Hydrophobic and decay-resistant green building wood modified by aromatic aldehydes based on Schiff base

The wood used for construction should be able to cope with complex environments, especially water and decay fungi. To enhance the wood’s decay resistance and hydrophobicity, aromatic aldehydes such as vanillin, cinnamaldehyde, syringaldehyde, or protocatechualdehyde were grafted onto wood. The poplar (Populus tomentosa Carr.) wood was impregnated with (3-aminopropyl) triethoxysilane (APTES) to aminate its cell wall, and then aromatic aldehydes were grafted onto the aminated wood through a Schiff base reaction. The findings indicated that this technique enhanced the leaching resistance of aromatic aldehydes in the wood. Furthermore, the durability level of wood grafted by vanillin or cinnamaldehyde was very durable (mass loss<5 %) even after the leaching test. Modified wood has hydrophobicity, manifested by strong anti-swelling efficiency (ASE), low equilibrium moisture content (EMC), and high water contact angle (>90°, air-dried) in 65 % relative humidity and saturated environments. The characterization of modified wood and its model compounds indicated that aromatic aldehydes were grafted onto the hydroxyl groups of wood through Schiff base under the mediation of APTES. This study obtained an outdoor green building wood with hydrophobic and decay resistance for outdoor use and expanded the application of aromatic aldehydes in wood.