Preparation and characterization of hydrophobic coatings on wood surfaces by a sol-gel method and post-aging heat treatment

摘要

To improve the hydrophobicity and moisture resistance of wood, a hydrophobic coating using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as precursors was prepared on a wood surface via sol-gel and post-aging heat treatment. The effects of the MTES/TEOS molar ratio and aging heat treatment temperature on the properties of the MTES/TEOS coatings based on a co-precursor (M/T-based) were analyzed. The coating structures were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analyzer. The results indicated that a higher MTES/TEOS molar ratio increased the hydrophobicity of the coatings because of a higher silica content or a higher coverage of the surface by methyl groups. However, the hydrolysis-condensation reaction of TEOS decreased when an excessive amount of MTES was used, decreasing the hydrophobicity of the coating. Moreover, with an increase in aging heat treatment temperature, the coated wood improved its resistance to wetting; however, the stability of the M/T-based sol decreased, and the particles agglomerated. Thermogravimetric analysis/infrared spectrometry results showed that the coatings exhibited good heat resistance and enhanced the thermal stability of the wood. Adhesion testing results indicated that the coatings exhibited good adhesion to the wood substrates.