Influence of Counterion Structure on Conductivity of Polymerized Ionic Liquids

Type
Article

Authors
Keith, Jordan R.
Rebello, Nathan J.
Cowen, Benjamin J.
Ganesan, Venkat

KAUST Grant Number
OSR-2016-CRG5-2993-1

Date
2019-03-25

Abstract
We performed long-time all-atom molecular dynamics simulations of cationic polymerized ionic liquids with eight mobile counterions, systematically varying size and shape to probe their influence on the decoupling of conductivity from polymer segmental dynamics. We demonstrated rigorous identification of the dilatometric glass-transition temperature (T g ) for polymerized ionic liquids using an all-atom force field. Polymer segmental relaxation rates are presumed to be consistent for different materials at the same glass-transition-normalized temperature (T g /T), allowing us to extract a relative order of decoupling by examining conductivity at the same T g /T. Size, or ionic volume, cannot fully explain decoupling trends, but within certain geometric and chemical-specific classes, small ions generally show a higher degree of decoupling. This size effect is not universal and appears to be overcome when structural results reveal substantial coordination delocalization. We also reveal a universal inverse correlation between ion-association structural relaxation time and absolute conductivity for these polymerized ionic liquids, supporting the ion-hopping interpretation of ion mobility in polymerized ionic liquids.

Citation
Keith, J. R., Rebello, N. J., Cowen, B. J., & Ganesan, V. (2019). Influence of Counterion Structure on Conductivity of Polymerized Ionic Liquids. ACS Macro Letters, 8(4), 387–392. doi:10.1021/acsmacrolett.9b00070

Acknowledgements
We acknowledge funding in part by grants from the Robert A. Welch Foundation (Grant F1599), the National Science Foundation (CBET-17069698 and DMR-1721512), and King Abdullah University of Science and Technology (OSR-2016-CRG5-2993-1). Acknowledgment is also made to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this research (56715-ND9). This research made use of the resources of the Texas Advanced Computing Center (TACC) and the High Performance Computing Center at Idaho National Laboratory which is supported by the Office of Nuclear Energy of the U.S. Department of Energy and the Nuclear Science User Facilities under Contract No. DE-AC07-05ID14517. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under Contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.

Publisher
American Chemical Society (ACS)

Journal
ACS Macro Letters

DOI
10.1021/acsmacrolett.9b00070

Additional Links
https://pubs.acs.org/doi/10.1021/acsmacrolett.9b00070

Permanent link to this record