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Title: Chain and Ion Dynamics in Precise Polyethylene Ionomers

Abstract

In this paper, we analyze the dynamics from microsecond-long, atomistic molecular dynamics (MD) simulations of a series of precise poly(ethylene- co-acrylic acid) ionomers neutralized with lithium, with three different spacer lengths between acid groups on the ionomers and at two temperatures. At short times, the intermediate structure factor calculated from the MD simulations is in reasonable agreement with quasi-elastic neutron scattering data for partially neutralized ionomers. For ionomers that are 100% neutralized with lithium, the simulations reveal three dynamic processes in the chain dynamics. The fast process corresponds to hydration librations, the medium-time process corresponds to local conformational motions of the portions of the chains between ionic aggregates, and the long-time process corresponds to relaxation of the ionic aggregates. At 600 K, the dynamics are sufficiently fast to observe the early stages of lithium-ion motion and ionic aggregate rearrangements. In the partially neutralized ionomers with isolated ionic aggregates, the Li-ion-containing aggregates rearrange by a process of merging and breaking up, similar to what has been observed in coarse-grained (CG) simulations. In the 100% neutralized ionomers that contain percolated ionic aggregates, the chains remain pinned by the percolated aggregate at long times, but the lithium ions are able to move alongmore » the percolated aggregate. In this work, the ion dynamics are also qualitatively similar to those seen in previous CG simulations.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [2]; ORCiD logo [1];  [3];  [4];  [3]; ORCiD logo [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies
  2. Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Materials Science and Engineering, and Dept. of Chemical and Biomolecular Engineering
  3. NIST Center for Neutron Research, Gaithersburg, MD (United States)
  4. NIST Center for Neutron Research, Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1574444
Report Number(s):
SAND-2019-12520J
Journal ID: ISSN 0024-9297; 680416
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 52; Journal Issue: 20; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Frischknecht, Amalie L., Paren, Benjamin A., Middleton, L. Robert, Koski, Jason P., Tarver, Jacob D., Tyagi, Madhusudan, Soles, Christopher L., and Winey, Karen I. Chain and Ion Dynamics in Precise Polyethylene Ionomers. United States: N. p., 2019. Web. doi:10.1021/acs.macromol.9b01712.
Frischknecht, Amalie L., Paren, Benjamin A., Middleton, L. Robert, Koski, Jason P., Tarver, Jacob D., Tyagi, Madhusudan, Soles, Christopher L., & Winey, Karen I. Chain and Ion Dynamics in Precise Polyethylene Ionomers. United States. doi:10.1021/acs.macromol.9b01712.
Frischknecht, Amalie L., Paren, Benjamin A., Middleton, L. Robert, Koski, Jason P., Tarver, Jacob D., Tyagi, Madhusudan, Soles, Christopher L., and Winey, Karen I. Fri . "Chain and Ion Dynamics in Precise Polyethylene Ionomers". United States. doi:10.1021/acs.macromol.9b01712.
@article{osti_1574444,
title = {Chain and Ion Dynamics in Precise Polyethylene Ionomers},
author = {Frischknecht, Amalie L. and Paren, Benjamin A. and Middleton, L. Robert and Koski, Jason P. and Tarver, Jacob D. and Tyagi, Madhusudan and Soles, Christopher L. and Winey, Karen I.},
abstractNote = {In this paper, we analyze the dynamics from microsecond-long, atomistic molecular dynamics (MD) simulations of a series of precise poly(ethylene-co-acrylic acid) ionomers neutralized with lithium, with three different spacer lengths between acid groups on the ionomers and at two temperatures. At short times, the intermediate structure factor calculated from the MD simulations is in reasonable agreement with quasi-elastic neutron scattering data for partially neutralized ionomers. For ionomers that are 100% neutralized with lithium, the simulations reveal three dynamic processes in the chain dynamics. The fast process corresponds to hydration librations, the medium-time process corresponds to local conformational motions of the portions of the chains between ionic aggregates, and the long-time process corresponds to relaxation of the ionic aggregates. At 600 K, the dynamics are sufficiently fast to observe the early stages of lithium-ion motion and ionic aggregate rearrangements. In the partially neutralized ionomers with isolated ionic aggregates, the Li-ion-containing aggregates rearrange by a process of merging and breaking up, similar to what has been observed in coarse-grained (CG) simulations. In the 100% neutralized ionomers that contain percolated ionic aggregates, the chains remain pinned by the percolated aggregate at long times, but the lithium ions are able to move along the percolated aggregate. In this work, the ion dynamics are also qualitatively similar to those seen in previous CG simulations.},
doi = {10.1021/acs.macromol.9b01712},
journal = {Macromolecules},
number = 20,
volume = 52,
place = {United States},
year = {2019},
month = {10}
}

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