Nanocellulose-Based Hollow Fibers for Advanced Water and Moisture Management

Naturalplant fibers such as cotton have favorable performancein water and moisture management; however, they suffer from inferiorprocessing ability due to limited diameter and length, as well asnatural defects. Although commercially available regenerated cellulosefibers such as lyocell fibers can have tunable structures, they relyon the complete dissolution of cellulose molecules, including thehighly crystalline parts, leading to inferior mechanical properties.Through a specially designed coaxial wet-spinning process, we preparea type of hollow fiber using only cellulose nanofibrils (CNFs) asbuilding blocks. It mimics cotton fibers with a lumen structure butwith a tunable diameter and a long length. Moreover, such hollow fibershave superior mechanical properties with a Young's modulusof 24.7 GPa and tensile strength of 341 MPa, surpassing lyocell fibersand most wet-spun CNF-based fibers. Importantly, they have 10 timeshigher wicking ability, wetting rate, drying rate, and maximum wettingratio compared to lyocell fibers. Together with a superior long-termperformance after 500 rounds of wetting-drying tests, suchCNF-based hollow fibers are sustainable choices for advanced textileapplications. And this study provides a greater understanding of nanoscalebuilding blocks and their assembled macromaterials, which may helpto reveal the magic hierarchical design of natural materials, in thiscase, plant fibers.