Novel ultrastrong wood bonding interface through chemical covalent crosslinking of aldehyde-amine

In this work, a new concept for a chemical wood bonding interface is proposed. Through interface tailoring, the synergistic interaction between wood interface and polyamine (PA(xn)' indicating the PA(xn) has x terminal groups) adhesive was created. The bonding strength and water resistance of the proposed chemical wood bonding interface were evaluated. An activated wood interface with abundant -CHO groups was constructed via spraying with an aqueous NaIO4 solution. The lap shear strengths of these activated wood interfaces using PA(4n)' PA(5n)' PA(6n)' PA(7n) adhesives were 0.84, 0.98, 1.85, 1.96 MPa, respectively, after a 4 + 4 + 1'' harsh test (soak the plywood specimens in boiling water for 4.0 h, then dry in oven for 20 h, soak again in boiling water for 4.0 h, and then soak in cold water for 1.0 h). These results indicate super-strong bonding performance and water resistance. In order to explore the bonding mechanism of the proposed chemical wood bonding interface, wood cell walls in the active gluing region of plywood were characterized on the nanoscale using AFM and SEM. XPS was used to clarify the chemical covalent cross-linking reaction between the PAxn adhesive and the activated wood interface. The results demonstrated that the chemical bonding (imine C=N and aminal N-C-N) at the wood: adhesive interface plays a decisive role in the improvement of bonding strength and water resistance. In summary, a novel wood bonding system dominated by adhesive-wood covalent linkages was constructed based on an activated wood interface and specific polyamine adhesives under a relatively low hot-pressing temperature (110 degrees C). This work provides new insights into how to design an unbreakable, moisture-proof, and highly durable bonding interface for wood-based materials.

Automated summary

This work proposes a new concept for a chemical wood bonding interface by tailoring the wood interface and polyamine adhesive. The activated wood interface shows super-strong bonding performance and water resistance through chemical bonding. The study provides new insights into designing an unbreakable and durable bonding interface for wood-based materials.