Wet-Spun Supramolecular Lignin/Alginate Fibers from Agricultural Residues

Purpose This is the 1st study to explore the development of fully biobased lignin/alginate fibers using lignin extracted from corn stover via the CELF process. It examines how lignin molecular weight and concentration affect fiber properties for sustainable material applications. Methods Low (LCSL) and high (HCSL) molecular weight lignin fractions were blended with sodium alginate and glycerol to form spinning dopes. Fibers were produced via water-based wet-spinning, air-dried, and water-washed. Characterization included NMR, GPC, FTIR, TGA, and assessments of rheological, mechanical, morphological, and antioxidant properties. Results Water washing removed glycerol and yielded lignin-rich fibers (46–86 wt%) with distinct characteristics. LCSL-based fibers showed higher antioxidant activity, smoother morphology, stronger hydrogen bonding and vanillin release. HCSL-based fibers exhibited greater thermal stability. Higher lignin content increased fiber diameter and roundness but reduced tensile strength due to the plasticizing effect of lignin. FTIR and TGA confirmed a supramolecular network formed via hydrogen and ionic bonding. Conclusion These lignin/alginate fibers offer a solvent-free, sustainable alternative for wound care, food packaging, and geotextiles. The inherent functionality of lignin imparts thermal and water stability, and antioxidant performance without the need for additional toxic finishing, and supramolecular structure of lignin/alginate allows for tunability in future applications. Statement of Novelty This study presents a sustainable method to create functional biobased fibers from lignin derived from corn stover, using a water-based wet-spinning process. While lignin/alginate have been synthesized in the form of films and hydrogels previously, this study reports the first successful wet-spun functional lignin/alginate fibers, which possess inherent and durable antioxidant activity, thermal and water stability, strong hydrogen bonding and vanillin release - without synthetic additives or harmful solvents. Additionally, fiber performance can be controlled by adjusting lignin fraction and concentration and the supramolecular structure of the fibers offer tunability. This work advances green materials science by transforming low-value agricultural residues into high-value, biodegradable fibers suitable for wound care, food packaging, e- textiles, and geotextiles, supporting a circular bioeconomy.