Abstract
Switchable ionic liquids (SWILs) derived from organic bases and alcohols are attractive due to their applications in gas capture, separations, and nanomaterial synthesis. However, their exact solvent structure still remains a mystery. We present the first chemical mapping of a SWIL solvent structure using in situ time-of-flight secondary ion mass spectrometry. In situ chemical mapping discovers two coexisting liquid phases and molecular structures vastly different from conventional ionic liquids. SWIL chemical speciation is found to be more complex than the known stoichiometry. Dimers and ionic clusters have been identified in SIMS spectra; and confirmed to be the chemical species differentiating from non-ionic liquids via spectral principal component analysis. Our unique in situ molecular imaging has advanced the understanding of SWIL chemistry and how this "heterogeneous" liquid structure may impact SWILs' physical and thermodynamic properties and associated applications.
| Original language | English |
|---|---|
| Pages (from-to) | 22627-22632 |
| Number of pages | 6 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 19 |
| Issue number | 34 |
| DOIs | |
| State | Published - 2017 |
| Externally published | Yes |
Funding
We are grateful for the support from the Pacific Northwest National Laboratory (PNNL) Materials Synthesis and Simulation across Scales Initiative (MS3). DJH is grateful for the United States Department of Energy’s Office of Science Basic Energy Sciences Early Career Research program FWP 67038 for funding. Dr Craig Szymanski supported SPI-MS data acquisition. The research was performed in the W. R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by OBER and located at PNNL. Access to the ALS beamline 9.0.2 was supported via the General User Proposal (ALS-07554). MA and TPT are supported by the Director, Office of Science, Office of Basic Energy Sciences (CPIMS), of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, through the Chemical Sciences Division. The ALS is supported through the same contract. PNNL is operated for DOE by Battelle.