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
Fernando J. Carmona Esteva, Yong Zhang, Yamil J. Colón, Edward J. Maginn
Abstract
We present the results of molecular dynamics simulations of the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C 2 C 1 im][NTf 2 ] in the presence of external electric fields (EEFs) of varying strengths to understand the effects of EEFs on the glass transition temperature T g . We compute T g with an automated and 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 their original zero-field T g when heated. By examining the dynamics and structure of the liquid phase, we find that the EEF lowers the activation energy for diffusion, reducing the energetic barrier for movement and consequently T g . We show that the effect can be leveraged to drive an electrified nonvapor compression refrigeration cycle.