lotus effect otherwise superhydrophobicity (rus. эффект лотоса otherwise лотос-эффект; супергидрофобность) — the effect of almost absolute liquid repellency of a solid’s surface due to the topographic features of that surface at micro-nanoscale, which leads to a reduced contact area between the liquid and the surface of that solid.

Description

The natural phenomenon of poor wettability and, as a consequence, the surface self-cleaning effect is observed on leaves and flowers of such plants as lotus, lupine etc., as well as insects’ wings. Electron microscopy helped to find that such surfaces have unique surface features in the form of spikes, made of water repellent substances (fig. 1). A water droplet on such a surface has a small contact area and cannot adhere to the surface, rolls down, and takes away the dust, soot, spores of fungi and other surface contamination, leading to the self-cleaning effect. Thus, the interface between a lotus leaf and the water droplet is less than 1% of the total area of the droplet and the contact angle between the leaf surfaces and the droplet can reach 170° (highly water repellent).

Now the lotus effect form the basis for developing materials and coatings with the high water repellency due to the surface structure, including at the nanoscale (fig. 2.).

Illustrations

Fig. 1. Surface texture of a peacock butterfly (Lat. Inachis io) wing. Author: Victor I. B
Fig. 1. Surface texture of a peacock butterfly (Lat. Inachis io) wing. Author: Victor I. Balabanov, Timiriazev Russian State Agroengineering University - Moscow Agricultural Academy.
Рис. 2. Микрофотография супергидрофобной поверхности полипропилена. Авторы: А. А. Елисеев
Рис. 2. Микрофотография супергидрофобной поверхности полипропилена. Авторы: А. А. Елисеев и Р.П. Иванов, Lomonosov Moscow State University, Department of Materials Science.

Author

  • Balabanov Victor I.

Sources

  1. Neinhuis C., Barthlott W. Characterization and distribution of water-repellent, self-cleaning plant surfaces // Annals of Botany. 1997. V. 79. P. 667–677.
  2. Balabanov V.I., Balabanov I.V. Nanotechnology: Truth and Fiction (in Russian). – Moscow: Eksmo, 2010. – 384 p.
  3. Onda T. Super-Water-Repellent Fractal Surfaces // Langmuir. 1996. V. 12. P. 2125–2127.

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