Layer-by-layer Deposition of TiO2 Nanoparticles in the Wood Surface and its Superhydrophobic Performance

A hydrophilic wood surface was transformed to become superhydrophobic by layer-by-layer (LbL) assembly of polyelectrolyte/titanium dioxide (TiO2) nanoparticles multilayers and subsequent hydrophobic modification with 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane (POTS). The chemical composition of the wood samples before and after treatment was characterized by energy dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These analyses showed that a highsurface-roughness film of TiO2 nanoparticles deposited by LbL became combined on the wood surface with a low-surface-energy thin layer of POTS. The microstructure and the hydrophobicity of the wood samples were analyzed by scanning electron microscope (SEM) and contact angle measurements, respectively. The morphology and the values of water contact angle (WCA) demonstrated that the reaction pH and number of self-assembled layers were the main factors affecting hydrophobic wood samples. After assembly with 5 or more multilayers, the wood surface exhibited excellent superhydrophobicity with the highest WCA of 161°.