Strong Fully Reprocessable Engineered Wood Composites.

Developing fully reprocessable engineered wood composites (EWCs) with high mechanical strength under mild fabrication conditions remains a significant challenge. Here, a hyperbranched adhesive with complementary imine-bond and hydrogen-bond networks was designed and combined with wood particles to fabricate a wood composite (WP/HTP) by hot pressing at 120°C. The hyperbranched structure and multiple hydrogen bonds of the adhesive minimize steric hindrance while facilitating molecular-chain mobility, thereby synergistically accelerating imine-bond exchange. The WP/HTP exhibits outstanding reprocessability, retaining 100% of its mechanical properties after three cycles of reprocessing. Meanwhile, the reprocessed WP/HTP exhibits a modulus of rupture (MOR) of 89 MPa and a modulus of elasticity (MOE) of 5.2 GPa, far surpassing those of current commercial EWCs, which typically exhibit recovery rates of 3%-18%, MOR of 1-5 MPa, and MOE of 0.1-0.8 GPa. This study provides a practical strategy for fabricating strong, reprocessable EWCs for advanced manufacturing and represents a fundamental approach to addressing the wood-waste problem.