Molecular Dynamics Simulation of the Influence of External Electric Fields on the Glass Transition Temperature of the Ionic Liquid 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide

FC Esteva and Y Zhang and Y Colón and EJ Maginn, JOURNAL OF PHYSICAL CHEMISTRY B, 127, 4623-4632 (2023).

DOI: 10.1021/acs.jpcb.3c00936

We present the results of moleculardynamics simulationsof theionic liquid (IL) 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imideC(2)C(1)im-NTf2 in the presence ofexternal electric fields (EEFs) of varying strengths to understandthe effects of EEFs on the glass transition temperature T (g). We compute T (g) with an automatedand objective method and observe a depression in T (g) when cooling the IL within an EEF above a critical strength.The effect is reversible, and glasses prepared with EEFs recover theiroriginal zero-field T (g) when heated. Byexamining the dynamics and structure of the liquid phase, we findthat the EEF lowers the activation energy for diffusion, reducingthe energetic barrier for movement and consequently T (g). We show that the effect can be leveraged to drive anelectrified nonvapor compression refrigeration cycle.

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