Topological Linking Drives Anomalous Thickening of Ring Polymers in Weak Extensional Flows.

TitleTopological Linking Drives Anomalous Thickening of Ring Polymers in Weak Extensional Flows.
Publication TypeJournal Article
Year of Publication2020
AuthorsTC O'Connor, T Ge, M Rubinstein, and GS Grest
JournalPhysical Review Letters
Volume124
Issue2
Start Page027801
Date Published01/2020
Abstract

Molecular dynamics simulations confirm recent extensional flow experiments showing ring polymer melts exhibit strong extension-rate thickening of the viscosity at Weissenberg numbers Wi≪1. Thickening coincides with the extreme elongation of a minority population of rings that grows with Wi. The large susceptibility of some rings to extend is due to a flow-driven formation of topological links that connect multiple rings into supramolecular chains. Links form spontaneously with a longer delay at lower Wi and are pulled tight and stabilized by the flow. Once linked, these composite objects experience larger drag forces than individual rings, driving their strong elongation. The fraction of linked rings depends nonmonotonically on Wi, increasing to a maximum when Wi∼1 before rapidly decreasing when the strain rate approaches 1/τ_{e}.

DOI10.1103/physrevlett.124.027801
Short TitlePhysical Review Letters