TY  - JOUR
AU  - Zamponi, M.
AU  - Kruteva, M.
AU  - Monkenbusch, M.
AU  - Willner, L.
AU  - Wischnewski, A.
AU  - Hoffmann, I.
AU  - Richter, D.
TI  - Cooperative Chain Dynamics of Tracer Chains in Highly Entangled Polyethylene Melts
JO  - Physical review letters
VL  - 126
IS  - 18
SN  - 0031-9007
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2021-01528
SP  - 187801
PY  - 2021
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - 34018790
UR  - <Go to ISI:>//WOS:000652837900004
DO  - DOI:10.1103/PhysRevLett.126.187801
UR  - https://juser.fz-juelich.de/record/891446
ER  -