1
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Mirfendereski S, Park JS. Multiscale nature of electric-field-induced structural formations in non-colloidal suspensions. SOFT MATTER 2022; 18:6916-6926. [PMID: 36047429 DOI: 10.1039/d2sm00617k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Non-colloidal suspensions undergoing dipolar interactions in an electric field have been extensively studied and are also known as smart materials as they share similarities with electrorheological (ER) fluids. Although the macroscopic responses are well-documented, the multiscale nature of such suspensions is still lacking. In this study, a large-scale Stokesian dynamics simulation is used to investigate the structural formation of such suspensions in an electric field up to highly concentrated regimes across different length scales: from particle-level (microscale) to particle cluster-level (mesoscale) and stress response-level (macroscale). It is observed that at a volume fraction of ϕ ≈ 30%, the steady-state structures are the most isotropic at the microscale, but at the macroscale, their normal stress fields are the most anisotropic. Interestingly, these structures are also the most heterogeneous at both the microscale and mesoscale. Furthermore, the effects of confinement on the multiscale responses are explored, revealing that there could be a strong link between the mesoscale and macroscale. This multiscale nature can offer the potential for precisely controlling or designing ER fluids in practical applications.
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Affiliation(s)
- Siamak Mirfendereski
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA.
| | - Jae Sung Park
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA.
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2
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Rendos A, Cao W, Chern M, Lauricella M, Succi S, Werner JG, Dennis AM, Brown KA. Electric field induced macroscopic cellular phase of nanoparticles. SOFT MATTER 2022; 18:1991-1996. [PMID: 35080230 DOI: 10.1039/d1sm01650d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A suspension of nanoparticles with very low volume fraction is found to assemble into a macroscopic cellular phase that is composed of particle-rich walls and particle-free voids under the collective influence of AC and DC voltages. Systematic study of this phase transition shows that it was the result of electrophoretic assembly into a two-dimensional configuration followed by spinodal decomposition into particle-rich walls and particle-poor cells mediated principally by electrohydrodynamic flow. This mechanistic understanding reveals two characteristics needed for a cellular phase to form, namely (1) a system that is considered two dimensional and (2) short-range attractive, long-range repulsive interparticle interactions. In addition to determining the mechanism underpinning the formation of the cellular phase, this work presents a method to reversibly assemble microscale continuous structures out of nanoscale particles in a manner that may enable the creation of materials that impact diverse fields including energy storage and filtration.
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Affiliation(s)
- Abigail Rendos
- Division of Materials Science & Engineering, Boston University, Boston, MA, USA.
| | - Wenhan Cao
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | - Margaret Chern
- Division of Materials Science & Engineering, Boston University, Boston, MA, USA.
| | - Marco Lauricella
- Istituto per le Applicazioni del Calcolo, Consiglio Nazionale delle Ricerche, via dei Taurini 19, Rome, 00185, Italy
| | - Sauro Succi
- Center for Life Nano-Neuro Science at La Sapienza, Rome, Italy
| | - Jörg G Werner
- Division of Materials Science & Engineering, Boston University, Boston, MA, USA.
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | - Allison M Dennis
- Division of Materials Science & Engineering, Boston University, Boston, MA, USA.
- Biomedical Engineering Department, Boston University, Boston, MA, USA
| | - Keith A Brown
- Division of Materials Science & Engineering, Boston University, Boston, MA, USA.
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
- Physics Department, Boston University, Boston, MA, USA
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3
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Qian X, Ruan X, Li S. Effect of interparticle dipolar interaction on pore clogging during microfiltration. Phys Rev E 2022; 105:015102. [PMID: 35193311 DOI: 10.1103/physreve.105.015102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 12/07/2021] [Indexed: 01/01/2023]
Abstract
We present numerical investigations on the clogging of adhesive particles carrying electric dipoles at pore scale using an adhesive discrete element method (DEM). Based on the simulation results, the long-range dipolar interaction is reported to promote the clogging process, which is quantified by the bulk permeability, the penetrating particle number, and the particle capture efficiency. A clogging phase diagram is constructed in terms of the Stokes number (St) and the adhesion parameter (Ad) for both neutral and polarized particles. The influence of the dipolar interaction on the clogging-nonclogging transition is then described by the shifted boundary on the diagram. Also, the cake structure is characterized by different mathematical descriptions. A looser structure is formed with the increase of both the short-range adhesion and the long-range dipolar interaction. More ordered structures, such as particle chains, are observed in the presence of the stronger dipolar interaction. Furthermore, fluid stress is found to be essential in the compression and restructuring of the cake structure. Finally, a schematic representation of the cake structure is established, which provides a general physical picture showing the relationship between the cake structure and the particle-scale interactions.
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Affiliation(s)
- Xiaoyu Qian
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Xuan Ruan
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Shuiqing Li
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
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4
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Tiribocchi A, Montessori A, Lauricella M, Bonaccorso F, Brown KA, Succi S. Microscale modelling of dielectrophoresis assembly processes. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200407. [PMID: 34455845 DOI: 10.1098/rsta.2020.0407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/04/2021] [Indexed: 06/13/2023]
Abstract
This work presents a microscale approach for simulating the dielectrophoresis assembly of polarizable particles under an external electric field. The model is shown to capture interesting dynamical and topological features, such as the formation of chains of particles and their incipient aggregation into hierarchical structures. A quantitative characterization in terms of the number and size of these structures is also discussed. This computational model could represent a viable numerical tool to study the mechanical properties of particle-based hierarchical materials and suggest new strategies for enhancing their design and manufacture. This article is part of the theme issue 'Progress in mesoscale methods for fluid dynamics simulation'.
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Affiliation(s)
- A Tiribocchi
- Center for Life Nano Science@La Sapienza, Istituto Italiano di Tecnologia, 00161 Roma, Italy
- Istituto per le Applicazioni del Calcolo CNR, via dei Taurini, 19, 00185 Rome, Italy
| | - A Montessori
- Istituto per le Applicazioni del Calcolo CNR, via dei Taurini, 19, 00185 Rome, Italy
| | - M Lauricella
- Istituto per le Applicazioni del Calcolo CNR, via dei Taurini, 19, 00185 Rome, Italy
| | - F Bonaccorso
- Center for Life Nano Science@La Sapienza, Istituto Italiano di Tecnologia, 00161 Roma, Italy
- Istituto per le Applicazioni del Calcolo CNR, via dei Taurini, 19, 00185 Rome, Italy
- Department of Physics and INFN, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 1 00133 Rome, Italy
| | - K A Brown
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - S Succi
- Center for Life Nano Science@La Sapienza, Istituto Italiano di Tecnologia, 00161 Roma, Italy
- Istituto per le Applicazioni del Calcolo CNR, via dei Taurini, 19, 00185 Rome, Italy
- Institute for Applied Computational Science, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
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5
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Spatafora-Salazar A, Lobmeyer DM, Cunha LHP, Joshi K, Biswal SL. Hierarchical assemblies of superparamagnetic colloids in time-varying magnetic fields. SOFT MATTER 2021; 17:1120-1155. [PMID: 33492321 DOI: 10.1039/d0sm01878c] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Magnetically-guided colloidal assembly has proven to be a versatile method for building hierarchical particle assemblies. This review describes the dipolar interactions that govern superparamagnetic colloids in time-varying magnetic fields, and how such interactions have guided colloidal assembly into materials with increasing complexity that display novel dynamics. The assembly process is driven by magnetic dipole-dipole interactions, whose strength can be tuned to be attractive or repulsive. Generally, these interactions are directional in static external magnetic fields. More recently, time-varying magnetic fields have been utilized to generate dipolar interactions that vary in both time and space, allowing particle interactions to be tuned from anisotropic to isotropic. These interactions guide the dynamics of hierarchical assemblies of 1-D chains, 2-D networks, and 2-D clusters in both static and time-varying fields. Specifically, unlinked and chemically-linked colloidal chains exhibit complex dynamics, such as fragmentation, buckling, coiling, and wagging phenomena. 2-D networks exhibit controlled porosity and interesting coarsening dynamics. Finally, 2-D clusters have shown to be an ideal model system for exploring phenomena related to statistical thermodynamics. This review provides recent advances in this fast-growing field with a focus on its scientific potential.
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Affiliation(s)
- Aldo Spatafora-Salazar
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
| | - Dana M Lobmeyer
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
| | - Lucas H P Cunha
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
| | - Kedar Joshi
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
| | - Sibani Lisa Biswal
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
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6
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Carmack JM, Millett PC. Tuning thin-film bijels with applied external electric fields. SOFT MATTER 2018; 14:4344-4354. [PMID: 29761184 DOI: 10.1039/c8sm00638e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The tunability of thin-film bijels using applied external electric fields is explored using a Cahn-Hilliard Langevin dynamics computational model. Dielectric contrast between liquid domains governs liquid domain alignment and was varied in the simulations. Dielectric contrast between colloidal particles and liquid matrix induces dipolar particle interactions and was also varied in the simulations. The study reveals unique internal morphologies including those with through-thickness liquid domains. Significant results include identification of electric field effects on phase evolution and final morphology as well as relevant mechanisms. It was also found that particle chains act as nucleation sites for phase separation. The resultant morphologies were analyzed in terms of particle attachment to phase interface regions as well as the average channel diameter. Electric field effects and mechanisms on morphology are identified and compared with other morphology-tuning parameters such as particle loading and liquid-liquid composition.
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Affiliation(s)
- Joseph M Carmack
- Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
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7
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Azari A, Crassous JJ, Mihut AM, Bialik E, Schurtenberger P, Stenhammar J, Linse P. Directed Self-Assembly of Polarizable Ellipsoids in an External Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13834-13840. [PMID: 29111755 PMCID: PMC5719464 DOI: 10.1021/acs.langmuir.7b02040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/30/2017] [Indexed: 05/29/2023]
Abstract
The interplay between shape anisotropy and directed long-range interactions enables the self-assembly of complex colloidal structures. As a recent highlight, ellipsoidal particles polarized in an external electric field were observed to associate into well-defined tubular structures. In this study, we systematically investigate such directed self-assembly using Monte Carlo simulations of a two-point-charge model of polarizable prolate ellipsoids. In spite of its simplicity and computational efficiency, we demonstrate that the model is capable of capturing the complex structures observed in experiments on ellipsoidal colloids at low volume fractions. We show that, at sufficiently high electric field strength, the anisotropy in shape and electrostatic interactions causes a transition from three-dimensional crystal structures observed at low aspect ratios to two-dimensional sheets and tubes at higher aspect ratios. Our work thus illustrates the rich self-assembly behavior accessible when exploiting the interplay between competing long- and short-range anisotropic interactions in colloidal systems.
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8
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Santos AP, Pȩkalski J, Panagiotopoulos AZ. Thermodynamic signatures and cluster properties of self-assembly in systems with competing interactions. SOFT MATTER 2017; 13:8055-8063. [PMID: 29052681 DOI: 10.1039/c7sm01721a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Colloidal particles, amphiphiles and functionalized nanoparticles are examples of systems that frequently exhibit short-range attraction coupled with long-range repulsion. We vary the ratio of attraction and repulsion in a simple isotropic model with competing interactions, using molecular simulations, and observe significant differences in the properties of the self-assembled clusters that form. We report conditions that lead to the self-assembly of clusters of a preferred size, accompanied by a change in the slope of the pressure with respect to density, similar to micelles formed by amphiphilic molecules. We also report conditions where repulsion dominates, clusters of a preferred size form and the pressure vs. density slope is unaffected by self-assembly. We investigate cluster structure by calculating the size distributions, free colloid density, cluster shape and density profiles. The system dynamics are characterized by cluster life-times. We do not find qualitative differences in structure or dynamics of the clusters, regardless the pressure behavior. Therefore, thermodynamic and structural quantities are required to classify the different clustering characteristics that are observable in systems with competing interactions. Our results have implications in terms of development of design principles for stable cluster self-assembly.
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Affiliation(s)
- Andrew P Santos
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
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9
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Segovia-Gutiérrez JP, de Vicente J, Puertas AM, Hidalgo-Alvarez R. Describing magnetorheology under a colloidal glass approach. Phys Rev E 2017; 95:052601. [PMID: 28618613 DOI: 10.1103/physreve.95.052601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Indexed: 06/07/2023]
Abstract
The equilibrium structure and dynamics of magnetorheological (MR) fluids are studied in this work by simulations, where particles are modeled as dipoles with a quasihard spherical core. Upon increasing the interaction strength, controlled experimentally by the magnetic field, elongated clusters grow and, for intense fields, thick columns form, aligned with the field. The dynamics of the system is monitored by the mean-squared displacement and density correlation functions, which show an increasing slowing down with the attraction strength. The correlation function shows a two-step decay, with a separation between microscopic and long time dynamics, a typical hallmark of undercooled fluids. We have therefore analyzed the dynamics of this MR fluid using the typical concepts for undercooled fluids. Thus, the second decay of the density correlation function is fitted with a stretched exponential, and the wave-vector dependence of the fitting parameters studied. Both the amplitude and the time scale oscillate in phase with the structure factor. Our results support the idea that the magnetorheological effect is in fact the manifestation of a colloidal system approaching an attractive glass transition (or gel transition).
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Affiliation(s)
- J P Segovia-Gutiérrez
- Department of Applied Physics, Faculty of Sciences, University of Granada, Fuentenueva s/n, 18071-Granada, Spain
| | - J de Vicente
- Department of Applied Physics, Faculty of Sciences, University of Granada, Fuentenueva s/n, 18071-Granada, Spain
| | - Antonio M Puertas
- Group of Complex Fluids Physics, Department of Applied Physics, University of Almeria, 04120 Almería, Spain
| | - R Hidalgo-Alvarez
- Department of Applied Physics, Faculty of Sciences, University of Granada, Fuentenueva s/n, 18071-Granada, Spain
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10
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Clusters in sedimentation equilibrium for an experimental hard-sphere-plus-dipolar Brownian colloidal system. Sci Rep 2015; 5:13572. [PMID: 26323363 PMCID: PMC4555105 DOI: 10.1038/srep13572] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/30/2015] [Indexed: 11/08/2022] Open
Abstract
In this work, we use structure and dynamics in sedimentation equilibrium, in the presence of gravity, to examine, via confocal microscopy, a Brownian colloidal system in the presence of an external electric field. The zero field equation of state (EOS) is hard sphere without any re-scaling of particle size, and the hydrodynamic corrections to the long-time self-diffusion coefficient are quantitatively consistent with the expected value for hard spheres. Care is taken to ensure that both the dimensionless gravitational energy, which is equivalent to a Peclet number Peg, and dipolar strength Λ are of order unity. In the presence of an external electric field, anisotropic chain-chain clusters form; this cluster formation manifests itself with the appearance of a plateau in the diffusion coefficient when the dimensionless dipolar strength Λ ~ 1. The structure and dynamics of this chain-chain cluster state is examined for a monodisperse system for two particle sizes.
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11
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Yang Y, Pham AT, Cruz D, Reyes C, Wiley BJ, Lopez GP, Yellen BB. Assembly of colloidal molecules, polymers, and crystals in acoustic and magnetic fields. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:4725-4731. [PMID: 26179877 DOI: 10.1002/adma.201500462] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/02/2015] [Indexed: 05/28/2023]
Abstract
A dynamically adjustable colloidal assembly technique is presented, which combines magnetic and acoustic fields to produce a wide range of colloidal structures, ranging from discrete colloidal molecules, to polymer networks and crystals. The structures can be stabilized and dried, making them suitable for the fabrication of advanced materials.
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Affiliation(s)
- Ye Yang
- Department of Mechanical Engineering and Materials Science, Duke University, Box 90300 Hudson Hall, Durham, NC, 27708, USA
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
| | - An T Pham
- Department of Mechanical Engineering and Materials Science, Duke University, Box 90300 Hudson Hall, Durham, NC, 27708, USA
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
| | - Daniela Cruz
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Christopher Reyes
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
| | - Benjamin J Wiley
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
| | - Gabriel P Lopez
- Department of Mechanical Engineering and Materials Science, Duke University, Box 90300 Hudson Hall, Durham, NC, 27708, USA
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Benjamin B Yellen
- Department of Mechanical Engineering and Materials Science, Duke University, Box 90300 Hudson Hall, Durham, NC, 27708, USA
- NSF Research Triangle Materials Research Science and Engineering Center (MRSEC), Duke University, Box 90217, Durham, NC, 27708, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- University of Michigan - Shanghai Jiao Tong University, Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Rd, Shanghai, 200240, China
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12
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Abstract
Colloidal particles in a liquid crystal (LC) behave very differently from their counterparts in isotropic fluids. Elastic nature of the orientational order and surface anchoring of the director cause long-range anisotropic interactions and lead to the phenomenon of levitation. The LC environment enables new mechanisms of particle transport that are reviewed in this work. Among them the motion of particles caused by gradients of the director, and effects in the electric field: backflow powered by director reorientations, dielectrophoresis in LC with varying dielectric permittivity and LC-enabled nonlinear electrophoresis with velocity that depends on the square of the applied electric field and can be directed differently from the field direction.
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13
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Kantorovich S, Ivanov AO, Rovigatti L, Tavares JM, Sciortino F. Nonmonotonic magnetic susceptibility of dipolar hard-spheres at low temperature and density. PHYSICAL REVIEW LETTERS 2013; 110:148306. [PMID: 25167048 DOI: 10.1103/physrevlett.110.148306] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Indexed: 05/15/2023]
Abstract
We investigate, via numerical simulations, mean field, and density functional theories, the magnetic response of a dipolar hard sphere fluid at low temperatures and densities, in the region of strong association. The proposed parameter-free theory is able to capture both the density and temperature dependence of the ring-chain equilibrium and the contribution to the susceptibility of a chain of generic length. The theory predicts a nonmonotonic temperature dependence of the initial (zero field) magnetic susceptibility, arising from the competition between magnetically inert particle rings and magnetically active chains. Monte Carlo simulation results closely agree with the theoretical findings.
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Affiliation(s)
- Sofia Kantorovich
- Ural Federal University, Lenin Avenue 51, 620083, Ekaterinburg, Russia and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Alexey O Ivanov
- Ural Federal University, Lenin Avenue 51, 620083, Ekaterinburg, Russia
| | - Lorenzo Rovigatti
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - José Maria Tavares
- Instituto Superior de Engenharia de Lisboa-ISEL, Rua Conselheiro Emídio Navarro 1, P-1950-062 Lisbon, Portugal and Centro de Física Teórica e Computacional, Avenida Professor Gama Pinto 2, P-1649-003 Lisbon, Portugal
| | - Francesco Sciortino
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy and CNR-ISC, Università di Roma La Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
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14
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Malik V, Petukhov AV, He L, Yin Y, Schmidt M. Colloidal crystallization and structural changes in suspensions of silica/magnetite core-shell nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:14777-83. [PMID: 22794064 DOI: 10.1021/la301942t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The microradian X-ray scattering technique is used to investigate the colloidal crystallization of silica/magnetite core-shell magnetic nanoparticles. Particle self-assembly ranging from 2D sheets to 3D semicrystalline structures is observed as a function of the sedimentation-induced variation of the local particle concentration and the applied magnetic field. Because the particle size is comparable to the wavelength of light, these structures possess photonic properties that can be manipulated by an external stimulus.
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Affiliation(s)
- Vikash Malik
- Physics Department, University of Wisconsin-Milwaukee, 1900 E. Kenwood Blvd., Milwaukee, Wisconsin 53211, USA.
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15
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Pishnyak OP, Shiyanovskii SV, Lavrentovich OD. Aggregation of colloidal particles in a non-equilibrium backflow induced by electrically-driven reorientation of the nematic liquid crystal. J Mol Liq 2011. [DOI: 10.1016/j.molliq.2011.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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16
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Richardi J, Weis JJ. Low density mesostructures of confined dipolar particles in an external field. J Chem Phys 2011; 135:124502. [DOI: 10.1063/1.3638048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Nagaoka Y, Morimoto H, Maekawa T. Ordered complex structures formed by paramagnetic particles via self-assembly under an ac/dc combined magnetic field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:9160-9164. [PMID: 21707033 DOI: 10.1021/la201156q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We apply ac and dc magnetic fields simultaneously in orthogonal directions to each other to a solution, in which paramagnetic microparticles are dispersed, and show that complex secondary structures composed of oscillating chain clusters, that is, long linear clusters interconnected by T-, L-, and criss-cross-junctions, are self-assembled. Disklike clusters are formed at some junctions and the number of disklike clusters increases as the frequency of the ac magnetic field increases. We finally show that the angle between long linear clusters can be altered by changing the ratio of the intensities of the ac and dc magnetic fields.
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Affiliation(s)
- Yutaka Nagaoka
- Bio-Nano Electronics Research Center, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
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18
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Almudallal AM, Saika-Voivod I. Simulation of a two-dimensional model for colloids in a uniaxial electric field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:011402. [PMID: 21867166 DOI: 10.1103/physreve.84.011402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Indexed: 05/31/2023]
Abstract
We perform Monte Carlo simulations of a simplified two-dimensional model for colloidal hard spheres in an external uniaxial ac electric field. Experimentally, the external field induces dipole moments in the colloidal particles, which in turn form chains. We therefore approximate the system as composed of well-formed chains of dipolar hard spheres of a uniform length. The dipolar interaction between colloidal spheres gives rise to an effective interaction between the chains, which we treat as disks in a plane, that includes a short-range attraction and long-range repulsion. Hence, the system favors finite clustering over bulk phase separation, and indeed we observe at low temperature and density that the system does form a cluster phase. As the density increases, percolation is accompanied by a pressure anomaly. The percolated phase, despite being composed of connected, locally crystalline domains, does not bear the typical signatures of a hexatic phase. At very low densities, we find no indication of a "void phase" with a cellular structure seen recently in experiments.
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Affiliation(s)
- Ahmad M Almudallal
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St John's, Newfoundland, Canada A1B 3X7
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19
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Bartlett AP, Agarwal AK, Yethiraj A. Dynamic templating of colloidal patterns in three dimensions with nonuniform electric fields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:4313-4318. [PMID: 21417342 DOI: 10.1021/la200179c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Order-disorder transitions in colloidal systems are an attractive option for making switchable materials. Electric-field-driven order-disorder transitions are especially attractive for this purpose because the tuning parameter is easily and externally controllable. However, precise positional control of 3D structure is immensely challenging. Using patterned electrodes, we demonstrate that ac electric fields-dominantly dielectrophoresis (DEP) coupled with an electrohydrodynamic mechanism consisting of induced-charge electro-osmosis (ICEO)-can be used to template colloidal order dynamically in three dimensions. We find that the electric field geometry dictates the location, size, and shape of colloidal patterns and can produce patterns with surprising complexity.
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Affiliation(s)
- Andrew P Bartlett
- Department of Physics and Physical Oceanography, Memorial University, St. John's, Newfoundland and Labrador, Canada A1B 3X7
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Park JS, Saintillan D. Electric-field-induced ordering and pattern formation in colloidal suspensions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:041409. [PMID: 21599160 DOI: 10.1103/physreve.83.041409] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 03/06/2011] [Indexed: 05/30/2023]
Abstract
The long-time dynamics and pattern formation in semidilute suspensions of colloidal spheres in a viscous electrolyte under a uniform electric field are investigated using numerical simulations. The rapid chain formation that occurs in the field direction as a result of dipolar interactions is found to be followed by a slow coarsening process by which chains coalesce into hexagonal sheets and eventually rearrange to form mesoscale cellular structures, in qualitative agreement with recent experiments. The morphology and characteristic wavelength of the patterns that emerge at steady state are shown to depend on the suspension's volume fraction, electrode spacing, and field strength, suggesting additional ways of controlling effective suspension properties in practical applications.
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Affiliation(s)
- Jae Sung Park
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Pishnyak OP, Shiyanovskii SV, Lavrentovich OD. Inelastic collisions and anisotropic aggregation of particles in a nematic collider driven by backflow. PHYSICAL REVIEW LETTERS 2011; 106:047801. [PMID: 21405363 DOI: 10.1103/physrevlett.106.047801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Indexed: 05/09/2023]
Abstract
We design a nematic collider for controlled out-of-equilibrium anisotropic aggregation of spherical colloidal particles. The nematic surrounding imparts dipolar interactions among the spheres. A bidirectional backflow of the nematic liquid crystal in a periodic electric field forces the spheres to collide with each other. The inelastic collisions are of two types, head to tail and head to head. Head-to-tail collisions of dipoles result in longitudinal aggregation while head-to-head collisions promote aggregation in the transversal direction. The frequency of head-to-head collisions is set by the impact parameter that controls the resulting shape of aggregates, their anisotropy, and fractal dimension.
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Affiliation(s)
- Oleg P Pishnyak
- Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA
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Barhoum S, Yethiraj A. NMR Detection of an Equilibrium Phase Consisting of Monomers and Clusters in Concentrated Lysozyme Solutions. J Phys Chem B 2010; 114:17062-7. [DOI: 10.1021/jp108995k] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Suliman Barhoum
- Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland and Labrador, Canada
| | - Anand Yethiraj
- Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland and Labrador, Canada
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