| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 104 === Recently, the research of surface wettability has attracted increasing interest due to its wide variety of applications, such as self-cleaning, antibacterial, and anti-fogging. Therefore, understanding and controlling the surface wettability of solid materials is absolutely essential. The surface wettability of metal oxide materials has been studied extensively. However, the exact mechanism of the wetting behaviors of metal oxide surfaces under different experimental conditions is not yet well defined.
In this study, various metal oxide thin films and nanowires were fabricated by thermal oxidation of pure metal films. The evolutions of surface morphology, crystal structure, chemical composition, and surface wettability of metal oxide films after different experimental treatments have been investigated by SEM, TEM, ATR-FTIR, and water contact angle measurements. The obtained results showed that all the as-oxidized metal oxide thin films were hydrophilic in nature. However, their surface wettability would gradually transform from hydrophilic to hydrophobic with increasing the storage time under atmospheric ambient or vacuum environment at room temperature. The reversible switching of the surface wettability of metal oxide films can be accomplished by alternate annealing in oxygen ambient and storage in vacuum or in atmosphere.
The surface wettability were also investigated in this study, and it was found that the silicon dioxide and gold films have the same wetting behaviors as those of metal oxides. The reversible wettability conversion is likely due to the surface state variety. The oxygen related defects and oxygen adatoms created by oxygen annealing make the surfaces have high surface free energy, in which results hydrophilic surfaces. However, these defects were not stable. When the storage time is long enough, the surface will return to its hydrophobic state.
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