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Lotus-Effect®: Biomimetic super-hydrophobic surfaces and their application

Wilhelm Barthlott ,  Henning Immink 

University of Bonn, Nees-Institute for Biodiversity of Plants, Meckenheimer Allee 170, Bonn 53115, Germany

Abstract

Biological surfaces exhibit a large diversity of structures. Especially the cuticles of many plant species are not smooth but microstructured, often additionally covered with wax crystals in the nanometer-dimension. This combination of micro- and nanostructures, together with the hydrophobic chemistry of the waxes, produces a fascinating phenomenon defined as super-hydrophobicity: Water droplets on these surfaces exhibit contact angles exceeding 140°. Due to the reduced contact area dirt particles cannot adhere and are removed by running water. This property is called “self-cleaning”. The principles of this self-cleaning effect were successfully applied to technical prototypes. The technical conversion was patented and the trade mark Lotus-Effect® was introduced. In the mid-1990s a large cooperation project started with industrial partners. Since then several Lotus-Effect® products have been marketed: a facade paint and a rendering by Sto, a coating for glass and metal surfaces by Ferro, a spray and a nano-particle powder (Aeroxide LE®) for multipurpose applications by Evonik. In 2005 a new project linked with Lotus-Effect® got under way. It focuses on floating plants and semiaquatic animals which have surface structures enabling them to retain an air film under water. A first textile prototype based on the principles of these structures has already been developed. A major target of this project is to develop surfaces that create stable underwater air films. Such films applied in ships and pipelines result in significant drag reduction and yield considerable savings of energy. Experiments with a biomimetic prototype on the hull of a model ship showed a drag reduction of up to 10 percent. Further information: www.lotus-effect.com

 

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Related papers

Presentation: Invited oral at E-MRS Fall Meeting 2008, Symposium H, by Henning Immink
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-09 14:06
Revised:   2009-06-07 00:48