A novel method to fabricate organic-free superhydrophobic surface on titanium substrates by removal of surface hydroxyl groups

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發表狀態：

Applied Surface Science 479 (2019) 1089–1097

研究團隊：

Hao Wu, Li Xie, Ruitao Zhang, Yuan Tian Suru Liu, Min He, Chao Huang, Weidong Tian

研究內容：

鈦（Ti）及其合金已廣泛用于生物醫學應用，并且表面潤濕性在其應用過程中產生很大差異,特別是接觸角(WCA)>150°的超疏水表面引起了人們的極大興趣。到目前為止，大多數在Ti襯底上制造超疏水表面的方法都會引入具有低表面自由能（SFE）的外部有機物，這些有機物可能會影響Ti表面的固有化學成分，并且長時間暴露會面臨降解的風險,但矛盾的是在沒有有機涂層的情況下，要在Ti基材上實現超疏水表面似乎非常困難，很少有研究報道。本文通過包括陽極氧化、H2O2和時效處理在內的新方法成功地制造了超疏水Ti表面（WCA = 151.9°），在此過程中，沒有引入低SFE的外部有機物。所制備的表面涂有TiO2層，呈現出多孔形貌，其坑洼結構的數量（Ra）約為1.21μm。其機理在于碳氫化合物的吸收和羥基（OH）基團的減少共同改變了Ti表面的固有潤濕性，其中H2O2去除OH基團和時效處理起著至關重要的作用。結果表明，表面微粗糙度和固有潤濕性下降是形成超疏水性的原因，這種新方法可以在不改變Ti / TiO2表面固有性質的情況下實現超疏水性，在生物醫學應用中具有巨大的潛力。

Abstract

Tianium (Ti) and its alloys have been extensively used for biomedical applications and surface wettability makes large differences during their applications. Especially, superhydrophobic surfaces with water contact angle (WCA)>150° are under great interest and are now finding increased use in the biomedical arena. Up to now, most fabrication of superhydrophobic surface on Ti substrates would introduce external organics with low surface free energy (SFE), which could influence the intrinsic chemical components of Ti surface and face the risk of degradation when exposed for a long time. But it seems quite difficult to achieve superhydrophobic surfaces on Ti substrates without organic coating and few researches have been reported. Herein, a superhydrophobic Ti surface (WCA = 151.9°) was successfully fabricated by a novel method including anodization, H2O2 and aging treatment. During this procedure, no external organics with low SFE were introduced. Then surface topography and roughness, 3D morphology, wettability, crystalline structure and chemical components of the as-prepared samples were characterized. The as-prepared surface was coated with a TiO2 layer, and exhibited a porous morphology with numbers of crater structures with roughness value (Ra) about 1.21 μm. It was found the absorption of hydrocarbon and decrease of hydroxyl (OH) groups together changed the intrinsic wettability of Ti surface, where the removal of OH groups by H2O2 and aging treatment played a critical role. The results indicated that surface micro-roughness and declined intrinsic wettability were responsible for the formation of superhydrophobicity. This novel method could achieve superhydrophobicity without changing the intrinsic properties of Ti/TiO2 surface and would have great potential in biomedical applications.