The self-reinforcement strategy: upcycling agricultural waste into advanced sustainable cellulose/lignin nanocomposites

A mild one-step alkali–milling process converts xylose residue into robust LCNF films. • In-situ lignin regeneration precisely controls lignin size, dispersion, and compatibility. • Acid-driven lignin cleavage–repolymerization yields nanoscale lignin rich in phenolic groups. • Reconstructed lignin enables strong hydrogen bonding and π–π interactions for high strength. • The films show excellent wet stability, hydrophobicity, thermal durability, and UV-shielding. The valorization of agricultural waste such as corncob-derived xylose residue into high-performance materials is of great importance for sustainable development, but it is often limited by complex processing routes and inefficient utilization of lignin. Herein, we report a simple and efficient self-reinforcement strategy to directly convert xylose residue into robust lignin-containing cellulose nanofibril (LCNF) films. A mild alkaline treatment (0.3 wt%) combined with mechanical ball milling was used to simultaneously liberate cellulose nanofibrils and dissolve lignin, followed by acid precipitation to reconstruct and redistribute lignin within the cellulose network. This process effectively reduced large-scale lignin aggregation and promoted a more homogeneous dispersion of lignin in the film matrix. Semi-quantitative HSQC analysis showed that the relative β-O-4 linkage content decreased from 15.53% to 7.60% after acid precipitation, indicating substantial lignin structural evolution during reconstruction. Response surface methodology optimized the regeneration conditions at pH 3, 27°C, and 8 min. Under these conditions, the reconstructed films exhibited markedly improved mechanical performance, with tensile strength and elongation at break increasing from 32.09 MPa and 1.11% for the untreated film to 55.12 MPa and 2.61%, respectively, while the wet tensile strength reached 24.77 MPa at extended titration time. In addition, the films showed improved water resistance and effective UV shielding, while retaining moderate visible-light transparency. This work provides a feasible route for the high-value utilization of lignin-containing agricultural residues and offers useful insights into lignin reconstruction as a reinforcement strategy for biomass-based nanocomposites. Download: Download high-res image (165KB) Download: Download full-size image