Surface Characterization and Adhesion and Friction Properties of Hydrophobic Leaf Surfaces and Nanopatterned Polymers for Superhydrophobic Surfaces

Superhydrophobic surfaces on metal substrates are often prepared via roughing the surfaces and lowering their surface energy. The superhydrophobic aluminum surface with a water contact angle of 162.5° and rolling angle less than 6° was fabricated via electrochemical etching and re-deposition using the alkalic Na3PO4 electrolyte and then fluorination treating. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results show that the surface consists of the micrometer-scale lumps and protrusions, and many nanometer-scale mastoids are filled in these protrusions. These hierarchical micro/nanometer-scale binary structures, which are similar to the micro-structures of lotus leaf surfaces, play an important role in achieving superhydrophobicity. The main components of the binary geometric structures are Al2O3, AlPO4, and H2O. The effects of the processing time and processing voltage on the macro-morphology were also investigated. The macro-rough structures appeared on the edge of the aluminum surface firstly, and then spread gradually to the entire surface.

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Surface characterization and adhesion and friction properties of hydrophobic leaf surfaces

Ultramicroscopy ◽

10.1016/j.ultramic.2005.10.007 ◽

2006 ◽

Vol 106 (8-9) ◽

pp. 709-719 ◽

Cited By ~ 149

Author(s):

Zachary Burton ◽

Bharat Bhushan

Keyword(s):

Surface Characterization ◽

Leaf Surfaces

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Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.5.93 ◽

2014 ◽

Vol 5 ◽

pp. 812-821 ◽

Cited By ~ 30

Author(s):

Matthias J Mayser ◽

Holger F Bohn ◽

Meike Reker ◽

Wilhelm Barthlott

Keyword(s):

Buoyancy Force ◽

Force Transducer ◽

Superhydrophobic Surfaces ◽

Highly Sensitive ◽

Custom Made ◽

Leaf Surfaces ◽

Air Layers ◽

Novel Method ◽

Good Agreement

Some plants and animals feature superhydrophobic surfaces capable of retaining a layer of air when submerged under water. Long-term air retaining surfaces (Salvinia-effect) are of high interest for biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly sensitive custom made strain gauge force transducer setup. The volume of air held by a surface was quantified by comparing the buoyancy force of the specimen with and then without an air layer. Air volumes retained by the Salvinia-surfaces ranged between 0.15 and 1 L/m2 depending on differences in surface architecture. We verified the precision of the method by comparing the measured air volumes with theoretical volume calculations and could find a good agreement between both values. In this context we present techniques to calculate air volumes on surfaces with complex microstructures. The introduced method also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes.

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The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071107 ◽

1973 ◽

Vol 31 ◽

pp. 132-133 ◽

Cited By ~ 1

Author(s):

R. E. Herfert

Keyword(s):

Surface Characterization ◽

Analytical Techniques ◽

X Ray Diffraction ◽

Depth Of Penetration ◽

X Ray ◽

The Past ◽

Transmission Electron ◽

Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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