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Schiltz-Rouse E, Row H, Mallory SA. Kinetic temperature and pressure of an active Tonks gas. Phys Rev E 2023; 108:064601. [PMID: 38243499 DOI: 10.1103/physreve.108.064601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/06/2023] [Indexed: 01/21/2024]
Abstract
Using computer simulation and analytical theory, we study an active analog of the well-known Tonks gas, where active Brownian particles are confined to a periodic one-dimensional (1D) channel. By introducing the notion of a kinetic temperature, we derive an accurate analytical expression for the pressure and clarify the paradoxical behavior where active Brownian particles confined to 1D exhibit anomalous clustering but no motility-induced phase transition. More generally, this work provides a deeper understanding of pressure in active systems as we uncover a unique link between the kinetic temperature and swim pressure valid for active Brownian particles in higher dimensions.
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Affiliation(s)
- Elijah Schiltz-Rouse
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Hyeongjoo Row
- Department of Chemical and Biomolecular Engineering, UC Berkeley, Berkeley, California 94720, USA
| | - Stewart A Mallory
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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2
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Qiao Y, Liu Z, Ma X, Keim NC, Cheng X. Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12032-12040. [PMID: 37590891 DOI: 10.1021/acs.langmuir.3c01085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
The formation of particle clusters can substantially modify the dynamics and mechanical properties of suspensions in both two and three dimensions. While it has been well established that large network-spanning clusters increase the rigidity of particle systems, it is still unclear how the presence of localized nonpercolating clusters affects the dynamics and mechanical properties of particle suspensions. Here, we introduce self-assembled localized particle clusters at a fluid-fluid interface by mixing a fraction of Janus particles in a monolayer of homogeneous colloids. Each Janus particle binds to a few nearby homogeneous colloids, resulting in numerous small clusters uniformly distributed across the interface. Using a custom magnetic rod interfacial stress rheometer, we apply linear oscillatory shear to the particle-laden fluid interface. By analyzing the local affine deformation of particles from optical microscopy, we show that particles in localized clusters experience substantially lower shear-induced stretching than their neighbors outside clusters. We hypothesize that such heterogeneous dynamics induced by particle clusters increase the effective surface coverage of particles, which in turn enhances the shear moduli of the interface, as confirmed by direct interfacial rheological measurements. Our study illustrates the microscopic dynamics of small clusters in a shear flow and reveals their profound effects on the macroscopic rheology of particle-laden fluid interfaces. Our findings open an avenue for designing interfacial materials with improved mechanical properties via the control of formation of localized particle clusters.
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Affiliation(s)
- Yiming Qiao
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Zhengyang Liu
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Xiaolei Ma
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Nathan C Keim
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Xiang Cheng
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Wei M, Ben Zion MY, Dauchot O. Reconfiguration, Interrupted Aging, and Enhanced Dynamics of a Colloidal Gel Using Photoswitchable Active Doping. PHYSICAL REVIEW LETTERS 2023; 131:018301. [PMID: 37478452 DOI: 10.1103/physrevlett.131.018301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/06/2023] [Accepted: 06/01/2023] [Indexed: 07/23/2023]
Abstract
We study quasi-2D gels made of a colloidal network doped with Janus particles activated by light. Following the gel formation, we monitor both the structure and dynamics before, during, and after the activation period. Before activity is switched on, the gel is slowly aging. During the activation, the mobility of the passive particles exhibits a characteristic scale-dependent response, while the colloidal network remains connected, and the gel maintains its structural integrity. Once activity is switched off, the gel stops aging and keeps the memory of the structure inherited from the active phase. Remarkably, the motility remains larger than that of the gel, before the active period. The system has turned into a genuinely softer gel, with frozen dynamics, but with more space for thermal fluctuations. The above conclusions remain valid long after the activity period.
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Affiliation(s)
- Mengshi Wei
- Gulliver UMR CNRS 7083, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France
| | - Matan Yah Ben Zion
- School of Physics and Astronomy, and the Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Olivier Dauchot
- Gulliver UMR CNRS 7083, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France
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Saud KT, Solomon MJ. Microdynamics of active particles in defect-rich colloidal crystals. J Colloid Interface Sci 2023; 641:950-960. [PMID: 36989821 DOI: 10.1016/j.jcis.2023.03.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 02/04/2023] [Accepted: 03/02/2023] [Indexed: 03/11/2023]
Abstract
HYPOTHESIS Because they are self-propulsive, active colloidal particles can interact with their environment in ways that differ from passive, Brownian particles. Here, we explore how interactions in different microstructural regions may contribute to colloidal crystal annealing. EXPERIMENTS We investigate active particles propagating in a quasi-2D colloidal crystal monolayer produced by alternating current electric fields (active-to-passive particle ratio ∼ 1:720). The active particle is a platinum Janus sphere propelled by asymmetric decomposition of hydrogen peroxide. Crystals are characterized for changes in void properties. The mean-squared-displacement of Janus particles are measured to determine how active microdynamics depend on the local microstructure, which is comprised of void regions, void-adjacent regions (defined as within three particle diameters of a void), and interstitial regions. FINDINGS At active particle energy EA = 2.55 kBT, the average void size increases as much as three times and the average void anisotropy increases about 40% relative to the passive case. The average microdynamical enhancement, <δ(t)>, of Janus particles in the crystal relative to an equivalent passive Janus particle is reduced compared to that of a free, active particle (<δ(t) > is 1.88 ± 0.04 and 2.66 ± 0.08, respectively). The concentration of active particles is enriched in void and void-adjacent regions. Active particles exhibit the greatest change in dynamics relative to the passive control in void-adjacent regions (<δ(t)> = 2.58 ± 0.06). The results support the conjecture that active particle microdynamical enhancement in crystal lattices is affected by local defect structure.
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Affiliation(s)
- Keara T Saud
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, United States; Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
| | - Michael J Solomon
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States; Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States.
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García Daza FA, Puertas AM, Cuetos A, Patti A. Microrheology of isotropic and liquid-crystalline phases of hard rods by dynamic Monte Carlo simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Qiao Y, Ma X, Liu Z, Manno MA, Keim NC, Cheng X. Tuning the rheology and microstructure of particle-laden fluid interfaces with Janus particles. J Colloid Interface Sci 2022; 618:241-247. [PMID: 35339960 DOI: 10.1016/j.jcis.2022.03.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/07/2022] [Accepted: 03/09/2022] [Indexed: 12/21/2022]
Abstract
HYPOTHESIS Particle-laden fluid interfaces are the central component of many natural and engineering systems. Understanding the mechanical properties and improving the stability of such interfaces are of great practical importance. Janus particles, a special class of heterogeneous colloids, might be used as an effective surface-active agent to control the assembly and interfacial rheology of particle-laden fluid interfaces. EXPERIMENTS Using a custom-built interfacial stress rheometer, we explore the effect of Janus particle additives on the interfacial rheology and microscopic structure of particle-laden fluid interfaces. FINDINGS We find that the addition of a small amount of platinum-polystyrene (Pt-PS) Janus particles within a monolayer of PS colloids (1:40 number ratio) can lead to more than an order-of-magnitude increase in surface moduli with enhanced elasticity, which improves the stability of the interface. This drastic change in interfacial rheology is associated with the formation of local particle clusters surrounding each Janus particle. We further explain the origin of local particle clusters by considering the interparticle interactions at the interface. Our experiments reveal the effect of local particle structures on the macroscopic rheological behaviors of particle monolayers and demonstrate a new way to tune the microstructure and mechanical properties of particle-laden fluid interfaces.
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Affiliation(s)
- Yiming Qiao
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Xiaolei Ma
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhengyang Liu
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Michael A Manno
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Nathan C Keim
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
| | - Xiang Cheng
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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McGlasson A, Bradley LC. Investigating Time-Dependent Active Motion of Janus Micromotors using Dynamic Light Scattering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2104926. [PMID: 34655162 DOI: 10.1002/smll.202104926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/17/2021] [Indexed: 06/13/2023]
Abstract
Advances in fabrication methods have positioned Janus micromotors (JMs) as candidates for use as autonomous devices in applications across diverse fields, spanning drug delivery to environmental remediation. While the design of most micromotors is straightforward, the non-steady state active motion exhibited by these systems is complex and difficult to characterize. Traditionally, JM active motion is characterized using optical microscopy single particle tracking for systems confined in 2D. Dynamic light scattering (DLS) offers an alternative high-throughput method for characterizing the 3D active motion in bulk JM dispersions with additional capabilities to quantify time-dependent behavior for a broader range of JM sizes. Here, the active motion of spherical JMs is examined by DLS and it is demonstrated that the method enables decoupling of the translational and rotational diffusion. Systematic studies quantifying the time-dependent diffusive properties as a function of fuel concentration, JM concentration, and time after fuel addition are presented. The analyses presented in this work position DLS to facilitate future advances of JM systems by serving as a fast-screening characterization method for active motion.
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Affiliation(s)
- Alex McGlasson
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Laura C Bradley
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, MA, 01003, USA
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Chirinos-Flores D, Sánchez R, Díaz-Leyva P, Kozina A. Gelation of amphiphilic janus particles in an apolar medium. J Colloid Interface Sci 2021; 590:12-18. [PMID: 33524712 DOI: 10.1016/j.jcis.2021.01.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 10/22/2022]
Abstract
HYPOTHESIS The anisotropic nature of colloidal particles results in orientation-dependent interactions that organize the particles into peculiar structures different from those formed by isotropic colloids. Particles with a hydrophilic hemisphere are expected to assemble in hydrophobic solvents due to the contribution of hydrophobic interactions as observed for molecular amphiphiles. EXPERIMENTS Asymmetrically decorated silica-based Janus particles are dispersed in an apolar solvent, chloroform, and their structure and dynamics are studied by light scattering and compared with computer simulations. FINDINGS Gelation of amphiphilic Janus particles with asymmetric surface decoration is observed in a hydrophobic medium. The influence of particle asymmetry on gel structure and dynamics is discussed. Unlike particles with long-range repulsive interactions in water, these systems rapidly form rather compact structures that are nevertheless more ramified than those made of isotropic hydrophobic particles. Comparison with computer simulations allows visualization of the gel and reveals a contribution of asymmetric short-range attractions and cross-term repulsions to the net effective interaction potential.
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Affiliation(s)
- Denise Chirinos-Flores
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Mexico City, Mexico
| | - Rodrigo Sánchez
- Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco 186, 09340 Mexico City, Mexico
| | - Pedro Díaz-Leyva
- Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco 186, 09340 Mexico City, Mexico
| | - Anna Kozina
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Mexico City, Mexico.
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Cho JH, Bischofberger I. Two modes of cluster dynamics govern the viscoelasticity of colloidal gels. Phys Rev E 2021; 103:032609. [PMID: 33862797 DOI: 10.1103/physreve.103.032609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/05/2021] [Indexed: 11/07/2022]
Abstract
Colloidal gels formed by strongly attractive particles at low particle volume fractions are composed of space-spanning networks of uniformly sized clusters. We study the thermal fluctuations of the clusters using differential dynamic microscopy by decomposing them into two modes of dynamics, and link them to the macroscopic viscoelasticity via rheometry. The first mode, dominant at early times, represents the localized, elastic fluctuations of individual clusters. The second mode, pronounced at late times, reflects the collective, viscoelastic dynamics facilitated by the connectivity of the clusters. By mixing two types of particles of distinct attraction strengths in different proportions, we control the transition time at which the collective mode starts to dominate, and hence tune the frequency dependence of the linear viscoelastic moduli of the binary gels.
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Affiliation(s)
- Jae Hyung Cho
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Irmgard Bischofberger
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Mallory SA, Bowers ML, Cacciuto A. Universal reshaping of arrested colloidal gels via active doping. J Chem Phys 2020; 153:084901. [PMID: 32872893 DOI: 10.1063/5.0016514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Colloids that interact via a short-range attraction serve as the primary building blocks for a broad range of self-assembled materials. However, one of the well-known drawbacks to this strategy is that these building blocks rapidly and readily condense into a metastable colloidal gel. Using computer simulations, we illustrate how the addition of a small fraction of purely repulsive self-propelled colloids, a technique referred to as active doping, can prevent the formation of this metastable gel state and drive the system toward its thermodynamically favored crystalline target structure. The simplicity and robust nature of this strategy offers a systematic and generic pathway to improving the self-assembly of a large number of complex colloidal structures. We discuss in detail the process by which this feat is accomplished and provide quantitative metrics for exploiting it to modulate the self-assembly. We provide evidence for the generic nature of this approach by demonstrating that it remains robust under a number of different anisotropic short-ranged pair interactions in both two and three dimensions. In addition, we report on a novel microphase in mixtures of passive and active colloids. For a broad range of self-propelling velocities, it is possible to stabilize a suspension of fairly monodisperse finite-size crystallites. Surprisingly, this microphase is also insensitive to the underlying pair interaction between building blocks. The active stabilization of these moderately sized monodisperse clusters is quite remarkable and should be of great utility in the design of hierarchical self-assembly strategies. This work further bolsters the notion that active forces can play a pivotal role in directing colloidal self-assembly.
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Affiliation(s)
- S A Mallory
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - M L Bowers
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - A Cacciuto
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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