Plant cell wall reconstruction towards enhancing moisture stability and toughness by assembling delignified wood with alkali lignin

Developing a moisture-stable structural material with high toughness is essential for improving the stability of packaging and building materials. Wood is a pervasive structural material with naturally good mechanical properties. However, insufficient moisture stability and toughness compromises its safety and structural requirements. Herein, we constructed a moisture-stable wood veneer with high toughness by assembling the choline chloride-ethanolamine delignified wood with alkali lignin, followed by hot-pressing to densify the material. Lignin can be assembled into the microchannel of the delignified wood as a filler and binder for reducing molecular transportation and increasing internal bonding. The enhanced tensile strength (582.0 MPa) and strain (3.6%) are accompanied by a significant increase in the toughness to 11.1 MJ/m³, which is 37 times higher than that of natural wood. The excellent mechanical property can be preserved to a large extent after retaining in tropic moisture conditions (38 °C, 90% RH) with retention of 66.2% and 60.8% for tensile strength and toughness, respectively. A stable water contact angle on the surface and limited water adsorption of reconstructed wood indicate a lowered water infiltration velocity, suggesting highly improved moisture stability as needed for structural materials.