Modulation of electroosmotic flow by electric field-responsive polyelectrolyte brushes: a molecular dynamics study

Cao, Qi; Zuo, Chao; Li, Lujuan; Zhang, Yinhe

doi:10.1007/s10404-011-0865-7

Cited by 26 publications

(30 citation statements)

References 25 publications

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“…A series of Molecular dynamics (MD) simulations gave support to their predictions regarding the dependence of the polymer length on the coatings. The influence of the polymeric structure and of the solvent on the EOF was also investigated at length scales smaller than the Debye length [19][20][21] . Slater and coworkers [22,23] found by MD that the direction of the EOF can reverse in the region near the walls.…”

Section: Introductionmentioning

confidence: 99%

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Marconi

Monteferrante

Melchionna

2014

Phys. Chem. Chem. Phys.

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Motivated by recent experiments, we present a theoretical investigation of how the electro-osmotic flow occurring in a capillary is modified when its charged surfaces are coated by charged polymers. The theoretical treatment is based on a three dimensional model consisting of a ternary fluid-mixture, representing the solvent and two species for the ions, confined between two parallel charged plates decorated by a fixed array of scatterers representing the polymer coating. The electro-osmotic flow, generated by a constant electric field applied in a direction parallel to the plates, is studied numerically by means of Lattice Boltzmann simulations. In order to gain further understanding we performed a simple theoretical analysis by extending the Stokes-Smoluchowski equation to take into account the porosity induced by the polymers in the region adjacent the walls. We discuss the nature of the velocity profiles by focusing on the competing effects of the polymer charges and the frictional forces they exert. We show evidence of the flow reduction and of the flow inversion phenomenon when the polymer charge is opposite to the surface charge. By using the density of polymers and the surface charge as control variables, we propose a phase diagram that discriminates the direct and the reversed flow regimes and determine its dependence on the ionic concentration.

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Section: Introductionmentioning

confidence: 99%

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Marconi

Monteferrante

Melchionna

2014

Phys. Chem. Chem. Phys.

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“…So far, most computational studies focus on the EOF through polymercoated channels. [27][28][29][30][31][32][33][34][35][36] However, how nanoparticles migrate through channels modied by polymers are not studied thoroughly. Our previous work has addressed transport mechanisms of nanoparticles in polymer-coated nanochannels.…”

Section: Introductionmentioning

confidence: 99%

Transport of polymer-modified nanoparticles in nanochannels coated with polymers

Cao

Líu

et al. 2019

RSC Adv.

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Using molecular dynamics simulations based on explicit-solvent model, we study migration of polymermodified nanoparticles through nanochannels coated with polymers. The polymers densely grafted on the spherical nanoparticle and the channel surface form spherical polymer brush (SPB) and planar polymer brush (PPB), respectively. The migration of the neutral polymer-modified nanoparticle is driven by electroosmotic flow (EOF). The effects of the electric field strength and the SPB-PPB interaction on polymer conformations and transport dynamics of the SPB are explored. The migration velocity of the SPB reduces as the interaction between the SPB and the PPB increases. For strong SPB-PPB interaction, the directional migration of the SPB can be triggered only after the electric field strength exceeds a critical value. The high EOF velocity forces the center of mass of the spherical nanoparticle to keep near the central region of the channel due to high shear rate close to the brush-fluid interface. Unlike electrophoresis of charged polymer-grafted spherical particles, the SPB adopts a more extended conformation in the plane perpendicular to the EOF direction. Fig. 7 Radius of gyration of the polymer chains from the SPB (a) as a function of 3 sw at E ¼ 1.0E*, and (b) as a function of E at 3 sw ¼ 0.13 LJ and 1.03 LJ . R gt and R gk represent perpendicular and parallel components of the radius of gyration.This journal is

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“…In these works, we analyze the roles of the charge sequence, chain rigidity and grafting density in affecting the brush configuration. Up to now, most attention focuses on the interfacial structure and electrohydrodynamics in the systems with surfaces modified by neutral polymers or polyelectrolytes . The purpose of our work is to address systemically the influences of various parameters including the grafting density, electric field, chain length, and charge sequence on the electrophoretic motion of a soft colloid formed by coating the polyampholytes onto a spherical core.…”

Section: Introductionmentioning

confidence: 99%

Electrohydrodynamics of spherical polyampholyte-grafted nanoparticles: Multiscale simulations by coupling of molecular dynamics and lattice-boltzmann method

Cao

Zuo

2017

J. Polym. Sci. Part B: Polym. Phys.

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We perform multiscale simulations based on the coupling of molecular dynamics and lattice-Boltzmann (LB) method to study the electrohydrodynamics of a polyampholyte-grafted spherical nanoparticle. The long-range hydrodynamic interactions are modeled by coupling the movement of particles to a LB fluid. Our results indicate that the netneutral soft particle moves with a nonzero mobility under applied electric fields. We systematically explore the effects of different parameters, including the chain length, grafting density, electric field, and charge sequence, on the structures of the polymer layer and the electrophoretic mobility of the soft particle. It shows that the mobility of nanoparticles has remarkable dependence on these parameters. We find that the When a charged colloidal particle is immersed in electrolyte solution, an electrical double layer (EDL) is formed close to the charged surface. The EDL consists of a thin ion layer tightly adsorbed to the surface (so-called Stern layer) and a diffuse layer where ions can move freely. If an external electric field is applied, the colloidal particle and its counterions can be induced to migrate in opposite directions. An electroosmotic flow (EOF) is generated around the particle, and the viscous friction primarily happens over the Debye length. The movement of charged components perturbs the solvent flow, which triggers complicated hydrodynamic interactions. The electrophoretic mobility is determined by the hydrodynamic interactions, electrostatic forces between charged species, and external electric field strength. For polymermodified soft colloids, the deformation of polymers induced by the electric field, monomer-monomer hydrodynamic interactions, and counterion shearing flow further complicated the analysis on experimental phenomena and theoretical derivation.Many physical mechanisms on microscopic levels involving the electrokinetics of charged soft particles still remain poorly understood. Computer simulation provides deeper

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Modulation of electroosmotic flow by electric field-responsive polyelectrolyte brushes: a molecular dynamics study

Cited by 26 publications

References 25 publications

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Transport of polymer-modified nanoparticles in nanochannels coated with polymers

Electrohydrodynamics of spherical polyampholyte-grafted nanoparticles: Multiscale simulations by coupling of molecular dynamics and lattice-boltzmann method

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