Aldehyde-enabled interfacial engineering of lignocellulosic nanofibrils and wood surfaces for reliable bio-based wood bonding.

The development of high-performance and environmentally friendly biomass wood adhesives is of great importance for achieving green and sustainable development in the wood industry. Here, we introduce an aldehyde-enabled interfacial engineering based on periodate oxidation applied to both lignocellulosic nanofibrils (LCNF) adhesive and wood substrate, yielding aldehyde-functionalized LCNF (Ald-LCNF) and aldehyde-activated wood surfaces (Ald-Wood), respectively. The Ald-LCNF adhesive retained a nanoscale fibrillar network while providing abundant aldehyde groups, and the Ald-Wood offered complementary reactive sites. Upon hot-pressing, the adhesive penetrated into wood microstructures and formed an integrated bonding interphase through physical entanglement, hydrogen bonding, and aldehyde-mediated interfacial reactions, potentially involving hemiacetal/acetal formation, which delivered high-strength and water-resistant bonding. Specifically, three-layer plywood prepared under this strategy exhibited excellent bonding performance, with the highest dry and wet shear strengths reaching 4.38 MPa and 1.56 MPa, respectively. Notably, the strategy was applicable to multiple wood species, and seven-layer eucalyptus plywood exhibited MOE and MOR values of 7300 MPa and 47.8 MPa, meeting the requirements of GB/T 9846-2015. This study provides a novel approach for the development of bio-based, no-added-formaldehyde, high-performance wood composites.