Super-hydrophobicity can be achieved on relatively smooth surfaces. Short, wide pillars slightly rough surfaces are shown to produce super-hydrophobic (see Figure) where neither the nor slight roughness suffice alone. This use of two length scales create directly mimics mechanism used by some plants including lotus.

Intrinsically superhydrophobic foams with contact angles greater than 150° were prepared using a sol−gel phase-separation process. Hydrophobicity was built in by organofunctionalized inorganic monomers and setting the conditions so that they retained product. The materials characterized advancing receding water angle measurements, scanning electron microscopy, infrared spectroscopy. preparation method used simple produced roughness hydrophobicity same material, thus obviating need for...

The evaporation process for small, 1-2-mm-diameter droplets of water from patterned polymer surfaces is followed and characterized. consist circular pillars (5-15 microm diameter) SU-8 photoresist arranged in square lattice patterns such that the center-to-center separation between 20-30 microm. These types surface provide superhydrophobic systems with theoretical initial Cassie-Baxter contact angles up to 140-167 degrees, which are significantly larger than can be achieved by smooth...

The relationship between perturbations to contact angles on a rough or textured surface and the super-hydrophobic enhancement of equilibrium angle is discussed theoretically. Two models are considered. In first (Wenzel) case, has very high droplet completely contacts upon which it rests. second (Cassie-Baxter) angle, but bridges across protrusions. theoretical treatment emphasizes concept contact-angle amplification attenuation distinguishes increases in due roughening texturing surfaces...

The ability of particles to adhere a fluid–fluid interface can stabilize the formation an emulsion. When encapsulated fluid is liquid and in which it immersed air, object formed called "Liquid Marble". Here we discuss how marbles be created, their fundamental properties transport potential uses. We show they arise naturally as insect waste disposal system, from impact droplets on powders hydrophobic soil, mixing particulate containing liquids. Our principal aim review research macroscopic...

Superhydrophobic surfaces combine high aspect ratio micro- or nano-topography and hydrophobic surface chemistry to create super water-repellent surfaces. Most studies consider their effect on droplets, which ball-up roll-off. However, properties are not restricted modification of the behaviour but potentially influence any process occurring at solid-liquid interface. Here, we highlight three recent developments focused theme immersed superhydrophobic The first illustrates ability a act as...

The study of particle stabilized interfaces has a long history in terms emulsions, foams and related dry powders. same underlying interfacial energy principles also allow hydrophobic particles to encapsulate individual droplets into stable form as macroscopic objects, which have recently been called "Liquid Marbles". Here we discuss conceptual similarities superhydrophobic surfaces, capillary origami, slippery liquids-infused porous surfaces (SLIPS) Leidenfrost droplets. We provide review...

There are two pure modes of evaporation liquid drops on surfaces: one at constant contact area and angle. Constant mode is the dominating for water many other solids when initial angle less than 90°. However, has been reported in a few instances, such as drop poly(tetrafluoroethylene) where greater In this work, we report n-butanol, toluene, n-nonane, n-octane surface, which occurs with an Video microscopy digital image analysis techniques were applied to monitor evaporation. The decrease...

Rough and patterned copper surfaces were produced using etching and, separately, electrodeposition. In both of these approaches the roughness can be varied in a controlled manner when hydrophobized, show contact angles that increase with increasing to above 160 degrees . We transitions from Wenzel mode, whereby liquid follows contours surface, Cassie-Baxter bridges between features on surface. Measured etched samples could modeled quantitatively within few by equations. The angle hysteresis...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEvaporation of Microdroplets and the Wetting Solid SurfacesS. M. Rowan, I. Newton, G. McHaleCite this: J. Phys. Chem. 1995, 99, 35, 13268–13271Publication Date (Print):August 1, 1995Publication History Published online1 May 2002Published inissue 1 August 1995https://pubs.acs.org/doi/10.1021/j100035a034https://doi.org/10.1021/j100035a034research-articleACS PublicationsRequest reuse permissionsArticle Views2246Altmetric-Citations240LEARN ABOUT THESE...

Roughening a hydrophobic surface enhances its nonwetting properties into superhydrophobicity. For liquids other than water, roughness can induce complete rollup of droplet. However, topographic effects also enhance partial wetting by given liquid to create superwetting. In this work, model system spreading droplets nonvolatile on surfaces having lithographically produced pillars is used show that superwetting modifies the dynamics spreading. The edge speed-dynamic contact angle relation...

The transport of a Newtonian liquid through smooth pipe or tube is dominated by the frictional drag on against walls. resistance to flow solid can, however, be reduced introducing layer gas at near boundary between and liquid. This can occur vaporization surface temperature above Leidenfrost point, cushion air (e.g. below hovercraft), producing bubbles interface. These methods require continuous energy input, but more recent discovery possibility using superhydrophobic surface. Most reported...

The receding contact angles of water drops on PMMA and PET surfaces were determined by using video microscopy to follow the time-dependent evaporation sessile drops. Depending initial drop size, θr = 54−64° for 64−66° found with an average hysteresis 23.5 ± 1.5 19.5 1.5°, respectively. Advancing angles, θa θr, also needle-syringe inclined plane methods comparison. discrepancies from mean maximum minimum angle results both larger than expected all polymer surfaces. A general trend was seen...

Switching between superhydrophobicity and superhydrophilicity in porous materials was predicted theoretically demonstrated experimentally with the example of thermally induced contact angle change; tunability this system also demonstrated.

Wall adsorption is a common problem in microfluidic devices, particularly when proteins are used. Here we show how superhydrophobic surfaces can be used to reduce protein and promote desorption. Hydrophobic surfaces, both smooth having high surface roughness of varying length scales (to generate superhydrophobicity), were incubated solution. The samples then exposed flow shear device designed simulate environment. Results that similar amount adsorbed onto nanometer-scale rough although...

Abstract Superhydrophobicity is the extreme water repellence of highly textured surfaces. The field superhydrophobicity research has reached a stage where huge numbers candidate treatments have been proposed and jumps made in theoretically describing them. There now seems to be move more practical concerns considering demands individual applications instead general cases. With these developments, polymeric surfaces with their variety properties come fore are fast becoming material choice for...

Most insects and spiders drown when submerged during flooding or tidal inundation, but some are able to survive others can remain indefinitely without harm. Many achieve this by natural adaptations their surface morphology trap films of air, creating plastrons which fix the water-vapor interface provide an incompressible oxygen-carbon dioxide exchange surface. Here authors demonstrate how extremely water-repellent foam mimics mechanism underwater respiration allows direct extraction oxygen...

The wetting of solid surfaces can be modified by altering the surface free energy balance between solid, liquid, and vapor phases. Here we show that liquid dielectrophoresis induced nonuniform electric fields used to enhance control dielectric liquids. In limit thick droplets, theoretically cosine contact angle follows a simple voltage squared relationship analogous found for electrowetting on dielectric. Experimental observations confirm this predicted dielectrowetting behavior is...

Super water-repellent surfaces occur naturally on plants and aquatic insects are created in the laboratory by combining micro- or nanoscale surface topographic features with hydrophobic chemistry. When such types of submerged they can retain a film air (a plastron). In this work, we report measurements terminal velocity solid acrylic spheres various treatments settling under action gravity water. We observed increases corresponding to drag reduction between 5% 15% for superhydrophobic that...

Abstract In this work, we disclose a non-invasive method for the monitoring and predicting of swarming process within honeybee colonies, using vibro-acoustic information. Two machine learning algorithms are presented prediction swarming, based on vibration data recorded accelerometers placed in heart hives. Both successfully discriminate between colonies intending not to swarm with high degree accuracy, over 90% each method, successful up 30 days prior event. We show that instantaneous...

The evaporation of a small droplet volatile fluid from solid surface differs according to whether the wets surface. When initial contact angle is less than 90°, initially proceeds with an accompanying decrease in but no change radius. This stage dominates time scale and has previously been described by diffusion model. However, when greater it radius that decreases rather angle. In this work we report detailed measurements drops water Teflon film. On deposition angles rapidly relax around...