Surface Modification of Transparent Wood Composite with Variable Wettability: From Superhydrophilicity to Superhydrophobicity

Abstract Transparent wood composite (TWC) has gained widespread attention in the recent years for its applications in smart buildings, including smart windows and roofs, due to its attractive optical, mechanical, and thermal properties. This study investigates the surface modification of TWC using argon (Ar) and hydrogen (H 2 ) plasma etching treatment and superhydrophobic coating to achieve tunable surface wettability, ranging from superhydrophilicity to superhydrophobicity. In the untreated state, TWC exhibited slight hydrophilicity with a water contact angle of approximately 75°. Immediately after the Ar + H 2 plasma treatment, the TWC surfaces showed hydrophilicity (with contact angle 22.9°–24.7°) arising due to changes in surface microstructure. However, upon 24–36 h of vacuum conditioning, the etched samples displayed a water contact angle of 56.5°. To further induce superhydrophobicity, a superhydrophobic coating was applied on the TWC samples. This resulted in a high water contact angle in the range of 159° with a sliding angle (roll‐off angle) of less than 15° indicating superhydrophobic surface and revealing near lotus leaf effect. The introduction of superhydrophobicity on TWC surfaces would provide additional advantages for outdoor usage by providing water repellency. Field‐emission scanning electron microscopy and atomic force microscopy were used to analyze morphological changes in the sample surfaces before and after treatment and coating. The samples exhibited increased surface roughness in their microstructure. X‐ray diffraction spectra revealed changes in the crystallinity of the structural elements.