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“Etch and coat” methods, potentially useful for large scale production of superhydrophobic surfaces on metals, have been extended by introduction of a thin 20 nm Au interlayer which allowed thiol surface modifiers to be investigated. Fe, Ti and Zn surfaces modified in this way with a polyfluorothiol generally had lower contact angles, θ, than their silane modified equivalents but were more uniform and reproducible. The higher θ values for silanes appear to be associated with an increased effective roughness that is not seen in the thiol coatings, which follow the underlying surface. For Fe, Ti and Zn, θ increased to a maximum with etching time but then decreased significantly. Electron microscopy of samples etched for long times showed fewer grain boundaries, suggesting that the loss of hydrophobicity was related to reduced roughness. ...
Surface tension in water gives rise to a variety of phenomena some of which, such as the rise of water inside hydrophilic tubes under capillary action or the ability of pond skaters to walk on the surface of water, are so familiar that they seldom excite comment. However, there is still potential for new insights and discoveries to be made in this area. Two recent examples are the discovery that liquid marbles can be prepared by coating solvent droplets with powder and the elucidation of a general mechanism for the attraction of buoyant objects in liquids, the Cheerios effect . Here we report a method for preparing large (up to 0.4 mm diameter) superhydrophobic copper particles and show that these particles, which have extraordinarily large contact angles but are much denser than water, give rise to a range of striking effects, includ...
Much of the recent research on hydrophobic materials has been inspired by the water-repellent nature of lotus leaves (Nelumbo nucifera and N. lutea), which show a double roughness on their surfaces (nanohairs on microbumps) along with a waxy coating.
Superhydrophobic “lotus effect” materials are typically not sufficiently robust for most real world applications because their small surface features are both easily damaged and vulnerable to fouling. Here, a method for preparing a new type of superhydrophobic (θ > 162°) composite material by compression of superhydrophobic metal particles is reported. This material, which has no natural analogue, has low-surface-energy microstructures extending throughout its whole volume. Removing its outer layer by abrasion or cutting deep into it does not result in loss of superhydrophobicity because it merely exposes a fresh portion of the underlying superhydrophobic material. The high contact angle is therefore retained even after accidental damage, and vigorous abrasion can be used to restore hydrophobicity after fouling.
Want to know more?If you want to know more about this cutting edge product, or schedule a demonstration on your own organisation, please feel free to contact us or read the available documentation at http://www.keep.pt/produtos/retrievo/?lang=en