Triphilic Ionic‐Liquid Mixtures: Fluorinated and Non‐fluorinated Aprotic Ionic‐Liquid Mixtures

Abstract

We present here the possibility of forming triphilic mixtures from alkyl- and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domains—polar and nonpolar—three stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self-associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long-range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment.

Domain Analysis in Nanostructured Liquids: A Post‐Molecular Dynamics Study at the Example of Ionic Liquids

“…The newly implemented domain analysis in TRAVIS [39] allowed analysiso f the domains in terms of their numbers and their shape on aq ualitative and also quantitative basis. Furthermore, in as ubsequenta rticle [47] we apply this analysis to triphilic ionic-liquidm ixtures, which are obtained from fluorinated andn on-fluorinated aprotic ionic liquids. The alkyl side chains, however, show completely different aggregation behavior.A lthough the fluorouss ide chains are also more or less connected in one or maximally in two domains, the alkyl phases are dispersed in al arge amount of domains that are more spherical than the other domains.…”

“…The polar region (including the anion and the head group of the cation) always forms as ingle domain in the liquids, in the form of lengthy, more nonspherical channels. [47] Thus, with this newly developed analysis tool we are now ablet oo btain deeper insight into the nanostructuring of liquids.…”

Temperature‐Dependent Surface Enrichment Effects in Binary Mixtures of Fluorinated and Non‐Fluorinated Ionic Liquids

“…While non‐fluorinated ILs are known to form bulk nanostructures consisting of polar and nonpolar domains, fluorinated ILs typically exhibit additional nonpolar fluorous domains, in which the fluorinated chains preferentially agglomerate –. Alkylated and fluorinated chains can be present either in one single IL (e.g.…”

“…alkyl chains in the cation and fluorinated chains in the anion or vice versa), or in IL mixtures with one IL containing alkyl chains and the other one containing fluorinated chains. Changing the relative chain length in one IL or the molar ratio of the two ILs in the mixture influences the related properties and the domain structure . It should be emphasized that using IL mixtures allows for fine‐tuning the properties in a very subtle way.…”

“…Therefore, investigations of the topmost layers of IL mixtures are getting more into the focus of research. A variety of studies has been performed, using reactive‐atom scattering with laser‐induced fluorescence detection (RAS‐LIF), neutron scattering, small‐angle X‐ray scattering and X‐ray reflectivity, time of flight secondary ion mass spectrometry (TOF‐SIMS), Rutherford backscattering spectroscopy (RBS), low‐energy ion scattering (LEIS), X‐ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations …”