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Williams I, Oğuz EC, Löwen H, Poon WCK, Royall CP. The rheology of confined colloidal hard disks. J Chem Phys 2022; 156:184902. [DOI: 10.1063/5.0087444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Colloids may be treated as “big atoms” so that they are good models for atomic and molecular systems. Colloidal hard disks are, therefore, good models for 2d materials, and although their phase behavior is well characterized, rheology has received relatively little attention. Here, we exploit a novel, particle-resolved, experimental setup and complementary computer simulations to measure the shear rheology of quasi-hard-disk colloids in extreme confinement. In particular, we confine quasi-2d hard disks in a circular “corral” comprised of 27 particles held in optical traps. Confinement and shear suppress hexagonal ordering that would occur in the bulk and create a layered fluid. We measure the rheology of our system by balancing drag and driving forces on each layer. Given the extreme confinement, it is remarkable that our system exhibits rheological behavior very similar to unconfined 2d and 3d hard particle systems, characterized by a dynamic yield stress and shear-thinning of comparable magnitude. By quantifying particle motion perpendicular to shear, we show that particles become more tightly confined to their layers with no concomitant increase in density upon increasing the shear rate. Shear thinning is, therefore, a consequence of a reduction in dissipation due to weakening in interactions between layers as the shear rate increases. We reproduce our experiments with Brownian dynamics simulations with Hydrodynamic Interactions (HI) included at the level of the Rotne–Prager tensor. That the inclusion of HI is necessary to reproduce our experiments is evidence of their importance in transmission of momentum through the system.
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Affiliation(s)
- Ian Williams
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
- H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
- Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol BS8 1FD, United Kingdom
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Erdal C. Oğuz
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 6997801, Israel
- School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Hartmut Löwen
- Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
| | - Wilson C. K. Poon
- SUPA and School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - C. Patrick Royall
- H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
- Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol BS8 1FD, United Kingdom
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
- Gulliver UMR CNRS 7083, ESPCI Paris, Université PSL, 75005 Paris, France
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Ordering and Dynamics of Interacting Colloidal Particles under Soft Confinement. COLLOIDS AND INTERFACES 2021. [DOI: 10.3390/colloids5020029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Confinement can induce substantial changes in the physical properties of macromolecules in suspension. Soft confinement is a particular class of restriction where the boundaries that constraint the particles in a region of the space are not well-defined. This scenario leads to a broader structural and dynamical behavior than observed in systems enclosed between rigid walls. In this contribution, we study the ordering and diffusive properties of a two-dimensional colloidal model system subjected to a one-dimensional parabolic trap. Increasing the trap strength makes it possible to go through weak to strong confinement, allowing a dimensional transition from two- to one-dimension. The non-monotonic response of the static and dynamical properties to the gradual dimensionality change affects the system phase behavior. We find that the particle dynamics are connected to the structural transitions induced by the parabolic trap. In particular, at low and intermediate confinement regimes, complex structural and dynamical scenarios arise, where the softness of the external potential induces melting and freezing, resulting in faster and slower particle diffusion, respectively. Besides, at strong confinements, colloids move basically along one direction, and the whole system behaves structurally and dynamically similar to a one-dimensional colloidal system.
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Nowack L, Rice SA. Monitoring local order in the liquid-X interface. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1875076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Linsey Nowack
- Department of Chemistry, Chicago Centre for Theoretical Chemistry, The University of Chicago, Chicago, IL, USA
| | - Stuart A. Rice
- James Franck Institute, The University of Chicago, Chicago, IL, USA
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Xu XB, Wang ZH, Xu XN, Fang GY, Gu M. Structural transitions for 2D systems with competing interactions in logarithmic traps. J Chem Phys 2020; 152:054906. [DOI: 10.1063/1.5140816] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- X. B. Xu
- Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Z. H. Wang
- Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
| | - X. N. Xu
- Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
| | - G. Y. Fang
- Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
| | - M. Gu
- Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
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Gurin P, Varga S. Beyond the single-file fluid limit using transfer matrix method: Exact results for confined parallel hard squares. J Chem Phys 2015; 142:224503. [DOI: 10.1063/1.4922154] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Péter Gurin
- Institute of Physics and Mechatronics, University of Pannonia, P.O. Box 158, Veszprém H-8201, Hungary
| | - Szabolcs Varga
- Institute of Physics and Mechatronics, University of Pannonia, P.O. Box 158, Veszprém H-8201, Hungary
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Williams I, Oğuz EC, Jack RL, Bartlett P, Löwen H, Royall CP. The effect of boundary adaptivity on hexagonal ordering and bistability in circularly confined quasi hard discs. J Chem Phys 2014; 140:104907. [PMID: 24628205 DOI: 10.1063/1.4867785] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The behaviour of materials under spatial confinement is sensitively dependent on the nature of the confining boundaries. In two dimensions, confinement within a hard circular boundary inhibits the hexagonal ordering observed in bulk systems at high density. Using colloidal experiments and Monte Carlo simulations, we investigate two model systems of quasi hard discs under circularly symmetric confinement. The first system employs an adaptive circular boundary, defined experimentally using holographic optical tweezers. We show that deformation of this boundary allows, and indeed is required for, hexagonal ordering in the confined system. The second system employs a circularly symmetric optical potential to confine particles without a physical boundary. We show that, in the absence of a curved wall, near perfect hexagonal ordering is possible. We propose that the degree to which hexagonal ordering is suppressed by a curved boundary is determined by the "strictness" of that wall.
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Affiliation(s)
- Ian Williams
- H.H. Wills Physics Laboratory, Tyndall Ave., Bristol BS8 1TL, United Kingdom
| | - Erdal C Oğuz
- Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
| | - Robert L Jack
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Paul Bartlett
- School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Hartmut Löwen
- Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
| | - C Patrick Royall
- H.H. Wills Physics Laboratory, Tyndall Ave., Bristol BS8 1TL, United Kingdom
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Gurin P, Varga S. Pair correlation functions of two- and three-dimensional hard-core fluids confined into narrow pores: Exact results from transfer-matrix method. J Chem Phys 2013; 139:244708. [DOI: 10.1063/1.4852181] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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Euán-Díaz EC, Misko VR, Peeters FM, Herrera-Velarde S, Castañeda-Priego R. Single-file diffusion in periodic energy landscapes: the role of hydrodynamic interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:031123. [PMID: 23030882 DOI: 10.1103/physreve.86.031123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Indexed: 06/01/2023]
Abstract
We report on the dynamical properties of interacting colloids confined to one dimension and subjected to external periodic energy landscapes. We particularly focus on the influence of hydrodynamic interactions on the mean-square displacement. Using Brownian dynamics simulations, we study colloidal systems with two types of repulsive interparticle interactions, namely, Yukawa and superparamagnetic potentials. We find that in the homogeneous case, hydrodynamic interactions lead to an enhancement of the particle mobility and the mean-square displacement at long times scales as t(α), with α=1/2+ε and ε being a small correction. This correction, however, becomes much more important in the presence of an external field, which breaks the homogeneity of the particle distribution along the line and, therefore, promotes a richer dynamical scenario due to the hydrodynamical coupling among particles. We provide here the complete dynamical scenario in terms of the external potential parameters: amplitude and commensurability.
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Affiliation(s)
- E C Euán-Díaz
- Division of Sciences and Engineering, University of Guanajuato, Loma del Bosque 103, Lomas del Campestre, 37150 León, Guanajuato, Mexico
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Wonder E, Lin B, Rice SA. Single-particle diffusion in dense inhomogeneous colloid suspensions in ribbon channels. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:041403. [PMID: 22181142 DOI: 10.1103/physreve.84.041403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/21/2011] [Indexed: 05/31/2023]
Abstract
We report the results of a study of single-particle diffusion in dense colloid fluids confined in a ribbon channel geometry that is intermediate between quasione dimensional (q1D) and quasitwo dimensional (q2D). This paper complements a previous paper about pair diffusion in the same system [Phys. Rev. E 82, 031403 (2010)]. In all of the systems studied, the colloid density distribution transverse to the ribbon channel is stratified with peak amplitudes that depend on the colloid density. Although the virtual walls that confine a stratum are structured with a scale length of the colloid diameter, that structure does not have an apparent influence on the single-particle diffusion, which shows the characteristic features of diffusion in a q1D channel with smooth walls. We find that, for all channel widths and packing fractions studied, the single-particle transverse diffusion coefficient in a stratum is smaller than the single-particle longitudinal diffusion coefficient in the same stratum and that the single-particle longitudinal diffusion coefficient varies very little from stratum to stratum, being only slightly smaller in the dense strata next to the walls than in the central strata. The lack of variation in the longitudinal diffusion coefficient with apparent stratum density is explained by the application of the Fischer-Methfessel approximation to the local density in an inhomogeneous liquid. The ratio of the transverse to longitudinal diffusion coefficients varies very slowly with ribbon width, implying a very slow transition from q1D to q2D behavior.
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Affiliation(s)
- Emily Wonder
- Department of Chemistry, CARS and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
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Liu KA, I L. Packing and melting of mesoscopically confined two-dimensional Coulomb crystals in straight narrow channels. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:041504. [PMID: 21230279 DOI: 10.1103/physreve.82.041504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Revised: 09/22/2010] [Indexed: 05/30/2023]
Abstract
The microstructure and melting dynamics of the two-dimensional mesoscopic Coulomb crystal with 1/r-type mutual interaction force and parabolic transverse confining potential, under different degrees of incommensurability, are investigated through molecular-dynamics simulation. To tune the degree of incommensurability, N(a) extra particles are added into the commensurate uniform triangular lattice which has seven-layer structure and 40 particles in each layer with the periodic longitudinal boundary condition, until the system reaches another commensurate packing with eight-layer structure at N(a)=40. It is found that the increasing incommensurability with the increasing N(a) or 40-N(a) gradually deteriorates the structural order with the presence of intrinsic defects and the anisotropic bond-length distribution, except for the defect-free configurations at a few magic N(a)'s. The system prefers the seven- and the eight-layer single structures through the entire crystal for the low- and the high-N(a) regimes, respectively, and the configurations with seven- and eight-layer domain mixtures for 18≤N(a)≤24. The increasing strain or the worse local particle interlocking around the intrinsic defects with the increasing incommensurability also causes the easier structural rearrangement associated with the easier particle hopping and the earlier onset of melting transition. The transverse confinement suppresses the transverse motion, induces nonuniform melting, and sustains the layered structure after melting.
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Affiliation(s)
- Kuo-An Liu
- Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China
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Herrera-Velarde S, Zamudio-Ojeda A, Castañeda-Priego R. Ordering and single-file diffusion in colloidal systems. J Chem Phys 2010; 133:114902. [DOI: 10.1063/1.3479003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Novikov S, Rice SA, Cui B, Diamant H, Lin B. Hydrodynamic interactions in ribbon channels: from quasi-one-dimensional to quasi-two-dimensional behavior. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:031403. [PMID: 21230073 DOI: 10.1103/physreve.82.031403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 08/13/2010] [Indexed: 05/30/2023]
Abstract
We present a study of the dynamics of confined suspensions whose dimensionality is intermediate between quasi-one-dimensional and quasi-two-dimensional (q2D) using microfluidic channels of various widths. The crossover between the two limiting behaviors is found to occur to different extent for different dynamic correlations between a pair of particles. In particular, the transverse coupling diffusion coefficient of particle pairs significantly deviates from its q2D form even in surprisingly wide channels.
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Affiliation(s)
- Sergey Novikov
- Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
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Tkachenko DV, Misko VR, Peeters FM. Dynamics of colloids in a narrow channel driven by a nonuniform force. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:051401. [PMID: 20364979 DOI: 10.1103/physreve.80.051401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Indexed: 05/29/2023]
Abstract
Using Brownian dynamics simulations, we investigate the dynamics of colloids confined in two-dimensional narrow channels driven by a nonuniform force Fdr(y) . We considered linear-gradient, parabolic, and deltalike driving-force profiles. This driving force induces melting of the colloidal solid (i.e., shear-induced melting), and the colloidal motion experiences a transition from elastic to plastic regime with increasing Fdr. For intermediate Fdr (i.e., in the transition region) the response of the system, i.e., the distribution of the velocities of the colloidal chains upsiloni(y) , in general does not coincide with the profile of the driving force Fdr(y), and depends on the magnitude of Fdr, the width of the channel, and the density of colloids. For example, we show that the onset of plasticity is first observed near the boundaries while the motion in the central region is elastic. This is explained by: (i) (in)commensurability between the chains due to the larger density of colloids near the boundaries, and (ii) the gradient in Fdr. Our study provides a deeper understanding of the dynamics of colloids in channels and could be accessed in experiments on colloids (or in dusty plasma) with, e.g., asymmetric channels or in the presence of a gradient potential field.
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Affiliation(s)
- D V Tkachenko
- Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
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