Mail M, Moosmann M, Häger P, Barthlott W
Nees Institute for Biodiversity of Plants, University of Bonn , Venusbergweg 22, D-53115 Bonn , Germany.
Philos Trans A Math Phys Eng Sci. 2019 Jul 29;377(2150):20190126. doi: 10.1098/rsta.2019.0126. Epub 2019 Jun 10.
Extreme water repellent 'superhydrophobic' surfaces evolved in plants and animals about 450 Ma: a combination of hydrophobic chemistry and hierarchical structuring causes contact angles of greater than 150°. Technical biomimetic applications and technologies for water repellency, self-cleaning (Lotus Effect) and drag reduction (Salvinia Effect) have become increasingly important in the last two decades. Drag reduction (e.g. for ship hulls) requires the presence of a rather thick and persistent air layer under water. All existing technical solutions are based on fragile elastic hairs, micro-pillars or other solitary structures, preferably with undercuts (Salvinia Effect). We propose and provide experimental data for a novel alternative technology to trap persistent air layers by superhydrophobic grids or meshes superimposed to the solid surface: AirGrids. AirGrids provide a simple and stable solution to generate air trapping surfaces for drag reduction under water as demonstrated by first prototypes. Different architectural solutions, including possible recovery techniques for the air layer under hydrodynamic conditions, are discussed. The most promising target backed by first results is the combination of Air Retaining Grids with the existing microbubble technology. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology (part 2)'.
极端疏水的“超疏水”表面大约在4.5亿年前在动植物中演化形成：疏水化学与分级结构相结合导致接触角大于150°。在过去二十年中，用于防水、自清洁（荷叶效应）和减阻（槐叶萍效应）的技术仿生应用和技术变得越来越重要。减阻（例如用于船体）需要在水下存在相当厚且持久的空气层。所有现有的技术解决方案都基于脆弱的弹性毛发、微柱或其他单独的结构，最好带有底切（槐叶萍效应）。我们提出并提供了一种新型替代技术的实验数据，该技术通过叠加在固体表面的超疏水网格或网眼来捕获持久的空气层：空气网格。空气网格为在水下生成用于减阻的空气捕获表面提供了一种简单而稳定的解决方案，首批原型已证明了这一点。本文讨论了不同的结构解决方案，包括在流体动力学条件下空气层可能的恢复技术。首批结果支持的最有前景的目标是将空气保留网格与现有的微泡技术相结合。本文是主题为“绿色科学与技术的仿生材料和表面（第2部分）”的一部分。
