This title appears in the Scientific Report :
2021
Please use the identifier:
http://hdl.handle.net/2128/27803 in citations.
Please use the identifier: http://dx.doi.org/10.1103/PhysRevLett.126.187801 in citations.
Cooperative Chain Dynamics of Tracer Chains in Highly Entangled Polyethylene Melts
Cooperative Chain Dynamics of Tracer Chains in Highly Entangled Polyethylene Melts
By neutron spin echo spectroscopy, we have studied the center of mass motion of short tracer chains on the molecular length scale within a highly entangled polymer matrix. The center of mass mean square displacements of the tracers independent of their molecular weight is subdiffusive at short times...
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Personal Name(s): | Zamponi, M. (Corresponding author) |
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Kruteva, M. / Monkenbusch, M. / Willner, L. / Wischnewski, A. / Hoffmann, I. / Richter, D. | |
Contributing Institute: |
JCNS-FRM-II; JCNS-FRM-II JCNS-4; JCNS-4 Streumethoden; JCNS-2 Neutronenstreuung; JCNS-1 Heinz Maier-Leibnitz Zentrum; MLZ |
Published in: | Physical review letters, 126 (2021) 18, S. 187801 |
Imprint: |
College Park, Md.
APS
2021
|
DOI: |
10.1103/PhysRevLett.126.187801 |
Document Type: |
Journal Article |
Research Program: |
Materials – Quantum, Complex and Functional Materials Jülich Centre for Neutron Research (JCNS) (FZJ) |
Subject (ZB): | |
Link: |
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Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1103/PhysRevLett.126.187801 in citations.
By neutron spin echo spectroscopy, we have studied the center of mass motion of short tracer chains on the molecular length scale within a highly entangled polymer matrix. The center of mass mean square displacements of the tracers independent of their molecular weight is subdiffusive at short times until it has reached the size of the tube d; then, a crossover to Fickian diffusion takes place. This observation cannot be understood within the tube model of reptation, but is rationalized as a result of important interchain couplings that lead to cooperative chain motion within the entanglement volume ∼d3. Thus, the cooperative tracer chain motions are limited by the tube size d. If the center of mass displacement exceeds this size, uncorrelated Fickian diffusion takes over. Compared to the prediction of the Rouse model we observe a significantly reduced contribution of the tracer’s internal modes to the spectra corroborating the finding of cooperative rather than Rouse dynamics within d3. |