that slide-ring-only networks suffer from ring aggregation and chain slippage under strain, which leads the multifolded axis chains to straighten and unfold, ultimately forming highly oriented structures. In contrast, DCNs utilize covalent anchors to regulate the ring mobility, stabilize multifolded chain structures, and balance energy dissipation with mechanical integrity. These molecular-level insights are supported by experiments. By tuning the slide-ring cross-linking fraction and introducing Zr⁴⁺ ions as dynamic supramolecular regulators, we achieved highly aligned nanofibers with both exceptional tensile strength (1.18 GPa) and toughness (135 MJ m^–3). The synergy between dynamic and permanent cross-links enables efficient stress redistribution and crack resistance. This work provides inspiration for the design of high-performance fiber materials.