Local Dynamics and Primitive Path Analysis for a Model Polymer Melt near a Surface

Vladkov, Mihail; Barrat, Jean‐Louis

doi:10.1021/ma062607r

Cited by 55 publications

(73 citation statements)

References 22 publications

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“…Globally, we find that confinement leads to a decrease in the average number of entanglements per chain. Qualitatively, this result is in good agreement with the one observed in experiments, 10,37,38 simulations, 17,39,40 and with the theoretical model proposed in Ref. 19.…”

Section: Statistics Of Entanglements In Bulksupporting

confidence: 92%

Entanglement Reduction Induced by Geometrical Confinement in Polymer Thin Films

García

Barrat

2018

Macromolecules

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We report simulation results on melts of entangled linear polymers confined in a freestanding thin film. We study how the geometric constraints imposed by the confinement alter the entanglement state of the system compared to the equivalent bulk system using various observables. We find that the confinement compresses the chain conformation uniaxially, decreasing the volume pervaded by the chain, which in turn reduces the number of the accessible inter-chain contact that could lead to entanglements. This local and non-uniform effect depends on the position of the chain within the film. We also test a recently presented theory that predicts how the number of entanglements decreases with geometrical confinement. arXiv:1809.03831v1 [cond-mat.soft]

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Section: Statistics Of Entanglements In Bulksupporting

confidence: 92%

Entanglement Reduction Induced by Geometrical Confinement in Polymer Thin Films

García

Barrat

2018

Macromolecules

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“…Additionally, the anisotropic filler particles might be oriented during LAOS. The increase of the entanglement concentration close to the filler surface, which was found by molecular dynamics simulations,, is another possible explanation for the increase of I 3/1 with increasing φ.…”

Section: Resultsmentioning

confidence: 99%

Fourier-Transform Rheology of Unvulcanized, Carbon Black Filled Styrene Butadiene Rubber

Schwab

Hojdis

Lacayo

et al. 2016

Macromol. Mater. Eng.

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Rubber materials filled with reinforcing fillers display nonlinear rheological behavior at small strain amplitudes below γ0 < 0.1. Nevertheless, rheological data are analyzed mostly in terms of linear parameters, such as shear moduli (G′, G″), which loose their physical meaning in the nonlinear regime. In this work styrene butadiene rubber filled with carbon black (CB) under large amplitude oscillatory shear (LAOS) is analyzed in terms of the nonlinear parameter I3/1. Three different CB grades are used and the filler load is varied between 0 and 70 phr. It is found that I3/1(φ) is most sensitive to changes of the total accessible filler surface area at low strain amplitudes (γ0 = 0.32). The addition of up to 70 phr CB leads to an increase of I3/1(φ) by a factor of more than ten. The influence of the measurement temperature on I3/1 is pronounced for CB levels above the percolation threshold.

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“…A key concept is the behavior of entanglements between different polymer molecules in the vicinity of a confining surface. There has been much interest in the changes in properties and density of entanglements for such systems [6][7][8][9][10][11][12] . Ever since the seminal work by Fetters et al 13 , the success of the Lin-Noolandi conjecture [14][15][16] has been cited in predictions of a large increase in the entanglement molecular weight for polymer melts under steric confinement 17 .…”

Section: Introductionmentioning

confidence: 99%

“…Several studies using computer simulation have examined the system average 'entanglement length', N e , of confined melts, found from Primitive Path Analysis (PPA) 19 . In some cases an 'S-coil' 20 definition of entanglement length was employed 7,12 that makes an assumption of Gaussian chain statistics. This assumption is usually considered appropriate in the bulk melt but appears questionable for confined systems.…”

Section: Introductionmentioning

confidence: 99%

Entanglement dynamics at flat surfaces: Investigations using multi-chain molecular dynamics and a single-chain slip-spring model

Kirk

Wang

Ilg

2019

The Journal of Chemical Physics

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The dynamics of an entangled polymer melt confined in a channel by parallel plates is investigated by Molecular Dynamics (MD) simulations of a detailed, multi-chain model. A primitive path analysis predicts that the density of entanglements remains approximately constant throughout the gap and drops to lower values only in the immediate vicinity of the surface. Based on these observations, we propose a coarse-grained, single-chain slip-spring model with a uniform density of slip-spring anchors and slip-links. The slip-spring model is compared to the Kremer-Grest MD bead-spring model via equilibrium correlation functions of chain orientations. Reasonably good agreement between the single-chain model and the detailed multi-chain model is obtained for chain relaxation dynamics, both away from the surface and for chains whose center of mass positions are at a distance from the surface that is less than the bulk chain radius of gyration, without introducing any additional model parameters. Our results suggest that there is no considerable drop in topological interactions for chains in the vicinity of a single flat surface. We infer from the slip-spring model that the experimental plateau modulus of a confined polymer melt may be different to a corresponding unconfined system even if there is no drop in topological interactions for the confined case.

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Local Dynamics and Primitive Path Analysis for a Model Polymer Melt near a Surface

Cited by 55 publications

References 22 publications

Entanglement Reduction Induced by Geometrical Confinement in Polymer Thin Films

Entanglement Reduction Induced by Geometrical Confinement in Polymer Thin Films

Fourier-Transform Rheology of Unvulcanized, Carbon Black Filled Styrene Butadiene Rubber

Entanglement dynamics at flat surfaces: Investigations using multi-chain molecular dynamics and a single-chain slip-spring model

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