Fabrication of Durable Hydrophobic/Superhydrophobic Wood Using an Alkyl Ketene Dimer by a Simple and Feasible Method.

To improve the hydrophobicity of precious hardwood, a facile sanding pretreatment and alkyl ketene dimer (AKD) modification were performed. After the AKD modification, the wood was highly hydrophobic, and the contact angle was 143°. The increased hydrophobicity could be attributed to the ester bond formed between the wood hydroxyl groups and AKD, which was confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy. Sanding pretreatment could further greatly increase the wood hydrophobicity and render it superhydrophobic, not only in a cross-section but also in the tangential and radial sections. The changed wood surface roughness could be responsible for the increased hydrophobicity, which was confirmed by characterization with a scanning electron microscope (SEM) and a three-dimensional optical microscope. Apart from the improved hydrophobicity, the AKD-modified wood exhibited excellent water, acid, and toluene resistance. After a 12 h immersion, the contact angle did not change significantly, and the acid immersion contributed to an improvement in the hydrophobicity of the wood. Furthermore, the resultant AKD-modified wood exhibited an excellent self-cleaning effect.