Plasma treatment switches the regime of wetting and floating of pepper seeds.

Cold radiofrequency plasma treatment modified wetting and floating regimes of pepper seeds. The wetting regime of plasma-treated seeds was switched from the Wenzel-like partial wetting to the complete wetting. No hydrophobic recovery following the plasma treatment was registered.

Under-Liquid Self-Assembly of Submerged Buoyant Polymer Particles.

The self-assembly of submerged cold-plasma-treated polyethylene beads (PBs) is reported. The plasma-treated immersed millimetrically sized PBs formed well-ordered 2D quasicrystalline structures. The submerged floating of "light" (buoyant) PBs is possible because of the energy gain achieved by the wetting of the high-energy plasma-treated polymer surface prevailing over the energy loss due to the upward climb of the liquid over the beads.

Superoleophobic Surfaces Obtained via Hierarchical Metallic Meshes.

Hierarchical metallic surfaces demonstrating pronounced water and oil repellence are reported. The surfaces were manufactured with stainless-steel microporous meshes, which were etched with perfluorononanoic acid. As a result, a hierarchical relief was created, characterized by roughness at micro- and sub-microscales.

Interpretation of elasticity of liquid marbles.

Liquid marbles are non-stick droplets covered with micro-scaled particles. Liquid marbles demonstrate quasi-elastic properties when pressed. The interpretation of the phenomenon of elasticity of liquid marbles is proposed.

Interaction of cold radiofrequency plasma with seeds of beans (Phaseolus vulgaris).

The impact of cold radiofrequency air plasma on the wetting properties and water imbibition of beans (Phaseolus vulgaris) was studied. The influence of plasma on wetting of a cotyledon and seed coat (testa) was elucidated. It was established that cold plasma treatment leads to hydrophilization of the cotyledon and tissues constituting the testa when they are separately exposed to plasma.

Physical mechanisms of interaction of cold plasma with polymer surfaces.

Physical mechanisms of the interaction of cold plasmas with organic surfaces are discussed. Trapping of plasma ions by the CH2 groups of polymer surfaces resulting in their electrical charging is treated. Polyethylene surfaces were exposed to the cold radiofrequency air plasma for different intervals of time.

On universality of scaling law describing roughness of triple line.

The fine structure of the three-phase (triple) line was studied for different liquids, various topographies of micro-rough substrates and various wetting regimes. Wetting of porous and pillar-based micro-scaled polymer surfaces was investigated. The triple line was visualized with the environmental scanning electron microscope and scanning electron microscope for the "frozen" triple lines.

On the role of the line tension in the stability of Cassie wetting.

The effect of line tension may increase or decrease the potential barrier separating the Cassie and the Wenzel wetting states, depending on the sign of the line tension and the topography of a relief. The formation of the barrier separating the Cassie and Wenzel wetting states on reentrant topographies, which demonstrate pronounced superhydrophobicity and superoleophobicity, is treated. Various topographies giving rise to high apparent contact angles are discussed.

Superhydrophobicity of lotus leaves versus birds wings: different physical mechanisms leading to similar phenomena.

Remarkable water repellency of birds' feathers and lotus leaves is discussed. It is demonstrated that physical mechanisms of superhydrophobicity of birds' feathers and lotus leaves are very different. The topography of lotus leaves is a truly hierarchical one, whereas birds' feathers manifest pseudohierarchical relief, where various scales do not interact.

How to make the Cassie wetting state stable?

Wetting of rough hydrophilic and hydrophobic surfaces is discussed. The stability of the Cassie state, with air trapped in relief details under the droplet, is necessary for the design of true superhydrophobic surfaces. The potential barrier separating the Cassie state and the Wenzel state, for which the substrate is completely wetted, is calculated for both hydrophobic and hydrophilic surfaces.

Shape, vibrations, and effective surface tension of water marbles.

The surface of water "marbles" obtained with hydrophobic lycopodium and polyvinylidene fluoride particles was investigated first with environmental scanning electron microscopy. The shape of water marbles was studied both experimentally and theoretically. The mathematical model describing the deformation of marbles by gravity is proposed.

Oblate spheroid model for calculation of the shape and contact angles of heavy droplets.

A model is proposed for calculation of the shape and contact angle of droplets placed on solid substrates, which is based on the oblate spheroid approximation. Illustrative examples of calculation of various geometrical characteristics of the droplets are presented. Calculated contact angles show their actual independence of the droplet weight in a broad range of volumes.

Characterization of rough surfaces with vibrated drops.

Wetting transitions were studied with vertically-vibrated drops on various artificial and natural rough substrates. Alternative pathways of wetting transitions were observed. The model of wetting transition is presented.

The reversible giant change in the contact angle on the polysulfone and polyethersulfone films exposed to UV irradiation.

Water contact angles on polysulfone and polyethersulfone films exposed to UV irradiation have been found to decrease dramatically. We relate this phenomenon to the formation and release of disulfonic acid from the irradiated films, a well-known surfactant. The phenomenon appears to be reversible, namely, cleansed surfaces retained their initial contact angle.

Contact angle hysteresis on polymer substrates established with various experimental techniques, its interpretation, and quantitative characterization.

The effect of contact angle hysteresis (CAH) was studied on various polymer substrates with traditional and new experimental techniques. The new experimental technique presented in the article is based on the slow deformation of the droplet, thus CAH is studied under the constant volume of the drop in contrast to existing techniques when the volume of the drop is changed under the measurement. The energy of hysteresis was calculated in the framework of the improved Extrand approach.

Resonance Cassie-Wenzel wetting transition for horizontally vibrated drops deposited on a rough surface.

The transition between the Cassie and Wenzel wetting regimes has been observed under horizontal vibrations of a water drop placed on the rough micrometrically scaled polymer pattern. The observed transition has a distinct resonance character. The resonance frequencies as established experimentally coincide with the calculated eigenfrequencies of capillary-gravity standing waves on the drop surface.

Cassie-Wenzel wetting transition in vibrating drops deposited on rough surfaces: is the dynamic Cassie-Wenzel wetting transition a 2D or 1D affair?

The transition between the Cassie and Wenzel wetting regimes has been observed under vertical vibration of a water drop placed on a rough micrometrically scaled polymer pattern. The transition takes place under the constant force per unit length of the triple contact line, not under constant pressure. A study of the vibrating drop deposited on the rough surface supplied valuable information concerning the Cassie-Wenzel wetting transition.

Environmental scanning electron microscopy study of the fine structure of the triple line and cassie-wenzel wetting transition for sessile drops deposited on rough polymer substrates.

The wetting of rough honeycomb micrometrically scaled polymer substrates was studied. A very strong dependence of the apparent contact angle on the drop volume has been established experimentally. The environmental scanning electron microscopy study of the fine structure of the triple line is reported first.

Why do pigeon feathers repel water? Hydrophobicity of pennae, Cassie-Baxter wetting hypothesis and Cassie-Wenzel capillarity-induced wetting transition.

Wetting of pigeon feathers has been studied. It was demonstrated that the Cassie-Baxter wetting regime is inherent for pigeon pennae. The water drop, supported by network formed by barbs and barbules, sits partially on air pockets.

Wetting properties of the multiscaled nanostructured polymer and metallic superhydrophobic surfaces.

A superhydrophobic surface is produced from industrial grade polymer materials. The surface comprises partly disordered triple-scaled arrays of polyvinylidene fluoride (PVDF) globules. An inherently superhydrophobic metallic surface is produced with polymer template.

Droplet behavior on flat and textured surfaces: co-occurrence of Deegan outward flow with Marangoni solute instability.

It is demonstrated experimentally that the solution droplet behavior is governed by the co-occurrence of outward hydrodynamic and surface tension (solute Marangoni) induced flows. Potassium ferrocyanide allows the effective visualization of the processes taking place in the droplet. Wetting properties of the substrate govern the shape evolution of the evaporated droplet.

Micrometrically scaled textured metallic hydrophobic interfaces validate the Cassie-Baxter wetting hypothesis.

The possibility of forming a hydrophobic metallic interface is shown when it is micrometrically textured. On such surface obtained by gold coating the polymer honeycomb template, the apparent contact angle of water was observed to be close to or greater than 90 degrees . The metal hydrophobicity is explained by trapping air inside pores of pattern according to the Cassie-Baxter wetting model.

Patterning in rapidly evaporated polymer solutions: formation of annular structures under evaporation of the poor solvent.

Patterning in the intensively evaporated polymer solutions based on polystyrene and poor solvent (acetone) was investigated. SEM and AFM studies demonstrated that annular elements of the surface topography are formed in this case, in contrast to the honeycomb patterns obtained under the evaporation of the good solvent (chloroform). The authors suggest that the theory of viscous dewetting developed by de Gennes explains the phenomenon satisfactorily.