1
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Swinkels PJM, Sinaasappel R, Gong Z, Sacanna S, Meyer WV, Sciortino F, Schall P. Networks of Limited-Valency Patchy Particles. PHYSICAL REVIEW LETTERS 2024; 132:078203. [PMID: 38427857 DOI: 10.1103/physrevlett.132.078203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 11/27/2023] [Accepted: 01/17/2024] [Indexed: 03/03/2024]
Abstract
Equilibrium gels provide physically attractive counterparts of nonequilibrium gels, allowing statistical understanding and design of the equilibrium gel structure. Here, we assemble two-dimensional equilibrium gels from limited-valency "patchy" colloidal particles and follow their evolution at the particle scale to elucidate cluster-size distributions and free energies. By finely adjusting the patch attraction with critical Casimir forces, we let a mixture of two-valent and pseudo-three-valent patchy particles approach the percolated network state through a set of equilibrium states. Comparing this equilibrium route with a deep quench, we find that both routes approach the percolated state via the same equilibrium states, revealing that the network topology is uniquely set by the particle bond angles, independent of the formation history. The limited-valency system follows percolation theory remarkably well, approaching the percolation point with the expected universal exponents.
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Affiliation(s)
- P J M Swinkels
- Institute of Physics, University of Amsterdam, 1098XH Amsterdam, The Netherlands
| | - R Sinaasappel
- Institute of Physics, University of Amsterdam, 1098XH Amsterdam, The Netherlands
| | - Z Gong
- Molecular Design Institute, Department of Chemistry, New York University, New York, NY 10003-6688, USA
| | - S Sacanna
- Molecular Design Institute, Department of Chemistry, New York University, New York, NY 10003-6688, USA
| | - W V Meyer
- Universities Space Research Association, with GEARS, NASA Glenn Research Center, 2001 Aerospace Parkway, Brook Park, Ohio 44152, USA
| | | | - P Schall
- Institute of Physics, University of Amsterdam, 1098XH Amsterdam, The Netherlands
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2
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McEldrew M, Goodwin ZAH, Zhao H, Bazant MZ, Kornyshev AA. Correlated Ion Transport and the Gel Phase in Room Temperature Ionic Liquids. J Phys Chem B 2021; 125:2677-2689. [PMID: 33689352 DOI: 10.1021/acs.jpcb.0c09050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Here we present a theory of ion aggregation and gelation of room temperature ionic liquids (RTILs). Based on it, we investigate the effect of ion aggregation on correlated ion transport-ionic conductivity and transference numbers-obtaining closed-form expressions for these quantities. The theory depends on the maximum number of associations a cation and anion can form and the strength of their association. To validate the presented theory, we perform molecular dynamics simulations on several RTILs and a range of temperatures for one RTIL. The simulations indicate the formation of large clusters, even percolating through the system under certain circumstances, thus forming a gel, with the theory accurately describing the obtained cluster distributions in all cases. However, based on the strength and lifetime of associations in the simulated RTILs, we expect free ions to dominate ionic conductivity despite the presence of clusters, and we do not expect the percolating cluster to trigger structural arrest in the RTIL.
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Affiliation(s)
- Michael McEldrew
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Zachary A H Goodwin
- Department of Chemistry, Imperial College of London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K.,Thomas Young Centre for Theory and Simulation of Materials, Imperial College of London, South Kensington Campus, London SW7 2AZ, U.K
| | - Hongbo Zhao
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Martin Z Bazant
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alexei A Kornyshev
- Department of Chemistry, Imperial College of London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K.,Thomas Young Centre for Theory and Simulation of Materials, Imperial College of London, South Kensington Campus, London SW7 2AZ, U.K.,Institute of Molecular Science and Engineering, Imperial College of London, South Kensington Campus, London SW7 2AZ, U.K
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3
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Whitelam S. Strong bonds and far-from-equilibrium conditions minimize errors in lattice-gas growth. J Chem Phys 2018; 149:104902. [DOI: 10.1063/1.5034789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Stephen Whitelam
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
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4
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Corezzi S, Sciortino F, De Michele C. Exploiting limited valence patchy particles to understand autocatalytic kinetics. Nat Commun 2018; 9:2647. [PMID: 29980675 PMCID: PMC6035234 DOI: 10.1038/s41467-018-04977-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 06/08/2018] [Indexed: 11/09/2022] Open
Abstract
Autocatalysis, i.e., the speeding up of a reaction through the very same molecule which is produced, is common in chemistry, biophysics, and material science. Rate-equation-based approaches are often used to model the time dependence of products, but the key physical mechanisms behind the reaction cannot be properly recognized. Here, we develop a patchy particle model inspired by a bicomponent reactive mixture and endowed with adjustable autocatalytic ability. Such a coarse-grained model captures all general features of an autocatalytic aggregation process that takes place under controlled and realistic conditions, including crowded environments. Simulation reveals that a full understanding of the kinetics involves an unexpected effect that eludes the chemistry of the reaction, and which is crucially related to the presence of an activation barrier. The resulting analytical description can be exported to real systems, as confirmed by experimental data on epoxy-amine polymerizations, solving a long-standing issue in their mechanistic description.
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Affiliation(s)
- Silvia Corezzi
- Dipartimento di Fisica e Geologia, Universitá di Perugia, I-06123, Perugia, Italy.
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5
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Tavares JM, Dias CS, Araújo NAM, Telo da Gama MM. Dynamics of Patchy Particles in and out of Equilibrium. J Phys Chem B 2018; 122:3514-3518. [PMID: 29251935 DOI: 10.1021/acs.jpcb.7b10726] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We combine particle-based simulations, mean-field rate equations, and Wertheim's theory to study the dynamics of patchy particles in and out of equilibrium, at different temperatures and densities. We consider an initial random distribution of nonoverlapping three-patch particles, with no bonds, and analyze the time evolution of the breaking and bonding rates of a single bond. We find that the asymptotic (equilibrium) dynamics differs from the initial (out of equilibrium) one. These differences are expected to depend on the initial conditions, temperature, and density.
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Affiliation(s)
- J M Tavares
- Centro de Física Teórica e Computacional , Universidade de Lisboa , 1749-016 Lisboa , Portugal.,Instituto Superior de Engenharia de Lisboa, ISEL, Avenida Conselheiro Emídio Navarro, 1 , 1950-062 Lisboa , Portugal
| | - C S Dias
- Centro de Física Teórica e Computacional , Universidade de Lisboa , 1749-016 Lisboa , Portugal.,Departamento de Fı́sica, Faculdade de Ciências , Universidade de Lisboa , 1749-016 Lisboa , Portugal
| | - N A M Araújo
- Centro de Física Teórica e Computacional , Universidade de Lisboa , 1749-016 Lisboa , Portugal.,Departamento de Fı́sica, Faculdade de Ciências , Universidade de Lisboa , 1749-016 Lisboa , Portugal
| | - M M Telo da Gama
- Centro de Física Teórica e Computacional , Universidade de Lisboa , 1749-016 Lisboa , Portugal.,Departamento de Fı́sica, Faculdade de Ciências , Universidade de Lisboa , 1749-016 Lisboa , Portugal
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6
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Dias CS, Araújo NAM, Telo da Gama MM. Dynamics of network fluids. Adv Colloid Interface Sci 2017; 247:258-263. [PMID: 28802478 DOI: 10.1016/j.cis.2017.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/16/2017] [Accepted: 07/02/2017] [Indexed: 11/20/2022]
Abstract
Network fluids are structured fluids consisting of chains and branches. They are characterized by unusual physical properties, such as, exotic bulk phase diagrams, interfacial roughening and wetting transitions, and equilibrium and nonequilibrium gels. Here, we provide an overview of a selection of their equilibrium and dynamical properties. Recent research efforts towards bridging equilibrium and non-equilibrium studies are discussed, as well as several open questions.
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Affiliation(s)
- C S Dias
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal; Centro de Física Teórica e Computacional, Universidade de Lisboa, Lisboa 1749-016, Portugal.
| | - N A M Araújo
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal; Centro de Física Teórica e Computacional, Universidade de Lisboa, Lisboa 1749-016, Portugal
| | - M M Telo da Gama
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal; Centro de Física Teórica e Computacional, Universidade de Lisboa, Lisboa 1749-016, Portugal
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7
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8
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Xu D, Gersappe D. Structure formation in nanocomposite hydrogels. SOFT MATTER 2017; 13:1853-1861. [PMID: 28177007 DOI: 10.1039/c6sm02543a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We use molecular dynamics simulations to study structure formation in physically associating nanocomposite hydrogels. Nanofillers were modeled as rigid bodies of disk-like shapes and physical crosslinks were simulated by introducing a short-range attraction between the nanofillers and polymer chain ends. The structure, dynamics and mechanics of these polymer gels were studied as a function of nanofiller volume fraction. We observe the formation of a percolated network in the hydrogels, with an ordered local structure but disordered globally, as we increase the filler fraction. This locally ordered structure was a result of the anisotropy of the disk-like fillers. The dynamics of polymers showed significant caging effects in the gel state. Stress autocorrelation and elongation results were analyzed as a function of nano-filler concentrations. Comparisons with nanofillers of different shapes showed that disk-like nanofillers are more effective in strengthening the hydrogels than spherical nanofillers.
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Affiliation(s)
- Di Xu
- Department of Material Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
| | - Dilip Gersappe
- Department of Material Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
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9
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De Michele C, De Los Rios P, Foffi G, Piazza F. Simulation and Theory of Antibody Binding to Crowded Antigen-Covered Surfaces. PLoS Comput Biol 2016; 12:e1004752. [PMID: 26967624 PMCID: PMC4788199 DOI: 10.1371/journal.pcbi.1004752] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 01/12/2016] [Indexed: 01/08/2023] Open
Abstract
In this paper we introduce a fully flexible coarse-grained model of immunoglobulin G (IgG) antibodies parametrized directly on cryo-EM data and simulate the binding dynamics of many IgGs to antigens adsorbed on a surface at increasing densities. Moreover, we work out a theoretical model that allows to explain all the features observed in the simulations. Our combined computational and theoretical framework is in excellent agreement with surface-plasmon resonance data and allows us to establish a number of important results. (i) Internal flexibility is key to maximize bivalent binding, flexible IgGs being able to explore the surface with their second arm in search for an available hapten. This is made clear by the strongly reduced ability to bind with both arms displayed by artificial IgGs designed to rigidly keep a prescribed shape. (ii) The large size of IgGs is instrumental to keep neighboring molecules at a certain distance (surface repulsion), which essentially makes antigens within reach of the second Fab always unoccupied on average. (iii) One needs to account independently for the thermodynamic and geometric factors that regulate the binding equilibrium. The key geometrical parameters, besides excluded-volume repulsion, describe the screening of free haptens by neighboring bound antibodies. We prove that the thermodynamic parameters govern the low-antigen-concentration regime, while the surface screening and repulsion only affect the binding at high hapten densities. Importantly, we prove that screening effects are concealed in relative measures, such as the fraction of bivalently bound antibodies. Overall, our model provides a valuable, accurate theoretical paradigm beyond existing frameworks to interpret experimental profiles of antibodies binding to multi-valent surfaces of different sorts in many contexts. Antibodies are the main working horses of the human immune system. Remarkably, no matter the size or the shape of the pathological intruders, these extremely flexible three-lobe molecules are able to form a complex, thus eliciting an immune response. What makes antibodies so effective? To answer this and other questions, we have developed a simplified computational scheme to simulate the dynamics of many antibodies interacting with each other and with antigens. Coarse-grained models are a great opportunity, as they give access to a true multi-scale approach to biologically relevant problems. In this work, our innovative method allowed us to simulate the binding process of many antibodies to surface-adsorbed antigens. This led us to elucidate and quantify many important physical aspects of their biological function in agreement with experiments, such as the role of their flexibility and crowding effects at the hapten-covered surface, which were shown to finely regulate the avidity.
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Affiliation(s)
| | - Paolo De Los Rios
- Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Giuseppe Foffi
- Laboratoire de Physique des Solides (LPS), UMR8502, Université Paris sud, Orsay, France
| | - Francesco Piazza
- Université d'Orléans, Centre de Biophysique Moléculaire, CNRS-UPR4301, Orléans, France
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10
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Duguet É, Hubert C, Chomette C, Perro A, Ravaine S. Patchy colloidal particles for programmed self-assembly. CR CHIM 2016. [DOI: 10.1016/j.crci.2015.11.013] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Kogler F, Velev OD, Hall CK, Klapp SHL. Generic model for tunable colloidal aggregation in multidirectional fields. SOFT MATTER 2015; 11:7356-7366. [PMID: 26278680 DOI: 10.1039/c5sm01103e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Based on Brownian Dynamics computer simulations in two dimensions we investigate aggregation scenarios of colloidal particles with directional interactions induced by multiple external fields. To this end we propose a model which allows continuous change in the particle interactions from point-dipole-like to patchy-like (with four patches). We show that, as a result of this change, the non-equilibrium aggregation occurring at low densities and temperatures transforms from conventional diffusion-limited cluster aggregation (DLCA) to slippery DLCA involving rotating bonds; this is accompanied by a pronounced change of the underlying lattice structure of the aggregates from square-like to hexagonal ordering. Increasing the temperature we find a transformation to a fluid phase, consistent with results of a simple mean-field density functional theory.
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Affiliation(s)
- Florian Kogler
- Institute of Theoretical Physics, Technical University of Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
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12
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Dias C, Araújo N, Telo da Gama M. Effect of the number of patches on the growth of networks of patchy colloids on substrates. Mol Phys 2015. [DOI: 10.1080/00268976.2014.986239] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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13
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Dias CS, Araújo NAM, Telo da Gama MM. Adsorbed films of three-patch colloids: continuous and discontinuous transitions between thick and thin films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:032302. [PMID: 25314441 DOI: 10.1103/physreve.90.032302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Indexed: 06/04/2023]
Abstract
We investigate numerically the role of spatial arrangement of the patches on the irreversible adsorption of patchy colloids on a substrate. We consider spherical three-patch colloids and study the dependence of the kinetics on the opening angle between patches. We show that growth is suppressed below and above minimum and maximum opening angles, revealing two absorbing phase transitions between thick and thin film regimes. While the transition at the minimum angle is continuous, in the directed percolation class, that at the maximum angle is clearly discontinuous. For intermediate values of the opening angle, a rough colloidal network in the Kardar-Parisi-Zhang universality class grows indefinitely. The nature of the transitions was analyzed in detail by considering bond flexibility, defined as the dispersion of the angle between the bond and the center of the patch. For the range of flexibilities considered we always observe two phase transitions. However, the range of opening angles where growth is sustained increases with flexibility. At a tricritical flexibility, the discontinuous transition becomes continuous. The practical implications of our findings and the relation to other nonequilibrium transitions are discussed.
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Affiliation(s)
- C S Dias
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, P-1749-016 Lisboa, Portugal and Centro de Física Teórica e Computacional, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa, Portugal
| | - N A M Araújo
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, P-1749-016 Lisboa, Portugal and Centro de Física Teórica e Computacional, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa, Portugal
| | - M M Telo da Gama
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, P-1749-016 Lisboa, Portugal and Centro de Física Teórica e Computacional, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa, Portugal
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14
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Dickinson E. Structure and rheology of colloidal particle gels: insight from computer simulation. Adv Colloid Interface Sci 2013; 199-200:114-27. [PMID: 23916723 DOI: 10.1016/j.cis.2013.07.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 07/08/2013] [Accepted: 07/09/2013] [Indexed: 10/26/2022]
Abstract
A particle gel is a network of aggregated colloidal particles with soft solid-like mechanical properties. Its structural and rheological properties, and the kinetics of its formation, are dependent on the sizes and shapes of the constituent particles, the volume fraction of the particles, and the nature of the interactions between the particles before, during and after gelation. Particle gels may be permanent or transient depending on whether the colloidal forces between the aggregating particles lead to irreversible bonding or weak reversible interactions. With short-range reversible interactions, network formation is typically associated with phase separation or kinetic arrest due to particle crowding. Much existing knowledge has been derived from computer simulations of idealized model systems containing spherical particles interacting with well-defined pair potentials. The status of current progress is reviewed here by summarizing the underlying methodology and key findings from a range of simulation approaches: Monte Carlo, molecular dynamics, Brownian dynamics, Stokesian dynamics, dissipative particle dynamics, multiparticle collision dynamics, and fluid particle dynamics. Then it is described how the technique of Brownian dynamics simulation, in particular, has provided detailed insight into how different kinds of bonding and weak reversible interactions can affect the aggregate fractal structure, the percolation behaviour, and the small-deformation rheological properties of network-forming colloidal systems. A significant ongoing development has been the establishment and testing of efficient algorithms that are able to capture the subtle dynamic structuring effects that arise from effects of interparticle hydrodynamic interactions. This has led to an appreciation recently of the potentially important role of these particle-particle hydrodynamic effects in controlling the evolving morphology of simulated colloidal aggregates and in defining the location of the sol-gel phase boundary.
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15
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Whitelam S, Schulman R, Hedges L. Self-assembly of multicomponent structures in and out of equilibrium. PHYSICAL REVIEW LETTERS 2012; 109:265506. [PMID: 23368583 DOI: 10.1103/physrevlett.109.265506] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 10/09/2012] [Indexed: 06/01/2023]
Abstract
Theories of phase change and self-assembly often invoke the idea of a "quasiequilibrium," a regime in which the nonequilibrium association of building blocks results nonetheless in a structure whose properties are determined solely by an underlying free energy landscape. Here we study a prototypical example of multicomponent self-assembly, a one-dimensional fiber grown from red and blue blocks. We find that if the equilibrium structure possesses compositional correlations different from those characteristic of random mixing, then it cannot be generated without error at any finite growth rate: there is no quasiequilibrium regime. However, by exploiting dynamic scaling, structures characteristic of equilibrium at one point in phase space can be generated, without error, arbitrarily far from equilibrium. Our results, supported by mean-field theory in higher dimensions, thus suggest a "nonperturbative" strategy for multicomponent self-assembly in which the target structure is, by design, not the equilibrium one.
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Affiliation(s)
- Stephen Whitelam
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
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16
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Liu Y, Han X, He L, Yin Y. Thermoresponsive Assembly of Charged Gold Nanoparticles and Their Reversible Tuning of Plasmon Coupling. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201201816] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Liu Y, Han X, He L, Yin Y. Thermoresponsive Assembly of Charged Gold Nanoparticles and Their Reversible Tuning of Plasmon Coupling. Angew Chem Int Ed Engl 2012; 51:6373-7. [DOI: 10.1002/anie.201201816] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/03/2012] [Indexed: 11/11/2022]
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18
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De Michele C, Bellini T, Sciortino F. Self-Assembly of Bifunctional Patchy Particles with Anisotropic Shape into Polymers Chains: Theory, Simulations, and Experiments. Macromolecules 2011. [DOI: 10.1021/ma201962x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Cristiano De Michele
- Dipartimento di Fisica, Sapienza - Università di Roma, P. le A. Moro
2, 00185 Roma, Italy
| | - Tommaso Bellini
- Dipartimento
di Chimica, Biochimica
e Biotecnologie per la Medicina, Università di Milano, , I-20122 Milano, Italy
| | - Francesco Sciortino
- Dipartimento di Fisica and CNR-ISC, Sapienza - Università di Roma, P. le A. Moro
2, 00185 Roma, Italy
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19
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Schmit JD, Whitelam S, Dill K. Electrostatics and aggregation: how charge can turn a crystal into a gel. J Chem Phys 2011; 135:085103. [PMID: 21895221 DOI: 10.1063/1.3626803] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The crystallization of proteins or colloids is often hindered by the appearance of aggregates of low fractal dimension called gels. Here we study the effect of electrostatics upon crystal and gel formation using an analytic model of hard spheres bearing point charges and short range attractive interactions. We find that the chief electrostatic free energy cost of forming assemblies comes from the entropic loss of counterions that render assemblies charge-neutral. Because there exists more accessible volume for these counterions around an open gel than a dense crystal, there exists an electrostatic entropic driving force favoring the gel over the crystal. This driving force increases with increasing sphere charge, but can be counteracted by increasing counterion concentration. We show that these effects cannot be fully captured by pairwise-additive macroion interactions of the kind often used in simulations, and we show where on the phase diagram to go in order to suppress gel formation.
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Affiliation(s)
- Jeremy D Schmit
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, USA.
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20
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Bianchi E, Blaak R, Likos CN. Patchy colloids: state of the art and perspectives. Phys Chem Chem Phys 2011; 13:6397-410. [DOI: 10.1039/c0cp02296a] [Citation(s) in RCA: 377] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Abstract
In this article I will review some recent studies of the phase behavior and of the self-assembly of patchy colloidal particles. These studies have been based on simple primitive models for colloid–colloid interactions, effectively extending to soft matter the seminal work of I. Nezbeda on associated fluids. I will discuss the possibilities offered by the study of the self-assembly of particles with limited valence in deepening our understanding of the onset of the liquid state, of the differences between gels and glasses and of the possible connection between physical and chemical gels. A review with 55 references.
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22
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Corezzi S, Fioretto D, De Michele C, Zaccarelli E, Sciortino F. Modeling the Crossover between Chemically and Diffusion-Controlled Irreversible Aggregation in a Small-Functionality Gel-Forming System. J Phys Chem B 2010; 114:3769-75. [DOI: 10.1021/jp911165b] [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)
- S. Corezzi
- Dipartimento di Fisica, Università di Perugia, Via A. Pascoli, I-06100 Perugia, Italy, and Dipartimento di Fisica and CNR-ISC, Università di Roma “La Sapienza”, Piazzale A. Moro 2, I-00185 Roma, Italy
| | - D. Fioretto
- Dipartimento di Fisica, Università di Perugia, Via A. Pascoli, I-06100 Perugia, Italy, and Dipartimento di Fisica and CNR-ISC, Università di Roma “La Sapienza”, Piazzale A. Moro 2, I-00185 Roma, Italy
| | - C. De Michele
- Dipartimento di Fisica, Università di Perugia, Via A. Pascoli, I-06100 Perugia, Italy, and Dipartimento di Fisica and CNR-ISC, Università di Roma “La Sapienza”, Piazzale A. Moro 2, I-00185 Roma, Italy
| | - E. Zaccarelli
- Dipartimento di Fisica, Università di Perugia, Via A. Pascoli, I-06100 Perugia, Italy, and Dipartimento di Fisica and CNR-ISC, Università di Roma “La Sapienza”, Piazzale A. Moro 2, I-00185 Roma, Italy
| | - F. Sciortino
- Dipartimento di Fisica, Università di Perugia, Via A. Pascoli, I-06100 Perugia, Italy, and Dipartimento di Fisica and CNR-ISC, Università di Roma “La Sapienza”, Piazzale A. Moro 2, I-00185 Roma, Italy
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Tartaglia P. Gel formation through reversible and irreversible aggregation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:504109. [PMID: 21836220 DOI: 10.1088/0953-8984/21/50/504109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study the kinetics of formation of branched loopless structures in mixtures of particles with different shapes and functionalities. These systems are treated with the appropriate Smoluchowski rate equations, including condensation and fragmentation terms, and it is shown that it is possible to provide a parameter-free description of the assembly process, including the limit of irreversible aggregation at low temperatures. Using dynamics simulations we provide evidence of a connection between physical and chemical gelation in low-valence particle systems, and the possibility of relating ageing time with temperature.
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Affiliation(s)
- Piero Tartaglia
- Dipartimento di Fisica and CNR-INFM-SMC, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185, Roma, Italy
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Russo J, Tartaglia P, Sciortino F. Reversible gels of patchy particles: role of the valence. J Chem Phys 2009; 131:014504. [PMID: 19586107 DOI: 10.1063/1.3153843] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We simulate a binary mixture of colloidal patchy particles with two and three patches, respectively, for several relative concentrations and hence relative average valences. For these limited-valence systems, it is possible to reach low temperatures, where the lifetime of the patch-patch interactions becomes longer than the observation time without encountering phase separation in a colloid-poor (gas) and a colloid rich (liquid) phase. The resulting arrested state is a fully connected long-lived network where particles with three patches provide the branching points connecting chains of two-patch particles. We investigate the effect of the valence on the structural and dynamic properties of the resulting gel and attempt to provide a theoretical description of the formation and of the resulting gel structure based on a combination of the Wertheim theory for associated liquids and the Flory-Stockmayer approach for modeling chemical gelation.
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Affiliation(s)
- John Russo
- Dipartimento di Fisica and INFM-CNR-SOFT, Università di Roma La Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy.
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