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Mei B, Schweizer KS. Penetrant shape effects on activated dynamics and selectivity in polymer melts and networks based on self-consistent cooperative hopping theory. SOFT MATTER 2023; 19:8744-8763. [PMID: 37937332 DOI: 10.1039/d3sm01139a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
We generalize and apply the microscopic self-consistent cooperative hopping theory for activated penetrant dynamics in polymer melts and crosslinked networks to address the role of highly variable non-spherical molecular shape. The focus is on vastly different shaped penetrants that have identical space filling volume in order to isolate how non-spherical shape explicitly modifies dynamics over a wide range of temperature down to the kinetic glass transition temperature. The theory relates intramolecular and intermolecular structure and kinetic constraints, and reveals how different solvation packing of polymer monomers around variable shaped penetrants impact penetrant hopping. A highly shape-dependent penetrant activated relaxation, including alpha time decoupling and trajectory level cooperativity of the hopping process, is predicted in the deeply supercooled regime for relatively larger penetrants which is sensitive to whether the polymer matrix is a melt or heavily crosslinked network. In contrast, for smaller size penetrants or at high/medium temperatures the effect of isochoric penetrant shape is relatively weak. We propose an aspect ratio variable that organizes how penetrant shape influences the activated relaxation times, leading to a (near) collapse or master curve. The relative absolute values of the penetrant relaxation time (inverse hopping rate) in polymer melts versus in crosslinked networks are found to be opposite when compared at a common absolute temperature versus when they are compared at a fixed value of distance from the glass transition based on the variable Tg/T with Tg the glass transition temperature. Quantitative comparison with recent diffusion experiments on chemically complex molecular penetrants of variable shape but fixed volume in crosslinked networks reveals good agreement, and testable new predictions are made. Extension of the theoretical approach to more complex systems of high experimental interest are discussed, including applications to realize selective transport in membrane separation applications.
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Affiliation(s)
- Baicheng Mei
- Department of Materials Science, University of Illinois, Urbana, IL 61801, USA.
- Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA
| | - Kenneth S Schweizer
- Department of Materials Science, University of Illinois, Urbana, IL 61801, USA.
- Department of Chemistry, University of Illinois, Urbana, IL 61801, USA
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana, IL 61801, USA
- Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA
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2
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Mei B, Lin TW, Sheridan GS, Evans CM, Sing CE, Schweizer KS. How Segmental Dynamics and Mesh Confinement Determine the Selective Diffusivity of Molecules in Cross-Linked Dense Polymer Networks. ACS CENTRAL SCIENCE 2023; 9:508-518. [PMID: 36968535 PMCID: PMC10037493 DOI: 10.1021/acscentsci.2c01373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Indexed: 06/18/2023]
Abstract
The diffusion of molecules ("penetrants") of variable size, shape, and chemistry through dense cross-linked polymer networks is a fundamental scientific problem broadly relevant in materials, polymer, physical, and biological chemistry. Relevant applications include separation membranes, barrier materials, drug delivery, and nanofiltration. A major open question is the relationship between transport, thermodynamic state, and penetrant and polymer chemical structure. Here we combine experiment, simulation, and theory to unravel these competing effects on penetrant transport in rubbery and supercooled polymer permanent networks over a wide range of cross-link densities, size ratios, and temperatures. The crucial importance of the coupling of local penetrant hopping to polymer structural relaxation and the secondary importance of mesh confinement effects are established. Network cross-links strongly slow down nm-scale polymer relaxation, which greatly retards the activated penetrant diffusion. The demonstrated good agreement between experiment, simulation, and theory provides strong support for the size ratio (penetrant diameter to the polymer Kuhn length) as a key variable and the usefulness of coarse-grained simulation and theoretical models that average over Angstrom scale structure. The developed theory provides an understanding of the physical processes underlying the behaviors observed in experiment and simulation and suggests new strategies for enhancing selective polymer membrane design.
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Affiliation(s)
- Baicheng Mei
- Department
of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Materials
Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
| | - Tsai-Wei Lin
- Department
of Chemical & Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801, United States
- Materials
Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
| | - Grant S. Sheridan
- Department
of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Materials
Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
| | - Christopher M. Evans
- Department
of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Department
of Chemical & Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801, United States
- Materials
Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
| | - Charles E. Sing
- Department
of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Department
of Chemical & Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801, United States
- Materials
Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
| | - Kenneth S. Schweizer
- Department
of Materials Science, University of Illinois, Urbana, Illinois 61801, United States
- Department
of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
- Department
of Chemical & Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801, United States
- Materials
Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
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3
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Elucidation of the physical factors that control activated transport of penetrants in chemically complex glass-forming liquids. Proc Natl Acad Sci U S A 2022; 119:e2210094119. [PMID: 36194629 PMCID: PMC9565165 DOI: 10.1073/pnas.2210094119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the activated transport of penetrant or tracer atoms and molecules in condensed phases is a challenging problem in chemistry, materials science, physics, and biophysics. Many angstrom- and nanometer-scale features enter due to the highly variable shape, size, interaction, and conformational flexibility of the penetrant and matrix species, leading to a dramatic diversity of penetrant dynamics. Based on a minimalist model of a spherical penetrant in equilibrated dense matrices of hard spheres, a recent microscopic theory that relates hopping transport to local structure has predicted a novel correlation between penetrant diffusivity and the matrix thermodynamic dimensionless compressibility, S0(T) (which also quantifies the amplitude of long wavelength density fluctuations), as a consequence of a fundamental statistical mechanical relationship between structure and thermodynamics. Moreover, the penetrant activation barrier is predicted to have a factorized/multiplicative form, scaling as the product of an inverse power law of S0(T) and a linear/logarithmic function of the penetrant-to-matrix size ratio. This implies an enormous reduction in chemical complexity that is verified based solely on experimental data for diverse classes of chemically complex penetrants dissolved in molecular and polymeric liquids over a wide range of temperatures down to the kinetic glass transition. The predicted corollary that the penetrant diffusion constant decreases exponentially with inverse temperature raised to an exponent determined solely by how S0(T) decreases with cooling is also verified experimentally. Our findings are relevant to fundamental questions in glassy dynamics, self-averaging of angstrom-scale chemical features, and applications such as membrane separations, barrier coatings, drug delivery, and self-healing.
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Mei B, Schweizer KS. Theory of the Effects of Specific Attractions and Chain Connectivity on the Activated Dynamics and Selective Transport of Penetrants in Polymer Melts. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Baicheng Mei
- Department of Materials Science, University of Illinois, Urbana, Illinois61801, United States
- Materials Research Laboratory, University of Illinois, Urbana, Illinois61801, United States
| | - Kenneth S. Schweizer
- Department of Materials Science, University of Illinois, Urbana, Illinois61801, United States
- Department of Chemistry, University of Illinois, Urbana, Illinois61801, United States
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana, Illinois61801, United States
- Materials Research Laboratory, University of Illinois, Urbana, Illinois61801, United States
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5
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Mei B, Schweizer KS. Theory of the effect of external stress on the activated dynamics and transport of dilute penetrants in supercooled liquids and glasses. J Chem Phys 2021; 155:054505. [PMID: 34364324 DOI: 10.1063/5.0056920] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We generalize the self-consistent cooperative hopping theory for a dilute spherical penetrant or tracer activated dynamics in dense metastable hard sphere fluids and glasses to address the effect of external stress, the consequences of which are systematically established as a function of matrix packing fraction and penetrant-to-matrix size ratio. All relaxation processes speed up under stress, but the difference between the penetrant and matrix hopping (alpha relaxation) times decreases significantly with stress corresponding to less time scale decoupling. A dynamic crossover occurs at a critical "slaving onset" stress beyond which the matrix activated hopping relaxation time controls the penetrant hopping time. This characteristic stress increases (decreases) exponentially with packing fraction (size ratio) and can be well below the absolute yield stress of the matrix. Below the slaving onset, the penetrant hopping time is predicted to vary exponentially with stress, differing from the power law dependence of the pure matrix alpha time due to system-specificity of the stress-induced changes in the penetrant local cage and elastic barriers. An exponential growth of the penetrant alpha relaxation time with size ratio under stress is predicted, and at a fixed matrix packing fraction, the exponential relation between penetrant hopping time and stress for different size ratios can be collapsed onto a master curve. Direct connections between the short- and long-time activated penetrant dynamics and between the penetrant (or matrix) alpha relaxation time and matrix thermodynamic dimensionless compressibility are also predicted. The presented results should be testable in future experiments and simulations.
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Affiliation(s)
- Baicheng Mei
- Department of Materials Science, University of Illinois, Urbana, Illinois 61801, USA
| | - Kenneth S Schweizer
- Department of Materials Science, University of Illinois, Urbana, Illinois 61801, USA
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Egorov SA. Nanoparticle diffusion in polymer melts in the presence of weak nanoparticle-monomer attractive interactions: A mode-coupling theory study. J Chem Phys 2021; 155:044904. [PMID: 34340386 DOI: 10.1063/5.0058164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mode-coupling theory is developed and employed to compute the nanoparticle diffusion coefficient in polymer solutions. Theoretical results are compared with molecular dynamics simulation data for a similar model. The theory properly reproduces the simulated effects of the nanoparticle size, mass, and concentration on the nanoparticle diffusion coefficient. Within the mode-coupling theory framework, a microscopic interpretation of the nonmonotonic dependence of the diffusion coefficient on the nanoparticle concentration is given in terms of structural and dynamic effects. Both the size dependence and mass dependence of the diffusion coefficient indicate a pronounced breakdown of the Stokes-Einstein relation for the present model.
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Affiliation(s)
- Sergei A Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
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7
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Mei B, Schweizer KS. Activated penetrant dynamics in glass forming liquids: size effects, decoupling, slaving, collective elasticity and correlation with matrix compressibility. SOFT MATTER 2021; 17:2624-2639. [PMID: 33528485 DOI: 10.1039/d0sm02215b] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We employ the microscopic self-consistent cooperative hopping theory of penetrant activated dynamics in glass forming viscous liquids and colloidal suspensions to address new questions over a wide range of high matrix packing fractions and penetrant-to-matrix particle size ratios. The focus is on the mean activated relaxation time of smaller tracers in a hard sphere fluid of larger particle matrices. This quantity also determines the penetrant diffusion constant and connects directly with the structural relaxation time probed in an incoherent dynamic structure factor measurement. The timescale of the non-activated fast dissipative process is also studied and is predicted to follow power laws with the contact value of the penetrant-matrix pair correlation function and the penetrant-matrix size ratio. For long time penetrant relaxation, in the relatively lower packing fraction metastable regime the local cage barriers are dominant and matrix collective elasticity effects unimportant. As packing fraction and/or penetrant size grows, much higher barriers emerge and the collective elasticity associated with the correlated matrix dynamic displacement that facilitates penetrant hopping becomes important. This results in a non-monotonic variation with packing fraction of the degree of decoupling between the matrix and penetrant alpha relaxation times. The conditions required for penetrant hopping to become slaved to the matrix alpha process are determined, which depend mainly on the penetrant to matrix particle size ratio. By analyzing the absolute and relative importance of the cage and elastic barriers we establish a mechanistic understanding of the origin of the predicted exponential growth of the penetrant hopping time with size ratio predicted at very high packing fractions. A dynamics-thermodynamics power law connection between the penetrant activation barrier and the matrix dimensionless compressibility is established as a prediction of theory, with different scaling exponents depending on whether matrix collective elasticity effects are important. Quantitative comparisons with simulations of the penetrant relaxation time, diffusion constant, and transient localization length of tracers in dense colloidal suspensions and cold viscous liquids reveal good agreements. Multiple new predictions are made that are testable via future experiments and simulations. Extension of the theoretical approach to more complex systems of high experimental interest (nonspherical molecules, semiflexible polymers, crosslinked networks) interacting via variable hard or soft repulsions and/or short range attractions is possible, including under external deformation.
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Affiliation(s)
- Baicheng Mei
- Department of Materials Science, University of Illinois, Urbana, IL 61801, USA. and Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA
| | - Kenneth S Schweizer
- Department of Materials Science, University of Illinois, Urbana, IL 61801, USA. and Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA and Department of Chemistry, University of Illinois, Urbana, IL 61801, USA and Department of Chemical & Biomolecular Engineering, University of Illinois, Urbana, IL 61801, USA
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8
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Kanduč M, Kim WK, Roa R, Dzubiella J. How the Shape and Chemistry of Molecular Penetrants Control Responsive Hydrogel Permeability. ACS NANO 2021; 15:614-624. [PMID: 33382598 PMCID: PMC7844830 DOI: 10.1021/acsnano.0c06319] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 12/28/2020] [Indexed: 06/12/2023]
Abstract
The permeability of hydrogels for the selective transport of molecular penetrants (drugs, toxins, reactants, etc.) is a central property in the design of soft functional materials, for instance in biomedical, pharmaceutical, and nanocatalysis applications. However, the permeation of dense and hydrated polymer membranes is a complex multifaceted molecular-level phenomenon, and our understanding of the underlying physicochemical principles is still very limited. Here, we uncover the molecular principles of permeability and selectivity in hydrogel permeation. We combine the solution-diffusion model for permeability with comprehensive atomistic simulations of molecules of various shapes and polarities in a responsive hydrogel in different hydration states. We find in particular that dense collapsed states are extremely selective, owing to a delicate balance between the partitioning and diffusivity of the penetrants. These properties are sensitively tuned by the penetrant size, shape, and chemistry, leading to vast cancellation effects, which nontrivially contribute to the permeability. The gained insights enable us to formulate semiempirical rules to quantify and extrapolate the permeability categorized by classes of molecules. They can be used as approximate guiding ("rule-of-thumb") principles to optimize penetrant or membrane physicochemical properties for a desired permeability and membrane functionality.
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Affiliation(s)
- Matej Kanduč
- Jožef
Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Won Kyu Kim
- Korea
Institute for Advanced Study, 85 Hoegiro, Seoul 02455, Republic of Korea
| | - Rafael Roa
- Departamento
de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071 Málaga, Spain
| | - Joachim Dzubiella
- Applied
Theoretical Physics−Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Strasse 3, D-79104 Freiburg, Germany
- Research
Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
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9
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Kim WK, Chudoba R, Milster S, Roa R, Kanduč M, Dzubiella J. Tuning the selective permeability of polydisperse polymer networks. SOFT MATTER 2020; 16:8144-8154. [PMID: 32935731 DOI: 10.1039/d0sm01083a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We study the permeability and selectivity ('permselectivity') of model membranes made of polydisperse polymer networks for molecular penetrant transport, using coarse-grained, implicit-solvent computer simulations. In our work, permeability P is determined on the linear-response level using the solution-diffusion model, P = KDin, i.e., by calculating the equilibrium penetrant partition ratio K and penetrant diffusivity Din inside the membrane. We vary two key parameters, namely the network-network interaction, which controls the degree of swelling and collapse of the network, and the network-penetrant interaction, which tunes the selective penetrant uptake and microscopic energy landscape for diffusive transport. We find that the partitioning K covers four orders of magnitude and is a non-monotonic function of the parameters, well interpreted by a second-order virial expansion of the free energy of transferring one penetrant from a reservoir into the membrane. Moreover, we find that the penetrant diffusivity Din in the polydisperse networks, in contrast to highly ordered membrane structures, exhibits relatively simple exponential decays. We propose a semi-empirical scaling law for the penetrant diffusion that describes the simulation data for a wide range of densities and interaction parameters. The resulting permeability P turns out to follow the qualitative behavior (including maximization and minimization) of partitioning. However, partitioning and diffusion are typically anti-correlated, yielding large quantitative cancellations, controlled and fine-tuned by the network density and interactions, as rationalized by our scaling laws. We finally demonstrate that even small changes of network-penetrant interactions, e.g., by half a kBT, modify the permselectivity by almost one order of magnitude.
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Affiliation(s)
- Won Kyu Kim
- Korea Institute for Advanced Study, Seoul 02455, Republic of Korea.
| | - Richard Chudoba
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany and Division of Theoretical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden
| | - Sebastian Milster
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany and Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany.
| | - Rafael Roa
- Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain
| | - Matej Kanduč
- JoŽef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Joachim Dzubiella
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany and Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany. and Cluster of Excellence livMatS @ FIT - Freiburg Center for Interactive Materials and Bioinspired Technologies, Albert-Ludwigs-Universität Freiburg, D-79110 Freiburg, Germany
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10
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Popova H, Egorov SA, Milchev A. Nanoparticle diffusion in polymer melts: Molecular dynamics simulations and mode-coupling theory. J Chem Phys 2020; 152:234902. [PMID: 32571048 DOI: 10.1063/5.0005301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nanoparticle diffusion in polymer melts is studied by the combination of Molecular Dynamics (MD) simulations and Mode-Coupling Theory (MCT). In accord with earlier experimental, simulation, and theoretical studies, we find that the Stokes-Einstein (SE) hydrodynamic relation Dn ∼ 1/Rn holds when the nanoparticle radius Rn is greater than the polymer gyration radius Rg, while in the opposite regime, the measured nanoparticle diffusion coefficient Dn exceeds the SE value by as much as an order of magnitude. The MCT values of Dn are found to be consistently higher than the MD simulation values. The observed discrepancy is attributed to the approximations involved in constructing the microscopic friction as well as to the approximate forms for dynamic structure factors used in MCT. In a thorough test of underlying MCT assumptions and approximations, various structural and dynamical quantities required as input for MCT are obtained directly from MD simulations. We present the improved MCT approach, which involves splitting of the microscopic time-dependent friction into two terms: binary (originating from short-time dynamics) and collective (due to long-time dynamics). Using MD data as input in MCT, we demonstrate that the total friction is largely dominated by its binary short-time term, which, if neglected, leads to severe overestimation of Dn. As a result, the revised version of MCT, in agreement with the present MD data, predicts 1/Rn 2 scaling of the probe diffusion coefficient in a non-hydrodynamic regime when Rn < Rg. If the total friction is dominated by the collective long-time component, one would observe 1/Rn 3 scaling of Dn in accordance with previous studies.
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Affiliation(s)
- Hristina Popova
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Sergei A Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
| | - Andrey Milchev
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
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11
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Greenfield ML. Representing polymer molecular structure using molecular simulations for the study of liquid sorption and diffusion. Curr Opin Chem Eng 2020. [DOI: 10.1016/j.coche.2020.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Kim WK, Kanduč M, Roa R, Dzubiella J. Tuning the Permeability of Dense Membranes by Shaping Nanoscale Potentials. PHYSICAL REVIEW LETTERS 2019; 122:108001. [PMID: 30932643 DOI: 10.1103/physrevlett.122.108001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/17/2018] [Indexed: 06/09/2023]
Abstract
Permeability is one of the most fundamental transport properties in soft matter physics, material engineering, and nanofluidics. Here, we report by means of Langevin simulations of ideal penetrants in a nanoscale membrane made of a fixed lattice of attractive interaction sites, how the permeability can be massively tuned, even minimized or maximized, by tailoring the potential energy landscape for the diffusing penetrants, depending on the membrane attraction, topology, and density. Supported by limiting scaling theories we demonstrate that the observed nonmonotonic behavior and the occurrence of extreme values of the permeability is far from trivial and triggered by a strong anticorrelation and substantial (orders of magnitude) cancellation between penetrant partitioning and diffusivity, especially within dense and highly attractive membranes.
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Affiliation(s)
- Won Kyu Kim
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin, D-14109 Berlin, Germany
| | - Matej Kanduč
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin, D-14109 Berlin, Germany
- Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Rafael Roa
- Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
| | - Joachim Dzubiella
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin, D-14109 Berlin, Germany
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
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13
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Karatrantos A, Composto RJ, Winey KI, Clarke N. Nanorod Diffusion in Polymer Nanocomposites by Molecular Dynamics Simulations. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02141] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Argyrios Karatrantos
- Materials Research and Technology, Luxembourg Institute of Science and Technology, 5, Avenue des Hauts-Fourneaux, L-4362 Esch-sur-Alzette, Luxembourg
| | - Russell J. Composto
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Karen I. Winey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Nigel Clarke
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
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14
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Abedini A, Crabtree E, Bara JE, Turner CH. Molecular analysis of selective gas adsorption within composites of ionic polyimides and ionic liquids as gas separation membranes. Chem Phys 2019. [DOI: 10.1016/j.chemphys.2018.08.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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15
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Kanduč M, Kim WK, Roa R, Dzubiella J. Selective Molecular Transport in Thermoresponsive Polymer Membranes: Role of Nanoscale Hydration and Fluctuations. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00735] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Matej Kanduč
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
| | - Won Kyu Kim
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
| | - Rafael Roa
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
- Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071 Málaga, Spain
| | - Joachim Dzubiella
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Strasse 3, D-79104 Freiburg, Germany
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16
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Zhang K, Meng D, Müller-Plathe F, Kumar SK. Coarse-grained molecular dynamics simulation of activated penetrant transport in glassy polymers. SOFT MATTER 2018; 14:440-447. [PMID: 29261207 DOI: 10.1039/c7sm01941f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Membrane separations of gas mixtures strive to maximize the permeability of a desired species while keeping out undesired ones. Permeability vs. selectivity data from many polymer membranes for a given gas pair with diameters dA and dB are typically collected in a "Robeson plot"', and are bound from above by a line with a slope λ = (dB/dA)2 - 1. A microscopic understanding of this relationship, especially λ, is still missing. We perform molecular dynamics simulations of penetrant diffusion using three different coarse-grained polymer models over a wide range of penetrant sizes, temperatures, and monomer densities. The empirically relevant λ = (dB/dA)2 - 1 is only found for polymers that are either supercooled liquids with caged segmental dynamics or glasses and when the penetrant size is approximately half the Kuhn length of the chains, for which the penetrant diffusion is an activated process.
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Affiliation(s)
- Kai Zhang
- Department of Chemical Engineering, Columbia University, New York, New York 10027, USA.
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