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 degrees. 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.