Sol-Gel Deposition of TiO<sub>2</sub> Nanocoatings on Wood Surfaces with Enhanced Hydrophobicity and Photostability
Keywords:TiO<sub>2</sub>, nanocoatings, hydrophobicity, photostability, wood
AbstractTo enhance the resistance of wood against weathering, Chinese fir (Cunninghamia lanceolata) wood was modified via a two-step process by first growing titanium dioxide (TiO2) nanocoatings on the wood substrate using a sol-gel process followed by low-surface free-energy treatment with hydrolyzed hexadecyltrimethoxysilane (HDTMS). The morphology and chemical composition of the formed coatings were examined by field-emission scanning electron microscopy, energy dispersive X-ray analysis, and Fourier transform IR spectroscopy. Water contact angle (WCA) was used to characterize hydrophobicity. UV-Vis spectroscopy and accelerated weathering were used to evaluate the UV-shielding properties of the nanocoatings and the photostability of the treated wood, respectively. The results showed that the introduction of TiO2 nanoparticles facilitated the generation of a dual-size roughness on the wood substrate, and the long-chain alkyl groups of HDTMS were covalently linked to the surface of the particles. The WCA of the treated wood was improved remarkably up to ≈138° displaying high hydrophobicity. The TiO2 coatings also exhibited strong absorption of UV radiation and imparted the underlying wood substrate with enhanced photostability, which was highly dependent on the TiO2 loadings in the coatings.
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