Super‐Strong and Super‐Stiff Chitosan Filaments with Highly Ordered Hierarchical Structure

Abstract Currently, the world is facing the problems of the gradual depletion of non‐renewable fossil resources and the severe harm of non‐degradable plastic waste to the land and marine ecological environment. Because of the rapid increase in the demand for fiber materials, the development of high‐performance biomass‐based fibers has emerged as an important research topic to reduce the reliance on petroleum‐based synthetic fibers. In this study, a novel green wet‐spinning strategy is used for the fabrication of super‐strong and super‐stiff chitosan filaments from an aqueous KOH/urea solution using a two‐step drawing process. The highly ordered hierarchical structure of the resulting filaments contributes to their excellent mechanical properties. The tensile strength and Young's modulus of the chitosan filaments are 878 ± 123 MPa and 44.7 ± 12.3 GPa, respectively, and these values are comparable to those of spider silk and bacterial cellulose. The chitosan filaments prepared in this study are superior to low‐density steel in terms of the specific strength and modulus. The green and scalable strategy proposed in this study will broaden the application range of chitosan filaments in flexible bioelectronics, biomaterials, and textiles.