Effect of Chain Length Dispersity on the Mobility of Entangled Polymers

Brandon L. Peters, K. Michael Salerno, Ting Ge, Dvora Perahia, and Gary S. Grest
Phys. Rev. Lett. 121, 057802 – Published 2 August 2018

Abstract

While nearly all theoretical and computational studies of entangled polymer melts have focused on uniform samples, polymer synthesis routes always result in some dispersity, albeit narrow, of distribution of molecular weights (ĐM=Mw/Mn1.021.04). Here, the effects of dispersity on chain mobility are studied for entangled, disperse melts using a coarse-grained model for polyethylene. Polymer melts with chain lengths set to follow a Schulz-Zimm distribution for the same average Mw=36kg/mol with ĐM=1.0 to 1.16, were studied for times of 600800μs using molecular dynamics simulations. This time frame is longer than the time required to reach the diffusive regime. We find that dispersity in this range does not affect the entanglement time or tube diameter. However, while there is negligible difference in the average mobility of chains for the uniform distribution ĐM=1.0 and ĐM=1.02, the shortest chains move significantly faster than the longest ones offering a constraint release pathway for the melts for larger ĐM.

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  • Received 5 April 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.057802

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Polymers & Soft Matter

Authors & Affiliations

Brandon L. Peters1, K. Michael Salerno2, Ting Ge3, Dvora Perahia4, and Gary S. Grest1

  • 1Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
  • 2U.S. Naval Research Laboratory, Washington, DC 20375, USA
  • 3Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
  • 4Department of Chemistry and Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA

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Issue

Vol. 121, Iss. 5 — 3 August 2018

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