(La0.5,Sr0.5)CoO3 (LSCO) ®lms were prepared by a sol-gel method on silica grown by various methods such as thermal oxidation, plasma enhanced chemical vapor deposition (PECVD) and atmospheric pressure chemical vapor deposition (APCVD). Polyvinyl alcohol (PVA) was used as a wetting agent to improve the surface wetting behavior of the LSCO precursor solution onto the silica. The surface wetting o...

We have developed a methodology that can be used to determine disjoining pressures (Π) in both stable and unstable wetting films from the spatial and temporal profiles of dynamic wetting films. The results show that wetting films drain initially by the capillary pressure created by the changes in curvature at the air/water interface and subsequently by the disjoining pressure created by surface...

The liquid He-cesium system is a nearly ideal one for studying wetting phenomena. However, it can show nonideal behavior such as an extreme wetting hysteresis and a memory of being in contact with liquid He. We believe that this is caused by the roughness of the Cs surface. We review the wetting characteristics of Cs surfaces produced by various methods, and we qualitatively classify Cs surface...

Dynamic wetting problems are fundamental to understanding the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness c...

Micromodels with a simplified porous network that represents geological porous media have been used as experimental test beds for multiphase flow studies in the petroleum industry. We present a new method to fabricate reservoir micromodels with heterogeneous wetting properties. Photopatterned, copolymerized microstructures were fabricated in a bottom-up manner. The use of rationally designed co...

The wetting of rough surfaces remains a subject of active investigation by scientists. The contact angle (CA) is a traditional parameter used to characterize the hydrophobicity/philicity of a solid surface. However, it was found recently that high CAs can coexist with strong adhesion between water and a solid surface in the case of the so-called 'rose petal effect'. Several additional parameter...

We study the thickness of wetting layers in the binary-liquid mixture cyclohexane methanol. Far from the bulk critical point, the wetting layer thickness is independent of temperature, resulting from the competition between van der Waals and gravitational forces. Upon approaching the bulk critical temperature [t=(T(c)-T)/T(c)-->0], we observe that the wetting layer thickness diverges as t(-beta...

We examine the wettability of rough surfaces through a measurement approach that harnesses a wrinkling instability to produce model substrate topographies. Specifically, we probe the wetting of liquids on anisotropic micro-wrinkled features that exhibit well-defined aspect ratios (amplitude versus wavelength of the wrinkles) that can be actively tuned. Our study provides new insight into the we...

One of the most questionable issues in wetting is the force balance that includes the vertical component of liquid surface tension. On soft solids, the vertical component leads to a microscopic protrusion of the contact line, that is, a 'wetting ridge'. The wetting principle determining the tip geometry of the ridge is at the heart of the issues over the past half century. Here we reveal a univ...