Layering and packing in confined colloidal suspensions

Villada-Balbuena, Alejandro; Jung, Gerhard; Zuccolotto-Bernez, Angel B; Franosch, Thomas; Egelhaaf, Stefan U.

doi:10.1039/d2sm00412g

Cited by 8 publications

(11 citation statements)

References 88 publications

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“…The shape and the type of interaction between colloidal particles combined with the presence of distinct confining surfaces have key roles in self-assembly, phase separation, interfacial activities and anomalous behavior of systems modeled by CS potentials [49][50][51][52][53]. Those peculiarities are in agreement with several experiments involving colloidal cluster, formation of self-assembled mesophases, layering packing and synthesis of new structures using amphiphilic molecules [54][55][56][57][58][59].…”

Section: Of 12supporting

confidence: 84%

How Dimensionality Affects the Structural Anomaly in a Core-Softened Collo

Krott¹,

Bordin²

2023

Preprint

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The interaction between hard-core soft-shell colloids are characterized by having two characteristic distances: one associated with the penetrable, soft corona and another one corresponding to the impenetrable core. Isotropic core-softened potentials with two characteristic length scales have long been applied to understand the properties of such colloids. Those potentials usually show waterlike anomalies, and recent findings have indicated the existence of multiple anomalous regions in the 2D limit under compression, while in 3D only one anomalous region is observed. In this direction, we perform Molecular Dynamics simulations to unveil the details about the structural behavior in the quasi-2D limit of a core-softened colloid. The fluid was confined between highly repulsive solvophobic walls, and the behavior at distinct wall separation and colloid density was analyzed. Our results indicated a straight relation between the 2D or 3D-like behavior and the layers separation. We can relate that if the system behaves as independent 2D-layers, it will have a 2D-like behavior. However, for some separations the layers are connected, with colloids hopping from one layer to another – having then a 3D-like structural behavior. Those findings fill the gap in the depiction of the anomalous behavior from 2D to 3D.

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Section: Of 12supporting

confidence: 84%

How Dimensionality Affects the Structural Anomaly in a Core-Softened Collo

Krott¹,

Bordin²

2023

Preprint

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“…Period boundary conditions were used in the x - and y -directions. The repulsion from the wall also affects the particle behaviors . In this study, it was assumed that the particles are affected by repulsion from the walls when the distance between the walls and the particles is less than δ /2.…”

Section: Methodsmentioning

confidence: 99%

“…When particles are placed in a thin space between two parallel walls, − structures such as the face-centered cubic (FCC) structure, hexagonal close-packed structure, buckling structure, and prism phase are created, depending on the width between the walls, particle density, or pressure. In addition to the system size, system shape, − and particle shape, ,, the structures created in such small systems also depend on the interaction between particles. ,,,− The way in which structures are created in narrow systems has been investigated with consideration of many cases.…”

Section: Introductionmentioning

confidence: 99%

Structures Formed by Particles with Shoulderlike Repulsive Interaction in Thin Systems

Muragishi,

Sato

2023

ACS Omega

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When particles are constructed in thin systems between two parallel flat walls, structures that are not observed in bulk systems are created and the created structures change, depending on the width between the walls. In this study, the structures formed by particles constructed in thin systems were investigated through performing isothermal–isobaric Monte Carlo simulations, where the interaction between the particles is given by the hard-core square shoulder potential. By controlling the width of the shoulder-like repulsive interaction and the system width, several novel structures such as the connection of rhombuses and the square lattice of the (100) face of the body-centered cubic lattice were created.

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“…In addition, the bulk response of the suspension can be very sensitive to the material close to the confining boundaries [9][10][11][12]. Planar boundaries promote the formation of layers of particles parallel to the boundaries [9,13], enabling more efficient shearing as layers slide past each other with reduced close particle interactions, and a resulting reduction in the local viscosity [14][15][16]. The layering also enhances ordering within the layer, and in many circumstances the sliding layers show a high degree of hexagonal ordering, similar to what is seen in two dimensional colloidal crystals [12,17].…”

Section: Introductionmentioning

confidence: 99%

Order and density fluctuations near the boundary in sheared dense suspensions

2022

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We introduce a novel approach to reveal ordering fluctuations in sheared dense suspensions, using line scanning in a combined rheometer and laser scanning confocal microscope. We validate the technique with a moderately dense suspension, observing modest shear-induced ordering and a nearly linear flow profile. At high concentration (ϕ = 0.55) and applied stress just below shear thickening, we report ordering fluctuations with high temporal resolution, and directly measure a decrease in order with distance from the suspension’s bottom boundary as well as a direct correlation between order and particle concentration. Higher applied stress produces shear thickening with large fluctuations in boundary stress which we find are accompanied by dramatic fluctuations in suspension flow speeds. The peak flow rates are independent of distance from the suspension boundary, indicating that they likely arise from transient jamming that creates solid-like aggregates of particles moving together, but only briefly because the high speed fluctuations are interspersed with regions flowing much more slowly, suggesting that shear thickening suspensions possess complex internal structural dynamics, even in relatively simple geometries.

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Layering and packing in confined colloidal suspensions

Abstract: Confinement modifies the properties of a fluid. The particle density is no longer uniform but depends on the distance from the walls; parallel to the walls, layers with different particle...

Cited by 8 publications

References 88 publications

How Dimensionality Affects the Structural Anomaly in a Core-Softened Collo

How Dimensionality Affects the Structural Anomaly in a Core-Softened Collo

Structures Formed by Particles with Shoulderlike Repulsive Interaction in Thin Systems

Order and density fluctuations near the boundary in sheared dense suspensions

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