Charge Tethering Drives Intermediate-Range Order and Slow Dynamics in Zwitterionic Liquids
Raphael Ogbodo1, Laxmi Adhikari2, Clinton Adu3
1Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States.
The Journal of Physical Chemistry. B
|July 10, 2026
Summary
Zwitterionic liquids exhibit surprising self-assembly and slow dynamics, forming unique networks. These molecular liquids, unlike ionic liquids, show significant structural order due to large molecular dipoles, leading to highly viscous fluids.
Area of Science:
- Materials Science
- Physical Chemistry
- Polymer Science
Background:
- Zwitterionic liquids (ZwLs) are a unique class of compounds with both positive and negative charges within the same molecule.
- Understanding their structural behavior and network formation is crucial for applications in various fields.
- Ionic liquids (ILs) share some similarities but lack the tethered charge characteristic of ZwLs.
Purpose of the Study:
- To synthesize and characterize novel zwitterionic liquids (ZwLs).
- To computationally investigate the structural behavior and network-forming properties of ZwLs.
- To compare ZwLs with isostructural ionic liquid (IL) analogues.
Main Methods:
- Synthesis and characterization of poly(ethylene oxide) imidazolium cation-based ZwLs with alkyl sulfonate anions.
- Computational studies comparing ZwLs and chemically untethered IL analogues.
- Analysis of self-assembly, intermediate-range order, and dynamics.
Main Results:
- Molecular liquids, not ILs, exhibited the most self-assembly and intermediate-range order.
- ZwLs displayed significantly slower dynamics compared to ILs.
- Large molecular dipoles in zwitterions contribute to versatile network-building and high viscosity.
Conclusions:
- ZwLs form unique networks intermediate between chemical connectivity and IL Coulombic networks.
- The observed network structures are critical for understanding the viscoelastic relaxation of these liquids.
- Zwitterionic liquids present versatile properties for developing novel materials.
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