1
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Svaneborg C, Everaers R. Multiscale equilibration of highly entangled isotropic model polymer melts. J Chem Phys 2023; 158:054903. [PMID: 36754791 DOI: 10.1063/5.0123431] [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
We present a computationally efficient multiscale method for preparing equilibrated, isotropic long-chain model polymer melts. As an application, we generate Kremer-Grest melts of 1000 chains with 200 entanglements and 25 000-2000 beads/chain, which cover the experimentally relevant bending rigidities up to and beyond the limit of the isotropic-nematic transition. In the first step, we employ Monte Carlo simulations of a lattice model to equilibrate the large-scale chain structure above the tube scale while ensuring a spatially homogeneous density distribution. We then use theoretical insight from a constrained mode tube model to introduce the bead degrees of freedom together with random walk conformational statistics all the way down to the Kuhn scale of the chains. This is followed by a sequence of simulations with carefully parameterized force-capped bead-spring models, which slowly introduce the local bead packing while reproducing the larger-scale chain statistics of the target Kremer-Grest system at all levels of force-capping. Finally, we can switch to the full Kremer-Grest model without perturbing the structure. The resulting chain statistics is in excellent agreement with literature results on all length scales accessible in brute-force simulations of shorter chains.
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Affiliation(s)
- Carsten Svaneborg
- University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Ralf Everaers
- ENSL, CNRS, Laboratoire de Physique and Centre Blaise Pascal de l'École Normale Supérieure de Lyon, F-69342 Lyon, France
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2
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Everaers R, Karimi-Varzaneh HA, Fleck F, Hojdis N, Svaneborg C. Kremer–Grest Models for Commodity Polymer Melts: Linking Theory, Experiment, and Simulation at the Kuhn Scale. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02428] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ralf Everaers
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS, Laboratoire de Physique and Centre Blaise Pascal de l’ENS de Lyon, F-69342 Lyon, France
| | | | - Frank Fleck
- Continental Reifen Deutschland GmbH, Jädekamp 30, D-30419 Hannover, Germany
| | - Nils Hojdis
- Institute of Applied Polymer Chemistry, Aachen University of Applied Sciences, Heinrich-Mussmann-Str.1, 52428 Jülich, Germany
| | - Carsten Svaneborg
- University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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3
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Lentzakis H, Costanzo S, Vlassopoulos D, Colby RH, Read DJ, Lee H, Chang T, van Ruymbeke E. Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00251] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Helen Lentzakis
- Institute of Electronic Structure & Laser, Heraklion, Foundation for Research and Technology Hellas (FORTH), Heraklion, Crete 70013, Greece
- Department of Materials Science & Technology, University of Crete, Heraklion, Crete 70013, Greece
| | - Salvatore Costanzo
- Institute of Electronic Structure & Laser, Heraklion, Foundation for Research and Technology Hellas (FORTH), Heraklion, Crete 70013, Greece
- Department of Materials Science & Technology, University of Crete, Heraklion, Crete 70013, Greece
| | - Dimitris Vlassopoulos
- Institute of Electronic Structure & Laser, Heraklion, Foundation for Research and Technology Hellas (FORTH), Heraklion, Crete 70013, Greece
- Department of Materials Science & Technology, University of Crete, Heraklion, Crete 70013, Greece
| | - Ralph H. Colby
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
| | - Daniel Jon Read
- Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K
| | - Hyojoon Lee
- Department of Chemistry and Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Taihyun Chang
- Department of Chemistry and Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Evelyne van Ruymbeke
- Bio and Soft Matter, Institute on Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain (UCL), Louvain 1348, Belgium
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Uneyama T. A transient bond model for dynamic constraints in meso-scale coarse-grained systems. J Chem Phys 2019; 150:024901. [DOI: 10.1063/1.5062495] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Takashi Uneyama
- Center for Computational Science, Graduate School of Engineering, Nagoya University, Nagoya, Japan
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5
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Affiliation(s)
- Yuichi Masubuchi
- Department of Materials Physics, Nagoya University, Nagoya, Japan
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6
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Liu L, den Otter WK, Briels WJ. Coarse-Grained Simulations of Three-Armed Star Polymer Melts and Comparison with Linear Chains. J Phys Chem B 2018; 122:10210-10218. [DOI: 10.1021/acs.jpcb.8b03104] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Li Liu
- Department of Information Science and Engineering, Dalian Polytechnic University, Dalian 116034, China
| | | | - Wim J. Briels
- Forschungszentrum Jülich, ICS 3, D-52425 Jülich, Germany
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7
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Metri V, Louhichi A, Yan J, Baeza GP, Matyjaszewski K, Vlassopoulos D, Briels WJ. Physical Networks from Multifunctional Telechelic Star Polymers: A Rheological Study by Experiments and Simulations. Macromolecules 2018; 51:2872-2886. [PMID: 29910512 PMCID: PMC5997402 DOI: 10.1021/acs.macromol.7b02613] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/26/2018] [Indexed: 11/29/2022]
Abstract
The equilibrium mechanical properties of a cross-linked gel of telechelic star polymers are studied by rheology and Brownian dynamics simulations. The Brownian dynamics model consists of cores to which Rouse arms are attached. Forces between the cores are obtained from a potential of mean force model developed by Likos and co-workers. Both experimentally and in the simulations, networks were created by attaching sticker groups to the ends of the arms of the polymers, which were next allowed to form bonds among them in a one to one fashion. Simulations were sped up by solving the Rouse dynamics exactly. Moreover, the Rouse model was extended to allow for different frictions on different beads. In order to describe the rheology of the non-cross-linked polymers, it had to be assumed that bead frictions increase with increasing bead number along the arms. This friction model could be transferred to describe the rheology of the network without any adjustments other than an overall increase of the frictions due to the formation of bonds. The slowing down at intermediate times of the network rheology compared to that of the non-cross-linked polymers is well described by the model. The percentage of stickers involved in forming inter-star bonds in the system was determined to be 25%, both from simulations and from an application of the Green-Tobolsky relation to the experimental plateau value of the shear relaxation modulus. Simulations with increasing cross-link percentages revealed that on approaching the gel transition the shear relaxation modulus develops an algebraic tail, which gets frozen at a percentage of maximum cross-linking of about 11%.
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Affiliation(s)
- Vishal Metri
- Computational Chemical Physics, Faculty of Science
and Technology, and MESA+ Institute
for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Ameur Louhichi
- Institute
of Electronic Structure & Laser, FORTH, P.O. Box 1527, 70013 Heraklion, Crete Greece
- Department
of Materials Science & Technology, University
of Crete, Voutes Campus, 70013 Heraklion, Crete Greece
| | - Jiajun Yan
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Guilhem P. Baeza
- CNRS,
MATEIS, University of Lyon, INSA-Lyon, UMR5510-7 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Krzysztof Matyjaszewski
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Dimitris Vlassopoulos
- Institute
of Electronic Structure & Laser, FORTH, P.O. Box 1527, 70013 Heraklion, Crete Greece
- Department
of Materials Science & Technology, University
of Crete, Voutes Campus, 70013 Heraklion, Crete Greece
| | - Wim J. Briels
- Computational Chemical Physics, Faculty of Science
and Technology, and MESA+ Institute
for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
- ICS 3, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
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8
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Salerno KM, Bernstein N. Persistence Length, End-to-End Distance, and Structure of Coarse-Grained Polymers. J Chem Theory Comput 2018. [DOI: 10.1021/acs.jctc.7b01229] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. Michael Salerno
- NRC Research Associate, Resident at Center for Computational Materials Science, US Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Noam Bernstein
- US Naval Research Laboratory, 4555 Overlook Ave SW, Washington, D.C. 20375, United States
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Ramos J, Vega J, Martínez-Salazar J. Predicting experimental results for polyethylene by computer simulation. Eur Polym J 2018. [DOI: 10.1016/j.eurpolymj.2017.12.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Fitzgerald BW, Briels WJ. A Mesoscopic Model with Vectorial Structure Parameter for Interacting Star Polymers. MACROMOL THEOR SIMUL 2017. [DOI: 10.1002/mats.201700069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Barry W. Fitzgerald
- Process & Energy Department; Delft University of Technology; Leeghwaterstraat 39 2628 CB Delft The Netherlands
| | - Wim J. Briels
- Computational Biophysics; University of Twente; P.O. Box 217 7500 AE Enschede The Netherlands
- MESA+; Institute of Nanotechnology; University of Twente; P.O. Box 217 7500 AE Enschede The Netherlands
- Forschungszentrum Jülich; ICS 3 D-52425 Jülich Germany
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11
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Takahashi KZ, Nishimura R, Yamato N, Yasuoka K, Masubuchi Y. Onset of static and dynamic universality among molecular models of polymers. Sci Rep 2017; 7:12379. [PMID: 28959052 PMCID: PMC5620073 DOI: 10.1038/s41598-017-08501-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/12/2017] [Indexed: 12/03/2022] Open
Abstract
A quantitatively accurate prediction of properties for entangled polymers is a long-standing challenge that must be addressed to enable efficient development of these materials. The complex nature of polymers is the fundamental origin of this challenge. Specifically, the chemistry, structure, and dynamics at the atomistic scale affect properties at the meso and macro scales. Therefore, quantitative predictions must start from atomistic molecular dynamics (AMD) simulations. Combined use of atomistic and coarse-grained (CG) models is a promising approach to estimate long-timescale behavior of entangled polymers. However, a systematic coarse-graining is still to be done for bridging the gap of length and time scales while retaining atomistic characteristics. Here we examine the gaps among models, using a generic mapping scheme based on power laws that are closely related to universality in polymer structure and dynamics. The scheme reveals the characteristic length and time for the onset of universality between the vastly different scales of an atomistic model of polyethylene and the bead-spring Kremer-Grest (KG) model. The mapping between CG model of polystyrene and the KG model demonstrates the fast onset of universality, and polymer dynamics up to the subsecond time scale are observed. Thus, quantitatively traceable timescales of polymer MD simulations can be significantly increased.
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Affiliation(s)
- Kazuaki Z Takahashi
- Multi-scale Soft-matter Simulation Team, Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan.
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan.
| | - Ryuto Nishimura
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Nobuyoshi Yamato
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Yuichi Masubuchi
- National Composite Center, Nagoya University, Furocho, Chikusa, Nagoya, 464-8630, Japan
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Gooneie A, Schuschnigg S, Holzer C. A Review of Multiscale Computational Methods in Polymeric Materials. Polymers (Basel) 2017; 9:E16. [PMID: 30970697 PMCID: PMC6432151 DOI: 10.3390/polym9010016] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/07/2016] [Accepted: 12/22/2016] [Indexed: 11/17/2022] Open
Abstract
Polymeric materials display distinguished characteristics which stem from the interplay of phenomena at various length and time scales. Further development of polymer systems critically relies on a comprehensive understanding of the fundamentals of their hierarchical structure and behaviors. As such, the inherent multiscale nature of polymer systems is only reflected by a multiscale analysis which accounts for all important mechanisms. Since multiscale modelling is a rapidly growing multidisciplinary field, the emerging possibilities and challenges can be of a truly diverse nature. The present review attempts to provide a rather comprehensive overview of the recent developments in the field of multiscale modelling and simulation of polymeric materials. In order to understand the characteristics of the building blocks of multiscale methods, first a brief review of some significant computational methods at individual length and time scales is provided. These methods cover quantum mechanical scale, atomistic domain (Monte Carlo and molecular dynamics), mesoscopic scale (Brownian dynamics, dissipative particle dynamics, and lattice Boltzmann method), and finally macroscopic realm (finite element and volume methods). Afterwards, different prescriptions to envelope these methods in a multiscale strategy are discussed in details. Sequential, concurrent, and adaptive resolution schemes are presented along with the latest updates and ongoing challenges in research. In sequential methods, various systematic coarse-graining and backmapping approaches are addressed. For the concurrent strategy, we aimed to introduce the fundamentals and significant methods including the handshaking concept, energy-based, and force-based coupling approaches. Although such methods are very popular in metals and carbon nanomaterials, their use in polymeric materials is still limited. We have illustrated their applications in polymer science by several examples hoping for raising attention towards the existing possibilities. The relatively new adaptive resolution schemes are then covered including their advantages and shortcomings. Finally, some novel ideas in order to extend the reaches of atomistic techniques are reviewed. We conclude the review by outlining the existing challenges and possibilities for future research.
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Affiliation(s)
- Ali Gooneie
- Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Stephan Schuschnigg
- Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Clemens Holzer
- Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
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Choudhury CK, Carbone P, Roy S. Scalability of Coarse-Grained Potentials Generated from Iterative Boltzmann Inversion for Polymers: Case Study on Polycarbonates. MACROMOL THEOR SIMUL 2016. [DOI: 10.1002/mats.201500079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | - Paola Carbone
- School of Chemical Engineering and Analytical Science; The University of Manchester; Manchester UK
| | - Sudip Roy
- Physical Chemistry Division; National Chemical Laboratory; Pune India
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14
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Salerno KM, Agrawal A, Perahia D, Grest GS. Resolving Dynamic Properties of Polymers through Coarse-Grained Computational Studies. PHYSICAL REVIEW LETTERS 2016; 116:058302. [PMID: 26894738 DOI: 10.1103/physrevlett.116.058302] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Indexed: 06/05/2023]
Abstract
Coupled length and time scales determine the dynamic behavior of polymers and underlie their unique viscoelastic properties. To resolve the long-time dynamics it is imperative to determine which time and length scales must be correctly modeled. Here we probe the degree of coarse graining required to simultaneously retain significant atomistic details and access large length and time scales. The degree of coarse graining in turn sets the minimum length scale instrumental in defining polymer properties and dynamics. Using linear polyethylene as a model system, we probe how the coarse-graining scale affects the measured dynamics. Iterative Boltzmann inversion is used to derive coarse-grained potentials with 2-6 methylene groups per coarse-grained bead from a fully atomistic melt simulation. We show that atomistic detail is critical to capturing large-scale dynamics. Using these models we simulate polyethylene melts for times over 500 μs to study the viscoelastic properties of well-entangled polymer melts.
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Affiliation(s)
| | - Anupriya Agrawal
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri 63130, USA
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA
| | - Dvora Perahia
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA
| | - Gary S Grest
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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15
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Snijkers F, Pasquino R, Olmsted PD, Vlassopoulos D. Perspectives on the viscoelasticity and flow behavior of entangled linear and branched polymers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:473002. [PMID: 26558404 DOI: 10.1088/0953-8984/27/47/473002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We briefly review the recent advances in the rheology of entangled polymers and identify emerging research trends and outstanding challenges, especially with respect to branched polymers. Emphasis is placed on the role of well-characterized model systems, as well as the synergy of synthesis-characterization, rheometry and modeling/simulations. The theoretical framework for understanding the observed linear and nonlinear rheological phenomena is the tube model, which is critically assessed in view of its successes and shortcomings, and alternative approaches are briefly discussed. Finally, intriguing experimental findings and controversial issues that merit consistent explanation, such as shear banding instabilities, multiple stress overshoots in transient simple shear and enhanced steady-state elongational viscosity in polymer solutions, are discussed, and future directions such as branch point dynamics and anisotropic monomeric friction are outlined.
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Affiliation(s)
- F Snijkers
- FORTH, Institute of Electronic Structure and Laser, Heraklion, Crete 71110, Greece. CNRS/Solvay UMR 5268, Laboratoire Polymères et Matériaux Avancés, Saint-Fons 69190, France
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Santos de Oliveira IS, Fitzgerald BW, den Otter WK, Briels WJ. Mesoscale modeling of shear-thinning polymer solutions. J Chem Phys 2014; 140:104903. [PMID: 24628201 DOI: 10.1063/1.4867787] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We simulate the linear and nonlinear rheology of two different viscoelastic polymer solutions, a polyisobutylene solution in pristane and an aqueous solution of hydroxypropylcellulose, using a highly coarse-grained approach known as Responsive Particle Dynamics (RaPiD) model. In RaPiD, each polymer has originally been depicted as a spherical particle with the effects of the eliminated degrees of freedom accounted for by an appropriate free energy and transient pairwise forces. Motivated by the inability of this spherical particle representation to entirely capture the nonlinear rheology of both fluids, we extended the RaPiD model by introducing a deformable particle capable of elongation. A Finite-Extensible Non-Linear Elastic potential provides a free energy penalty for particle elongation. Upon disentangling, this deformability allows more time for particles to re-entangle with neighbouring particles. We show this process to be integral towards recovering the experimental nonlinear rheology, obtaining excellent agreement. We show that the nonlinear rheology is crucially dependent upon the maximum elongation and less so on the elasticity of the particles. In addition, the description of the linear rheology has been retained in the process.
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Affiliation(s)
- I S Santos de Oliveira
- Computational Biophysics, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - B W Fitzgerald
- Computational Biophysics, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - W K den Otter
- Computational Biophysics, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - W J Briels
- Computational Biophysics, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
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Liu L, den Otter WK, Briels WJ. Coarse grain forces in star polymer melts. SOFT MATTER 2014; 10:7874-7886. [PMID: 25158294 DOI: 10.1039/c4sm00767k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An analysis is presented of forces acting on the centers of mass of three-armed star polymers in the molten state. The arms consist of 35 Kremer-Grest beads, which is slightly larger than needed for one entanglement mass. For a given configuration of the centers of mass, instantaneous forces fluctuate wildly around averages which are two orders of magnitude smaller than their root mean square deviations. Average forces are well described by an implicit many-body potential, while pair models fail completely. The fluctuating forces are modelled by means of dynamical variables quantifying the degree of mixing of the various polymer pairs. All functions and parameters in a coarse grain model based on these concepts are obtained from the underlying small scale simulation. The coarse model reproduces both the diffusion coefficient and the shear relaxation modulus. Ways to improve the model suggest themselves on the basis of our findings.
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Affiliation(s)
- L Liu
- Computational Biophysics, MESA+, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
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19
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Fitzgerald BW, Lentzakis H, Sakellariou G, Vlassopoulos D, Briels WJ. A computational and experimental study of the linear and nonlinear response of a star polymer melt with a moderate number of unentangled arms. J Chem Phys 2014; 141:114907. [PMID: 25240372 DOI: 10.1063/1.4895610] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We present from simulations and experiments results on the linear and nonlinear rheology of a moderate functionality, low molecular weight unentangled polystyrene (PS) star melt. The PS samples were anionically synthesized and close to monodisperse while their moderate functionality ensures that they do not display a pronounced core effect. We employ a highly coarse-grained model known as Responsive Particle Dynamics where each star polymer is approximated as a point particle. The eliminated degrees of freedom are used in the definition of an appropriate free energy as well as describing the transient pair-wise potential between particles that accounts for the viscoelastic response. First we reproduce very satisfactorily the experimental moduli using simulation. We then consider the nonlinear response of the same polymer melts by implementing a start-up shear protocol for a wide range of shear rates. As in experiments, we observe the development of a stress overshoot with increasing shear rate followed by a steady-state shear stress. We also recover the shear-thinning nature of the melt, although we slightly overestimate the extent of shear-thinning with simulations. In addition, we study relaxations upon the removal of shear where we find encouraging agreement between experiments and simulations, a finding that corroborates our agreement for the linear rheology.
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Affiliation(s)
- Barry W Fitzgerald
- Computational Biophysics, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Helen Lentzakis
- Foundation for Research and Technology (FORTH), Institute of Electronic Structure and Laser, Heraklion 71110, Crete, Greece
| | | | - Dimitris Vlassopoulos
- Foundation for Research and Technology (FORTH), Institute of Electronic Structure and Laser, Heraklion 71110, Crete, Greece
| | - Wim J Briels
- Computational Biophysics, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
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