Sustainable, tough, and water-resistant cellulose-based straws via hierarchical fiber networks and Fe3+ cross-linking

The wide use of plastic straws has posed a persistent environmental challenge, which promotes the development of sustainable alternatives. In this work, inspired by the hierarchical structures of natural materials, we reported a facile approach to prepare straws with high toughness and good water resistance from microscale and nanoscale cellulose fibers. Pulp fibers from rice stalk were treated to prepare cellulose microfibers (CMF) and cellulose nanofibers (CNF), which were hybridized to form a film and roll up for straws. The straws prepared from both micro- and nano- fibers in ratio of 2:3 (CMF:CNF) show the best overall performance in terms of tensile strength (104.5 MPa), toughness (12.6 MJ/m 3 ) and elongation at break (17.0 %). Besides, the straws further cross-linked with Fe 3+ to enhance the network bindings between hierarchical cellulose fibers and effectively improve the water resistance. The ionic cross-linking treatment with 50 mM Fe 3+ for 2 h resulted in the straws with a water contact angle of ∼126°. The obtained straws can completely disintegrate in natural soil within 45 days. These cellulose-based straws are fully in line with the concept of environmental and ecological sustainability.