1
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Bera A, Binder K, Egorov SA, Das SK. Phase behavior and dynamics in a colloid-polymer mixture under spherical confinement. SOFT MATTER 2023; 19:3386-3397. [PMID: 37128824 DOI: 10.1039/d3sm00362k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
From studies via molecular dynamics simulations, we report results on structure and dynamics in mixtures of active colloids and passive polymers that are confined inside a spherical container with a repulsive boundary. All interactions in the fully passive limit are chosen in such a way that in equilibrium coexistence between colloid-rich and polymer-rich phases occurs. For most part of the studies the chosen compositions give rise to Janus-like structure: nearly one side of the sphere is occupied by the colloids and the rest by the polymers. This partially wet situation mimics approximately a neutral wall in the fully passive scenario. Following the introduction of a velocity-aligning activity to the colloids, the shape of the polymer-rich domain changes to that of an ellipsoid, around the long axis of which the colloid-rich domain attains a macroscopic angular momentum. In the steady state, the orientation of this axis evolves via diffusion, magnitude of which depends upon the strength of activity, but only weakly.
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Affiliation(s)
- Arabinda Bera
- Theoretical Sciences Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India.
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität, D-55099 Mainz, Staudinger Weg 7, Germany
| | - Sergei A Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
| | - Subir K Das
- Theoretical Sciences Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India.
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2
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Klippenstein V, van der Vegt N. Cross-Correlation Corrected Friction in Generalized Langevin Models: Application to the continuous Asakura-Oosawa Model. J Chem Phys 2022; 157:044103. [DOI: 10.1063/5.0093056] [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
In a previous study we proposed a method to parameterize isotropic, configuration independent, non-Markovian generalized Langevin thermostats to achieve dynamic consistency in coarse-grained models. In the current study, by applying the same strategy, we develop coarse-grained implicit solvent models for the continuous Asakura-Oosawa model, which under certain conditions allows to develop very accurate coarse-grained potentials. By developing coarse-grained models for different reference systems with varying parameters, we test the broader applicability of the proposed procedure and demonstrate the relevance of accurate coarse-grained potentials in bottom-up derived dissipative models. We study how different system parameters affect the dynamic representability of the coarse-grained models. In particular we find that the quality of the coarse-grained potential is crucial to correctly model the backscattering effect due to collisions on the coarse-grained scale. In the dynamics of colloid suspensions the hydrodynamic interactions affect the long-time scale dynamics by solvent mediated momentum transfer. These interactions are not explicitly modeled in the presented coarse-grained models, which poses some limitations to the proposed coarse-graining scheme. The Asakura-Oosawa model allows a tuning of system parameters, to gain an improved understanding of these limitations. We also propose three new iterative optimization schemes to fine tune the generalized Langevin thermostat to exactly match the reference velocity-autocorrelation function.
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Affiliation(s)
| | - Nico van der Vegt
- Chemistry, Technische Universität Darmstadt Fachbereich Chemie, Germany
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3
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Miyazaki K, Schweizer KS, Thirumalai D, Tuinier R, Zaccarelli E. The Asakura–Oosawa theory: Entropic forces in physics, biology, and soft matter. J Chem Phys 2022; 156:080401. [DOI: 10.1063/5.0085965] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- K. Miyazaki
- Department of Physics, Nagoya University, Nagoya 464-8602, Japan
| | - K. S. Schweizer
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA
- Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
- Department of Materials Science, University of Illinois, Urbana, Illinois 61801, USA
| | - D. Thirumalai
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - R. Tuinier
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - E. Zaccarelli
- CNR-ISC (National Research Council–Institute for Complex Systems) and Department of Physics, Sapienza University of Rome, Rome, Italy
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4
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Dittrich F, Speck T, Virnau P. Critical behavior in active lattice models of motility-induced phase separation. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:53. [PMID: 33860860 PMCID: PMC8052248 DOI: 10.1140/epje/s10189-021-00058-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/15/2021] [Indexed: 05/04/2023]
Abstract
Lattice models allow for a computationally efficient investigation of motility-induced phase separation (MIPS) compared to off-lattice systems. Simulations are less demanding, and thus, bigger systems can be accessed with higher accuracy and better statistics. In equilibrium, lattice and off-lattice models with comparable interactions belong to the same universality class. Whether concepts of universality also hold for active particles is still a controversial and open question. Here, we examine two recently proposed active lattice systems that undergo MIPS and investigate numerically their critical behavior. In particular, we examine the claim that these systems and MIPS in general belong to the Ising universality class. We also take a more detailed look on the influence and role of rotational diffusion and active velocity in these systems.
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Affiliation(s)
- Florian Dittrich
- Institute of Physics, Johannes Gutenberg-Universität, Mainz, Germany
| | - Thomas Speck
- Institute of Physics, Johannes Gutenberg-Universität, Mainz, Germany
| | - Peter Virnau
- Institute of Physics, Johannes Gutenberg-Universität, Mainz, Germany
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5
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Pathania Y, Chakraborty D, Höfling F. Continuous Demixing Transition of Binary Liquids: Finite‐Size Scaling from the Analysis of Sub‐Systems. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202000235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Yogyata Pathania
- Indian Institute of Science Education and Research Mohali Knowledge City, Sector 81, S. A. S. Nagar Manauli 140306 India
| | - Dipanjan Chakraborty
- Indian Institute of Science Education and Research Mohali Knowledge City, Sector 81, S. A. S. Nagar Manauli 140306 India
| | - Felix Höfling
- Freie Universität Berlin, Fachbereich Mathematik und Informatik Arnimallee 6 Berlin 14195 Germany
- Zuse Institute Berlin Takustr. 7 Berlin 14195 Germany
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6
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Handle PH, Rovigatti L, Sciortino F. q-Independent Slow Dynamics in Atomic and Molecular Systems. PHYSICAL REVIEW LETTERS 2019; 122:175501. [PMID: 31107067 DOI: 10.1103/physrevlett.122.175501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Indexed: 06/09/2023]
Abstract
Investigating million-atom systems for very long simulation times, we demonstrate that the collective density-density correlation time (τ_{α}) in simulated supercooled water and silica becomes wave-vector independent (q^{0}) when the probing wavelength is several times larger than the interparticle distance. The q independence of the collective density-density correlation functions, a feature clearly observed in light-scattering studies of some soft-matter systems, is thus a genuine feature of many (but not all) slow-dynamics systems, either atomic, molecular, or colloidal. Indeed, we show that when the dynamics of the density fluctuations includes particle-type diffusion, as in the case of the Lennard-Jones binary-mixture model, the q^{0} regime does not set in and the relaxation time continues to scale as τ_{α}∼q^{-2} even at small q.
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Affiliation(s)
- Philip H Handle
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Lorenzo Rovigatti
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- CNR-ISC, UoS Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Francesco Sciortino
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
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7
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Trefz B, Siebert JT, Speck T, Binder K, Virnau P. Estimation of the critical behavior in an active colloidal system with Vicsek-like interactions. J Chem Phys 2017; 146:074901. [DOI: 10.1063/1.4975812] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- Benjamin Trefz
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
- Graduate School Material Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - Jonathan Tammo Siebert
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Thomas Speck
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Kurt Binder
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Peter Virnau
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
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8
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D’Adamo G, Pelissetto A, Pierleoni C. Phase Diagram and Structure of Mixtures of Large Colloids and Linear Polymers under Good-Solvent Conditions. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Andrea Pelissetto
- Dipartimento di Fisica, Sapienza Università di Roma and INFN, Sezione di Roma I, P.le Aldo Moro
2, I-00185 Rome, Italy
| | - Carlo Pierleoni
- Dipartimento di Scienze Fisiche
e Chimiche, Università dell’Aquila, V. Vetoio 10, Loc. Coppito, I-67100 L’Aquila, Italy
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9
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Trefz B, Das SK, Egorov SA, Virnau P, Binder K. Activity mediated phase separation: Can we understand phase behavior of the nonequilibrium problem from an equilibrium approach? J Chem Phys 2016; 144:144902. [DOI: 10.1063/1.4945365] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Benjamin Trefz
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55128 Mainz, Germany
- Graduate School Material Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - Subir K. Das
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
| | - Sergei A. Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
| | - Peter Virnau
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55128 Mainz, Germany
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55128 Mainz, Germany
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10
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Požar M, Lovrinčević B, Zoranić L, Primorać T, Sokolić F, Perera A. Micro-heterogeneity versus clustering in binary mixtures of ethanol with water or alkanes. Phys Chem Chem Phys 2016; 18:23971-9. [DOI: 10.1039/c6cp04676b] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Snapshots of the difference in complex disorder, with analogy with direct (ethanol–water) and inverse (ethanol–alkanes) emulsions.
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Affiliation(s)
- Martina Požar
- Laboratoire de Physique Théorique de la Matière Condensée (UMR CNRS 7600)
- Université Pierre et Marie Curie
- Paris cedex 05
- France
- Department of Physics
| | | | - Larisa Zoranić
- Department of Physics
- Faculty of Sciences
- University of Split
- Split
- Croatia
| | - Tomislav Primorać
- Department of Physics
- Faculty of Sciences
- University of Split
- Split
- Croatia
| | - Franjo Sokolić
- Department of Physics
- Faculty of Sciences
- University of Split
- Split
- Croatia
| | - Aurélien Perera
- Laboratoire de Physique Théorique de la Matière Condensée (UMR CNRS 7600)
- Université Pierre et Marie Curie
- Paris cedex 05
- France
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11
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Rovigatti L, Gnan N, Parola A, Zaccarelli E. How soft repulsion enhances the depletion mechanism. SOFT MATTER 2015; 11:692-700. [PMID: 25428843 DOI: 10.1039/c4sm02218a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate binary mixtures of large colloids interacting through soft potentials with small, ideal depletants. We show that softness has a dramatic effect on the resulting colloid-colloid effective potential when the depletant-to-colloid size ratio q is small, with significant consequences on the colloidal phase behaviour. We provide an exact relationship that allows us to obtain the effective pair potential for any type of colloid-depletant interaction in the case of ideal depletants, without having to rely on complicated and expensive full-mixture simulations. We also show that soft repulsion among depletants further enhances the tendency of colloids to aggregate. Our theoretical and numerical results demonstrate that--in the limit of small q--soft mixtures cannot be mapped onto hard systems and hence soft depletion is not a mere extension of the widely used Asakura-Oosawa potential.
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Affiliation(s)
- Lorenzo Rovigatti
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria.
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12
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Almarza NG, Martín C, Lomba E, Bores C. Demixing and confinement of non-additive hard-sphere mixtures in slit pores. J Chem Phys 2015; 142:014702. [DOI: 10.1063/1.4905273] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- N. G. Almarza
- Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid, Spain
| | - C. Martín
- Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid, Spain
| | - E. Lomba
- Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid, Spain
| | - C. Bores
- Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid, Spain
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13
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López de Haro M, Tejero CF, Santos A, Yuste SB, Fiumara G, Saija F. Virial coefficients and demixing in the Asakura–Oosawa model. J Chem Phys 2015; 142:014902. [DOI: 10.1063/1.4904891] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Mariano López de Haro
- Instituto de Energías Renovables, Universidad Nacional Autónoma de México (U.N.A.M.), Temixco, Morelos 62580, Mexico
| | - Carlos F. Tejero
- Facultad de Ciencias Físicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Andrés Santos
- Departamento de Física and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06071 Badajoz, Spain
| | - Santos B. Yuste
- Departamento de Física and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06071 Badajoz, Spain
| | - Giacomo Fiumara
- Department of Mathematics and Computer Science, University of Messina, Viale F. Stagno D’Alcontres 31, I-98166 Messina, Italy
| | - Franz Saija
- CNR-IPCF, Viale F. Stagno d’Alcontres, 37-98158 Messina, Italy
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14
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Binder K, Virnau P, Statt A. Perspective: The Asakura Oosawa model: A colloid prototype for bulk and interfacial phase behavior. J Chem Phys 2014; 141:140901. [DOI: 10.1063/1.4896943] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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15
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D'Adamo G, Pelissetto A, Pierleoni C. Phase diagram of mixtures of colloids and polymers in the thermal crossover from good to θ solvent. J Chem Phys 2014; 141:024902. [PMID: 25028041 DOI: 10.1063/1.4885818] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We determine the phase diagram of mixtures of spherical colloids and neutral nonadsorbing polymers in the thermal crossover region between the θ point and the good-solvent regime. We use the generalized free-volume theory, which takes into account the polymer-concentration dependence of the depletion thickness and of the polymer compressibility. This approach turns out to be quite accurate as long as q = Rg/Rc ≲ 1 (Rg is the radius of gyration of the polymer and Rc is the colloid radius). We find that, close to the θ point, the phase diagram is not very sensitive to solvent quality, while, close to the good-solvent region, changes of the solvent quality modify significantly the position of the critical point and of the binodals. We also analyze the phase behavior of aqueous solutions of charged colloids and polymers, using the approach proposed by Fortini et al. [J. Phys.: Condens. Matter 17, 7783 (2005)].
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Affiliation(s)
| | - Andrea Pelissetto
- Dipartimento di Fisica, Sapienza Università di Roma and INFN, Sezione di Roma I, P.le Aldo Moro 2, I-00185 Roma, Italy
| | - Carlo Pierleoni
- Dipartimento di Scienze Fisiche e Chimiche, Università dell'Aquila and CNISM, UdR dell'Aquila, V. Vetoio 10, Loc. Coppito, I-67100 L'Aquila, Italy
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16
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Das SK, Egorov SA, Trefz B, Virnau P, Binder K. Phase behavior of active swimmers in depletants: molecular dynamics and integral equation theory. PHYSICAL REVIEW LETTERS 2014; 112:198301. [PMID: 24877969 DOI: 10.1103/physrevlett.112.198301] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Indexed: 06/03/2023]
Abstract
We study the structure and phase behavior of a binary mixture where one of the components is self-propelling in nature. The interparticle interactions in the system are taken from the Asakura-Oosawa model for colloid-polymer mixtures for which the phase diagram is known. In the current model version, the colloid particles are made active using the Vicsek model for self-propelling particles. The resultant active system is studied by molecular dynamics methods and integral equation theory. Both methods produce results consistent with each other and demonstrate that the Vicsek model-based activity facilitates phase separation, thus, broadening the coexistence region.
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Affiliation(s)
- Subir K Das
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Post Office, Bangalore 560064, India
| | - Sergei A Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
| | - Benjamin Trefz
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55128 Mainz, Germany and Graduate School of Excellence Material Science in Mainz, Staudinger Weg 7, 55128 Mainz, Germany
| | - Peter Virnau
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55128 Mainz, Germany
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55128 Mainz, Germany
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17
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Binder K. Simulations of Interfacial Phenomena in Soft Condensed Matter and Nanoscience. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/510/1/012002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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18
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Winkler A, Virnau P, Binder K, Winkler RG, Gompper G. Hydrodynamic mechanisms of spinodal decomposition in confined colloid-polymer mixtures: a multiparticle collision dynamics study. J Chem Phys 2013; 138:054901. [PMID: 23406143 DOI: 10.1063/1.4789267] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A multiscale model for a colloid-polymer mixture is developed. The colloids are described as point particles interacting with each other and with the polymers with strongly repulsive potentials, while polymers interact with each other with a softer potential. The fluid in the suspension is taken into account by the multiparticle collision dynamics method (MPC). Considering a slit geometry where the suspension is confined between parallel repulsive walls, different possibilities for the hydrodynamic boundary conditions (b.c.) at the walls (slip versus stick) are treated. Quenching experiments are considered, where the system volume is suddenly reduced (keeping the density of the solvent fluid constant, while the colloid and polymer particle numbers are kept constant) and thus an initially homogeneous system is quenched deeply into the miscibility gap, where it is unstable. For various relative concentrations of colloids and polymers, the time evolution of the growing colloid-rich and polymer-rich domains are studied by molecular dynamics simulation, taking hydrodynamic effects mediated by the solvent into account via MPC. It is found that the domain size [script-l](d)(t) grows with time t as [script-l](d)(t) [proportionality] t(1/3) for stick and (at late stages) as [script-l](d)(t) [proportionality] t(2/3) for slip b.c., while break-up of percolating structures can cause a transient "arrest" of growth. While these findings apply for films that are 5-10 colloid diameters wide, for ultrathin films (1.5 colloid diameters wide) a regime with [script-l](d)(t) [proportionality] t(1/2) is also identified for rather shallow quenches.
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Affiliation(s)
- Alexander Winkler
- Insitut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55099 Mainz, Germany
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19
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Statt A, Winkler A, Virnau P, Binder K. Controlling the wetting properties of the Asakura-Oosawa model and applications to spherical confinement. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:464122. [PMID: 23114220 DOI: 10.1088/0953-8984/24/46/464122] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate for the Asakura-Oosawa model and an extension of this model that uses continuous rather than hard potentials, how wetting properties at walls can be easily controlled. By increasing the interaction range of the repulsive wall potential acting on the colloids (while keeping the polymer-wall interactions constant) polymers begin to substitute colloids at walls and the system can be driven from complete wetting of colloids via partial wetting to complete wetting of polymers. As an application, we discuss the morphology and wetting behavior of colloid-polymer mixtures in spherical confinement. We apply the recently developed 'ensemble switch method' where the Hamiltonian is extended to a combination of a system with walls and of a system without walls to calculate the surface excess free energies of colloid-rich and polymer-rich phases. The contact angle then is inferred from Young's equation.
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Affiliation(s)
- A Statt
- Institut für Physik, Johannes Gutenberg-Universität, D-55099 Mainz, Germany
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20
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Annunziata MA, Pelissetto A. Colloids and polymers in random colloidal matrices: demixing under good-solvent conditions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:041804. [PMID: 23214607 DOI: 10.1103/physreve.86.041804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Indexed: 06/01/2023]
Abstract
We consider a simplified coarse-grained model for colloid-polymer mixtures, in which polymers are represented as monoatomic molecules interacting by means of pair potentials. We use it to study polymer-colloid segregation in the presence of a quenched matrix of colloidal hard spheres. We fix the polymer-to-colloid size ratio to 0.8 and consider matrices such that the fraction f of the volume that is not accessible to the colloids due to the matrix is equal to 40%. As in the Asakura-Oosawa-Vrij (AOV) case, we find that binodal curves in the polymer and colloid volume-fraction plane have a small dependence on disorder. As for the position of the critical point, the behavior differs from that observed in the AOV case: While the critical colloid volume fraction is essentially the same in the bulk and in the presence of the matrix, the polymer volume fraction at criticality increases as f increases. At variance with the AOV case, no capillary colloid condensation or evaporation is generically observed.
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Affiliation(s)
- Mario Alberto Annunziata
- CNR, Istituto dei Sistemi Complessi (Area della Ricerca di Roma Tor Vergata) Via del Fosso del Cavaliere 100, I-00133 Roma, Italy.
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21
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Overduin SD, Patey GN. Understanding the Structure Factor and Isothermal Compressibility of Ambient Water in Terms of Local Structural Environments. J Phys Chem B 2012; 116:12014-20. [DOI: 10.1021/jp3075749] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S. D. Overduin
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
V6T 1Z1
| | - G. N. Patey
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
V6T 1Z1
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Beyer R, Iacopini S, Palberg T, Schöpe HJ. Polymer induced changes of the crystallization scenario in suspensions of hard sphere like microgel particles. J Chem Phys 2012; 136:234906. [DOI: 10.1063/1.4729562] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Reith D, Bucior K, Yelash L, Virnau P, Binder K. Spinodal decomposition of polymer solutions: molecular dynamics simulations of the two-dimensional case. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:115102. [PMID: 22301356 DOI: 10.1088/0953-8984/24/11/115102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
As a generic model system for phase separation in polymer solutions, a coarse-grained model for hexadecane/carbon dioxide mixtures has been studied in two-dimensional geometry. Both the phase diagram in equilibrium (obtained from a finite size scaling analysis of Monte Carlo data) and the kinetics of state changes caused by pressure jumps (studied by large scale molecular dynamics simulations) are presented. The results are compared to previous work where the same model was studied in three-dimensional geometry and under confinement in slit geometry. For deep quenches the characteristic length scale ℓ(t) of the formed domains grows with time t according to a power law close to [Formula: see text]. Since in this problem both the polymer density ρ(p) and the solvent density ρ(s) matter, the time evolution of the density distribution P(L)(ρ(p),ρ(s),t) in L × L subboxes of the system is also analyzed. It is found that in the first stage of phase separation the system separates locally into low density carbon dioxide regions that contain no polymers and regions of high density polymer melt that are supersaturated with this solvent. The further coarsening proceeds via the growth of domains of rather irregular shapes. A brief comparison of our findings with results of other models is given.
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Affiliation(s)
- Daniel Reith
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
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Annunziata MA, Pelissetto A. Fluid–fluid demixing curves for colloid–polymer mixtures in a random colloidal matrix. Mol Phys 2011. [DOI: 10.1080/00268976.2011.622724] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Binder K, Müller M, Vink RLC. Phase Behavior of Polymer-Containing Systems: Recent Advances Through Computer Simulation. MACROMOL THEOR SIMUL 2011. [DOI: 10.1002/mats.201100046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lu B, Denton AR. Crowding of polymer coils and demixing in nanoparticle-polymer mixtures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:285102. [PMID: 21709352 DOI: 10.1088/0953-8984/23/28/285102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Asakura-Oosawa-Vrij (AOV) model of colloid-polymer mixtures idealises nonadsorbing polymers as effective spheres that are fixed in size and impenetrable to hard particles. Real polymer coils, however, are intrinsically polydisperse in size (radius of gyration) and may be penetrated by smaller particles. Crowding by nanoparticles can affect the size distribution of polymer coils, thereby modifying effective depletion interactions and thermodynamic stability. To analyse the influence of crowding on polymer conformations and demixing phase behaviour, we adapt the AOV model to mixtures of nanoparticles and ideal, penetrable polymer coils that can vary in size. We perform Gibbs ensemble Monte Carlo simulations, including trial nanoparticle-polymer overlaps and variations in the radius of gyration. Results are compared with predictions of free-volume theory. Simulation and theory consistently predict that ideal polymers are compressed by nanoparticles, and that compressibility and penetrability stabilise nanoparticle-polymer mixtures.
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Affiliation(s)
- Ben Lu
- Department of Physics, North Dakota State University, Fargo, ND 58108-6050, USA
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Amore S, Horbach J, Egry I. Is there a relation between excess volume and miscibility in binary liquid mixtures? J Chem Phys 2011; 134:044515. [DOI: 10.1063/1.3528217] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Medina S, Virnau P, Binder K. Confined binary two-dimensional colloidal crystals: Monte Carlo simulation of crack formation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:035105. [PMID: 21406860 DOI: 10.1088/0953-8984/23/3/035105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Binary mixtures (A, B) of colloidal particles of different sizes in two dimensions may form crystals with square lattice structure (the A-particles occupying the white sites and the B-particles the black sites of a checkerboard). Confining such a system by two parallel 'walls' a distance D apart, long-range order in the direction parallel to the walls is stabilized by 'corrugated walls' that are commensurate with the lattice structure but destabilized by structureless 'hard walls', even if there is no misfit between the strip width D and the crystal lattice spacing. The crossover to quasi-one-dimensional behavior is studied by Monte Carlo simulations, analyzing Lindemann parameters and displacement correlation functions. When D is reduced and thus a misfit created, the stress in the crystal increases up to a critical value, at which the stress jumps to much smaller values due to the formation of an (almost periodic) crack pattern. These cracks typically have a width of several particle diameters, and are mostly disordered, although sometimes small domains with hexagonal order can be identified. At very large misfits, glass-like structures appear. We discuss various methods to characterize order and disorder in such systems.
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Affiliation(s)
- Stefan Medina
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
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Zykova-Timan T, Horbach J, Binder K. Monte Carlo simulations of the solid-liquid transition in hard spheres and colloid-polymer mixtures. J Chem Phys 2010; 133:014705. [DOI: 10.1063/1.3455504] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Zausch J, Horbach J, Virnau P, Binder K. A combined molecular dynamics and Monte Carlo study of the approach towards phase separation in colloid-polymer mixtures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:104120. [PMID: 21389454 DOI: 10.1088/0953-8984/22/10/104120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A coarse-grained model for colloid-polymer mixtures is investigated where both colloids and polymer coils are represented as point-like particles interacting with spherically symmetric effective potentials. Colloid-colloid and colloid-polymer interactions are described by Weeks-Chandler-Andersen potentials, while the polymer-polymer interaction is very soft, of strength k(B)T/2 for maximum polymer-polymer overlap. This model can be efficiently simulated both by Monte Carlo and molecular dynamics methods, and its phase diagram closely resembles that of the well-known Asakura-Oosawa model. The static and dynamic properties of the model are presented for systems at critical colloid density, varying the polymer density in the one-phase region. Applying Lees-Edwards boundary conditions, colloid-polymer mixtures exposed to shear deformation are considered, and the resulting anisotropy of correlations is studied. Whereas for the considered shear rate, [Formula: see text], radial distribution functions and static structure factors indicate only small structural changes under shear, an appropriate projection of these correlation functions onto spherical harmonics is presented that allows us to directly quantify the structural anisotropies. However, the considered shear rate is probably not high enough to see anisotropies in static structure factors at small wavenumbers that have been predicted by Onuki and Kawasaki (1979 Ann. Phys. 121 456) for the critical behavior of systems under shear. The anomalous dependence of the polymer's self-diffusion constant on polymer density is referred to the clustering of the colloid particles when approaching the critical point.
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Affiliation(s)
- Jochen Zausch
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
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Binder K, Mognetti B, Paul W, Virnau P, Yelash L. Computer Simulations and Coarse-Grained Molecular Models Predicting the Equation of State of Polymer Solutions. POLYMER THERMODYNAMICS 2010. [DOI: 10.1007/12_2010_82] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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