Mimicking the Hierarchical Structure of Spider Silk: Pseudoprotein Nanofiber Yarns with Unprecedented Toughness

Abstract Preparing high‐performance artificial spider silk with hierarchical structures using purely chemical synthesis methods is challenging, albeit promising. Herein, a high‐molecular‐weight pseudoprotein material (CPPUU) synthesized by introducing polypeptide fragments (PZLY) and cystine dimethyl ester (CDE) into a polyurethane/urea macromolecular chain is described. Nanofiber yarn is subsequently prepared using an improved electrospinning process. After pre‐stretching, the tensile strength of the nanofiber yarn is 286.0 ± 47.1 MPa, and the toughness is an unprecedented 925.4 ± 116.1 MJ m−3, surpassing that of both natural and synthetic fibers reported to date. Moreover, the nanofiber yarn can lift a weight 100 000 times its mass and withstand the free fall of a weight 25 000 times its mass. Structural analysis indicates that the yarn contains structures such as random coils, α‐helices, and β‐sheets commonly found in spider silk; additionally, the existence of β‐turns in pseudoprotein materials is verified. The hierarchical structural resemblance to spider silk and the stress–strain curve suggest that a self‐toughening mechanism is responsible for the excellent mechanical properties displayed by the yarn. This study should promote the production of artificial spider silk, with potential applications in various high‐performance materials and industries.