以机械高速搅拌法制备了具有草莓结构的CaCO3/S iO2复合粒子,并对其进行了表面修饰改性.利用聚硅氧烷的自组装功能,将制备的复合粒子与硅氧烷一起制备了具有“荷叶效应”的超疏水涂层,静态水接触角达169°,滚动角约为2°.通过扫描电镜观察涂层的表面微观形貌,发现该涂层具有微米-纳米相结合的双层粗糙结构.微米凸起的粒径在2~3μm左右,纳米凸起的粒径约为200nm左右,与荷叶具有类似的结构排布方式.通过原子力显微镜和接触角的测试,探讨了表面微观结构、涂层粗糙度和涂层疏水性能之间的关系.结果表明:复合粒子构成的非均相界面的水接触角符合Cassie模型.复合粒子赋予涂层的双微观粗糙结构与自组装成膜硅氧烷的低表面能的协同效应,使涂层具有了优良的超疏水性能.
A superhydrophobic CaCO3/SiO2 composite surface coating, with a very high water contact angle (WCA) of 169° and a small sliding angle (SA) of 2°, was prepared by means of self-assembly function of polydimethylsilioxane (PDMS). Dual-size surface roughness, which mimicked the surface topology of the lotus leaf, was originated from well-defined CaCO3/SiO2 raspberry-like particles which were prepared by violent stirring and surface modification. The coating surface morphologies were observed with scanning electron microscope. Roughness and WCA were measured with atom force microscope and WCA tester, respectively. It is found that there are many mieroeonvexities with binary structure uniformly distributed on the surface lower of the film with diameter of about 2 to 3 μm and nanoeonvexities or submicroconvexities on the atop surface layer of the coating with diameter of about 200nm, and the surface microstrueture is similar to that of lotus surface. Relationships between the surface mierostructure, roughness and the wettability of the surface coating are discussed. The possible reason for the excellent superhydrophobic properties on the coating surface is due to co-effect of forming an appropriate surface roughness with well-defined composite particles and the low surface energy of PDMS.