Photoresponsive wettability switching of TiO2-coated micropillar arrays with different geometries of overhang roofs
Photoresponsive wettability switching of TiO2-coated micropillar arrays with different geometries of overhang roofs
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DOI：
10.1049/mnl.2017.0121
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发表时间：
2017-08
影响因子：
1.3
通讯作者：
Taizou Kobayashi;H. Maeda;S. Konishi
中科院分区：
文献类型：
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作者：
Taizou Kobayashi;H. Maeda;S. Konishi
在这项工作中，微柱阵列结构与悬垂屋顶，增加了二氧化钛光响应润湿性的切换范围，已经制造。当液滴在TiO 2表面的接触角（θ TiO 2）大于悬顶与微柱垂直轴之间的几何角（θ）时，由于液-气界面向柱顶后退，液滴呈现Cassie-Baxter超疏水状态。由于TiO 2的光致超亲水性，当TiO 2的θ值小于λ时，在较大的微柱阵列表面积处，Cassie-Baxter态可以转变为Wenzel态。具有小θ的金红石TiO 2涂层微柱阵列表现出更快的从Wenzel态到Cassie-Baxter态的反向润湿性转变，尽管在黑暗中θ TiO 2增加相对较小。此外，润湿性反转时间从180分钟缩短到6分钟后，减少从51°到9°的润湿性反转。
In this work, micropillar array structures with overhang roofs which increase the switching range of the TiO2 photoresponsive wettability, have been fabricated. The liquid droplet placed on the micropillar array exhibits the Cassie–Baxter superhydrophobic state because of the receding of the liquid–air interface to the pillar top, when its contact angle (θ TiO2) on the TiO2 surface exceeds than the geometrical angle (ψ) between the overhang roof and the vertical micropillar shaft. The Cassie–Baxter state can be transformed into the Wenzel state at a relatively large surface area of the micropillar array when the magnitude of θ TiO2 becomes smaller than ψ after ultraviolet irradiation due to the photoinduced superhydrophilicity of TiO2. The rutile TiO2-coated micropillar array with a small ψ exhibits faster reverse wettability transformation from the Wenzel state to the Cassie–Baxter state despite the relatively small θ TiO2 increase in the dark. In addition, the wettability reversal time was shortened from 180 to 6 min after decreasing ψ from 51° to 9°.