Ultra‐Strong Regenerated Wool Keratin Fibers Regulating via Keratin Conformational Transition

Abstract By virtue of remarkable biocompatibility and their promising applications in biomedical fields, biomass‐regenerated fibers, such as wool keratin fiber and cellulose fiber, have attracted extensive attention. However, the insufficient mechanical performance still hinders their yarn manufacturing capability and further large‐scale applications. Herein, an ultra‐strong and ultra‐tough regenerated wool keratin fiber by regulating keratin conformation with high‐quality small‐size graphene (HQSGr) and mechanical training treatment (M‐HQSGr‐RWKF) is fabricated. With the assistance of mechanical training, a small addition of HQSGr (0.1 wt.%) remarkably augments the secondary structure transition from α‐helix to β‐sheet of the keratin, which delivers a tensile strength of 215.4 ± 5.2 MPa, surpassing all reported natural wool and regenerated wool or even poultry fibers. Benefiting from the excellent mechanical strength, wet‐state toughness (158.9 MJ m −3 ), and recoverable strain (205.0%), M‐HQSGr‐RWKF has been demonstrated as a biocompatible artificial muscle to drive the biomimetic motion, which manifests ultrahigh actuation strain greater than 100.0% and stress of 16.7 MPa. The derived ultra‐strong and ultra‐tough keratin fiber opens a new avenue for developing smart fiber from biomass resources.