Isotropic-nematic spinodals of rigid long thin rodlike colloids by event-driven Brownian dynamics simulations

Tao, Yu-Guo; Otter, Wouter K. den; Dhont, Jan K. G.; Briels, Willem J.

doi:10.1063/1.2180251

Cited by 57 publications

(86 citation statements)

References 51 publications

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“…22 Many examples of numerical simulations on Brownian non-spherical particles are reported in the recent literature. Brownian dynamics simulations of unbounded suspensions of rod-like particles [23][24][25][26][27] and arbitrarily shaped particles [28][29][30] have been carried out for different volume fractions, ranging from dilute to concentrated regimes, although interparticle hydrodynamic interactions are often neglected. The inclusion of hydrodynamic interactions gives rise to "corrective terms" in the Brownian dynamics.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics and Brownian motions of a spheroid near a rigid wall

Corato

Greco

D’Avino

et al. 2015

The Journal of Chemical Physics

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Articles you may be interested in PHYSICS 142, 194901 (2015) Hydrodynamics and Brownian motions of a spheroid near a rigid wall In this work, we study in detail the hydrodynamics and the Brownian motions of a spheroidal particle suspended in a Newtonian fluid near a flat rigid wall. We employ 3D Finite Element Method (FEM) simulations to compute how the mobility tensor of the spheroid varies with both the particle-wall separation distance and the particle orientation. We then study the Brownian motion of the spheroid by means of a discretized Langevin equation. We specifically focus on the additional drift terms arising from the position and orientational dependence of the mobility matrix. In this respect, we also propose a numerically convenient approximation of the orientational divergence of the mobility matrix that is required in the solution of the Langevin equation. Our results illustrate that both hydrodynamics and Brownian motions of a spheroidal particle near a confining wall display novel features from those of a sphere in the same type of confinement. C 2015 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Hydrodynamics and Brownian motions of a spheroid near a rigid wall

Corato

Greco

D’Avino

et al. 2015

The Journal of Chemical Physics

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“…(1) with an event-driven algorithm to detect the collisions between rod and obstacles [21][22][23]. The MSDs in fig.…”

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confidence: 99%

Effective Perrin theory for the anisotropic diffusion of a strongly hindered rod

Munk¹,

Höfling²,

Frey³

et al. 2009

Europhys. Lett.

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Abstract. -Slender rods in concentrated suspensions constitute strongly interacting systems with rich dynamics: transport slows down drastically and the anisotropy of the motion becomes arbitrarily large. We develop a mesoscopic description of the dynamics down to the length scale of the interparticle distance. Our theory is based on the exact solution of the Smoluchowski-Perrin equation; it is in quantitative agreement with extensive Brownian dynamics simulations in the dense regime. In particular, we show that the tube confinement is characterised by a power law decay of the intermediate scattering function with exponent 1/2.Brownian motion of highly anisotropic particles is considerably more complex than the diffusion of spherical objects, the basic understanding of which is founded on the seminal works by Einstein and von Smoluchowski. A shape anisotropy results in diffusion coefficients that depend on the direction of motion in the body frame, thus inducing a coupling of translation to the orientation. This anisotropic dynamics has been investigated in recent experiments measuring diffusion coefficients of micrometre sized ellipsoids and rods by single particle tracking [1-3]; in particular, non-Gaussian statistics has been observed [1]. Likewise in dynamic light scattering, the rotational and translational diffusion coefficients were determined simultaneously [4]. For these dilute systems, the ratio of diffusion parallel and perpendicular to the long symmetry axis was limited to values up to D /D ⊥ ≈ 4 in quasi two-dimensional (2D) confinement.Considerably higher values of this ratio have been observed in simulations of semi-dilute suspensions of slender rods, yielding D /D ⊥ up to values of 50 [5,6]. This increase in anisotropy is caused by the steric constraints imposed by surrounding rods; thereby the transverse and rotational motion is suppressed, whereas the longitudinal transport is barely influenced [7]. An intermediate regime of anisotropic diffusion has been derived for ballistic needles within kinetic theory [8] and was observed in simulations [9].For a finite width b, the rods undergo a phase transition to the nematic phase at densities of the order of 1/bL 2 as predicted by Onsager [10]. The dynamics in this ordered phase becomes trivially anisotropic and splits into a fast diffusion along the nematic director axis and slower diffusion perpendicular to it. Such a pronounced anisotropic diffusion has been observed in simulations of nematic elongated ellipsoids [11] and spherocylinders [12,13]. Experiments have also clearly demonstrated orientation-dependent diffusion in colloidal nanorods in the isotropic and nematic phase [14] and in various liquid crystalline phases of fd viruses [15,16]. The phenomena connected with the nematic phase transition are essentially understood and will not be discussed in this work.In the isotropic phase, experiments and computer simulations have been restricted to determine the diffusion coefficients from the mean-square displacements. The complex interplay of tra...

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“…A Brownian dynamics simulation of phase separation in concentrated solutions of long (length/width ratios 10 − 60) hard rods has also very recently appeared. 19 However, also in view of the importance of the aforementioned applications, it is surprising that very little indeed is known on the mechanism of thermotropic liquid crystal nanodroplet formation, their internal structure and ordering, and how a change in temperature affects the droplet features. In this paper we wish to present a computer simulation of the separation of nematic nanodroplets from a homogeneous binary solution.…”

Section: Introductionmentioning

confidence: 99%

A computer simulation study of the formation of liquid crystal nanodroplets from a homogeneous solution

Berardi¹,

Costantini²,

Muccioli³

et al. 2007

The Journal of Chemical Physics

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The aggregation of liquid crystal nanodroplets from a homogeneous solution is an important but not well understood step in the preparation of various advanced photonic materials. Here, we have performed molecular dynamics computer simulations of the formation of liquid crystalline nanodroplets, starting from an isotropic and uniform binary solution of spherical Lennard-Jones (solvent) and elongated ellipsoidal Gay-Berne (solute) rigid particles in low (< 10%) concentration. We have studied the dynamics of demixing and the mesogen ordering process and we have characterised the resulting nanodroplets assessing the effect of temperature, composition, and specific solute-solvent interaction on the morphology, structure, and anisotropy. We find that the specific solute-solvent interaction, composition, and temperature can be adjusted to tune the nanodroplet growth and size.

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Isotropic-nematic spinodals of rigid long thin rodlike colloids by event-driven Brownian dynamics simulations

Cited by 57 publications

References 51 publications

Hydrodynamics and Brownian motions of a spheroid near a rigid wall

Hydrodynamics and Brownian motions of a spheroid near a rigid wall

Effective Perrin theory for the anisotropic diffusion of a strongly hindered rod

A computer simulation study of the formation of liquid crystal nanodroplets from a homogeneous solution

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