Ionic equilibria and swelling of soft permeable particles in electrolyte solutions

Silkina, Elena F.; Molotilin, Taras Y.; Maduar, Salim R.; Vinogradova, Olga I.

doi:10.1039/c9sm01602c

Cited by 9 publications

(11 citation statements)

References 45 publications

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“…Filled and open circles are obtained using Eqs. ( 37) and (38). Filled and open triangles correspond to Eqs.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Surface and zeta potentials of charged permeable nanocoatings

Silkina,

Bag,

Vinogradova

2020

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An electrokinetic (zeta) potential of charged permeable porous films on solid supports generally exceeds their surface potential, which often builds up to a quite high value itself. Recent work provided a quantitative understanding of zeta potentials of thick, compared to the extension of an inner electrostatic diffuse layer, porous films. Here, we consider porous coatings of a thickness comparable or smaller than that of the inner diffuse layer. Our theory, which is valid even when electrostatic potentials become quite high and accounts for a finite hydrodynamic permeability of the porous materials, provides a framework for interpreting the difference between values of surface and zeta potentials in various situations. Analytic approximations for the zeta potential in the experimentally relevant limits provide a simple explanation of transitions between different regimes of electro-osmotic flows, and also suggest strategies for its tuning in microfluidic applications.

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“…Filled and open circles are obtained using Eqs. ( 37) and (38). Filled and open triangles correspond to Eqs.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Surface and zeta potentials of charged permeable nanocoatings

Silkina,

Bag,

Vinogradova

2020

Preprint

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“…However, a light-induced DO flow can be generated when sedimented particles are porous [31]. At equilibrium such particles absorb the ionic species [36][37][38][39], but irradiation with blue light induces a rapid escape of cis-isomers out the pores. Consequently, each particle becomes a source of a laterally inhomogeneous excess of cis-isomers that leads to a concentration inhomogeneity along the wall.…”

Section: Active Particlesmentioning

confidence: 99%

Light-induced manipulation of passive and active microparticles

et al. 2021

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We consider sedimented at a solid wall particles that are immersed in water containing small additives of photosensitive ionic surfactants. It is shown that illumination with an appropriate wavelength, a beam intensity profile, shape and size could lead to a variety of dynamic, both unsteady and steady state, configurations of particles. These dynamic, well-controlled and switchable particle patterns at the wall are due to an emerging diffusio-osmotic flow that takes its origin in the adjacent to the wall electrostatic diffuse layer, where the concentration gradients of surfactant are induced by light. The conventional nonporous particles are passive and can move only with already generated flow. However, porous colloids actively participate themselves in the flow generation mechanism at the wall, which also sets their interactions that can be very long ranged. This light-induced diffusio-osmosis opens novel avenues to manipulate colloidal particles and assemble them to various patterns. We show in particular how to create and split optically the confined regions of particles of tunable size and shape, where well-controlled flow-induced forces on the colloids could result in their crystalline packing, formation of dilute lattices of well-separated particles, and other states. Graphic Abstract

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“…( 3) and Eq. ( 4) it follows that for planar films of any thickness ψ 0 and the surface potential, ψ s = ψ(H), are related as [12] ψ…”

Section: Heaviside Step Function θ(Z)mentioning

confidence: 99%

“…Analytic solutions based on a linearized mean-field Poisson-Boltzmann theory are known for weakly charged porous films [6][7][8], but these results do not apply to highly charged coatings, where nonlinear electrostatic effects could become significant, leading to super-properties. The non-linear electrostatic problem has been treated using numeric and semi-analytic approaches [6,9,10], and some simple expressions have also been proposed for thick, compared to the Debye screening length λ D , coatings [11,12]. The results suggest relations between the Donnan, Ψ D , and the surface, Ψ s , potentials for thick and/or weakly charged films [6,12], and that zeta-potential, which is the measure of electrokinetic mobility, generally exceeds Ψ s [10,13].…”

mentioning

confidence: 99%

“…The non-linear electrostatic problem has been treated using numeric and semi-analytic approaches [6,9,10], and some simple expressions have also been proposed for thick, compared to the Debye screening length λ D , coatings [11,12]. The results suggest relations between the Donnan, Ψ D , and the surface, Ψ s , potentials for thick and/or weakly charged films [6,12], and that zeta-potential, which is the measure of electrokinetic mobility, generally exceeds Ψ s [10,13]. Nevertheless, general principles to control Ψ s or electroosmotic velocity have not yet been established in the case of high intrinsic charge of coatings, where the implication of porosity is the most pronounced.…”

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confidence: 99%

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Electro-osmotic properties of porous permeable films

Silkina,

Bag,

Vinogradova

2020

Preprint

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Permeable porous coatings on a flat solid support significantly impact its electrostatic and electrokinetic properties. Existing work has focused on simplified cases, such as weakly charged and/or thick porous films, with limited theoretical guidance. Here, we consider the general case of coatings of any given volume charge density and obtain analytic formulas for electrostatic potential profiles, valid for any film thickness and salt concentration. They allow us to calculate analytically the difference between potentials at solid support and at interface with an outer electrolyte, that is the key parameter ascertaining the functionality of permeable coatings. Our analysis provides a framework for interpreting and predicting specific for porous films super-properties, from an enhanced ion absorption to a giant amplification of electro-osmotic flows. The results are relevant for hydrogel and zeolite coatings, porous carbon and ion-exchange resins, polyelectrolyte brushes, and more.

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Ionic equilibria and swelling of soft permeable particles in electrolyte solutions

Abstract: We report an analytical theory and coarse-grained simulations of electro-osmotic equilibria of uniformly charged soft permeable particles immersed in electrolyte solutions.

Cited by 9 publications

References 45 publications

Surface and zeta potentials of charged permeable nanocoatings

Surface and zeta potentials of charged permeable nanocoatings

Light-induced manipulation of passive and active microparticles

Electro-osmotic properties of porous permeable films

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