King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), and Biological and Environmental Science and Engineering (BESE) Division, Thuwal, 23955-6900, Saudi Arabia.
ACWA Power, KAUST ACWA Power Center of Excellence, 4700 King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
Sci Rep. 2020 May 13;10(1):7934. doi: 10.1038/s41598-020-64345-1.
Superomniphobic surfaces, which repel droplets of polar and apolar liquids, are used for reducing frictional drag, packaging electronics and foods, and separation processes, among other applications. These surfaces exploit perfluorocarbons that are expensive, vulnurable to physical damage, and have a long persistence in the environment. Thus, new approaches for achieving superomniphobicity from common materials are desirable. In this context, microtextures comprising "mushroom-shaped" doubly reentrant pillars (DRPs) have been shown to repel drops of polar and apolar liquids in air irrespective of the surface make-up. However, it was recently demonstrated that DRPs get instantaneously infiltrated by the same liquids on submersion because while they can robustly prevent liquid imbibition from the top, they are vulnerable to lateral imbibition. Here, we remedy this weakness through bio-inspiration derived from cuticles of Dicyrtomina ornata, soil-dwelling bugs, that contain cuboidal secondary granules with mushroom-shaped caps on each face. Towards a proof-of-concept demonstration, we created a perimeter of biomimicking pillars around arrays of DRPs using a two-photon polymerization technique; another variation of this design with a short wall passing below the side caps was investigated. The resulting gas-entrapping microtextured surfaces (GEMS) robustly entrap air on submersion in wetting liquids, while also exhibiting superomniphobicity in air. To our knowledge, this is the first-ever microtexture that confers upon intrinsically wetting materials the ability to simultaneously exhibit superomniphobicity in air and robust entrapment of air on submersion. These findings should advance the rational design of coating-free surfaces that exhibit ultra-repellence (or superomniphobicity) towards liquids.
超疏液表面能排斥极性和非极性液体的液滴，可用于减少摩擦阻力、包装电子和食品以及分离过程等。这些表面利用的全氟碳化合物既昂贵又易受物理损伤，在环境中的持久性也很长。因此，人们希望从常见材料中获得超疏液性的新方法。在这种情况下，由“蘑菇状”双复凹柱（DRP）组成的微纹理已被证明能排斥空气中的极性和非极性液体，而与表面组成无关。然而，最近的研究表明，DRP 在浸入液体时会立即被液体渗透，因为虽然它们可以从顶部牢固地防止液体吸入，但它们很容易受到侧向吸入的影响。在这里，我们通过从土壤昆虫 Dicyrtomina ornata 的外骨骼中获得的生物灵感来弥补这一弱点，外骨骼包含具有蘑菇状帽的立方二次颗粒。为了进行概念验证演示，我们使用双光子聚合技术在外延的 DRP 阵列周围创建了仿生支柱的边界；还研究了另一种变体，其中一个短壁从侧面帽下方通过。由此产生的气体捕获微纹理表面（GEMS）在浸入润湿液体时能牢固地捕获空气，同时在空气中也表现出超疏液性。据我们所知，这是第一个赋予本征润湿材料同时在空气中表现出超疏液性和浸入时牢固捕获空气的能力的微纹理。这些发现应该会推动无涂层表面的合理设计，这些表面对液体表现出超斥力（或超疏液性）。
