含氟硅丙烯酸酯乳液超疏水膜中疏水基团的梯度分布与表面微观结构研究

利用含氟疏水基团的梯度分布,结合草莓形纳米SiO2粒子提供的双重粗糙表面,制备了具有类"荷叶效应"的超疏水涂膜,水接触角达(174.2±2)°,滞后角几乎接近0°.通过原子力显微镜、扫描电镜和水接触角的测试对膜表面形貌及疏水性能进行了表征;探讨了其表面微观结构与表面疏水性能的关系.草莓形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,使水滴与涂膜表面接触时能够形成高的空气捕捉率,这种微观结构与疏水基团的梯度分布相结合,赋予了含氟硅丙烯酸酯乳液涂膜表面超疏水性能.

STUDIES ON GRADIENT DISTRIBUTION OF THE HYDROPHOBIC SEGMENT AND SURFACE MICROSTRUCTURE OF THE FLUORO-SILICON-CONTAINING METHACRYLATE SUPER HYDROPHOBIC COATINGS

Superhydrophobic surfaces are currently a subject of great interest and enthusiastic study because of their various important applications.In this paper,the relationships between contact angle,surface roughness and surface morphology were discussed to explore a simple procedure for preparing a superhydrophobic aqueous coating with tunable roughness surface.Transparent hydrophobic films with fluorine gradient distribution have been prepared from methacrylate copolymers modified with fluoroacrylate and siloxane(γ-methacryloxypropyltriisopropoxysilane) in emulsion polymerization.The fluorine gradient distribution resulted from fluorine self-assembled was examined by X-ray photoelectron spectroscopy analysis.The strawberry-like silica particles are obtained by utilizing the graft of different size silica particles modified with epoxy and amine functional groups,respectively.This makes the film form a composite interface with irregular binary structures and a hierarchical roughness to have high air-trapped ratio.The superhydrophobic surface was obtained by making use of silica particles to increase roughness and fluorocopolymer to provide low surface energy.By comparing the difference of water contact angles on the film surfaces between the admixture of fluoroemulsion with the sole diameter silica and that with composite silica particles,it was shown that the large roughness factor is not necessary while the high air-trapped ratio is indispensable.Although the composite silica particles play a vital role in governing the surface wettability,it is necessary to combine with a low surface energy to make a surface superhydrophobic.The composite surface turns from hydrophilic to superhydrophobic only when there is a proper cooperation with the fluorocopolymer having low surface energy,and the water contact angle will decrease when the mass ratio of emulsion to silica exceeds unity because of the filling of interspace on the film surface.The largest contact angle for water on the surface of hybrid film is about(174.2±2)° and the contact angle hysteresis is close to 0°.