Highly hydrophobic and self-cleaning bulk wood prepared by grafting long-chain alkyl onto wood cell walls

Highly hydrophobic bulk wood was successfully prepared by grafting long-chain octadecyl isocyanate (OTI) onto wood cell walls via a urethane linkage. The resulting wood was highly hydrophobic and showed significantly reduced surface free energy. The microstructure and chemical composition of the untreated and treated wood were characterized using the scanning electron microscopy, energy-dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy. The hydrophobic property of the wood was characterized using contact angle measurements. The mechanical and physical properties as well as the chemical durability of the highly hydrophobic wood were evaluated. The results suggested that the resultant OTI-treated wood presented fairly low surface free energy, high hydrophobicity even in the wood core, and excellent stability and durability against chemical corrosion and mechanical abrasion. Furthermore, the physical properties, including self-cleaning, dimensional stability, and water uptake, were significantly improved in the treated wood.