| 摘要: | 近年來，表面潤濕性的研究已經引起人們的關注，由於其廣泛的應用，如自潔，抗菌和抗霧等。因此了解和控制固體材料表面的潤濕性是非常重要的。雖然金屬氧化物材料表面的潤濕性目前已經被廣泛研究，然而，在不同實驗條件下所造成金屬氧化物表面擁有不同潤濕性之確切機制尚不明確。
本研究中，各式金屬氧化物薄膜和奈米線是由純金屬薄膜經熱氧化所製備而成。經不同實驗處理後之金屬氧化物薄膜的表面形貌、晶體結構、化學組成及表面潤濕性的轉換機制可藉由SEM、AFM、XRD、TEM、ATR-FTIR與水滴接觸角量測來進行一系列的分析與探討。並可發現，所有經熱氧化處理後之金屬氧化物薄膜表面為親水，經室溫下短時間抽真空與放置於大氣環境下數天，表面之水滴接觸角逐漸上升轉換成疏水性質，而奈米結構會增強其親疏水之效應。由上述結果，利用高溫退火及室溫下抽真空便能夠使得奈米材料表面擁有快速且可調變的的潤濕特性。
除此之外，本研究也利用二氧化矽及金薄膜針對潤濕性質進行一系列之探討，發現其表面親疏水特性與先前之金屬氧化物有相同的潤濕性。從實驗結果推測可逆之潤濕性轉換可能是由於表面狀態不同。經氧氣退火後，表面會產生許多的缺陷像是氧原子之懸鍵等使表面具有高的表面自由能，而有親水之表面特性。然而，由於此表面的缺陷非常不穩定，放置於大氣環境下會漸漸脫附或與相鄰之懸鍵相互鍵結，表面形成較穩定狀態，使得表面疏水，然而若進行抽真空之處理，會加速表面之缺陷脫附，並可快速由親水轉變為疏水。
;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. |
