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Title: Connecting Structural and Transport Properties of Ionic Liquids with Cationic Oligoether Chains

We used X-ray diffraction and molecular dynamics simulations to probe the structures of two families of ionic liquids containing oligoether tails on the cations. Imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)amide ILs with side chains ranging from 4 to 10 atoms in length, including both linear alkyl and oligo-ethylene oxide tails, were prepared. Furthermore, their physical properties, such as viscosity, conductivity and thermal profile, were measured and compared for systematic trends. Consistent with earlier literature, a single ether substituent substantially decreases the viscosity of pyrrolidinium and imidazolium ILs compared to their alkyl congeners. Remarkably, as the number of ether units in the pyrrolidinium ILs increases there is hardly any increase in the viscosity, in contrast to alkylpyrrolidinium ILs where the viscosity increases steadily with chain length. Viscosities of imidazolium ether ILs increase with chain length but always remain well below their alkyl congeners. To complement the experimentally determined properties, molecular dynamics simulations were run on the two ILs with the longest ether chains. Our results point to specific aspects that could be useful for researchers designing ILs for specific applications.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1] ;  [4] ;  [2] ;  [4]
  1. City Univ. (CUNY) Bayside, NY (United States). Dept. of Chemistry
  2. Rutgers Univ., Piscataway, NJ (United States). Dept. of Chemistry and Chemical Biology
  3. City Univ. (CUNY) Bayside, NY (United States). Dept. of Chemistry; Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Division
  4. Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Division
Publication Date:
Report Number(s):
BNL-113979-2017-JA
Journal ID: ISSN 0013-4651; R&D Project: CO-004; KC0301010
Grant/Contract Number:
SC00112704; AC02-98CH10886; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 8; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; conductivity; ether; h-bonding; imidazolium; molecular dynamics; pyrrolidinium; structure; viscosity; x-ray
OSTI Identifier:
1366347