1
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Zhuravlyov V, Goree J, Elvati P, Violi A. Finite-size effects in the static structure factor S(k) and S(0) for a two-dimensional Yukawa liquid. Phys Rev E 2023; 108:035211. [PMID: 37849136 DOI: 10.1103/physreve.108.035211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/29/2023] [Indexed: 10/19/2023]
Abstract
Finite-size effects in the static structure factor S(k) are analyzed for an amorphous substance. As the number of particles is reduced, S(0) increases greatly, up to an order of magnitude. Meanwhile, there is a decrease in the height of the first peak S_{peak}. These finite-size effects are modeled accurately by the Binder formula for S(0) and our empirical formula for S_{peak}. Procedures are suggested to correct for finite-size effects in S(k) data and in the hyperuniformity index H≡S(0)/S_{peak}. These principles generally apply to S(k) obtained from particle positions in noncrystalline substances. The amorphous substance we simulate is a two-dimensional liquid, with a soft Yukawa interaction modeling a dusty plasma experiment.
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Affiliation(s)
- Vitaliy Zhuravlyov
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
| | - J Goree
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
| | - Paolo Elvati
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Angela Violi
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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2
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Zhang H, Wang X, Zhang J, Yu HB, Douglas JF. Approach to hyperuniformity in a metallic glass-forming material exhibiting a fragile to strong glass transition. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:50. [PMID: 37380868 DOI: 10.1140/epje/s10189-023-00308-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 06/05/2023] [Indexed: 06/30/2023]
Abstract
We investigate a metallic glass-forming (GF) material (Al90Sm10) exhibiting a fragile-strong (FS) glass-formation by molecular dynamics simulation to better understand this highly distinctive pattern of glass-formation in which many of the usual phenomenological relations describing relaxation times and diffusion of ordinary GF liquids no longer apply, and where instead genuine thermodynamic features are observed in response functions and little thermodynamic signature is exhibited at the glass transition temperature, Tg. Given the many unexpected similarities between the thermodynamics and dynamics of this metallic GF material with water, we first focus on the anomalous static scattering in this liquid, following recent studies on water, silicon and other FS GF liquids. We quantify the "hyperuniformity index" H of our liquid, which provides a quantitative measure of molecular "jamming". To gain insight into the T-dependence and magnitude of H, we also estimate another more familiar measure of particle localization, the Debye-Waller parameter 〈u2〉 describing the mean-square particle displacement on a timescale on the order of the fast relaxation time, and we also calculate H and 〈u2〉 for heated crystalline Cu. This comparative analysis between H and 〈u2〉 for crystalline and metallic glass materials allows us to understand the critical value of H on the order of 10-3 as being analogous to the Lindemann criterion for both the melting of crystals and the "softening" of glasses. We further interpret the emergence of FS GF and liquid-liquid phase separation in this class of liquids to arise from a cooperative self-assembly process in the GF liquid.
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Affiliation(s)
- Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
| | - Xinyi Wang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada
| | - Jiarui Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada
| | - Hai-Bin Yu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Jack F Douglas
- Material Measurement Laboratory, Material Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
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3
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Tawade BV, Singh M, Apata IE, Veerasamy J, Pradhan N, Karim A, Douglas JF, Raghavan D. Polymer-Grafted Nanoparticles with Variable Grafting Densities for High Energy Density Polymeric Nanocomposite Dielectric Capacitors. JACS AU 2023; 3:1365-1375. [PMID: 37234129 PMCID: PMC10207098 DOI: 10.1021/jacsau.3c00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 05/27/2023]
Abstract
Designing high energy density dielectric capacitors for advanced energy storage systems needs nanocomposite-based dielectric materials, which can utilize the properties of both inorganic and polymeric materials. Polymer-grafted nanoparticle (PGNP)-based nanocomposites alleviate the problems of poor nanocomposite properties by providing synergistic control over nanoparticle and polymer properties. Here, we synthesize "core-shell" barium titanate-poly(methyl methacrylate) (BaTiO3-PMMA) grafted PGNPs using surface-initiated atom transfer polymerization (SI-ATRP) with variable grafting densities of (0.303 to 0.929) chains/nm2 and high molecular masses (97700 g/mL to 130000 g/mol) and observe that low grafted density and high molecular mass based PGNP show high permittivity, high dielectric strength, and hence higher energy densities (≈ 5.2 J/cm3) as compared to the higher grafted density PGNPs, presumably due to their "star-polymer"-like conformations with higher chain-end densities that are known to enhance breakdown. Nonetheless, these energy densities are an order of magnitude higher than their nanocomposite blend counterparts. We expect that these PGNPs can be readily used as commercial dielectric capacitors, and these findings can serve as guiding principles for developing tunable high energy density energy storage devices using PGNP systems.
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Affiliation(s)
- Bhausaheb V. Tawade
- Department
of Chemistry, Howard University, Washington, D.C. 20059, United States
| | - Maninderjeet Singh
- Department
of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Ikeoluwa E. Apata
- Department
of Chemistry, Howard University, Washington, D.C. 20059, United States
| | - Jagadesh Veerasamy
- Department
of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Nihar Pradhan
- Department
of Chemistry, Physics and Atmospheric Science, Jackson State University, Jackson, Mississippi 39217, United States
| | - Alamgir Karim
- Department
of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Jack F. Douglas
- Material
Science and Engineering Division, National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Dharmaraj Raghavan
- Department
of Chemistry, Howard University, Washington, D.C. 20059, United States
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4
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Yu S. Evolving scattering networks for engineering disorder. NATURE COMPUTATIONAL SCIENCE 2023; 3:128-138. [PMID: 38177628 PMCID: PMC10766560 DOI: 10.1038/s43588-022-00395-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/22/2022] [Indexed: 01/06/2024]
Abstract
Network science provides a powerful tool for unraveling the complexities of social, technological and biological systems. Constructing networks using wave phenomena is also of great interest in devising advanced hardware for machine learning, as shown in optical neural networks. Although most wave-based networks have employed static network models, the impact of evolving models in network science provides strong motivation to apply dynamical network modeling to wave physics. Here the concept of evolving scattering networks for scattering phenomena is developed. The network is defined by links, node degrees and their evolution processes modeling multi-particle interferences, which directly determine scattering from disordered materials. I demonstrate the concept by examining network-based material classification, microstructure screening and preferential attachment in evolutions, which are applied to stealthy hyperuniformity. The results enable independent control of scattering from different length scales, revealing superdense material phases in short-range order. The proposed concept provides a bridge between wave physics and network science to resolve multiscale material complexities and open-system material design.
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Affiliation(s)
- Sunkyu Yu
- Intelligent Wave Systems Laboratory, Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea.
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5
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Wang H, Stillinger FH, Torquato S. Realizability of iso- g2 processes via effective pair interactions. J Chem Phys 2022; 157:224106. [DOI: 10.1063/5.0130679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
An outstanding problem in statistical mechanics is the determination of whether prescribed functional forms of the pair correlation function g2( r) [or equivalently, structure factor S( k)] at some number density ρ can be achieved by many-body systems in d-dimensional Euclidean space. The Zhang–Torquato conjecture states that any realizable set of pair statistics, whether from a nonequilibrium or equilibrium system, can be achieved by equilibrium systems involving up to two-body interactions. To further test this conjecture, we study the realizability problem of the nonequilibrium iso- g2 process, i.e., the determination of density-dependent effective potentials that yield equilibrium states in which g2 remains invariant for a positive range of densities. Using a precise inverse algorithm that determines effective potentials that match hypothesized functional forms of g2( r) for all r and S( k) for all k, we show that the unit-step function g2, which is the zero-density limit of the hard-sphere potential, is remarkably realizable up to the packing fraction ϕ = 0.49 for d = 1. For d = 2 and 3, it is realizable up to the maximum “terminal” packing fraction ϕ c = 1/2 d, at which the systems are hyperuniform, implying that the explicitly known necessary conditions for realizability are sufficient up through ϕ c. For ϕ near but below ϕ c, the large- r behaviors of the effective potentials are given exactly by the functional forms exp[ − κ( ϕ) r] for d = 1, r−1/2 exp[ − κ( ϕ) r] for d = 2, and r−1 exp[ − κ( ϕ) r] (Yukawa form) for d = 3, where κ−1( ϕ) is a screening length, and for ϕ = ϕ c, the potentials at large r are given by the pure Coulomb forms in the respective dimensions as predicted by Torquato and Stillinger [Phys. Rev. E 68, 041113 (2003)]. We also find that the effective potential for the pair statistics of the 3D “ghost” random sequential addition at the maximum packing fraction ϕ c = 1/8 is much shorter ranged than that for the 3D unit-step function g2 at ϕ c; thus, it does not constrain the realizability of the unit-step function g2. Our inverse methodology yields effective potentials for realizable targets, and, as expected, it does not reach convergence for a target that is known to be non-realizable, despite the fact that it satisfies all known explicit necessary conditions. Our findings demonstrate that exploring the iso- g2 process via our inverse methodology is an effective and robust means to tackle the realizability problem and is expected to facilitate the design of novel nanoparticle systems with density-dependent effective potentials, including exotic hyperuniform states of matter.
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Affiliation(s)
- Haina Wang
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Frank H. Stillinger
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Salvatore Torquato
- Department of Chemistry, Department of Physics, Princeton Institute of Materials, and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA
- School of Natural Sciences, Institute for Advanced Study, 1 Einstein Drive, Princeton, New Jersey 08540, USA
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6
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Zhuravlyov V, Goree J, Douglas JF, Elvati P, Violi A. Comparison of the static structure factor at long wavelengths for a dusty plasma liquid and other liquids. Phys Rev E 2022; 106:055212. [PMID: 36559416 DOI: 10.1103/physreve.106.055212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/23/2022] [Indexed: 06/17/2023]
Abstract
Especially small values of the static structure factor S(k) at long wavelengths, i.e., small k, were obtained in an analysis of experimental data, for a two-dimensional dusty plasma in its liquid state. For comparison, an analysis of S(k) data was carried out for many previously published experiments with other liquids. The latter analysis indicates that the magnitude of S(k) at small k is typically in a range 0.02-0.13. In contrast, the corresponding value for a dusty plasma liquid was found to be as small as 0.0139. Another basic finding for the dusty plasma liquid is that S(k) at small k generally increases with temperature, with its lowest value, noted above, occurring near the melting point. Simulations were carried out for the dusty plasma liquid, and their results are generally consistent with the experiment. Since a dusty plasma has a soft interparticle interaction, our findings support earlier theoretical suggestions that a useful design strategy for creating materials having exceptionally low values of S(0), so-called hyperuniform materials, is the use of a condensed material composed of particles that interact softly at their periphery.
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Affiliation(s)
- Vitaliy Zhuravlyov
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
| | - J Goree
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Paolo Elvati
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Angela Violi
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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7
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Wu W, Singh M, Zhai Y, Masud A, Tonny W, Yuan C, Yin R, Al-Enizi AM, Bockstaller MR, Matyjaszewski K, Douglas JF, Karim A. Facile Entropy-Driven Segregation of Imprinted Polymer-Grafted Nanoparticle Brush Blends by Solvent Vapor Annealing Soft Lithography. ACS APPLIED MATERIALS & INTERFACES 2022; 14:45765-45774. [PMID: 36174114 DOI: 10.1021/acsami.2c11134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Polymer-grafted nanoparticles (PGNPs) have attracted extensive research interest due to their potential for enhancing mechanical and electrical properties of both bulk polymer composite materials, as well as thin polymer films incorporating these nanoparticles (NPs). In previous studies, we have shown that an entropic driving force serves to organize low-molecular-mass PGNPs in imprinted blend films of PGNPs with low-molecular-mass homopolymers. In this work, we developed a novel solvent vapor annealing soft lithography (SVA-SL) method to overcome the technical difficulties in processing the high-molecular-mass PGNP blends due to the intrinsically sluggish melt annealing kinetics found in the phase separation of these blend PGNP materials. In particular, we utilized SVA-SL to create nanopatterns in blends of PGNPs having relatively high-molecular-mass-grafted layers but with cores of NPs having greatly different sizes. The minimization of the entropic free energy in the present system corresponded to larger PGNPs partitioning almost exclusively into the "mesa" regions of the imprinted PGNP blend films, as quantified by the estimation of the partition coefficient, Kp. The use of the SVA-SL processing method is important because it allows facile imprint patterning of PGNP materials and large-scale organization of the PGNPs even when the grafted chain lengths are long enough for the chains to be highly entangled, allowing enhanced thermo-mechanical property enhancements of the resulting films and a corresponding extended range of potential nanotech applications.
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Affiliation(s)
- Wenjie Wu
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas77204, United States
| | - Maninderjeet Singh
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas77204, United States
| | - Yue Zhai
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Ali Masud
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas77204, United States
| | - Wafa Tonny
- Department of Materials Science and Engineering, University of Houston, Houston, Texas77204, United States
| | - Chuqing Yuan
- Department of Materials Science and Engineering, University of Houston, Houston, Texas77204, United States
| | - Rongguan Yin
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Abdullah M Al-Enizi
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh11451, Saudi Arabia
| | - Michael R Bockstaller
- Department of Materials Science and Engineering, University of Houston, Houston, Texas77204, United States
| | - Krzysztof Matyjaszewski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland20899, United States
| | - Alamgir Karim
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas77204, United States
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8
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Utomo NW, Deng Y, Zhao Q, Liu X, Archer LA. Structure and Evolution of Quasi-Solid-State Hybrid Electrolytes Formed Inside Electrochemical Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2110333. [PMID: 35765212 DOI: 10.1002/adma.202110333] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 06/06/2022] [Indexed: 06/15/2023]
Abstract
Solid-state electrolytes (SSEs) formed inside an electrochemical cell by polymerization of a liquid precursor provide a promising strategy for overcoming problems with electrolyte wetting in solid-state batteries. Hybrid solid-state polymer electrolytes (HSPEs) created by in situ polymerization of a conventional liquid precursor containing electrochemically inert nanostructures are of particular interest because they offer a mechanism for selectively reinforcing or adding new functionalities to the electrolyte-removing the need for high degrees of polymerization. The synthesis, structure, chemical kinetics, ion-transport properties and electrochemical characteristics of HSPEs created by Al(OTf)3 -initiated polymerization of 1,3-dioxolane (DOL) containing hairy, nano-sized SiO2 particles are reported. Small-angle X-ray scattering reveals the particles are well-dispersed in liquid DOL. Strong interaction between poly(ethylene glycol) molecules tethered to the SiO2 particles and poly(DOL) lead to co-crystallization-anchoring the nanoparticles in their host It also enables polymerization-depolymerization processes in DOL to be studied and controlled. The utility of the in-situ-formed HSPE, is demonstrated first in Li|HSPE|Cu half cells, which manifest Coulombic efficiencies (CE) values approaching 99%. HSPEs are also demonstrated in solid-state lithium-sulfur-polyacrylonitrile (SPAN) composite full-cell batteries. The in-situ-formed Li|HSPE|SPAN cells show good cycling stability and thus provide a promising path toward all-solid-state batteries.
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Affiliation(s)
- Nyalaliska W Utomo
- Robert Frederick School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853-5201, USA
| | - Yue Deng
- Department of Materials Science and Engineering, Cornell University, Bard Hall, Ithaca, NY, 14853-5201, USA
| | - Qing Zhao
- Robert Frederick School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853-5201, USA
| | - Xiaotun Liu
- Robert Frederick School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853-5201, USA
| | - Lynden A Archer
- Robert Frederick School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853-5201, USA
- Department of Materials Science and Engineering, Cornell University, Bard Hall, Ithaca, NY, 14853-5201, USA
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9
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Gury L, Kamble S, Parisi D, Zhang J, Lee J, Abdullah A, Matyjaszewski K, Bockstaller MR, Vlassopoulos D, Fytas G. Internal Microstructure Dictates Interactions of Polymer-grafted Nanoparticles in Solution. Macromolecules 2021; 54:7234-7243. [PMID: 34393270 PMCID: PMC8361431 DOI: 10.1021/acs.macromol.1c00907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/07/2021] [Indexed: 11/30/2022]
Abstract
Understanding the effects of polymer brush architecture on particle interactions in solution is requisite to enable the development of functional materials based on self-assembled polymer-grafted nanoparticles (GNPs). Static and dynamic light scattering of polystyrene-grafted silica particle solutions in toluene reveals that the pair interaction potential, inferred from the second virial coefficient, A 2, is strongly affected by the grafting density, σ, and degree of polymerization, N, of tethered chains. In the limit of intermediate σ (∼0.3 to 0.6 nm-2) and high N, A 2 is positive and increases with N. This confirms the good solvent conditions and can be qualitatively rationalized on the basis of a pair interaction potential derived for grafted (brush) particles. In contrast, for high σ > 0.6 nm-2 and low N, A 2 displays an unexpected reversal to negative values, thus indicating poor solvent conditions. These findings are rationalized by means of a simple analysis based on a coarse-grained brush potential, which balances the attractive core-core interactions and the excluded volume interactions imparted by the polymer grafts. The results suggest that the steric crowding of polymer ligands in dense GNP systems may fundamentally alter the interactions between brush particles in solution and highlight the crucial role of architecture (internal microstructure) on the behavior of hybrid materials. The effect of grafting density also illustrates the opportunity to tailor the physical properties of hybrid materials by altering geometry (or architecture) rather than a variation of the chemical composition.
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Affiliation(s)
- Leo Gury
- Institute
of Electronic Structure and Laser, FORTH, University of Crete, 70013 Heraklion, Greece
- Department
of Materials Science and Technology, University
of Crete, 70013 Heraklion, Greece
| | - Samruddhi Kamble
- Institute
of Electronic Structure and Laser, FORTH, University of Crete, 70013 Heraklion, Greece
| | - Daniele Parisi
- Institute
of Electronic Structure and Laser, FORTH, University of Crete, 70013 Heraklion, Greece
- Department
of Materials Science and Technology, University
of Crete, 70013 Heraklion, Greece
| | - Jianan Zhang
- Department
of Materials Science and Engineering, Carnegie
Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Jaejun Lee
- Department
of Materials Science and Engineering, Carnegie
Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Ayesha Abdullah
- Department
of Materials Science and Engineering, Carnegie
Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Krzysztof Matyjaszewski
- Chemistry
Department, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Michael R. Bockstaller
- Department
of Materials Science and Engineering, Carnegie
Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Dimitris Vlassopoulos
- Institute
of Electronic Structure and Laser, FORTH, University of Crete, 70013 Heraklion, Greece
| | - George Fytas
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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10
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Wu W, Singh M, Masud A, Wang X, Nallapaneni A, Xiao Z, Zhai Y, Wang Z, Terlier T, Bleuel M, Yuan G, Satija SK, Douglas JF, Matyjaszewski K, Bockstaller MR, Karim A. Control of Phase Morphology of Binary Polymer Grafted Nanoparticle Blend Films via Direct Immersion Annealing. ACS NANO 2021; 15:12042-12056. [PMID: 34255492 DOI: 10.1021/acsnano.1c03357] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
While the phase separation of binary mixtures of chemically different polymer-grafted nanoparticles (PGNPs) is observed to superficially resemble conventional polymer blends, the presence of a "soft" polymer-grafted layer on the inorganic core of these nanoparticles qualitatively alters the phase separation kinetics of these "nanoblends" from the typical pattern of behavior seen in polymer blends and other simple fluids. We investigate this system using a direct immersion annealing method (DIA) that allows for a facile tuning of the PGNPs phase boundary, phase separation kinetics, and the ultimate scale of phase separation after a sufficient "aging" time. In particular, by switching the DIA solvent composition from a selective one (which increases the interaction parameter according to Timmerman's rule) to an overall good solvent for both PGNP components, we can achieve rapid switchability between phase-separated and homogeneous states. Despite a relatively low and non-classical power-law coarsening exponent, the overall phase separation process is completed on a time scale on the order of a few minutes. Moreover, the roughness of the PGNP blend film saturates at a scale that is proportional to the in-plane phase separation pattern scale, as observed in previous blend and block copolymer film studies. The relatively low magnitude of the coarsening exponent n is attributed to a suppression of hydrodynamic interactions between the PGNPs. The DIA method provides a significant opportunity to control the phase separation morphology of PGNP blends by solution processing, and this method is expected to be quite useful in creating advanced materials.
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Affiliation(s)
- Wenjie Wu
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Maninderjeet Singh
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Ali Masud
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Xiaoteng Wang
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Asritha Nallapaneni
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Zihan Xiao
- Department of Materials Science and Engineering, University of Houston, Houston, Texas 77204, United States
| | - Yue Zhai
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Zongyu Wang
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Tanguy Terlier
- SIMS Laboratory, Shared Equipment Authority, Rice University, Houston, Texas 77005, United States
| | - Markus Bleuel
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Guangcui Yuan
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Sushil K Satija
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Krzysztof Matyjaszewski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Michael R Bockstaller
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Alamgir Karim
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
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11
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Torquato S. Structural characterization of many-particle systems on approach to hyperuniform states. Phys Rev E 2021; 103:052126. [PMID: 34134204 DOI: 10.1103/physreve.103.052126] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/04/2021] [Indexed: 11/07/2022]
Abstract
The study of hyperuniform states of matter is an emerging multidisciplinary field, impinging on topics in the physical sciences, mathematics, and biology. The focus of this work is the exploration of quantitative descriptors that herald when a many-particle system in d-dimensional Euclidean space R^{d} approaches a hyperuniform state as a function of the relevant control parameter. We establish quantitative criteria to ascertain the extent of hyperuniform and nonhyperuniform distance-scaling regimes as well as the crossover point between them in terms of the "volume" coefficient A and "surface-area" coefficient B associated with the local number variance σ^{2}(R) for a spherical window of radius R. The larger the ratio B/A, the larger the hyperuniform scaling regime, which becomes of infinite extent in the limit B/A→∞. To complement the known direct-space representation of the coefficient B in terms of the total correlation function h(r), we derive its corresponding Fourier representation in terms of the structure factor S(k), which is especially useful when scattering information is available experimentally or theoretically. We also demonstrate that the free-volume theory of the pressure of equilibrium packings of identical hard spheres that approach a strictly jammed state either along the stable crystal or metastable disordered branch dictates that such end states be exactly hyperuniform. Using the ratio B/A, as well as other diagnostic measures of hyperuniformity, including the hyperuniformity index H and the direct-correlation function length scale ξ_{c}, we study three different exactly solvable models as a function of the relevant control parameter, either density or temperature, with end states that are perfectly hyperuniform. Specifically, we analyze equilibrium systems of hard rods and "sticky" hard-sphere systems in arbitrary space dimension d as a function of density. We also examine low-temperature excited states of many-particle systems interacting with "stealthy" long-ranged pair interactions as the temperature tends to zero, where the ground states are disordered, hyperuniform, and infinitely degenerate. We demonstrate that our various diagnostic hyperuniformity measures are positively correlated with one another. The same diagnostic measures can be used to detect the degree to which imperfections in nearly hyperuniform systems cause deviations from perfect hyperuniformity. Moreover, the capacity to identify hyperuniform scaling regimes should be particularly useful in analyzing experimentally or computationally generated samples that are necessarily of finite size.
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Affiliation(s)
- Salvatore Torquato
- Department of Chemistry, Department of Physics, Princeton Institute for the Science and Technology of Materials, and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA
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12
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Douglas JF, Xu WS. Equation of State and Entropy Theory Approach to Thermodynamic Scaling in Polymeric Glass-Forming Liquids. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00075] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Wen-Sheng Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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13
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Liu X, Utomo NW, Zhao Q, Zheng J, Zhang D, Archer LA. Effects of Geometric Confinement on Caging and Dynamics of Polymer-Tethered Nanoparticle Suspensions. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01448] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Salvalaglio M, Bouabdellaoui M, Bollani M, Benali A, Favre L, Claude JB, Wenger J, de Anna P, Intonti F, Voigt A, Abbarchi M. Hyperuniform Monocrystalline Structures by Spinodal Solid-State Dewetting. PHYSICAL REVIEW LETTERS 2020; 125:126101. [PMID: 33016725 DOI: 10.1103/physrevlett.125.126101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
Materials featuring anomalous suppression of density fluctuations over large length scales are emerging systems known as disordered hyperuniform. The underlying hidden order renders them appealing for several applications, such as light management and topologically protected electronic states. These applications require scalable fabrication, which is hard to achieve with available top-down approaches. Theoretically, it is known that spinodal decomposition can lead to disordered hyperuniform architectures. Spontaneous formation of stable patterns could thus be a viable path for the bottom-up fabrication of these materials. Here, we show that monocrystalline semiconductor-based structures, in particular Si_{1-x}Ge_{x} layers deposited on silicon-on-insulator substrates, can undergo spinodal solid-state dewetting featuring correlated disorder with an effective hyperuniform character. Nano- to micrometric sized structures targeting specific morphologies and hyperuniform character can be obtained, proving the generality of the approach and paving the way for technological applications of disordered hyperuniform metamaterials. Phase-field simulations explain the underlying nonlinear dynamics and the physical origin of the emerging patterns.
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Affiliation(s)
- Marco Salvalaglio
- Institute of Scientific Computing, TU Dresden, 01062 Dresden, Germany
- Dresden Center for Computational Materials Science (DCMS), TU Dresden, 01062 Dresden, Germany
| | | | - Monica Bollani
- Istituto di Fotonica e Nanotecnologie-Consiglio Nazionale delle Ricerche, Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Via Anzani 42, 22100 Como, Italy
| | - Abdennacer Benali
- Aix Marseille Univ, Université de Toulon, CNRS, IM2NP 13397, Marseille, France
| | - Luc Favre
- Aix Marseille Univ, Université de Toulon, CNRS, IM2NP 13397, Marseille, France
| | - Jean-Benoit Claude
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Jerome Wenger
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Pietro de Anna
- Institut des Sciences de la Terre, University of Lausanne, Lausanne 1015, Switzerland
| | | | - Axel Voigt
- Institute of Scientific Computing, TU Dresden, 01062 Dresden, Germany
- Dresden Center for Computational Materials Science (DCMS), TU Dresden, 01062 Dresden, Germany
| | - Marco Abbarchi
- Aix Marseille Univ, Université de Toulon, CNRS, IM2NP 13397, Marseille, France
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15
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Chremos A. Design of nearly perfect hyperuniform polymeric materials. J Chem Phys 2020; 153:054902. [PMID: 32770903 PMCID: PMC7530914 DOI: 10.1063/5.0017861] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/15/2020] [Indexed: 01/18/2023] Open
Abstract
Disordered hyperuniform materials are exotic amorphous systems that simultaneously exhibit anomalous suppression of long-range density fluctuations, comparable in amplitude to that of crystals and quasi-crystalline materials, while lacking the translational order characteristic of simple liquids. We establish a framework to quantitatively predict the emergence of hyperuniformity in polymeric materials by considering the distribution of localized polymer subregions, instead of considering the whole material. We demonstrate that this highly tunable approach results in arbitrarily small long-range density fluctuations in the liquid state. Our simulations also indicate that long-ranged density fluctuation of the whole polymeric material is remarkably insensitive to molecular topology (linear chain, unknotted ring, star, and bottlebrush) and depends on temperature in an apparently near universal fashion. Our findings open the way for the creation of nearly perfect hyperuniform polymeric materials.
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Affiliation(s)
- Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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16
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Zaccone A. Relaxation and vibrational properties in metal alloys and other disordered systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:203001. [PMID: 31962298 DOI: 10.1088/1361-648x/ab6e41] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The relaxation dynamics and the vibrational spectra of amorphous solids, such as metal alloys, have been intensely investigated as well separated topics in the past. The aim of this review is to summarize recent results in both these areas in an attempt to establish, or unveil, deeper connections between the two phenomena of relaxation and vibration. Theoretical progress in the area of slow relaxation dynamics of liquid and glassy systems and in the area of vibrational spectra of glasses and liquids is reviewed. After laying down a generic modelling framework to connect vibration and relaxation, the physics of metal alloys is considered where the emergence of power-law exponents has been identified both in the vibrational density of states (VDOS) as well as in density correlations. Also, theoretical frameworks which connect the VDOS to the relaxation behaviour and mechanical viscoelastic response in metallic glasses are reviewed. The same generic interpretative framework is then applied to the case of molecular glass formers where the emergence of stretched-exponential relaxation in dielectric relaxation can be put in quantitative relation with the VDOS by means of memory-function approaches. Further connections between relaxation and vibration are provided by the study of phonon linewidths in liquids and glasses, where a natural starting point is given by hydrodynamic theories. Finally, an agenda of outstanding issues including the appearance of compressed exponential relaxation in the intermediate scattering function of experimental and simulated systems (metal alloys, colloidal gels, jammed packings) is presented in light of available (or yet to be developed) mathematical models, and compared to non-exponential behaviour measured with macroscopic means such as mechanical spectroscopy/rheology.
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Affiliation(s)
- Alessio Zaccone
- Department of Physics 'A. Pontremoli', University of Milan, via Celoria 16, 20133 Milano, Italy. Statistical Physics Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS Cambridge, United Kingdom. Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB30HE Cambridge, United Kingdom
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17
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Zhang G, Torquato S. Realizable hyperuniform and nonhyperuniform particle configurations with targeted spectral functions via effective pair interactions. Phys Rev E 2020; 101:032124. [PMID: 32289971 DOI: 10.1103/physreve.101.032124] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 02/24/2020] [Indexed: 11/07/2022]
Abstract
The capacity to identify realizable many-body configurations associated with targeted functional forms for the pair correlation function g_{2}(r) or its corresponding structure factor S(k) is of great fundamental and practical importance. While there are obvious necessary conditions that a prescribed structure factor at number density ρ must satisfy to be configurationally realizable, sufficient conditions are generally not known due to the infinite degeneracy of configurations with different higher-order correlation functions. A major aim of this paper is to expand our theoretical knowledge of the class of pair correlation functions or structure factors that are realizable by classical disordered ensembles of particle configurations, including exotic "hyperuniform" varieties. We first introduce a theoretical formalism that provides a means to draw classical particle configurations from canonical ensembles with certain pairwise-additive potentials that could correspond to targeted analytical functional forms for the structure factor. This formulation enables us to devise an improved algorithm to construct systematically canonical-ensemble particle configurations with such targeted pair statistics, whenever realizable. As a proof of concept, we test the algorithm by targeting several different structure factors across dimensions that are known to be realizable and one hyperuniform target that is known to be nontrivially unrealizable. Our algorithm succeeds for all realizable targets and appropriately fails for the unrealizable target, demonstrating the accuracy and power of the method to numerically investigate the realizability problem. Subsequently, we also target several families of structure-factor functions that meet the known necessary realizability conditions but are not known to be realizable by disordered hyperuniform point configurations, including d-dimensional Gaussian structure factors, d-dimensional generalizations of the two-dimensional one-component plasma (OCP), and the d-dimensional Fourier duals of the previous OCP cases. Moreover, we also explore unusual nonhyperuniform targets, including "hyposurficial" and "antihyperuniform" examples. In all of these instances, the targeted structure factors are achieved with high accuracy, suggesting that they are indeed realizable by equilibrium configurations with pairwise interactions at positive temperatures. Remarkably, we also show that the structure factor of nonequilibrium perfect glass, specified by two-, three-, and four-body interactions, can also be realized by equilibrium pair interactions at positive temperatures. Our findings lead us to the conjecture that any realizable structure factor corresponding to either a translationally invariant equilibrium or nonequilibrium system can be attained by an equilibrium ensemble involving only effective pair interactions. Our investigation not only broadens our knowledge of analytical functional forms for g_{2}(r) and S(k) associated with disordered point configurations across dimensions but also deepens our understanding of many-body physics. Moreover, our work can be applied to the design of materials with desirable physical properties that can be tuned by their pair statistics.
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Affiliation(s)
- Ge Zhang
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Salvatore Torquato
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA; Department of Physics, Princeton University, Princeton, New Jersey 08544, USA; Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA; and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA
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18
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Yatsyshin P, Fytas NG, Theodorakis PE. Mixing-demixing transition in polymer-grafted spherical nanoparticles. SOFT MATTER 2020; 16:703-708. [PMID: 31819935 DOI: 10.1039/c9sm01639b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polymer-grafted nanoparticles (PGNPs) can provide property profiles that cannot be obtained individually by polymers or nanoparticles (NPs). Here, we have studied the mixing-demixing transition of symmetric copolymer melts of polymer-grafted spherical nanoparticles by means of coarse-grained molecular dynamics simulation and a theoretical mean-field model. We find that a larger size of NPs leads to higher stability for a given number of grafted chains and chain lengths, reaching a point where demixing is not possible. Most importantly, the increase in the number of grafted chains, Ng, can initially favour the phase separation of PGNPs, but a further increase can lead to more difficult demixing. The reason is the increasing impact of an effective core that forms as the grafting density of the tethered polymer chains around the NPs increases. The range and exact values of Ng where this change in behaviour takes place depend on the NP size and the chain length of the grafted polymer chains. Our study elucidates the phase behaviour of PGNPs and in particular the influence of the grafting density on the phase behaviour of the systems, anticipating that it will open new doors in the understanding of these systems with implications in materials science and medicine.
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Affiliation(s)
- Peter Yatsyshin
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK.
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19
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Meyra AG, Zarragoicoechea GJ, Maltz AL, Lomba E, Torquato S. Hyperuniformity on spherical surfaces. Phys Rev E 2019; 100:022107. [PMID: 31574707 DOI: 10.1103/physreve.100.022107] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Indexed: 11/07/2022]
Abstract
We study and characterize local density fluctuations of ordered and disordered hyperuniform point distributions on spherical surfaces. In spite of the extensive literature on disordered hyperuniform systems in Euclidean geometries, to date few works have dealt with the problem of hyperuniformity in curved spaces. Indeed, some systems that display disordered hyperuniformity, like the spatial distribution of photoreceptors in avian retina, actually occur on curved surfaces. Here we will focus on the local particle number variance and its dependence on the size of the sampling window (which we take to be a spherical cap) for regular and uniform point distributions, as well as for equilibrium configurations of fluid particles interacting through Lennard-Jones, dipole-dipole, and charge-charge potentials. We show that the scaling of the local number variance as a function of the window size enables one to characterize hyperuniform and nonhyperuniform point patterns also on spherical surfaces.
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Affiliation(s)
- Ariel G Meyra
- IFLYSIB (UNLP, CONICET), 59 No. 789, B1900BTE La Plata, Argentina.,Instituto de Química Física Rocasolano, CSIC, Calle Serrano 119, E-28006 Madrid, Spain
| | - Guillermo J Zarragoicoechea
- IFLYSIB (UNLP, CONICET), 59 No. 789, B1900BTE La Plata, Argentina.,Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Argentina
| | - Alberto L Maltz
- Departamento de Matemática, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 72 Correo Central 1900 La Plata, Argentina
| | - Enrique Lomba
- Instituto de Química Física Rocasolano, CSIC, Calle Serrano 119, E-28006 Madrid, Spain
| | - Salvatore Torquato
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.,Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA
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20
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Frenzel L, Lehmkühler F, Lokteva I, Narayanan S, Sprung M, Grübel G. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett 2019; 10:5231-5236. [PMID: 31433650 DOI: 10.1021/acs.jpclett.9b01690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We present the structure and dynamics of highly concentrated core-shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell suspended in water. With X-ray photon correlation spectroscopy, we are able to follow dynamical changes over the volume phase transition of PNIPAm at LCST = 32 °C. On raising the temperature beyond LCST, the structural relaxation times continue to decrease. The effect is accompanied by a transition from stretched to compressed exponential shape of the intensity autocorrelation function. Upon further heating, we find a sudden slowing down for the particles in their collapsed state. The q dependence of the relaxation time shows an anomalous change from τc ∝ q-3 to τc ∝ q-1. Small angle X-ray scattering data evidence a temperature-induced transition from repulsive to attractive forces. Our results indicate a temperature-induced phase transition from a colloidal liquid with polymer-driven dynamics toward a colloidal gel.
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Affiliation(s)
- Lara Frenzel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Felix Lehmkühler
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Irina Lokteva
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Suresh Narayanan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Michael Sprung
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Gerhard Grübel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
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21
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Gury L, Gauthier M, Cloitre M, Vlassopoulos D. Colloidal Jamming in Multiarm Star Polymer Melts. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00674] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Léo Gury
- Foundation for Research and Technology Hellas, Institute of Electronic Structure & Laser, Nikolaou Plastira 100, Vassilika Vouton, 70013 Heraklion, Crete, Greece
- Department of Materials Science & Technology, University of Crete, Vassilika Vouton, 70013 Heraklion, Crete, Greece
| | - Mario Gauthier
- Department of Chemistry, Institute for Polymer Research, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - Michel Cloitre
- Molecular, Macromolecular Chemistry and Materials, ESPCI Paris, CNRS, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Dimitris Vlassopoulos
- Foundation for Research and Technology Hellas, Institute of Electronic Structure & Laser, Nikolaou Plastira 100, Vassilika Vouton, 70013 Heraklion, Crete, Greece
- Department of Materials Science & Technology, University of Crete, Vassilika Vouton, 70013 Heraklion, Crete, Greece
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22
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Chremos A, Douglas JF. Influence of Branching on the Configurational and Dynamical Properties of Entangled Polymer Melts. Polymers (Basel) 2019; 11:E1045. [PMID: 31207890 PMCID: PMC6631115 DOI: 10.3390/polym11061045] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 11/16/2022] Open
Abstract
We probe the influence of branching on the configurational, packing, and density correlation function properties of polymer melts of linear and star polymers, with emphasis on molecular masses larger than the entanglement molecular mass of linear chains. In particular, we calculate the conformational properties of these polymers, such as the hydrodynamic radius R h , packing length p, pair correlation function g ( r ) , and polymer center of mass self-diffusion coefficient, D, with the use of coarse-grained molecular dynamics simulations. Our simulation results reproduce the phenomenology of simulated linear and branched polymers, and we attempt to understand our observations based on a combination of hydrodynamic and thermodynamic modeling. We introduce a model of "entanglement" phenomenon in high molecular mass polymers that assumes polymers can viewed in a coarse-grained sense as "soft" particles and, correspondingly, we model the emergence of heterogeneous dynamics in polymeric glass-forming liquids to occur in a fashion similar to glass-forming liquids in which the molecules have soft repulsive interactions. Based on this novel perspective of polymer melt dynamics, we propose a functional form for D that can describe our simulation results for both star and linear polymers, covering both the unentangled to entangled polymer melt regimes.
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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23
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Li Q, Peng X, McKenna GB. Physical aging and compressed exponential behaviors in a model soft colloidal system. SOFT MATTER 2019; 15:2336-2347. [PMID: 30758036 DOI: 10.1039/c8sm02042f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Diffusing wave spectroscopy (DWS)-based micro-rheology has been used in different optical geometries (backscattering and transmission) as well as different sample thicknesses in order to probe system dynamics at different length scales [D. J. Pine, D. A. Weitz, J. X. Zhu, E. Herbolzheimer. J. Phys., 1990, 51(18), 2101-2127]. Previous study from this lab [Q. Li, X. Peng, G. B. McKenna. Soft Matter, 2017, 13(7), 1396-1404] indicates the DWS-based micro-rheology observes the system non-equilibrium behaviors differently from macro-rheology. The object of the present work was to further explore the non-equilibrium dynamics and to address the range of utility of DWS as a micro-rheological method. A thermo-sensitive core-shell colloidal system was investigated both during aging and subsequent to aging into a metastable equilibrium state using temperature-jump induced volume fraction-jump experiments. We find that in the non-equilibrium state, significant differences in the measured dynamics are observed for the different geometries and length scales. Compressed exponential relaxations for the autocorrelation function g2(t) were observed for large length scales. However, upon converting the g2(t) data to the mean square displacement (MSD), such differences with length scale diminished and the long-time MSD behavior was consistent with diffusive behavior. These observations in the non-equilibrium behaviors for different length scales leads to questioning of some interpretations in the current field of light scattering-based micro-rheology and provides a possibility to interrogate the aging mechanisms in colloidal glasses from a broader perspective than normally considered in measurements of g2(t) using DWS-based micro-rheology.
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Affiliation(s)
- Qi Li
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
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24
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Klatt MA, Lovrić J, Chen D, Kapfer SC, Schaller FM, Schönhöfer PWA, Gardiner BS, Smith AS, Schröder-Turk GE, Torquato S. Universal hidden order in amorphous cellular geometries. Nat Commun 2019; 10:811. [PMID: 30778054 PMCID: PMC6379405 DOI: 10.1038/s41467-019-08360-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 01/03/2019] [Indexed: 12/04/2022] Open
Abstract
Partitioning space into cells with certain extreme geometrical properties is a central problem in many fields of science and technology. Here we investigate the Quantizer problem, defined as the optimisation of the moment of inertia of Voronoi cells, i.e., similarly-sized ‘sphere-like’ polyhedra that tile space are preferred. We employ Lloyd’s centroidal Voronoi diagram algorithm to solve this problem and find that it converges to disordered states associated with deep local minima. These states are universal in the sense that their structure factors are characterised by a complete independence of a wide class of initial conditions they evolved from. They moreover exhibit an anomalous suppression of long-wavelength density fluctuations and quickly become effectively hyperuniform. Our findings warrant the search for novel amorphous hyperuniform phases and cellular materials with unique physical properties. Disordered hyperuniformity implies a hidden order on length scales that can be found in various amorphous materials. Klatt et al. analyse the evolution of random point patterns using Llyod’s algorithm and show that they converge to an effectively hyperuniform state regardless of the initial conditions.
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Affiliation(s)
- Michael A Klatt
- Institute of Stochastics, Karlsruhe Institute of Technology (KIT), Englerstr. 2, 76131, Karlsruhe, Germany.,Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Jakov Lovrić
- Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia.,School of Engineering and Information Technology, Murdoch University, 90 South St, Murdoch, WA, 6150, Australia.,PULS Group, Department of Physics and Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - Duyu Chen
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Sebastian C Kapfer
- Institut für Theoretische Physik I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7, 91058, Erlangen, Germany
| | - Fabian M Schaller
- Institute of Stochastics, Karlsruhe Institute of Technology (KIT), Englerstr. 2, 76131, Karlsruhe, Germany.,Institut für Theoretische Physik I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7, 91058, Erlangen, Germany
| | - Philipp W A Schönhöfer
- School of Engineering and Information Technology, Murdoch University, 90 South St, Murdoch, WA, 6150, Australia.,Institut für Theoretische Physik I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7, 91058, Erlangen, Germany
| | - Bruce S Gardiner
- School of Engineering and Information Technology, Murdoch University, 90 South St, Murdoch, WA, 6150, Australia.,School of Computer Science and Software Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Ana-Sunčana Smith
- Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia.,PULS Group, Department of Physics and Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - Gerd E Schröder-Turk
- School of Engineering and Information Technology, Murdoch University, 90 South St, Murdoch, WA, 6150, Australia.,Institut für Theoretische Physik I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7, 91058, Erlangen, Germany.,Department of Applied Mathematics, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT, 0200, Australia
| | - Salvatore Torquato
- Department of Chemistry, Department of Physics, Princeton Institute for the Science and Technology of Materials, and Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ, 08544, USA.
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Chremos A, Douglas JF. Hidden Hyperuniformity in Soft Polymeric Materials. PHYSICAL REVIEW LETTERS 2018; 121:258002. [PMID: 30608782 DOI: 10.1103/physrevlett.121.258002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Indexed: 06/09/2023]
Abstract
We investigate the nature of long-range density fluctuations in melts of model "soft" polymers, specifically stars and bottlebrushes, over a wide temperature range by molecular dynamics simulation. The cores of the stars and the backbones of bottlebrush polymers are found to have a hyperuniform distribution; i.e., they exhibit anomalously small density fluctuations over a wide temperature range above the glass transition temperature. The hyperuniformity of these substituent polymer subregions is hidden since the fluid as a whole does not exhibit this property. These findings offer a strategy for the practical design of hyperuniform polymeric materials.
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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26
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Bhadauriya S, Wang X, Pitliya P, Zhang J, Raghavan D, Bockstaller MR, Stafford CM, Douglas JF, Karim A. Tuning the Relaxation of Nanopatterned Polymer Films with Polymer-Grafted Nanoparticles: Observation of Entropy-Enthalpy Compensation. NANO LETTERS 2018; 18:7441-7447. [PMID: 30398875 PMCID: PMC6537094 DOI: 10.1021/acs.nanolett.8b02514] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Polymer films provide a versatile platform in which complex functional relief patterns can be thermally imprinted with a resolution down to few nanometers. However, a practical limitation of this method is the tendency for the imprinted patterns to relax ("slump"), leading to loss of pattern fidelity over time. While increasing temperature above glass transition temperature ( Tg) accelerates the slumping kinetics of neat films, we find that the addition of polymer-grafted nanoparticles (PGNP) can greatly enhance the thermal stability of these patterns. Specifically, increasing the concentration of poly(methyl methacrylate) (PMMA) grafted titanium dioxide (TiO2) nanoparticles in the composite films slows down film relaxation dynamics, leading to enhanced pattern stability for the temperature range that we investigated. Interestingly, slumping relaxation time is found to obey an entropy-enthalpy compensation (EEC) relationship with varying PGNP concentration, similar to recently observed relaxation of strain-induced wrinkling in glassy polymer films having variable film thickness. The compensation temperature, Tcomp was found to be in the vicintity of the bulk Tg of PMMA. Our results suggest a common origin of EEC relaxation in patterned polymer thin films and nanocomposites.
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Affiliation(s)
- Sonal Bhadauriya
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325 United States
| | - Xiaoteng Wang
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325 United States
| | - Praveen Pitliya
- Department of Chemistry, Howard University, Washington, District of Columbia 20059, United States
| | - Jianan Zhang
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Dharmaraj Raghavan
- Department of Chemistry, Howard University, Washington, District of Columbia 20059, United States
| | - Michael R. Bockstaller
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Christopher M. Stafford
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Alamgir Karim
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325 United States
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Chremos A, Douglas JF. A comparative study of thermodynamic, conformational, and structural properties of bottlebrush with star and ring polymer melts. J Chem Phys 2018; 149:044904. [DOI: 10.1063/1.5034794] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Douglas JF. Weak and Strong Gels and the Emergence of the Amorphous Solid State. Gels 2018; 4:E19. [PMID: 30674795 PMCID: PMC6318627 DOI: 10.3390/gels4010019] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/14/2018] [Accepted: 02/17/2018] [Indexed: 01/03/2023] Open
Abstract
Gels are amorphous solids whose macroscopic viscoelastic response derives from constraints in the material that serve to localize the constituent molecules or particles about their average positions in space. These constraints may either be local in nature, as in chemical cross-linking and direct physical associations, or non-local, as in case of topological "entanglement" interactions between highly extended fiber or sheet structures in the fluid. Either of these interactions, or both combined, can lead to "gelation" or "amorphous solidification". While gels are often considered to be inherently non-equilibrium materials, and correspondingly termed "soft glassy matter", this is not generally the case. For example, the formation of vulcanized rubbers by cross-linking macromolecules can be exactly described as a second order phase transition from an equilibrium fluid to an equilibrium solid state, and amorphous solidification also arises in diverse physical gels in which molecular and particle localization occurs predominantly through transient molecuar associations, or even topological interactions. As equilibrium, or near equilibrium systems, such gels can be expected to exhibit universal linear and non-linear viscoelastic properties, especially near the "critical" conditions at which the gel state first emerges. In particular, a power-law viscoelastic response is frequently observed in gel materials near their "gelation" or "amorphous solidification" transition. Another basic property of physical gels of both theoretical and practical interest is their response to large stresses at constant shear rate or under a fixed macrocopic strain. In particular, these materials are often quite sensitive to applied stresses that can cause the self-assembled structure to progressively break down under flow or deformation. This disintegration of gel structure can lead to "yield" of the gel material, i.e., a fluidization transition, followed by shear thinning of the resulting heterogeneous "jelly-like" fluid. When the stress is removed, however, the material can relax back to its former equilibrium gel state, i.e., gel rejuvenation. In constrast, a non-equilibrium material will simply change its form and properties in a way that depends on processing history. Physical gels are thus unique self-healing materials in which the existence of equilibrium ensures their eventual recovery. The existence of equilibrium also has implications for the nature of both the linear and non-linear rheological response of gel materials, and the present paper explores this phenomenon based on simple scaling arguments of the kind frequently used in describing phase transitions and the properties of polymer solutions.
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Affiliation(s)
- Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Chen D, Lomba E, Torquato S. Binary mixtures of charged colloids: a potential route to synthesize disordered hyperuniform materials. Phys Chem Chem Phys 2018; 20:17557-17562. [DOI: 10.1039/c8cp02616e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A new route to fabricate large samples of 2D disordered hyperuniform materials via self-assembly of mixtures of charged colloids.
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Affiliation(s)
- Duyu Chen
- Department of Chemistry
- Princeton University, Princeton
- USA
| | - Enrique Lomba
- Department of Chemistry
- Princeton University, Princeton
- USA
- Instituto de Química Física Rocasolano
- CSIC
| | - Salvatore Torquato
- Department of Chemistry
- Princeton University, Princeton
- USA
- Department of Physics
- Princeton University
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Lomba E, Weis JJ, Torquato S. Disordered hyperuniformity in two-component nonadditive hard-disk plasmas. Phys Rev E 2017; 96:062126. [PMID: 29347400 DOI: 10.1103/physreve.96.062126] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Indexed: 06/07/2023]
Abstract
We study the behavior of a classical two-component ionic plasma made up of nonadditive hard disks with additional logarithmic Coulomb interactions between them. Due to the Coulomb repulsion, long-wavelength total density fluctuations are suppressed and the system is globally hyperuniform. Short-range volume effects lead to phase separation or to heterocoordination for positive or negative nonadditivities, respectively. These effects compete with the hidden long-range order imposed by hyperuniformity. As a result, the critical behavior of the mixture is modified, with long-wavelength concentration fluctuations partially damped when the system is charged. It is also shown that the decrease of configurational entropy due to hyperuniformity originates from contributions beyond the two-particle level. Finally, despite global hyperuniformity, we show that in our system the spatial configuration associated with each component separately is not hyperuniform, i.e., the system is not "multihyperuniform."
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Affiliation(s)
- Enrique Lomba
- Instituto de Química Física Rocasolano, CSIC, Calle Serrano 119, E-28006 Madrid, Spain
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Jean-Jacques Weis
- Université de Paris-Sud, Laboratoire de Physique Théorique, UMR8627, Bâtiment 210, 91405 Orsay Cedex, France
| | - Salvatore Torquato
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
- Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA
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Zhang G, Stillinger FH, Torquato S. Classical many-particle systems with unique disordered ground states. Phys Rev E 2017; 96:042146. [PMID: 29347605 DOI: 10.1103/physreve.96.042146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Classical ground states (global energy-minimizing configurations) of many-particle systems are typically unique crystalline structures, implying zero enumeration entropy of distinct patterns (aside from trivial symmetry operations). By contrast, the few previously known disordered classical ground states of many-particle systems are all high-entropy (highly degenerate) states. Here we show computationally that our recently proposed "perfect-glass" many-particle model [Sci. Rep. 6, 36963 (2016)10.1038/srep36963] possesses disordered classical ground states with a zero entropy: a highly counterintuitive situation . For all of the system sizes, parameters, and space dimensions that we have numerically investigated, the disordered ground states are unique such that they can always be superposed onto each other or their mirror image. At low energies, the density of states obtained from simulations matches those calculated from the harmonic approximation near a single ground state, further confirming ground-state uniqueness. Our discovery provides singular examples in which entropy and disorder are at odds with one another. The zero-entropy ground states provide a unique perspective on the celebrated Kauzmann-entropy crisis in which the extrapolated entropy of a supercooled liquid drops below that of the crystal. We expect that our disordered unique patterns to be of value in fields beyond glass physics, including applications in cryptography as pseudorandom functions with tunable computational complexity.
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Affiliation(s)
- G Zhang
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - F H Stillinger
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - S Torquato
- Department of Chemistry, Department of Physics, Princeton Institute for the Science and Technology of Materials, and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA
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Martelli F, Torquato S, Giovambattista N, Car R. Large-Scale Structure and Hyperuniformity of Amorphous Ices. PHYSICAL REVIEW LETTERS 2017; 119:136002. [PMID: 29341697 DOI: 10.1103/physrevlett.119.136002] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Indexed: 06/07/2023]
Abstract
We investigate the large-scale structure of amorphous ices and transitions between their different forms by quantifying their large-scale density fluctuations. Specifically, we simulate the isothermal compression of low-density amorphous ice (LDA) and hexagonal ice to produce high-density amorphous ice (HDA). Both HDA and LDA are nearly hyperuniform; i.e., they are characterized by an anomalous suppression of large-scale density fluctuations. By contrast, in correspondence with the nonequilibrium phase transitions to HDA, the presence of structural heterogeneities strongly suppresses the hyperuniformity and the system becomes hyposurficial (devoid of "surface-area fluctuations"). Our investigation challenges the largely accepted "frozen-liquid" picture, which views glasses as structurally arrested liquids. Beyond implications for water, our findings enrich our understanding of pressure-induced structural transformations in glasses.
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Affiliation(s)
- Fausto Martelli
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA
| | - Salvatore Torquato
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA
- Department of Physics, Princeton University, Princeton, New Jersey, USA
| | - Nicolas Giovambattista
- Department of Physics, Brooklyn College of the City University of New York, New York, New York, USA
- Ph.D. Programs in Chemistry and Physics, The Graduate Center of the City University of New York, New York, New York 10016, USA
| | - Roberto Car
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA
- Department of Physics, Princeton University, Princeton, New Jersey, USA
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Chremos A, Jeong C, Douglas JF. Influence of polymer architectures on diffusion in unentangled polymer melts. SOFT MATTER 2017; 13:5778-5784. [PMID: 28766667 PMCID: PMC5773265 DOI: 10.1039/c7sm01018d] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent simulations have indicated that the thermodynamic properties and the glassy dynamics of polymer melts are strongly influenced by the average molecular shape, as quantified by the radius of gyration tensor of the polymer molecules, and that the average molecular shape can be tuned by varying the molecular topology (e.g., ring, star, linear chain, etc.). In the present work, we investigate if the molecular shape is similarly a predominant factor in understanding the polymer center of mass diffusion D in the melt, as already established for polymer solutions. We find that all our D data for unentangled polymer melts having a range of topologies can be reasonably described as a power law of the polymer hydrodynamic radius, Rh. In particular, this scaling is similar to the scaling of D for a tracer sphere having a radius on the order of the chain radius of gyration, Rg. We conclude that the chain topology influences the molecular dynamics in as much as the polymer topology influences the average molecular shape. Experimental evidence seems to suggest that this situation is also true for entangled polymer melts.
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Chremos A, Douglas JF. Solution properties of star polyelectrolytes having a moderate number of arms. J Chem Phys 2017; 147:044906. [PMID: 28764357 PMCID: PMC5702915 DOI: 10.1063/1.4995534] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate polyelectrolyte stars having a moderate number of arms by molecular dynamics simulations of a coarse-grained model over a range of polyelectrolyte concentrations, where both the counter-ions and solvent are treated explicitly. This class of polymeric materials is found to exhibit rather distinct static and dynamic properties from linear and highly branched star polyelectrolyte solutions emphasized in past studies. Moderately branched polymers are particle-like in many of their properties, while at the same time they exhibit large fluctuations in size and shape as in the case of linear chain polymers. Correspondingly, these fluctuations suppress crystallization at high polymer concentrations, leading apparently to an amorphous rather than crystalline solid state at high polyelectrolyte concentrations. We quantify the onset of this transition by measuring the polymer size and shape fluctuations of our model star polyelectrolytes and the static and dynamic structure factor of these solutions over a wide range of polyelectrolyte concentration. Our findings for star polyelectrolytes are similar to those of polymer-grafted nanoparticles having a moderate grafting density, which is natural given the soft and highly deformable nature of both of these "particles."
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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