Physics and Chemistry of Interfaces

Butt, Hans‐Jürgen; Graf, Karlheinz; Kappl, Michael

doi:10.1002/3527602313

Cited by 1,065 publications

(1,380 citation statements)

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“…In order to study the nano-scopic contact angle of a nanoscopic droplet [19], which could be observed, for example, using the atomic force microscope (AFM) [20], we have to include the thin film potential P (x). There are also the problem of line tension [21], which further modify the modified Cassie's law for the nanoscopic contact angle.…”

Section: Resultsmentioning

confidence: 99%

The validity of Cassie's law: A simple exercise using a simplified model

Iwamatsu

2006

Journal of Colloid and Interface Science

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The contact angle of a macroscopic droplet on a heterogeneous but flat substrate is studied using the interface displacement model which can lead to the augmented Young-Laplace equation. Droplets under the condition of constant volume as well as constant vapor pressure are considered. By assuming a cylindrical liquid-vapor surface (meniscus) and minimizing the total free energy of the interface displacement model, we derive an equation which is similar but different from the well known Cassie's law. Our modified Cassie's law is essentially the same as the formula obtained previously by Marmur [J.Colloid Interface Sci. 168, 40 (1994)]. A few consequences from this modified Cassie's law will be briefly described in the following sections of this paper. Several sets of recent experimental results seem to support the validity of our modified Cassie's law.

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Section: Resultsmentioning

confidence: 99%

The validity of Cassie's law: A simple exercise using a simplified model

Iwamatsu

2006

Journal of Colloid and Interface Science

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“…Within this review, we focus on material and design aspects rather than colloidal physics, which has been exhaustively discussed elsewhere. [91][92][93][94] Figure 4. Overview of types of patterned structures that can be created from colloidal self-assembly processes.…”

Section: (D) Multiple Porositiesmentioning

confidence: 99%

A colloidoscope of colloid-based porous materials and their uses

et al. 2016

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Nature evolved a variety of hierarchical structures that produce sophisticated functions. Inspired by these natural materials, colloidal self-assembly provides a convenient way to produce structures from simple building blocks with a variety of complex functions beyond those found in nature. In particular, colloid-based porous materials (CBPM) can be made from a wide variety of materials. The internal structure of CBPM also has several key attributes, namely porosity on a sub-micrometer length scale, interconnectivity of these pores, and a controllable degree of order. The combination of structure and composition allow CBPM to attain properties important for modern applications such as photonic inks, colorimetric sensors, self-cleaning surfaces, water purification systems, or batteries. This review summarizes recent developments in the field of CBPM, including principles for their design, fabrication, and applications, with a particular focus on structural features and materials' properties that enable these applications. We begin with a short introduction to the wide variety of patterns that can be generated by colloidal self-assembly and templating processes. We then discuss different applications of such structures, focusing on optics, wetting, sensing, catalysis, and electrodes. Different fields of applications require different properties, yet the modularity of the assembly process of CBPM provides a high degree of tunability and tailorability in composition and structure. We examine the significance of properties such as structure, composition, and degree of order on the materials' functions and use, as well as trends in and future directions for the development of CBPM.

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“…(12), we employ here another evolution method on the same grid system, the lattice Poisson method (LPM) 24 (26) rv; rg where the equilibrium distribution of the electric potential evolution variable g is a=O a I to 6 (27) a=7tol4…”

Section: Fig 4 the Lattice Direction System (A) For D3q 15 Modelmentioning

confidence: 99%

“…Although it is well known that the electrokinetic flow is sensitive to the surface properties 26 , little attention has been paid to the effects of surface roughness on electrokinetic transport due to its complexity, especially for random roughness in microchannels 27 • Dukhin and De~jaguin 28 may be the first ones who performed systematic theoretical studies on roughness effects on electrokinetic flows. They introduced two critical length scales to characterize the problem: the Debye length which is defined as the thickness of the electrical double layer, and the charactertistic length of surface roughness.…”

Section: Introductionmentioning

confidence: 99%

“…When the Debye length is comparable to the roughness height, the linearized models fail to describe the electrokinetic transport any more. Especially when the Debye length is much larger than the roughness size, the effective charge density on the rough surfaces is higher than the corresponding smooth surfaces due to the increased area by the roughness 26 • Thanks to the rapid development of computer and computational techniques, a few numerical approaches have been applied to model and predict the electrokinetic transport in rough microchannels. Hu et aL [29][30][31] studied the electroosmotic flow in microchannels with three dimensional rectangular roughness elements using a finite-volume-based numerical model within a thin Debye length limit.…”

Section: Introductionmentioning

confidence: 99%

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Electrokinetic Transport in Microchannels with Random Roughness

Wang

Kang

2009

Anal. Chem.

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I Email address: mwang(a),lanl.!!ov (M.W.); gkang@lanLgov (Q.K) Electrokinetic tr"t1'~n{',rt In microchannels Abstract: We present a numerical framework to model the electrokinetic transport in microchannels with random roughness. The three-dimensional microstructure of the rough channel is generated by a random generation-growth method with three statistical parameters to control the number density, the total volume fraction and anisotropy characteristics of roughness elements. The governing equations for the electrokinetic transport are solved by a high efficiency lattice Poisson-Boltzmann method in complex geometries. The effects from the geometric characteristics of roughness on the electrokinetic transport in microchannels are therefore modeled and analyzed. For a given total roughness volume fraction, a higher number density leads to a lower fluctuation due to the random factors. The electroosmotic permeability increases with the roughness number density nearly at a logarithmic law for a given volume fraction of roughness, but decreases with the volume fraction of roughness for a given roughness number density. When both the volume fraction and the number density of roughness are given, the electroosmotic permeability is enhanced by increases of the characteristic length along the external electric field direction or decreases of the length of the direction of across the channel.For a given microstructure of rough microchannel, the electroosmotic permeability decreases with the Debye length. Compared with the corresponding flows in a smooth channel, the rough surface may enhance the electrokinetic transport when the Debye length is smaller than the roughness characteristic height under the assumption of constant zeta potential for all surfaces.The present results may improve the understanding of the electrokinetic transport characteristics in microchannels.

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Physics and Chemistry of Interfaces

Cited by 1,065 publications

References 0 publications

The validity of Cassie's law: A simple exercise using a simplified model

The validity of Cassie's law: A simple exercise using a simplified model

A colloidoscope of colloid-based porous materials and their uses

Electrokinetic Transport in Microchannels with Random Roughness

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