Cooperative Relaxation Governs the Viscosity of Ionic Liquids.
5 affiliations
- 1School of Chemistry and University of Sydney Nano Institute, The University of Sydney, Sydney, NSW2006, Australia.
- 2Physical and Theoretical Chemistry Laboratory, University of Oxford, OxfordOX13QZ, United Kingdom.
- 3Institut Max von Laue-Paul Langevin (ILL), 71 avenue des Martyrs, CS 20156, Cedex 9, F-38042, Grenoble, France.
- 4School of Molecular Sciences, The University of Western Australia, Perth, WA6009, Australia.
- 5Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC7, D-10623, Berlin, Germany.
Abstract
Ionic liquids are promising solvents for batteries, biomass processing and critical mineral recovery, but their viscosities can exceed those of conventional molecular solvents by several orders of magnitude, impeding mass and charge transport and complicating process design. Using complementary neutron spin echo spectroscopy and nuclear magnetic resonance diffusometry, we probe local and long-range dynamics of three protic ionic liquids over time scales from 10-12 to 10-3 seconds. We identify a fast relaxation with closely corresponding self and collective time scales, indicating cooperative rearrangement of the surrounding molecular network. Its characteristic time scale correlates with bulk viscosity, while its temperature dependence reveals distinct Arrhenius activation energies depending on whether extended networks are dominated by hydrogen bonding or electrostatic interactions. These results link cooperative network relaxation to macroscopic viscosity and show how molecular structure can tune the energetic cost of structural relaxation through network connectivity.
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BibTeX
@article{miao2026cooperative,
title = {{Cooperative Relaxation Governs the Viscosity of Ionic Liquids.}},
author = {Shurui Miao and Bela Farago and Ingo Hoffmann and Rob Atkin and Michael Gradzielski and Gregory G Warr},
journal = {The journal of physical chemistry letters},
year = {2026},
month = oct,
doi = {10.1021/acs.jpclett.6c02640},
url = {https://europepmc.org/article/MED/42918220},
note = {CC BY},
}
RIS
TY - JOUR
TI - Cooperative Relaxation Governs the Viscosity of Ionic Liquids.
AU - Shurui Miao
AU - Bela Farago
AU - Ingo Hoffmann
AU - Rob Atkin
AU - Michael Gradzielski
AU - Gregory G Warr
PY - 2026
DA - 2026/10/01
JO - The journal of physical chemistry letters
DO - 10.1021/acs.jpclett.6c02640
UR - https://europepmc.org/article/MED/42918220
AB - Ionic liquids are promising solvents for batteries, biomass processing and critical mineral recovery, but their viscosities can exceed those of conventional molecular solvents by several orders of magnitude, impeding mass and charge transport and complicating process design. Using complementary neutron spin echo spectroscopy and nuclear magnetic resonance diffusometry, we probe local and long-range dynamics of three protic ionic liquids over time scales from 10-12 to 10-3 seconds. We identify a fast relaxation with closely corresponding self and collective time scales, indicating cooperative rearrangement of the surrounding molecular network. Its characteristic time scale correlates with bulk viscosity, while its temperature dependence reveals distinct Arrhenius activation energies depending on whether extended networks are dominated by hydrogen bonding or electrostatic interactions. These results link cooperative network relaxation to macroscopic viscosity and show how molecular structure can tune the energetic cost of structural relaxation through network connectivity.
SN - 1948-7185
ER -