Self-assembly media

Greavesa TL, Drummond CJ (2008) Ionic liquids as amphiphile self-assembly media. Chem Soc Rev 37 1709 1726... 

Recently, PILs have been extensively used in organic synthesis as catalysts and as self-assembly media. Drummond and Greaves published an extensive review on PILs, analysing the favourable features of these materials as protic solvents in several reactions. While the use of pure ILs as reaction media has been investigated in... 

Selected reviews of ionic liquid crystals (a) Binnemans, K. Ionic liquid crystals. Chem. Rev. 2005,105, 4148 204. (b) Kato, T. Mizoshita, N. Kishimoto, K. Functional hqnid-crystaUine assemblies Self-organized soft materials. Angew. Chem., Int. Ed. 2006, 45, 38-68. (c) Greaves, T. L. Drununond, C. J. Ionic liquids as amphiphUe self-assembly media. Chem. Soc. Rev. 2008,37,1709-1726. (d) Axenov, K. V Laschat, S. Thermotropic ionic liquid crystals. Materials 2011, 4, 206-259. 

The most extensively studied PIL is definitely ethylammonium nitrate (BAN). The interest in this salt has been largely driven by its many similarities in properties and behavior to water. These are discussed below, along with the behavior of surfactants in BAN—water solutions and the critical behavior of binary BAN and n-octanol solutions. The nse of a greater range of PILs as self-assembly media is discussed in section 5. 

Deperrdirrg on their stmcture, some PILs can be used as catiorric sttrfaclants in a solvent, can be ttsed as self-assembly media for amphiphiles (lyotropic phase behavior), or can tmdergo phase transitions with changes in temperature (thermotropic phase behavior). These three behaviors are described below. 

The Gordon parameter, G, gives a measure of the eohesiveness of a solvent and, hence, a measure of the abihty of the PIL to be amphiphile self-assembly media. The Gordon valne is described by eq 1, where y is the snrface tension and Fm is the molar volnme, and can be considered to indicate the driving force of the PILs toward self-assembly. 

In this review, the known range of protie ionie liqnids has been disenssed, inelnding their reported physicoehemical properties and the applieations where they have been used. In comparison to the vast amount of hterature for AILs, there have been relatively few papers on PILs, despite the fact that PILs can be nsed for many of the same applications as AILs, snch as in chromatography, in organic synthesis, as amphiphile self-assembly media, in electrochemistry, and as explosives, as well as additional applications where having an available proton is essential snch as many biological uses and as proton-condncting media for polymer membrane fuel cells. 

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