Nees Institute, University of Bonn, Meckenheimer Allee 170, 53115 Bonn, Germany.
Beilstein J Nanotechnol. 2011;2:152-61. doi: 10.3762/bjnano.2.19. Epub 2011 Mar 10.
Lotus leaves have become an icon for superhydrophobicity and self-cleaning surfaces, and have led to the concept of the 'Lotus effect'. Although many other plants have superhydrophobic surfaces with almost similar contact angles, the lotus shows better stability and perfection of its water repellency. Here, we compare the relevant properties such as the micro- and nano-structure, the chemical composition of the waxes and the mechanical properties of lotus with its competitors. It soon becomes obvious that the upper epidermis of the lotus leaf has developed some unrivaled optimizations. The extraordinary shape and the density of the papillae are the basis for the extremely reduced contact area between surface and water drops. The exceptional dense layer of very small epicuticular wax tubules is a result of their unique chemical composition. The mechanical robustness of the papillae and the wax tubules reduce damage and are the basis for the perfection and durability of the water repellency. A reason for the optimization, particularly of the upper side of the lotus leaf, can be deduced from the fact that the stomata are located in the upper epidermis. Here, the impact of rain and contamination is higher than on the lower epidermis. The lotus plant has successfully developed an excellent protection for this delicate epistomatic surface of its leaves.
荷叶已经成为超疏水和自清洁表面的标志，并催生了“荷叶效应”的概念。尽管许多其他植物也具有几乎相同接触角的超疏水表面，但荷叶在其疏水性的稳定性和完美性方面表现更好。在这里，我们比较了荷叶与其竞争者的微观和纳米结构、蜡的化学成分以及机械性能等相关特性。很快就会发现，荷叶的上表皮已经进行了一些无与伦比的优化。乳突的非凡形状和密度是表面与水滴之间接触面积极大减少的基础。非常小的表皮蜡质管的特殊密集层是其独特化学成分的结果。乳突和蜡质管的机械坚固性减少了损坏，是疏水性完美和耐用的基础。荷叶的优化，特别是上表面的优化，可以从气孔位于上表皮这一事实中推断出来。在这里，雨水和污染的冲击比在下表皮更高。因此，荷叶植物已经成功地为其叶片的这种精致的叶表提供了出色的保护。
