On the surface of petals of the rose water drops adhere particularly well.
Reading Chinese scientists have discovered the special surface properties of rose petals: The extreme attraction of water on the petal comes from creaky outgrowths on the surface of the leaves, each of which is roughened by fine wrinkles, the researchers found. Such a surface could even be artificially produced by the scientists in their experiments. The material with the "anti-lotus effect" could be used in biotechnology. Known by numerous applications in the art is the lotus effect, which had first described the German researchers on leaves of the lotus plant. In the effect, there is an extreme repulsion of water on the surface, which leads to the beading of the drops and thus ideally for the self-cleaning of the material. Corresponding coatings are already available, for example, for roof tiles or glass facades. The opposite effect has been studied by the Chinese researchers on the petals of red roses, which are so attractive to water that a drop even holds when the leaf is turned over and it hangs down.

The extremely hydrophilic property comes from a very special surface pattern, the Chinese researchers now found out when they examined rose petals under an electron microscope. Accordingly, the surface consists of a uniform pattern of elevations, which are about 7 thousandths of a millimeter high and have a diameter of about 16 thousandths of a millimeter. Each of these elevations is again covered with a relief of fine folds and grooves. With this combination of humps and grooves strong adhesion forces can build up on the water, the calculations showed.

The researchers also succeeded in their investigations to make the impression of a rose petal. They used this template to make artificial films with a rose petal structure, which showed similar attractive properties in experiments with water droplets. The scientists hope to use them to produce biotechnology materials. These could be used, for example, for cleaning surfaces.

Lin Feng (Tsinghua University, Beijing) et al .: Langmuir, vol. 24, p. 4114 ddp / science.de? Ulrich Dewald ad

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