真空紫外光响应超疏水和超亲水快速可逆转变的ZnO薄膜
Vacuum ultraviolet responded rapid reversible conversion of super-hydrophobicity and super-hydrophilicity of ZnO films
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摘要: 利用简单的低温液相技术,通过氢氟酸(HF)调控反应溶液的pH值,制备了真空紫外光响应的疏水-超亲水快速可逆转变的ZnO薄膜.该薄膜具有类似于芋头叶表面的特征,表面分布着具有纳米级亚结构的ZnO微米球,因而具有超疏水特征(水接触角为151°).在真空紫外光(VUV)照射30min后,薄膜表面显示了超亲水特征(水接触角小于5°);将VUV光照后的薄膜放置在暗室中6d后,薄膜表面又恢复到超疏水特征.VUV的使用及薄膜表面具有的独特微纳米阶层结构,加快了超疏水-超亲水之间的转变.这种快速转变特性,可促进ZnO薄膜在微流体器件上的应用.Abstract: ZnO films, with rapid reversible transition properties of super-hydrophobicity and super-hydrophilicity under vacuum ultraviolet (VUV) irradiation, were prepared by a simple and low-temperature solution method by controlling the pH value with hydrofluoric acid. The surface of the film exhibits hierarchical structure with nanostructure on the micro-spheres mimicking to the taro leaf surface. The fresh film shows the water contact angle (WCA) of 151°,turning into a super-hydrophilic (WCA〈5°) one after 30 min VUV irradiation. The super-hydrophilic film can be recovered to super-hydrophobic through being placed in the dark for 6 d. The wettability of the film can be reversibly switched circularly by the alternation of VUV irradiation and dark storage. The transition from super-hydrophobic to super-hydrophilic is more quickly than that of the past reports due to the use of VUV and the special hierarchical structure of the ZnO film surface. This study is expected to promote the applications of ZnO materials in micro-fluidic devices.