Sustainable Self-Healing Wood Adhesives from Cellulose and Lignin Derivatives via Dual Dynamic Networks

Replacing petrochemical thermosetting adhesives with renewable, repairable alternatives remains challenging. We reported a bio-based self-healing adhesive from ethyl cellulose and lignin-derived vanillin. An EC-based macroinitiator (EC-CPADP) was prepared by esterification, and then RAFT graft copolymerization of lauryl methacrylate (LMA) and vanillin glycidyl methacrylate (VGMA) yielded EC-g-P(LMA-co-VGMA). FT-IR and 1H NMR confirmed aldehyde and hydroxyl pendants, enabling crosslinking with polyetheramine via dynamic imine and hydrogen bonds. Varying VGMA content and crosslinker stoichiometry tuned Tg (6.3−49.2 °C) and tensile properties while maintaining high crosslinking (gel fraction up to 94%). The optimized adhesive achieved a 180° peel strength of 6.47 N·cm−1 on wood, outperforming many bio-based adhesives. The dual dynamic network provided room-temperature self-healing with recovery efficiencies of 91.7% and 81.7% after the first and third cycles, respectively. This modular cellulose-graft platform upgrades cellulose and lignin into high-value, tunable, circular adhesives for wood bonding.