Equilibrium structure of the multi-component <i>screened</i> charged hard-sphere fluid

Sánchez-Díaz, Luis E.; Méndez-Maldonado, Gloria Arlette; González‐Melchor, Minerva; Ruiz-Estrada, H.; Medina‐Noyola, Magdaleno

doi:10.1063/1.3600746

Cited by 9 publications

(6 citation statements)

References 26 publications

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“…Mixtures of charged colloids have been modeled, e.g., by integral-equation theory [64][65][66][67][68][69][70][71][72][73], Poisson-Boltzmann theory [74][75][76][77][78], and computer simulation [79][80][81][82][83]. Motivated by experimental observations, several studies of colloid-nanoparticle mixtures [69,71,77,78,80] computed effective pair interactions between colloids that are qualitatively consistent with the postulated nanoparticle haloing mechanism.…”

Section: Introductionmentioning

confidence: 99%

Effective electrostatic interactions in colloid-nanoparticle mixtures

Denton

2017

Phys. Rev. E

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Interparticle interactions and bulk properties of colloidal suspensions can be substantially modified by addition of nanoparticles. Extreme asymmetries in size and charge between colloidal particles and nanoparticles present severe computational challenges to molecular-scale modeling of such complex systems. We present a statistical mechanical theory of effective electrostatic interactions that can greatly ease large-scale modeling of charged colloid-nanoparticle mixtures. By applying a sequential coarse-graining procedure, we show that a multicomponent mixture of charged colloids, nanoparticles, counterions, and coions can be mapped first onto a binary mixture of colloids and nanoparticles and then onto a one-component model of colloids alone. In a linear-response approximation, the one-component model is governed by a single effective pair potential and a one-body volume energy, whose parameters depend nontrivially on nanoparticle size, charge, and concentration. To test the theory, we perform molecular dynamics simulations of the two-component and one-component models and compute structural properties. For moderate electrostatic couplings, colloid-colloid radial distribution functions and static structure factors agree closely between the two models, validating the sequential coarse-graining approach. Nanoparticles of sufficient charge and concentration enhance screening of electrostatic interactions, weakening correlations between charged colloids and destabilizing suspensions, consistent with experiments.

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Section: Introductionmentioning

confidence: 99%

Effective electrostatic interactions in colloid-nanoparticle mixtures

Denton

2017

Phys. Rev. E

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“…Theoretical and simulation investigations of nanoparticles suspensions at finite volume fractions are technically more difficult due to the large increase of integration space (with different length scales) in theoretical equations, or the huge number of particles in, necessarily, larger simulation boxes. Thus, many studies used some kind of charge renormalization [33,34,35,36], colloidal suspensions with no salt added [37], or very low salt concentration [18]. In general these investigations are for relatively low colloidal charge and volume fraction [38,39].…”

Section: Theorymentioning

confidence: 99%

Very long-range attractive and repulsive forces in model colloidal dispersions

González-Calderón

González‐Tovar

Lozada‐Cassou

2019

Eur. Phys. J. Spec. Top.

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Experiments with polymer latex solutions show the coexistence of order-disorder structures of macroions. Because of the large macroions' sizes, this order-disorder phase coexistence imply the existence of very long-range attractive and repulsive forces, which can not be explained in terms of conventional direct interaction potentials, which are short-range. Here we apply an integral equations theory to a simple model for colloidal dispersions, at finite concentrations, calculate the particles distribution functions and the involved effective forces. We find very long-range attractive and repulsive forces among the like-charged macroions. The distribution functions are in qualitative agreement with experimental results. The origin of these forces are discussed in terms of an energy-entropy balance.

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“…where the Hamaker constant A ij depends on the dielectric constants of both the particles and the medium. Since we restrict attention here to like-charged particles whose repulsive electrostatic interactions are sufficiently strong to prevent nanoparticle adsorption, we neglect dielectric polarization effects, as in previous studies of charged colloidal mixtures [23][24][25][26][27][28][29][30][31][32][33][34][35][37][38][39][40][41]. Although induced polarization charges may affect self-assembly of strongly coupled, oppositely charged colloidal mixtures [42], charge-charge interactions are expected to dominate in the moderately coupled, like-charged systems investigated here.…”

Section: Coarse-grained Model Of Colloid-nanoparticle Mixturesmentioning

confidence: 99%

“…Charged colloidal mixtures have been modeled by a variety of theoretical and computational methods, including computer simulations [22][23][24][25][26], integral-equation theory [27][28][29][30][31][32][33][34][35][36], and Poisson-Boltzmann theory [37][38][39][40][41]. Several recent studies of highly asymmetric mixtures of charged colloids and nanoparticles [23,32,33,40,41] yielded effective colloid-colloid pair interactions that support the postulated nanoparticle haloing mechanism for certain system parameters.…”

Section: Introductionmentioning

confidence: 99%

Structure and stability of charged colloid-nanoparticle mixtures

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Denton

2018

The Journal of Chemical Physics

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Physical properties of colloidal materials can be modified by addition of nanoparticles. Within a model of like-charged mixtures of particles governed by effective electrostatic interactions, we explore the influence of charged nanoparticles on the structure and thermodynamic phase stability of charge-stabilized colloidal suspensions. Focusing on salt-free mixtures of particles of high size and charge asymmetry, interacting via repulsive Yukawa effective pair potentials, we perform molecular dynamics simulations and compute radial distribution functions and static structure factors. Analysis of these structural properties indicates that increasing the charge and concentration of nanoparticles progressively weakens correlations between charged colloids. We show that addition of charged nanoparticles to a suspension of like-charged colloids can induce a colloidal crystal to melt and can facilitate aggregation of a fluid suspension due to attractive van der Waals interactions. We attribute the destabilizing influence of charged nanoparticles to enhanced screening of electrostatic interactions, which weakens repulsion between charged colloids. This interpretation is consistent with recent predictions of an effective interaction theory of charged colloid-nanoparticle mixtures.

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Equilibrium structure of the multi-component screened charged hard-sphere fluid

Cited by 9 publications

References 26 publications

Effective electrostatic interactions in colloid-nanoparticle mixtures

Effective electrostatic interactions in colloid-nanoparticle mixtures

Very long-range attractive and repulsive forces in model colloidal dispersions

Structure and stability of charged colloid-nanoparticle mixtures

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