Wettability performance and physicochemical properties of UV exposed superhydrophobized birch wood

The effect of prolonged ultraviolet (UV) irradiation on the performance of superhydrophobized birch and acetylated birch wood was investigated. The surface modification of the wood was based on a newly developed method using silicone nanofilaments. The combination of surface modification and acetylation of wood showed good wetting resistance also after 600 h of UV exposure, with water contact angles greater than 140° and water uptake 30 times lower by weight than that of the non-surface-modified wood as determined by multicycle Wilhelmy plate measurements. Scanning electron microscopy images revealed that the silicone nanofilaments can still be observed on the wood samples after UV irradiation. The surface-modified wood samples exhibited significant color change after UV exposure. FTIR spectra showed that lignin was degraded on both the non-surface-modified wood surfaces and the wood surface-modified with the silicone nanofilaments.