Center for BioModular Multiscale Systems for Precision Medicine, Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
Departments of Chemistry and Mechanical Engineering, University of Kansas, Lawrence, KS 66045, United States.
J Colloid Interface Sci. 2020 Aug 15;574:347-354. doi: 10.1016/j.jcis.2020.04.065. Epub 2020 Apr 18.
The superhydrophobic lotus leaf has dual-scale surface structures, that is, nano-bumps on micro-mountains. Large hydrophilic particles, due to its high surface energy and weight, have high affility to substrates and tend to precipitate at the bottom of coating films. Small hydrophobic particles, due to its low surface energy and weight, tends to sit on the top of coating films and form porous structures. To mimic the lotus leaf surface, it may be possible to develop dual-sized particle films, in which small particles are decorated on large particles.
A one-step spin coating of a mixture of dual-sized silica particles (55/200 nm) was used. Epoxy resin was added to improve the adhesion of particle films. The single-sized and dual-sized particle films were compared. The mechanical robustness of particle films was tested by tape peeling and droplet impact.
The novel combination of hydrophobic silica (55 nm) and hydrophilic silica (200 nm) is essential in creating the hierarchical structures. By combining the strong adhesion of hydrophilic silica (bottom of coating film) to polymer substrates and porous structures of hydrophobic silica (top of coating film), we first time report a one-step and versatile approach to create uniform, transparent, robust, and superhydrophobic surface.
具有双重尺度表面结构的超疏水荷叶，即微山上的纳米凸包。由于大亲水性粒子具有较高的表面能和重量，它们对基底具有高亲和力，倾向于沉淀在涂层底部。小疏水性粒子由于其低表面能和重量，倾向于位于涂层表面并形成多孔结构。为了模拟荷叶表面，可能开发出双重尺寸粒子膜，其中小粒子装饰在大粒子上。
采用一步旋涂法制备了双重尺寸二氧化硅粒子（55/200nm）的混合物。加入环氧树脂以提高粒子膜的附着力。比较了单尺寸和双尺寸粒子膜。通过胶带剥离和液滴冲击测试来测试粒子膜的机械强度。
疏水性二氧化硅（55nm）和亲水性二氧化硅（200nm）的新颖组合对于创建分层结构至关重要。通过结合亲水性二氧化硅（涂层底部）与聚合物基底的强附着力和疏水性二氧化硅（涂层顶部）的多孔结构，我们首次报道了一种一步法、通用的方法来创建均匀、透明、坚固且超疏水的表面。
