复合SiO_2粒子涂膜表面的超疏水性研究

Study on Superhydrophobicity of Composite Silica Film Surface

采用溶胶-凝胶法制备不同粒径和形状的SiO_2粒子,并利用氟硅氧烷的表面白组装功能制备了具有仿生类"荷叶效应"的超疏水涂膜.通过原子力显微镜、扫描电镜和水接触角的测试对膜结构及性能进行了表征,探讨了SiO_2粒子的粒径和形状对材料微观结构、表面粗糙度和疏水性能的关系.结果表明,含单一粒径涂膜表面水接触角符合Wenzel模型;而复合粒子构成了符合Cassie模型的非均相界面,单纯的粗糙度因子不能反映水接触角的变化,复合粒子在膜表面的无规则排列赋予涂膜表面不同等级的粗糙度,使得水滴与涂膜表面接触时能够形成高的空气捕捉率和较小的粗糙度因子,这与在涂膜表面能形成自组装分子膜的氟硅氧烷共同作用赋予了涂膜超疏水性能.

A superhydrophobic surface originated from strawberry-like or quincunx-shaped composite silica particles modified with fluorosiloxane was obtained. Different kinds of silica particles and fluorosiloxane were used for controlling surface morphology and chemistry, respectively. The dual size particles are obtained by utilizing the graft of different modified silica particles with epoxy functional group and amine functional group. This makes the surface of film form a composite interface to have irregular binary structure which plays an essential role in trapping air between the substrate surface and the liquid droplets to be necessary for high contact angle and low contact angle hysteresis. The maximum contact angle for water on the composite-paticles film is about （174.2±2）° and the contact angle hysteresis is close to 0°. It is shown that the hierarchical irregularly structure with a low roughness factor and high air-trapped ratio is indispensable for superhydrophobic surface by comparing the surface morphologies, roughness and the wettability on the surface of films containing different structural silica particles.