Authors
Zhenhua Wang, Yuyuan Lu, Lijia An, Zhen-Gang Wang
Published in
Physical review letters. Volume 136. Issue 24. Pages 248101. Jun 19, 2026.
Abstract
The tube model has long served as a cornerstone of entangled polymer dynamics and rheology. We test some of the key concepts of the tube model by investigating the equilibrium dynamics of a free chain in a fixed-topology polymer network using molecular dynamics simulation. Our results reveal significant position-dependent dynamical heterogeneity manifested as a rugged free energy landscape for the longitudinal motion, resulting in additional friction due to the topological interactions, and a "tube dilation" mechanism arising from the relaxation of entanglements formed by loop strands in the network in a "flip-flop" motion. On timescales less than the Rouse time, the mean-square displacement of the center of mass of the free chain displays a subdiffusive behavior that is slower than the expected t^{1/2} scaling. On longer timescales, the effects of topological friction amount to a renormalized monomer friction that is several times the intrinsic value. These results challenge some of the fundamental assumptions of the tube model, even under equilibrium conditions.
PMID:
42412478
Bibliographic data and abstract were imported from PubMed on 07 Jul 2026.
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