ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDrainage of a Thin Liquid Film Confined between Hydrophobic SurfacesOlga I. VinogradovaCite this: Langmuir 1995, 11, 6, 2213–2220Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://pubs.acs.org/doi/10.1021/la00006a059https://doi.org/10.1021/la00006a059research-articleACS PublicationsRequest reuse permissionsArticle Views3179Altmetric-Citations501LEARN ABOUT THESE METRICSArticle...

We describe a tensorial generalization of the Navier slip boundary condition and illustrate its use in solving for flows around anisotropic textured surfaces. Tensorial can be derived from molecular or microstructural theories simply postulated as constitutive relation, subject to certain general constraints on interfacial mobility. The power tensor formalism is capture complicated effects surface anisotropy, while preserving simple fluid domain. This demonstrated by exact solutions laminar...

A super-hydrophobic array of grooves containing trapped gas (stripes) has the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work focused on idealized cases stick-perfect slip stripes. Here, we analyse experimentally more relevant situation a pressure-driven flow past striped slip-stick surfaces with arbitrary local at sectors. We derive approximate formulas for maximal (longitudinal) minimal (transverse) directional effective lengths that are...

Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a microscopic texture. Recent work has focused on specific cases, such as arrays of pillars or grooves, with limited theoretical guidance. Here, we consider the experimentally relevant limit thin channels obtain rigorous bounds effective slip length for any two-component (e.g., low-slip high-slip) texture given area fractions. Among all anisotropic textures, parallel stripes attain largest...

We discuss how the wettability and roughness of a solid impacts its hydrodynamic properties. see in particular that hydrophobic slippage can be dramatically affected by presence roughness. Owing to development refined methods for setting very well controlled micro- or nanotextures on solid, these effects are being exploited induce novel properties, such as giant interfacial slip, superfluidity, mixing low drag, could not achieved without

We report the results of direct measurements velocity profiles in a microchannel with hydrophobic and hydrophilic walls, using new high-precision method double-focus spatial fluorescence cross correlation under confocal microscope. In vicinity both walls measured do not go to zero by supplying plateau constant velocity. This apparent slip is proven be due Taylor dispersion, an augmentation shear diffusion nanotracers direction flow. Comparing near for various conditions shows that there true...

We show that an electro-osmotic flow near the slippery hydrophobic surface depends strongly on mobility of charges, which are balanced by counterions electrostatic diffuse layer. For a with immobile fluid transport is considerably amplified existence hydrodynamic slippage. In contrast, mobile adsorbed it also controlled additional electric force, increases shear stress at slipping interface. To account for this, we formulate electrohydrodynamic boundary conditions interface, should be...

We present the results of investigations high-speed drainage a thin film confined between microscopic colloidal probe and substrate performed with new atomic force microscope-related setup. Theoretical calculations are used to formulate governing equation (force balance) for instantaneous deflection cantilever spring, which is due both concentrated forces acting on viscous drag itself. The suggested way subtract latter contribution allows design lubrication experiment. Two pairs interacting...

We report results of investigations a high-speed drainage thin aqueous films squeezed between randomly nanorough surfaces. A significant decrease in hydrodynamic resistance force as compared with predicted by Taylor's equation is observed. However, this reduction does not represents the slippage. The measured exactly same that equivalent smooth surfaces obeying no-slip boundary conditions, but located at intermediate position peaks and valleys asperities. shift thickness shown to be...

Patterned surfaces with large effective slip lengths, such as super-hydrophobic containing trapped gas bubbles, have the potential to greatly enhance electrokinetic phenomena. Existing theories assume either homogeneous flat or patterned thin double layers (compared texture correlation length) and thus predict simple surface-averaged, isotropic flows (independent of orientation). By analysing electro-osmotic over striped slip-stick arbitrary double-layer thickness, we show that surface...

We give a general theoretical description of electro-osmotic flow at striped super-hydrophobic surfaces in thin double layer limit, and derive relation between the mobility hydrodynamic slip-length tensors. Our analysis demonstrates that shows very rich behavior controlled by slip length charge gas sectors. In case uncharged liquid-gas interface, is same or inhibited relative to homogeneous channel with zero interfacial slip. By contrast, it can be amplified several orders magnitude provided...

Abstract The strong adhesion of sub-micron sized particles to surfaces is a nuisance, both for removing contaminating colloids from and conscious manipulation create test novel micro/nano-scale assemblies. obvious idea using detergents ease these processes suffers lack control: the action any conventional surface-modifying agent immediate global. With photosensitive azobenzene containing surfactants we overcome limitations. Such photo-soaps contain optical switches (azobenzene molecules),...

This study investigates kinetic and production parameters of a glucose-utilizing bacterial strain, C. eutrophus B-10646, its ability to synthesize PHA terpolymers. Optimization number culture (cell concentration in the inoculum, physiological activity determined by initial intracellular polymer content, glucose medium during cultivation) provided cell concentrations yields reaching 110 g/L 80%, respectively, under two-stage batch conditions. Addition precursor substrates (valerate,...

We study the interaction between hydrophobized silica surfaces of defined contact angle in water using an AFM-related force measuring device. In all cases attraction leads to a jump into from separations larger than expected if only van der Waals forces were acting. The distance was found vary dramatically for different pairs interacting surfaces. For given pair jump-in is smallest first approach, then increases and reaches steady-state value after 3−10 curves. This confirms that hydrophobic...

Thin film drainage measurements are presented for submicron films of an “ideal elastic” or Boger fluid, which is a high molecular weight polymer solution in viscosity solvent. The made surface force apparatus, with the fluid being squeezed between two mica surfaces crossed cylinder geometry and thickness measured as function time to study its behavior. No equilibrium forces detected this system, indicating that nonadsorbing. effect elasticity predicted make more rapid than equivalent...

We present a novel approach to probe elastic properties of polyelectrolyte multilayer microcapsules. The method is based on measurements the capsule load-deformation curves with atomic force microscope. experiment suggests that at low applied load deformations shell are elastic. Using theory membranes we relate force, deformation, moduli, and characteristic sizes capsule. Fitting prediction model yields lower limit for Young's modulus multilayers order 1-100 MPa, depending template solvent...

We study the deformation of nonadhesive polyelectrolyte microcapsules under applied load using an atomic force microscope (AFM)-related measuring device. Both "hollow" (water inside) and "filled" (water-polyanion solution are explored. The capsules were found to be much stiffer than ones. load−deformation profiles always included two regimes, characterized by different behavior. In first regime, with a low load, capsule is elastic reversible. Above certain deform substantially partly...

We present an experimental approach to flow profiling within femtoliter sample volumes, which allows the high-precision measurements at solid interface. The method is based on spatial cross-correlation of fluorescence response from labeled tracer particles (latex nanospheres or single dye molecules). Two excitation separated by a few micrometers, are created two laser foci under confocal microscope. velocity measured in channel about $100\ensuremath{\mu}\mathrm{m}$ wide typical accuracy...

We measure Young's modulus of a free polyelectrolyte multilayer film by studying osmotically induced swelling microcapsules filled with the solution. Different filling techniques and core templates were used for capsule preparation. Varying concentration inside capsule, its radius shell thickness yielded an estimate upper limit order 100 MPa. This corresponds to elastomer reflects strong interactions between polyanions polycations in multilayer.

The effect of four 1:1 electrolytes (KCl, KBr, NH4Cl, and CH3COONa) on optical (stimulated by laser pulse) cavitation in thin layers bounded hydrophobic hydrophilic surfaces has been explored. For water all salts (up to 1 M) the case surfaces, probability is enhanced as compared with walls. increased observed can be linked an concentration gas-filled submicrocavities close them. phenomenon seems depend strongly dissolved gas. Variations that occur electrolyte are significant its type....

Polyelectrolyte multilayer microcapsules were recently suggested as a new type of nanoengineered microstructures and are potentially important in many areas science technology. The present review focuses on the mechanics these microstructures, emphasizing novel experimental approaches main observations. Methods based confocal atomic force microscopy—osmotic buckling, osmotic swelling, compression experiments—are detailed. Also covered is preparation various encapsulation techniques. A...

We report results of lattice Boltzmann simulations a high-speed drainage liquid films squeezed between smooth sphere and randomly rough plane. A significant decrease in the hydrodynamic resistance force as compared with that predicted for two surfaces is observed. However, this reduction does not represent slippage. The computed exactly same equivalent obeying no-slip boundary conditions, but located at an intermediate position peaks valleys asperities. shift thickness shown to depend on...