Dissipative particle dynamics simulation of grafted polymer brushes under shear

Irfachsyad, Danial; Tildesley, Dominic J.; Malfreyt, Patrice

doi:10.1039/b110738k

Cited by 73 publications

(115 citation statements)

References 19 publications

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“…Note that in contrast to the ISL [28,29] as well as the full SCF calculations, [31] at higher grafting densities the monomer density profiles shown in Figure 1 exhibit no parabolic behavior but a region where the monomer profiles become rather flat. Such a behavior, is in agreement with previous MD [21,32] and DPD [40][41][42] simulation results. As pointed out by Laradji et al, [25] the discrepancy is expected to occur due to higher order virial terms being present in the simulation but being neglected in the SCF approach.…”

Section: Resultssupporting

confidence: 94%

“…[32] Several simulation studies have shown that the brush height follows the theoretical prediction h ∼ Nρ 1/3 a provided the grafting density is above the critical one ρ * a ∼ N −6/5 . [21,32,[40][41][42] In Figure 2, we plot the scaling behavior of the brush height measured both as the first moment of the density distribution h = zρ(z)dz/ ρ(z)dz and as the z component of the radius of gyration…”

Section: Resultsmentioning

confidence: 99%

“…[28,29] The DPD technique was also applied to simulate polymer brushes under shear. [41,42] Recently, the interface between a brush and a melt under shear was investigated by MD simulations using a DPD thermostat. [43] In this paper, we compare DPD simulation results with previous MD results and SCF predictions to investigate monomer density and chain stretching.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dissipative Particle Dynamics Simulations of Polymer Brushes: Comparison with Molecular Dynamics Simulations

Pal¹,

Seidel²

2006

Macro Theory & Simulations

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Summary:The structure of polymer brushes is investigated by dissipative particle dynamics (DPD) simulations that include explicit solvent particles. With an appropriate choice of the DPD interaction parameters a ij , we obtain good agreement with previous molecular dynamics (MD) results where the good solvent behavior has been modeled by an effective Lennard-Jones potential. The present results confirm that DPD simulation techniques can be applied for large length scale simulations of polymer brushes. A relation between the different length scales r c and σ is established.

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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dissipative Particle Dynamics Simulations of Polymer Brushes: Comparison with Molecular Dynamics Simulations

Pal¹,

Seidel²

2006

Macro Theory & Simulations

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“…Computational studies of polymeric liquids under non-equilibrium conditions have been performed intensively in recent decades [135][136][137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152]. This is not only related to the advancing computational resources that have made such studies possible, but mainly to the distinct advantages of numerical investigations.…”

Section: Non-equilibrium Molecular Dynamics Simulations Of Coarse-gramentioning

confidence: 99%

Molecular Simulation of Polymer Melts and Blends: Methods, Phase Behavior, Interfaces, and Surfaces

Virnau

Binder

Heinz

et al. 2010

Encyclopedia of Polymer Blends

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Understanding thermodynamic properties, including also the phase behavior of poly mer solutions, polymer melts, and blends, has been a long-standing challenge [1][2][3][4][5][6][7]. Initially, the theoretical description was based on the lattice model introduced by Flory and Huggins [1][2][3][4][5][6][7]. In this model, a flexible macromolecule is represented by a (self-avoiding) random walk on a (typically simple cubic) lattice, such that each bead of the polymer takes one node of the lattice, and a bond between neighboring beads of the chain molecule takes a link of the lattice. For a binary polymer blend (A,B), two types of chains occur on the lattice (and possibly also free volume or vacant sites, which we denote as ). The model (normally) does not take into account any disparity in size and shape of the (effective) monomeric units of the two partners of a polymer mixture. Between (nearest neighbor) pairs AA, AB, and BB of effective monomers, pairwise interaction energies, e AA , e AB and e BB , are assumed. Thus, this model dis regards all chemical detail (as would be embodied in the atomistic modeling [8-10], where different torsional potentials and bond-angle potentials of the two constituents can describe different chain stiffness).Despite the simplicity of this lattice model, it is still a formidable problem of statistical mechanics, and its numerically exact treatment already requires largescale Monte Carlo simulations [11][12][13]. Consequently, the standard approach has been [1-7] to treat this Flory-Huggins lattice model in mean-field approximation, which leads to the following expression for the excess free energy density of mixing [4]:1:1Here w A , w B and w V 1 w B are the volume fractions of monomers of type A, B and of vacant sites, respectively. Every lattice site has to be taken by either w A Edited by Avraam I. Isayev

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“…For water-soluble polymer brushes in aqueous environments, the presence of bound (or 'hydration') water surrounding the polymer chains can result in structural forces between the hydrated brushes [6]. Strongly hydrated polymers, together with a continuous rapid exchange of bound water with other free water molecules, keep the surfaces separated while maintaining a high fluidity at the brush-brush interface at high compressions, thus leading to a very low coefficient of friction [7,8].…”

Section: Introductionmentioning

confidence: 99%

Macrotribological Studies of Poly(L-lysine)-graft-Poly(ethylene glycol) in Aqueous Glycerol Mixtures

et al. 2009

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We have investigated the tribological properties of surfaces with adsorbed poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) sliding in aqueous glycerol solutions under different lubrication regimes. Glycerol is a polar, biocompatible liquid with a significantly higher viscosity than that of water. Macrotribological performance was investigated by means of pin-on-disk and mini-tractionmachine measurements in glycerol-PLL-g-PEG-aqueous buffer mixtures of varying compositions. Adsorption studies of PLL-g-PEG from these mixtures were conducted with the quartz-crystal-microbalance technique. The enhanced viscosity of the glycerol-containing lubricant reduces the coefficient of friction due to increased hydrodynamic forces, leading to a more effective separation of the sliding partners, while the presence of hydrated polymer brushes at the interface leads to an entropically driven repulsion, which also helps mitigate direct asperity-asperity contact between the solid surfaces under boundary-lubrication conditions. The combination of polymer layers on surfaces with aqueous phases of enhanced viscosity thus enables the friction to be reduced by several orders of magnitude, compared to the behavior of pure water, over a large range of sliding speeds. The individual contributions of the polymer and the aqueous glycerol solutions in reducing the friction have been studied across different lubrication regimes.

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Dissipative particle dynamics simulation of grafted polymer brushes under shear

Cited by 73 publications

References 19 publications

Dissipative Particle Dynamics Simulations of Polymer Brushes: Comparison with Molecular Dynamics Simulations

Dissipative Particle Dynamics Simulations of Polymer Brushes: Comparison with Molecular Dynamics Simulations

Molecular Simulation of Polymer Melts and Blends: Methods, Phase Behavior, Interfaces, and Surfaces

Macrotribological Studies of Poly(L-lysine)-graft-Poly(ethylene glycol) in Aqueous Glycerol Mixtures

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