New investigations on ferrofluidics: ferrofluidic marbles and magnetic-field-driven drops on superhydrophobic surfaces.

The motion of ferrofluidic marbles on flat polymer substrates is reported. Nanopowders of polyvinylidene fluoride and gammaFe2O3 were used for the preparation of ferrofluidic marbles. The marbles are activated easily with an external magnetic field.

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.

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.

Mesoscopic patterning in evaporated polymer solutions: new experimental data and physical mechanisms.

Mesoscopically ordered patterns were obtained when polymer solutions were applied to tilted substrates and evaporated immediately under ambient conditions in a slow air current. The patterns were studied with optical, scanning electron, and atomic force microscopy. Shadowgraph visualization of the patterning was carried out, and visualization of the flow with an ink tracer was performed.