Abstract
Room-temperature ionic liquids are promising candidates for applications ranging from electrolytes for energy storage devices to lubricants for food and cellulose processing to compounds for pharmaceutics, biotransformation, and biopreservation. Due to the ion complexity, many room-temperature ionic liquids readily form amorphous phases upon cooling, even at modest rates. Here, we investigate two commonly studied imidazolium-based room-temperature ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, as well as their mixtures, to demonstrate how the complex interplay between the crystalline and amorphous phases is affected by the processing conditions, such as thermal history, liquid mixing, and applied pressure. We show that quantum tunneling in the cation methyl groups, measured by high-resolution inelastic neutron scattering, can be used to probe the order-disorder in room-temperature ionic liquids (crystalline vs amorphous state) that develops as a result of variable processing conditions.
| Original language | English |
|---|---|
| Article number | 024303 |
| Journal | Structural Dynamics |
| Volume | 8 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 1 2021 |
Funding
The neutron scattering experiments were performed at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS) and were supported by the Scientific User Facilities Division, Office of Science (Basic Energy Sciences), U.S. Department of Energy (DOE). M.R.R. acknowledges the U.S. Department of Energy (DOE) Office of Science (Basic Energy Sciences) for additional research funding and the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility operated under Contract No. DE-AC02–05CH11231 for access to supercomputing resources. The authors thank Dr. Bianca Haberl, Dr. Reinhard Boehler, and Dr. Jamie J. Molaison for assistance with the ex situ pressure-cycling of the RTIL sample. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purpose. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/ downloads/doe-public-access-plan).
| Funders | Funder number |
|---|---|
| Scientific User Facilities Division | |
| U.S. Department of Energy | |
| Office of Science | DE-AC0500OR22725, DE-AC02–05CH11231 |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| National Energy Research Scientific Computing Center |