Title: Influence of Counterion Structure on Conductivity of Polymerized Ionic Liquids

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. Here, 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.

Authors:

Keith, Jordan R.  ^[1];

• Search DOE PAGES for author "Keith, Jordan R."
• Search DOE PAGES for ORCID "0000-0003-2639-3087"

Rebello, Nathan J. ^[1]; Cowen, Benjamin J. ^[2]; Ganesan, Venkat  ^[1]

• Search DOE PAGES for author "Ganesan, Venkat"
• Search DOE PAGES for ORCID "0000-0003-3899-5843"

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+ Show Author Affiliations

1. Univ. of Texas at Austin, Austin, TX (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Publication Date:

Mon Mar 25 00:00:00 EDT 2019

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1507409

Report Number(s):

SAND-2019-3066J
Journal ID: ISSN 2161-1653; 673567

Grant/Contract Number:  

AC04-94AL85000

Resource Type:

Accepted Manuscript

Journal Name:

ACS Macro Letters

Additional Journal Information:

Journal Volume: 8; Journal Issue: 4; Journal ID: ISSN 2161-1653

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY