The relation between molecular dynamics and configurational entropy in room temperature ionic liquids: Test of Adam-Gibbs model.

In this communication, the Adam-Gibbs model connecting molecular dynamics with configurational entropy is tested for the first time for ionic liquids. For this purpose, we investigate simultaneously the shear viscosity η and configurational entropy Sc of an aprotic ionic liquid: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIm TFSI). Comparing the Sc data obtained by the combination of Vogel-Fulcher-Tammann and Adam-Gibbs equations to the Sc points determined directly from the calorimetric experiment, good agreement is found in the entire supercooled liquid region. These results indicate the validity of the Adam-Gibbs model in materials with electrostatic interactions being dominated. These important findings not only generalize the applications of the Adam-Gibbs theory but also provide an opportunity to gain insight into the relationship between thermodynamics and molecular dynamics in ionic liquids.