Tail Aggregation and Domain Diffusion in Ionic Liquids

TitleTail Aggregation and Domain Diffusion in Ionic Liquids
Publication TypeJournal Article
Year of Publication2006
AuthorsWang, Y, Voth, GA
JournalJ Phys Chem B
KeywordsCarbon/chemistry Cations Chemistry, Molecular Models, Physical/*methods Diffusion Gas Chromatography-Mass Spectrometry/methods *Ions Liquid Crystals Models, Statistical Software Solvents Static Electricity Temperature

An extended multiscale coarse-graining model for ionic liquids is used to investigate the liquid crystal-like phase in certain ionic liquids. The tail groups of the cations with a sufficient side-chain length are found to aggregate, forming spatially heterogeneous domains, due to the competition between the electrostatic interactions between the charged head groups and the anions and the collective short-range interactions between the neutral tail groups. With a sufficiently long alkyl chain at a low enough temperature, the tail domains remain relatively stable, despite the diffusion of individual ions in the liquid phase. With increasing temperature, the average tail domains begin to diffuse, while beyond a transition temperature, their average density has an almost uniform distribution, although the tail groups still form instantaneous domains.