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Kozhukhov T, Shendruk TN. Mesoscopic simulations of active nematics. SCIENCE ADVANCES 2022; 8:eabo5788. [PMID: 36001669 PMCID: PMC9401632 DOI: 10.1126/sciadv.abo5788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Coarse-grained, mesoscale simulations are invaluable for studying soft condensed matter because of their ability to model systems in which a background solvent plays a substantial role but is not the primary interest. Such methods generally model passive solvents; however, far-from-equilibrium systems may also be composed of complex solutes suspended in an active fluid. Yet, few coarse-grained simulation methods exist to model an active medium. We introduce an algorithm to simulate active nematics, which builds on multiparticle collision dynamics (MPCD) for passive fluctuating nematohydrodynamics by introducing dipolar activity in the local collision operator. Active nematic MPCD (AN-MPCD) simulations not only exhibit the key characteristics of active nematic turbulence but, as a particle-based algorithm, also reproduce crucial attributes of active particle models. Thus, mesoscopic AN-MPCD is an approach that bridges microscopic and continuum descriptions, allowing simulations of composite active-passive systems.
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Perez Ocampo L, Weiss LB, Jardat M, Likos CN, Dahirel V. Electroosmotic Flow Induced Lift Forces on Polymer Chains in Nanochannels. ACS POLYMERS AU 2022; 2:245-256. [PMID: 35971422 PMCID: PMC9372999 DOI: 10.1021/acspolymersau.1c00058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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A major objective
of research in nanofluidics is to achieve better
selectivity in manipulating the fluxes of nano-objects and in particular
of biopolymers. Numerical simulations allow one to better understand
the physical mechanisms at play in such situations. We performed hybrid
mesoscale simulations to investigate the properties of polymers under
flows in slit pores at the nanoscale. We use multiparticle collision
dynamics, an algorithm that includes hydrodynamics and thermal fluctuations,
to investigate the properties of fully flexible and stiff polymers
under several types of flow, showing that Poiseuille flows and electroosmotic
flows can lead to quantitatively and qualitatively different behaviors
of the chain. In particular, a counterintuitive phenomenon occurs
in the presence of an electroosmotic flow: When the monomers are attracted
by the solid surfaces through van der Waals forces, shear-induced
forces lead to a stronger repulsion of the polymers from these surfaces.
Such focusing of the chain in the middle of the channel increases
its flowing velocity, a phenomenon that may be exploited to separate
different types of polymers.
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Affiliation(s)
- Lisbeth Perez Ocampo
- Sorbonne Université, CNRS, Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX, F-75005 Paris, France
| | - Lisa B. Weiss
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Marie Jardat
- Sorbonne Université, CNRS, Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX, F-75005 Paris, France
| | - Christos N. Likos
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Vincent Dahirel
- Sorbonne Université, CNRS, Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX, F-75005 Paris, France
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Dhamankar S, Webb MA. Chemically specific coarse‐graining of polymers: Methods and prospects. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210555] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Satyen Dhamankar
- Department of Chemical and Biological Engineering Princeton University Princeton New Jersey USA
| | - Michael A. Webb
- Department of Chemical and Biological Engineering Princeton University Princeton New Jersey USA
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Hagita K, Murashima T. Molecular Dynamics Simulations of Ring Shapes on a Ring Fraction in Ring–Linear Polymer Blends. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00656] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20, Hashirimizu, Yokosuka 239-8686, Japan
| | - Takahiro Murashima
- Department of Physics, Tohoku University, 6-3, Aramaki-aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
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Datta R, Yelash L, Schmid F, Kummer F, Oberlack M, Lukáčová-Medvid’ová M, Virnau P. Shear-Thinning in Oligomer Melts-Molecular Origins and Applications. Polymers (Basel) 2021; 13:2806. [PMID: 34451343 PMCID: PMC8399857 DOI: 10.3390/polym13162806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/12/2021] [Accepted: 08/14/2021] [Indexed: 12/04/2022] Open
Abstract
We investigate the molecular origin of shear-thinning in melts of flexible, semiflexible and rigid oligomers with coarse-grained simulations of a sheared melt. Entanglements, alignment, stretching and tumbling modes or suppression of the latter all contribute to understanding how macroscopic flow properties emerge from the molecular level. In particular, we identify the rise and decline of entanglements with increasing chain stiffness as the major cause for the non-monotonic behaviour of the viscosity in equilibrium and at low shear rates, even for rather small oligomeric systems. At higher shear rates, chains align and disentangle, contributing to shear-thinning. By performing simulations of single chains in shear flow, we identify which of these phenomena are of collective nature and arise through interchain interactions and which are already present in dilute systems. Building upon these microscopic simulations, we identify by means of the Irving-Kirkwood formula the corresponding macroscopic stress tensor for a non-Newtonian polymer fluid. Shear-thinning effects in oligomer melts are also demonstrated by macroscopic simulations of channel flows. The latter have been obtained by the discontinuous Galerkin method approximating macroscopic polymer flows. Our study confirms the influence of microscopic details in the molecular structure of short polymers such as chain flexibility on macroscopic polymer flows.
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Affiliation(s)
- Ranajay Datta
- Institute of Physics, Johannes Gutenberg University, Staudingerweg 9, 55128 Mainz, Germany; (R.D.); (F.S.)
| | - Leonid Yelash
- Institute of Mathematics, Johannes Gutenberg University, Staudingerweg 9, 55128 Mainz, Germany;
| | - Friederike Schmid
- Institute of Physics, Johannes Gutenberg University, Staudingerweg 9, 55128 Mainz, Germany; (R.D.); (F.S.)
| | - Florian Kummer
- Department of Mechanical Engineering, Technische Universität Darmstadt, Otto-Berndt-Str. 2, 64287 Darmstadt, Germany; (F.K.); (M.O.)
| | - Martin Oberlack
- Department of Mechanical Engineering, Technische Universität Darmstadt, Otto-Berndt-Str. 2, 64287 Darmstadt, Germany; (F.K.); (M.O.)
| | | | - Peter Virnau
- Institute of Physics, Johannes Gutenberg University, Staudingerweg 9, 55128 Mainz, Germany; (R.D.); (F.S.)
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Chubak I, Likos CN, Egorov SA. Multiscale Approaches for Confined Ring Polymer Solutions. J Phys Chem B 2021; 125:4910-4923. [PMID: 33938750 PMCID: PMC8279562 DOI: 10.1021/acs.jpcb.1c01953] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/18/2021] [Indexed: 11/29/2022]
Abstract
We apply a hierarchy of multiscale modeling approaches to investigate the structure of ring polymer solutions under planar confinement. In particular, we employ both monomer-resolved (MR-DFT) and a coarse-grained (CG-DFT) density functional theories for fully flexible ring polymers, with the former based on a flexible tangent hard-sphere model and the latter based on an effective soft-colloid representation, to elucidate the ring polymer organization within slits of variable width in different concentration regimes. The predicted monomer and polymer center-of-mass densities in confinement, as well as the surface tension at the solution-wall interface, are compared to explicit molecular dynamics (MD) simulations. The approaches yield quantitative (MR-DFT) or semiquantitative (CG-DFT) agreement with MD. In addition, we provide a systematic comparison between confined linear and ring polymer solutions. When compared to their linear counterparts, the rings are found to feature a higher propensity to structure in confinement that translates into a distinct shape of the depletion potentials between two walls immersed into a polymer solution. The depletion potentials that we extract from CG-DFT and MR-DFT are in semiquantitative agreement with each other. Overall, we find consistency among all approaches as regards the shapes, trends, and qualitative characteristics of density profiles and depletion potentials induced on hard walls by linear and cyclic polymers.
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Affiliation(s)
- Iurii Chubak
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Sorbonne
Université CNRS, Physico-Chimie des
Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
| | - Christos N. Likos
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Sergei A. Egorov
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22901, United States
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Moghimi E, Chubak I, Founta D, Ntetsikas K, Polymeropoulos G, Hadjichristidis N, Likos CN, Vlassopoulos D. The influence of arm composition on the self-assembly of low-functionality telechelic star polymers in dilute solutions. Colloid Polym Sci 2021. [DOI: 10.1007/s00396-020-04742-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractWe combine synthesis, physical experiments, and computer simulations to investigate self-assembly patterns of low-functionality telechelic star polymers (TSPs) in dilute solutions. In particular, in this work, we focus on the effect of the arm composition and length on the static and dynamic properties of TSPs, whose terminal blocks are subject to worsening solvent quality upon reducing the temperature. We find two populations, single stars and clusters, that emerge upon worsening the solvent quality of the outer block. For both types of populations, their spatial extent decreases with temperature, with the specific details (such as temperature at which the minimal size is reached) depending on the coupling between inter- and intra-molecular associations as well as their strength. The experimental results are in very good qualitative agreement with coarse-grained simulations, which offer insights into the mechanism of thermoresponsive behavior of this class of materials.
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Mayoral E, Goicochea AG. Modeling of Branched Thickening Polymers under Poiseuille Flow Gives Clues as to How to Increase a Solvent's Viscosity. J Phys Chem B 2021; 125:1692-1704. [PMID: 33544598 DOI: 10.1021/acs.jpcb.0c11087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The viscosity enhancement of a solvent produced by the addition of thickening branched polymers is predicted as a function of polymer concentration, branch length and persistence length, and strength of the covalent bonding interactions. Nonequilibrium, stationary-state Poiseuille numerical simulations are performed using the dissipative particle dynamics model to obtain the viscosity of the fluid. It is found that the clustering of the polymers into aggregates increases the viscosity and that it is more strongly affected by the strength of the bonding interactions. General scaling relationships are found for the viscosity as a function of the variables studied, which are expected to be useful for the design and synthesis of new viscosifying polymers. It is argued that our results can be applied to aqueous thickeners, of importance for colloidal fluids such as paints and coatings and also for nonpolar fluids such as supercritical CO2, which is a promising nonhydraulic fracking fluid also useful in enhanced oil recovery.
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Affiliation(s)
- E Mayoral
- Instituto Nacional de Investigaciones Nucleares, Carretera México Toluca s/n, La Marquesa Ocoyoacac 52750, Estado de México, Mexico
| | - A Gama Goicochea
- Departamento de Ingeniería Química y Bioquímica, Tecnológico de Estudios Superiores de Ecatepec, Ecatepec de Morelos 55210, Estado de México, Mexico
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Liebetreu M, Likos CN. Cluster prevalence in concentrated ring-chain mixtures under shear. SOFT MATTER 2020; 16:8710-8719. [PMID: 32996544 DOI: 10.1039/d0sm01309a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Semiflexible ring polymers are known to exhibit clustering behavior and form stacks in concentrated solutions. Recently, weak shear was suggested to re-orient these stacks with flow, a phenomenon more easily visible in more concentrated solutions [Liebetreu et al., ACS Appl. Polym. Mater., 2020, 2(8), 3505-3517, DOI: 10.1021/acsapm.0c00522]. In this work, we investigate the impact of mixing linear chains and rings in a similar system under shear, studying clustering in the presence of semiflexible, rod-like chains. We present a correlation between chain monomer fraction and clustering behavior as linear chains take up less space, thus decreasing the system's effective density and, subsequently, clustering. However, we suggest mixtures with a low chain concentration to maintain or potentially enhance clustering at equilibrium while this effect is destroyed under shear. The mixing of chains and rings may therefore be used to create more strongly organized structures susceptible to reorientation via weak shear.
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Affiliation(s)
- Maximilian Liebetreu
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
| | - Christos N Likos
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
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