Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

• Sławomir Boncel,
• Krzysztof Z. Walczak and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2011, 2, 311–317, doi:10.3762/bjnano.2.36

• allows us to qualify the herein considered HACNTs film as a “superhydrophobic” material [27]. In contrast, an unexpected behaviour in the series of aqueous solutions was observed for sucrose, which slowly, but entirely, infiltrated the HACNT film. Theoretically, two requirements for a successful

Hierarchically structured superhydrophobic flowers with low hysteresis of the wild pansy (Viola tricolor) – new design principles for biomimetic materials

• Anna J. Schulte,
• Damian M. Droste,
• Kerstin Koch and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 228–236, doi:10.3762/bjnano.2.27

• leaves (petals) of many plants are superhydrophobic, but water droplets do not roll-off when the surfaces are tilted. On such surfaces water droplets are in the “Cassie impregnating wetting state”, which is also known as the “petal effect”. By analyzing the petal surfaces of different species, we

• discovered interesting new wetting characteristics of the surface of the flower of the wild pansy (Viola tricolor). This surface is superhydrophobic with a static contact angle of 169° and very low hysteresis, i.e., the petal effect does not exist and water droplets roll-off as from a lotus (Nelumbo nucifera

• superhydrophobic, low adhesive surface design, which combines the hierarchical structuring of petals with a wetting behavior similar to that of the lotus leaf. Keywords: anti-adhesive; petal effect; petal structures; polymer replication; superhydrophobic; Introduction Plant surfaces provide a large diversity of

Superhydrophobicity in perfection: the outstanding properties of the lotus leaf

• Hans J. Ensikat,
• Petra Ditsche-Kuru,
• Christoph Neinhuis and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 152–161, doi:10.3762/bjnano.2.19

• 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

• with contact angles >150° and their surface morphologies. Many studies, in which the properties of lotus leaves were compared with those of other superhydrophobic plants, have shown the superiority of the upper side of the lotus leaf. A standard tool for the determination of wettability or water

• repellency is the measurement of the static contact angle by the ‘sessile drop’ method. Neinhuis and Barthlott (1997) [7] for example, measured contact angles on the lotus leaf of 162°, which are among the highest of the compared species, but many other (43%) of the tested superhydrophobic plants also showed

Capillary origami: superhydrophobic ribbon surfaces and liquid marbles

• Glen McHale,
• Michael I. Newton,
• Neil J. Shirtcliffe and
• Nicasio R. Geraldi

Beilstein J. Nanotechnol. 2011, 2, 145–151, doi:10.3762/bjnano.2.18

• wrapping and relate it to the same transition condition known to apply to superhydrophobic surfaces. The results are given for both droplets being wrapped by thin ribbons and for solid grains encapsulating droplets to form liquid marbles. Keywords: capillary origami; Cassie; contact angle

• ; superhydrophobic; Wenzel; Introduction In wetting, the usual implicit assumption is that a solid substrate is sufficiently thick or rigid, that it does not deform or change shape due to the interfacial forces that arise when it contacts a droplet of a liquid, however, in many natural systems this is not the case

• superhydrophobic surface [18][19]. Results and Discussion 1. Droplet wrapping theory To assess whether it is energetically favourable for a liquid to become wrapped in a solid we consider the change in interfacial energy as the solid–vapor interface is replaced by a solid–liquid interface together with the

Superhydrophobic surfaces of the water bug Notonecta glauca: a model for friction reduction and air retention

• Petra Ditsche-Kuru,
• Erik S. Schneider,
• Jan-Erik Melskotte,
• Martin Brede,
• Alfred Leder and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 137–144, doi:10.3762/bjnano.2.17

• Biomechanics, Christian-Albrechts-University of Kiel, Am Botanischen Garten 1–9, Kiel, 24098, Germany Lehrstuhl Strömungsmechanik, Universität Rostock, Albert Einstein Str. 2, Rostock, 18051, Germany 10.3762/bjnano.2.17 Abstract Superhydrophobic surfaces of plants and animals are of great interest for

• biomimetic applications. Whereas the self-cleaning properties of superhydrophobic surfaces have been extensively investigated, their ability to retain an air film while submerged under water has not, in the past, received much attention. Nevertheless, air retaining surfaces are of great economic and

• the air film on most superhydrophobic surfaces usually lasts no longer than a few days, a few semi-aquatic plants and insects are able to hold an air film over a longer time period. Currently, we found high air film persistence under hydrostatic conditions for the elytra of the backswimmer Notonecta

Biomimetic materials

• Wilhelm Barthlott and
• Kerstin Koch

Beilstein J. Nanotechnol. 2011, 2, 135–136, doi:10.3762/bjnano.2.16

• ) and radiation (e.g., sunlight). Boundary layers and, in particular, superhydrophobic surfaces and their interactions with the environment were thus the focus of this Thematic Series on Biomimetic materials. The most interesting phenomena happen on boundary layers: from the biosphere at the boundary

Biomimetics inspired surfaces for drag reduction and oleophobicity/philicity

• Bharat Bhushan

Beilstein J. Nanotechnol. 2011, 2, 66–84, doi:10.3762/bjnano.2.9

• animals, and seashells with properties of commercial interest. Certain plant leaves, such as lotus (Nelumbo nucifera) leaves, are known to be superhydrophobic and self-cleaning due to the hierarchical surface roughness and presence of a wax layer. In addition to a self-cleaning effect, these surfaces with

• superhydrophobic, self-cleaning, low adhesion, and drag reduction surfaces Drag reduction in fluid flow is of interest in various commercial applications. These include transportation vehicles and micro/nanofluidics based biosensor applications [3]. To reduce pressure drop and volume loss in micro/nanochannels

• hydrophobicity using a dynamic AFM method [16][33]. Data on one hydrophilic, one hydrophobic, and one superhydrophobic surface are presented in Table 2. Mica was taken as the hydrophilic surface. Hydrophobic and superhydrophobic surfaces were fabricated by deposition of evaporated plant wax on smooth epoxy