Biodegradable Alginate-based Fibers with High Mechanical Performance and Aqueous Stability via Stretch-mediated Network Engineering

Seaweed polysaccharide-based fibers featuring incomparable merits, such as green fabrication procedures and intrinsic functionalities, are promising sustainable alternatives to petrochemical fibers that threaten both the ecological environment and human health. However, achieving simultaneously high strength, toughness, and stability of seaweed polysaccharide fibers remains a long-standing challenge owing to their low crystallinity and ionic crosslinks. Herein, we report a stretch-mediated network engineering strategy to overcome this limitation. Anisotropic architectures composed of dual-crosslinked sodium alginate and chemically crosslinked poly(vinyl alcohol) are prepared by pre-stretching. The highly ordered chemically crosslinked networks endow the fibers with high strength, and the anisotropic double networks prevent stress concentration and enable high toughness. The resultant fibers exhibit a tensile strength of 547.8 MPa, Young’s modulus of 17.6 GPa, and toughness of 43.3 MJ/m³, surpassing most regenerated biomass fibers. Additionally, fibers with an anisotropic network exhibit good aqueous stability, guaranteeing their usage in diverse solution environments and potential applications in triboelectric textiles. This study demonstrates a general and scalable strategy to decouple the strength–toughness trade-off in polysaccharide fibers without sacrificing biodegradability, thereby providing new insights into the structural design of robust, stable, and sustainable biomass-based fibers.