Surface structure of ionic liquids under an external electric field

Abstract

Surface structure and properties play an important role in many applications of ionic liquids (ILs). ILs can form unique surface structures that are very different from the bulk. In imidazolium-based ILs, for example, polar groups form ordered layer structure, while cationic alkyl chains are bundled together and point out from the surface. In many applications, ILs work under an external electric field. However, the effect of external electric field on the surface structure of ILs is still not clear. Here by using coarse-grained molecular dynamics simulation, we found that an electric field as strong as 1 V/nm is required to alter the surface structure of 1-dodecyl-3-methylimidazolium nitrate. Under a strong external electric field, layered structure disappears, and instead a sparser, more homogeneous and less orientationally ordered surface develops.

Keywords:

• Ionic liquids
• surface
• molecular dynamics simulation
• electric field

Acknowledgements

YW also thanks the financial support through the CAS Interdisciplinary Innovation Team Project. The computations of this work were conducted on the HPC cluster of ITP-CAS.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the National Basic Research Program of China [973 program, grant number 2013CB932804]; National Natural Science Foundation of China [grant number 11421063].