Bulk superhydrophobility of wood via in-situ deposition of ZnO rods in wood structure

Abstract Bulk superhydrophobic wood can improve the anti-abrasion performance and durability of wood during application. However, the fabrication of bulk superhydrophobic wood remains challenging, especially it is difficult to realize the superhydrophobicity of wood internal surfaces (cross section and longitudinal section). In this study, the robust bulk superhydrophobic wood was prepared by combining hydrothermal method and vacuum impregnation method. First, zinc oxide rods were formed in situ using a hydrothermal method and vacuum impregnation method to construct a micro/nano rough structure in pristine wood. Then, hydroxyls on the wood cell and zinc oxide surface were substituted with long-chain alkyl to endow wood with low surface energy. The characterization results from morphology, composition and elemental analysis illustrates that zinc oxide rods form in the wood microstructure surfaces and ensure bulk superhydrophobic performance after long-chain hydrophobic group treatment. The contact angle of the treated wood can reach 155°. The surface contact angle is maintained at approximately 150° in 180 s after sawing and abrasion, stating that the superhydrophobic properties exist throughout wood entire structure along with excellent wear resistance. After treatment with different reagents, the contact angle of modified wood is maintained around 150°, indicating great chemical durability. These treatment methods can provide an inspiration to improve the stability and durability of superhydrophobic wood during its utilization, with the potential to be applied in wood manufacturing.