Insights on cholinium- and piperazinium-based ionic liquids under external electric fields: a molecular dynamics
Santiago Aparicio1, Mert Atilhan2, Nezih Pala3
1Department of Chemistry, University of Burgos, 09001 Burgos, Spain.
The Journal of Chemical Physics
|December 17, 2013
Summary
Strong electric fields significantly alter ionic liquid properties like ion movement and conductivity. Cholinium and piperazinium salts show enhanced dipolar alignment and diffusivity under applied fields, though less than imidazolium-based liquids.
Area of Science:
- Physical Chemistry
- Materials Science
- Computational Chemistry
Background:
- Ionic liquids (ILs) possess unique properties influenced by their structure and external stimuli.
- Understanding the response of ILs to electric fields is crucial for designing advanced materials and devices.
Purpose of the Study:
- To investigate the effects of static and dynamic electric fields on the rotational and translational behavior of specific cholinium and piperazinium-based ionic liquids.
- To quantify the changes in dipolar alignment, ion diffusivity, and electrical conductivity under varying electric field intensities and frequencies.
Main Methods:
- Non-equilibrium molecular dynamics (NEMD) simulations were employed.
- Simulations focused on cholinium benzoate, cholinium salicylate, piperazinium benzoate, and piperazinium salicylate.
- Analysis included rotational and translational motions, dipolar alignment, and ion diffusivities.
Main Results:
- High electric field intensities (>0.25 V Å(-1)) are required to induce significant changes in IL properties.
- Effective dipolar alignment along the field direction was observed, with rotation increasing with field intensity and decreasing with frequency.
- Translational movement and ionic diffusivities increased significantly (up to two orders of magnitude) under strong fields and low frequencies, enhancing electrical conductivity.
- The observed effects were less pronounced compared to common imidazolium-based ionic liquids.
Conclusions:
- External electric fields can effectively tune the transport properties and electrical conductivity of cholinium and piperazinium ionic liquids.
- The response is highly dependent on electric field strength and frequency.
- These findings provide insights for potential applications of these ILs in electric field-driven technologies.
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