Fractal Surfaces of Molecular Crystals Mimicking Lotus Leaf with Phototunable Double Roughness Structures

Abstract

Double roughness structure, the origin of the lotus effect of natural lotus leaf, was successfully reproduced on a diarylethene microcrystalline surface. Static superwater-repellency and dynamic water-drop-bouncing were observed on the surface, in the manner of natural lotus leaves. Double roughness structure was essential for water-drop-bouncing. This ability was not observed on a single roughness microcrystalline surface showing the lotus effect of the same diarylethene derivative. The double roughness structure was reversibly controlled by alternating irradiation with UV and visible light.

Photochromic Crystalline Systems Mimicking Bio‐Functions

“…Recently, it has become possible to control the fine motion of a water droplet by using surface structure . Here, we would like to show that it is possible to understand the water‐bouncing and ‐sliding phenomena based on the model experiments’ characteristic scales of a double‐roughness surface and on simple theory . To estimate this ability, we performed a water‐droplet‐bouncing experiment from a height of 1.8 mm on a diarylethene microcrystalline surface with double‐roughness structures and then compared the results with those of diarylethene with a single‐roughness structure and natural lotus leaf (Figure ).…”

“…[23] Here, we would like to show that it is possible to understand the water-bouncing and -sliding phenomena based on the model experiments' characteristic scales of ad ouble-roughness surface and on simple theory. [24,25] To estimate this ability,w ep erformed aw aterdroplet-bouncing experiment from ah eight of 1.8 mm on ad iarylethene microcrystalline surface with double-roughness structures and then compared the resultswith those of diarylethene with as ingle-roughness structure and natural lotus leaf ( Figure 10). Water droplets bounced on the surfaces of both lotus leaf and the diarylethene microcrystallines urface with double-roughness structures;h owever,n ob ouncing waso bserved on ad iarylethene microcrystallines urfacew ith singleroughnessstructure.…”

Antifouling Effect on Biomimetic Metamaterial Surfaces

“…In this paper, biomimetic technologies with oil repellent and antifouling effects are focused. It is known that the surface structure of the snail shell has an oil repellent effect by superhydrophilicity [5][6][7][8][9][10]. Semiconductor technologies, are applied to mimic the snail shells structure for demonstrating the oil repellent effect.…”

Computational Intelligence‐Assisted Understanding of Nature‐Inspired Superhydrophobic Behavior

“…Among these, self‐cleaning is one of the most significant applications 4. The lotus leaf is an excellent example of a superhydrophobic surface found in nature, upon which water droplets will exist in a spherical form rather than wetting the leaf by spreading out or staining the surface of the leaf; when such superhydrophobic surfaces are tilted slightly, sessile water droplets will roll off easily without leaving any trace of wetting, while the rolling motion of the droplet collects dirt from the surface, in such a way that lotus leaves can be described as “self‐cleaning.”5 To achieve superhydrophobicity, the lotus leaf surface has micrometer‐scale morphology combined with nanoscaled waxy fibrils to enable an extremely low affinity to water droplets 6. On such surfaces water droplets are able to bounce, and the contact time between bouncing water droplets and superhydrophobic surfaces becomes a key factor of their dynamic characterization 7.…”