The Electrostatic Interactions between Two Corrugated Charged Planes

Tsao, Heng Kwong

doi:10.1006/jcis.1999.6328

Cited by 4 publications

(5 citation statements)

References 25 publications

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“…Upon increase of ξ, the interaction energy tends to a constant value as the result of the diminishing of the extension of the double layers overlap in the direction given by the extremities of the two asperities. The conclusions pertaining to the effect of ξ on G are in line with those derived by Tsao for electrostatic interactions between two corrugated surfaces. In this paper, the interaction energy is computed using a perturbation theory valid for smooth corrugation and only the case of uniformly charged surfaces is examined.…”

Section: Resultssupporting

confidence: 87%

“…For the sake of simplicity, the constant (surface) potential condition is chosen but the analysis can also be performed for the constant charge case and extended, in a very elegant way, to the situation of interaction between two charged rough surfaces or between charged flat and rough surfaces (section A2). The development proposed constitutes an extension of the work by Tsao, because the Taylor expansion we derive here for ψ( x , y ) is valid for smooth as well as moderately rough surfaces (see below). A1.…”

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confidence: 99%

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Electrostatic Interactions between Double Layers: Influence of Surface Roughness, Regulation, and Chemical Heterogeneities

2004

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Electrostatic interactions between two surfaces as measured by atomic force microscopy (AFM) are usually analyzed in terms of DLVO theory. The discrepancies often observed between the experimental and theoretical behavior are usually ascribed to the occurrence of chemical regulation processes and/or to the presence of surface chemical or morphological heterogeneities (roughness). In this paper, a two-gradient mean-field lattice analysis is elaborated to quantifying double layer interactions between nonplanar surfaces. It allows for the implementation of the aforementioned sources of deviation from DLVO predictions. Two types of ion-surface interaction ensure the adjustment of charges and potentials upon double layer overlap, i.e., specific ionic adsorption at the surfaces and/or the presence of charge-determining ions for the surfaces considered. Upon double layer overlap, charges and potentials are adjusted via reequilibrium of the different ion adsorption processes. Roughness is modeled by grafting asperities on supporting planar surfaces, with their respective positions, shapes, and chemical properties being assigned at will. Local potential and charge distributions are derived by numerically solving the nonlinear Poisson-Boltzmann equation under the boundary conditions imposed by the surface profiles and regulation mechanism chosen. Finite size of the ions is taken into account. A number of characteristic situations are briefly discussed. It is shown how the surface irregularities are reflected in the Gibbs energy of interaction.

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Section: Resultssupporting

confidence: 87%

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confidence: 99%

Electrostatic Interactions between Double Layers: Influence of Surface Roughness, Regulation, and Chemical Heterogeneities

2004

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“…The interaction energy between mildly corrugated planes exhibiting periodic undulations (in the weak roughness regime, i.e. amplitude small compared to wavelength) has been calculated by means of Derjaguin approximation [32] by Tsao [33] and by Suresh et al [34]. The surface element integration (SEI) technique allowed overcoming the limitations of the Derjaguin approximation when calculating the interaction energy between curves surfaces, modeled as a collection of convex and concave regions (spherical or sinusoidal bumps or depressions) with arbitrarily large curvatures (yet within the limits of the linearized PB equations) [35], [36], [37], [38], [39].…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Roughness and Morphology Affect the IsoElectric Point of Titania Surfaces

et al. 2013

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We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2) surfaces in aqueous solutions. IsoElectric Points (IEPs) of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces.

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“…In a recent work, the presence of surface roughness not only suggested that the onset of the electric double-layer interaction should be shifted as mentioned, but it also entails the inclusion of an additional exponential repulsive interaction taking into account the steric hindrance of the compressed asperities upon contact. In other works, simplified geometrical representations of the surface roughness have been used, such as mild periodic undulations (in the weak-roughness regime, i.e., undulation amplitude is small compared to the wavelength of the undulation) − or collections of regions with different convexity and curvature. − In these works, it is recognized that the ratios of characteristic lengths of the system (Debye length, surface roughness, asperity separation, etc.) influence the relative strength of different contributions to the interaction energy (van der Waals, electrostatic, Lewis acid–base acidity, etc.).…”

Section: Introductionmentioning

confidence: 99%

Electrostatic Double-Layer Interaction at the Surface of Rough Cluster-Assembled Films: The Case of Nanostructured Zirconia

et al. 2018

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Here, we investigated the influence of the nanoscale surface morphology on the electrostatic double layer at corrugated surfaces in aqueous electrolytes. For this purpose, we have produced cluster-assembled nanostructured zirconium dioxide (ns-ZrO , x ≈ 2) films with controlled morphological properties by supersonic cluster beam deposition (SCBD) and measured the double-layer interaction by atomic force microscopy with colloidal probes. SCBD allowed tuning the characteristic widths of the corrugated interface (root-mean-square roughness, correlation length) across a wide range of values, matching the width of the electrostatic double layer (Debye length) and the typical size of nanocolloids (proteins, enzymes, and catalytic nanoparticles). To accurately characterize the surface charge density in the high-roughness regime, we have developed a two-exponential model of the electrostatic force that explicitly includes roughness and better accounts for the roughness-induced amplification of the interaction. We were then able to observe a marked reduction of the isoelectric point of ns-ZrO surfaces of increasing roughness. This result is in good agreement with our previous observations on cluster-assembled nanostructured titania films and demonstrates that the phenomenon is not limited to a specific material, but more generally depends on peculiar nanoscale morphological effects, related to the competition of the characteristic lengths of the system.

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The Electrostatic Interactions between Two Corrugated Charged Planes

Cited by 4 publications

References 25 publications

Electrostatic Interactions between Double Layers: Influence of Surface Roughness, Regulation, and Chemical Heterogeneities

Electrostatic Interactions between Double Layers: Influence of Surface Roughness, Regulation, and Chemical Heterogeneities

Nanoscale Roughness and Morphology Affect the IsoElectric Point of Titania Surfaces

Electrostatic Double-Layer Interaction at the Surface of Rough Cluster-Assembled Films: The Case of Nanostructured Zirconia

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