Cooperative Chain Dynamics of Tracer Chains in Highly Entangled Polyethylene Melts

Zamponi, Michaela; Kruteva, Margarita; Monkenbusch, M.; Willner, Lutz; Wischnewski, A.; Hoffmann, Ingo; Richter, D.

doi:10.1103/physrevlett.126.187801

Cited by 16 publications

(58 citation statements)

References 22 publications

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“…motion. The application of a theory for many chains interacting through a time-dependent potential of mean force where entanglements are present shows a remarkable agreement with the relaxation of the dynamic structure factor, as measured by experiments of the neutron spin echo [ 48 , 49 , 50 ].…”

Section: Resultsmentioning

confidence: 57%

“…The observed separation of timescales between slow- and fast-relaxing domains in the short time regime justifies the projection of the dynamics of the fluid onto the coordinates of a group of slow, interacting molecules, obtaining, in this way, a set of coupled equations of motion for the region of slowly rearranging dynamics that reproduce well the observed anomalous dynamics [ 49 , 50 ]. The analysis presented here formally connects the observed anomalous dynamics to microscopic mechanisms of heterogeneous dynamics and provides a consistent picture of the physical phenomena underlying the observed anomalous, slow center-of-mass diffusion in polymer melts.…”

Section: Discussionmentioning

confidence: 99%

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Anomalous Dynamics in Macromolecular Liquids

Guenza

2022

Polymers

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Macromolecular liquids display short-time anomalous behaviors in disagreement with conventional single-molecule mean-field theories. In this study, we analyze the behavior of the simplest but most realistic macromolecular system that displays anomalous dynamics, i.e., a melt of short homopolymer chains, starting from molecular dynamics simulation trajectories. Our study sheds some light on the microscopic molecular mechanisms responsible for the observed anomalous behavior. The relevance of the correlation hole, a unique property of polymer liquids, in relation to the observed subdiffusive dynamics, naturally emerges from the analysis of the van Hove distribution functions and other properties.

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Section: Resultsmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Anomalous Dynamics in Macromolecular Liquids

Guenza

2022

Polymers

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“…They were also used and illustrated in the previous work on PE. 28 Finally, we note that the application of RPA corrections is merely a technical means to correct the scattering function for admixtures of the longchain scattering signal to the observed S(Q, t) in the present contrast. It is unavoidable that with a finite concentration of the labeled component the nonlabeled (matrix) chains also gain some visibility.…”

Section: ■ Theorymentioning

confidence: 80%

Non-Gaussian and Cooperative Dynamics of Entanglement Strands in Polymer Melts

et al. 2021

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We present a study on tracer diffusion of short poly(ethylene oxide) (PEO) tracers in a strongly entangled PEO melt. We find that within the entanglement volume, the dynamics of entanglement strands is significantly non-Gaussian. Following theoretical predictions of Guenza [Guenza, M. G. Phys. Rev. E 2014, 895 052603], we quantify the non-Gaussian correction α 2 (t) in terms of a logarithmic Gaussian function with a maximum at a time in the order of the Rouse times of different tracers and a width that is independent of the tracer's length. The strength of the non-Gaussian correction is found to be equal for all tracers providing another proof that tracers mirror the host dynamics, which needs to be independent of the tracer length. As for polyethylene [Zamponi, M. et al. Phys. Rev. Lett. 2021, 12618 187801], independent of their molecular weight, the tracer's center-of-mass mean square displacements are subdiffusive at short times until they have reached the size of the reptation tube d; then, a crossover to Fickian diffusion takes place indicating cooperative chain motion within the entanglement volume d 3 . Thus, the host dynamics within the tube is not only cooperative but also significantly non-Gaussian.

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“…The dynamics of polymeric materials under small deformations are well described by a slightly extended version of the tube model originally proposed and described by de Gennes as well as Doi and Edwards [14][15][16][17][18][19][20][21]. However, the dynamics of strongly deformed and branched polymers can be expected to be much more complex and the validity of the tube model is highly challenged [9,[22][23][24].…”

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confidence: 99%

Small-Angle Neutron Scattering Study of the Structural Relaxation of Elongationally Oriented, Moderately Stretched Three-Arm Star Polymers

et al. 2021

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We present structural relaxation studies of a polystyrene star polymer after cessation of high-rate extensional flow. During the steady-state flow, the scattering pattern shows two sets of independent correlations peaks, reflecting the structure of a polymer confined in a fully oriented three-armed tube. Upon cessation of flow, the relaxation constitutes three distinct regimes. In a first regime, the perpendicular correlation peaks disappear, signifying disruption of the virtual tube. In a second regime, broad scattering arcs emerge, reflecting relaxation from highly aligned chains to more relaxed, still anisotropic form. New entanglements dominate the last relaxation regime where the scattering pattern evolves to a successively elliptical and circular pattern, reflecting relaxation via reptation.

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Cooperative Chain Dynamics of Tracer Chains in Highly Entangled Polyethylene Melts

Cited by 16 publications

References 22 publications

Anomalous Dynamics in Macromolecular Liquids

Anomalous Dynamics in Macromolecular Liquids

Non-Gaussian and Cooperative Dynamics of Entanglement Strands in Polymer Melts

Small-Angle Neutron Scattering Study of the Structural Relaxation of Elongationally Oriented, Moderately Stretched Three-Arm Star Polymers

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