Globally Suppressed Dynamics in Ion-Doped Polymers

Michael A. Webb, Umi Yamamoto, Brett M. Savoie, Zhen Gang Wang, Thomas F. Miller

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

We investigate how ion-polymer complexation suppresses molecular motion in conventional polymer electrolytes using molecular dynamics (MD) simulations of lithium hexafluorophosphate in poly(ethylene oxide) and a modified Rouse model. The employed model utilizes an inhomogeneous friction distribution to describe ion-polymer interactions and provides an effective way to examine how ion-polymer interactions affect polymer motion. By characterizing the subdiffusive Li+ transport and polymer relaxation times at several salt concentrations, we observe that increases in local friction due to ion-polymer complexation are significantly smaller than previously assumed. We find that a Rouse-based model that only considers local increases in friction cannot simultaneously capture the magnitude of increased polymer relaxation times and the apparent power-law exponent for Li+ subdiffusion observed in MD simulations. This incompatibility is reconciled by augmenting the modified Rouse model with a term that increases the global friction with the square of the salt concentration; this significantly improves the agreement between the model and MD, indicating the importance of ion-ion interactions and distributions on ion/polymer mobility.

Original languageEnglish (US)
Pages (from-to)734-738
Number of pages5
JournalACS Macro Letters
Volume7
Issue number6
DOIs
StatePublished - Jun 19 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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  • Cite this

    Webb, M. A., Yamamoto, U., Savoie, B. M., Wang, Z. G., & Miller, T. F. (2018). Globally Suppressed Dynamics in Ion-Doped Polymers. ACS Macro Letters, 7(6), 734-738. https://doi.org/10.1021/acsmacrolett.8b00237