Collective dynamics and conformal ordering in electrophoretically driven nematic colloids

Straube, Arthur V.; Pagès, Josep M.; Tierno, Pietro; Ignés‐Mullol, Jordi; Sagués, Francesc

doi:10.1103/physrevresearch.1.022008

Cited by 13 publications

(4 citation statements)

References 44 publications

(58 reference statements)

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“…It is known that soft condensed matter (or soft matter for short) can assemble into an array of nontrivial structures under non-equilibrium conditions. − These can be considered dynamic phase transitions, which may be readily observed over time scales that can be realized in experiments. Indeed, a variety of soft matter systems have been studied over a number of years, including effective self-propelling particles, , polymer blends, , and colloids, among others. − …”

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confidence: 99%

Phase Transitions of Oppositely Charged Colloidal Particles Driven by Alternating Current Electric Field

Wang

Shi

et al. 2021

ACS Nano

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We study systems containing oppositely charged colloidal particles under applied alternating current electric fields (AC fields) using overdamped Langevin dynamics simulations in three dimensions. We obtain jammed bands perpendicular to the field direction under intermediate frequencies and lanes parallel with the field under low frequencies. These structures also depend upon the particle charges. The pathway for generating jammed bands follows a stepwise mechanism, and intermediate bands are observed during lane formation in some systems. We investigate the component of the pressure tensors in the direction parallel to the field and observe that the jammed to lane transition occurs at a critical value for this pressure. We also find that the stable steady states appear to satisfy the principle of maximum entropy production. Our results may help to improve the understand of the underlying mechanisms for these types of dynamic phase transitions and the subsequent cooperative assemblies of colloidal particles under such non-equilibrium conditions.

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mentioning

confidence: 99%

Phase Transitions of Oppositely Charged Colloidal Particles Driven by Alternating Current Electric Field

Wang

Shi

et al. 2021

ACS Nano

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“…In this section, we overview the theoretical elements of the conformal crystal model and its connection to ground states of confined, long-range repulsive particles. The notion of a conformal crystal was introduced by Rothen, Pieranski, Rivier and Joyet [16,17], and its has been described and applied to numerous physical scenarios [7,10,[13][14][15]. Here, we summarize the key assumptions of the model and the mathematical connection between local density, lattice curvature and disclination defects.…”

Section: Elements Of the Conformal Crystal Modelmentioning

confidence: 99%

“…Low-temperature states formed by confined and mutually repulsive systems tend to break the prevailing paradigm of crystalline ground states, provided that either the interactions or the confining field acts over long range. Examples of such systems include multi-vortex arrays of confined superconductors [2][3][4][5][6][7], one-component plasmas [8][9][10][11], confined polyelectrolyte bundles [12,13], trapped, dipolar colloids [14] and particles at liquid crystalline interfaces [15]. In these systems, gradients in the pressure throughout the structure lead to a generic thermodynamic preference for non-uniform local density throughout the structure, which is generically incompatible with periodic lattice order of regular lattices.…”

Section: Introductionmentioning

confidence: 99%

Defects in Conformal Crystals: Discrete vs. Continuous Disclination Models

Meng,

Grason

2021

Preprint

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We study the relationship between topological defect formation and ground-state 2D packings in a model of repulsions in external confining potentials. Specifically we consider screened 2D Coulombic repulsions, which conveniently parameterizes the effects of interaction range, but also serves as simple physical model of confined, parallel arrays of polyelectrolyte filaments or vortices in type-II superconductors. The countervailing tendencies of repulsions and confinement to, respectively, spread and concentrate particle density leads to an energetic preference for non-uniform densities in the clusters. Ground states in such systmes have previously been modeled as conformal crystals, which are composed of locally equitriangular packings whose local areal densities exhibit long range gradients. Here, we assess two theoretical models that connect the preference for non-uniform density to the formation of disclination defects, one of which assumes a continuum distributions of defect, while the second considers the quantized and localized nature of disclinations in hexagonal conformal crystals. Comparing both theoretical descriptions to numerical simulations of discrete particles clusters, we show the influence of interaction range and confining potential on the topological charge, number and distribution of defects in ground states. We show that treating disclinations as continuously distributable well-captures the number of topological defects in the ground state in the regime of long-range interactions, while as interactions become shorter range, it dramatically overpredicts the to growth in total defect charge. Detailed analysis of the discretized defect theory suggests that that failure of the continuous defect theory in this limit can be attributed to the asymmetry in the preferred placement of positive vs. negative disclinations in the conformal crystal ground states, as well as a strongly asymmetric dependence of self-energy of disclinations on sign of topological charge.

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“…29–31 Here, the electrophoresis is nonlinear and the mobility depends on the defect structure, in particular the surrounding elastic distortions as well as the dielectric and conductivity anisotropies of LCs. 32–35 It has been shown that spherical silica particles inducing a quadrupolar director structure, namely particles with Saturn-ring and boojum defects, are non-motile due to the fore-aft symmetry of surrounding electroosmotic flows. 36 This symmetry is however broken for a particle with point defects (a dipolar particle) and it can move along the director n̂ (the direction of average molecular orientation).…”

Section: Introductionmentioning

confidence: 99%

Electrophoresis of metal-dielectric Janus particles with dipolar director symmetry in nematic liquid crystals

Sahu

Dhara

2022

Soft Matter

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Collective dynamics and conformal ordering in electrophoretically driven nematic colloids

Cited by 13 publications

References 44 publications

Phase Transitions of Oppositely Charged Colloidal Particles Driven by Alternating Current Electric Field

Phase Transitions of Oppositely Charged Colloidal Particles Driven by Alternating Current Electric Field

Defects in Conformal Crystals: Discrete vs. Continuous Disclination Models

Electrophoresis of metal-dielectric Janus particles with dipolar director symmetry in nematic liquid crystals

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