Ionosomes: Observation of Ionic Bilayer Water Clusters

Haiqiang Deng, Pekka Peljo, Xinjian Huang, Evgeny Smirnov, Sujoy Sarkar, Sunny Maye, Hubert H. Girault, Daniel Mandler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Emulsification of immiscible two-phase fluids, i.e., one condensed phase dispersed homogeneously as tiny droplets in an outer continuous medium, plays a key role in medicine, food, chemical separations, cosmetics, fabrication of micro-and nanoparticles and capsules, and dynamic optics. Herein, we demonstrate that water clusters/droplets can be formed in an organic phase via the spontaneous assembling of ionic bilayers. We term these clusters ionosomes, by analogy with liposomes where water clusters are encapsulated in a bilayer of lipid molecules. The driving force for the generation of ionosomes is a unique asymmetrical electrostatic attraction at the water/oil interface: small and more mobile hydrated ions reside in the inner aqueous side, which correlate tightly with the lipophilic bulky counterions in the adjacent outer oil side. These ionosomes can be formed through electrochemical (using an external power source) or chemical (by salt distribution) polarization at the liquid-liquid interface. The charge density of the cations, the organic solvent, and the synergistic effects between tetraethylammonium and lithium cations, all affecting the formation of ionosomes, were investigated. These results clearly prove that a new emulsification strategy is developed providing an alternative and generic platform, besides the canonical emulsification procedure with either ionic or nonionic surfactants as emulsifiers. Finally, we also demonstrate the detection of individual ionosomes via single-entity electrochemistry.

Original languageAmerican English
Pages (from-to)7671-7680
Number of pages10
JournalJournal of the American Chemical Society
Volume143
Issue number20
DOIs
StatePublished - 26 May 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

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