Sol-Gel Deposition of TiO<sub>2</sub> Nanocoatings on Wood Surfaces with Enhanced Hydrophobicity and Photostability
2014
Wang, Xiaoqing | Liu, Sichen | Chang, Huanjun | Liu, Junliang
To enhance the resistance of wood against weathering, Chinese fir (<i>Cunninghamia lanceolata</i>) wood was modified via a two-step process by first growing titanium dioxide (TiO<sub>2</sub>) 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 TiO<sub>2</sub> 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 TiO<sub>2</sub> coatings also exhibited strong absorption of UV radiation and imparted the underlying wood substrate with enhanced photostability, which was highly dependent on the TiO<sub>2</sub> loadings in the coatings.
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