Lower critical solution temperature (LCST) phase behaviour of an ionic liquid and its control by supramolecular host–guest interactions

Unique LCST phase behaviour of imidazolium-based ionic liquids is reported, which can be controlled by concentration, the choice of cation, anion and solvent, and by supramolecular complex formation. MD simulations provide insight into the molecular basis of this LCST phenomenon.

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Rheopectic Gel Formation of Stimuli-Responsive Ionic Liquid/Water Mixtures

Australian Journal of Chemistry ◽

10.1071/ch16228 ◽

2017 ◽

Vol 70 (1) ◽

pp. 74 ◽

Cited By ~ 2

Author(s):

Yukinobu Fukaya ◽

Takuro Nakano ◽

Hiroyuki Ohno

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Liquid Water ◽

Phase Behaviour ◽

Solution Temperature ◽

Stimuli Responsive ◽

Viscosity Change ◽

Critical Solution Temperature ◽

New Class ◽

External Stimuli

A new class of hydrophobic and polar ionic liquids was prepared by coupling hydrophobic tetraoctylphosphonium cation and polar phosphonate-derived anions. Mixtures of these ionic liquids and water showed lower critical solution temperature-type phase behaviour. Furthermore, these mixtures displayed thermoreversible, however, non-linear viscosity change despite their large content of water. The abrupt increase in the viscosity was explained by the occurrence of rheopectic gelation of the ionic liquid/water mixtures by external stimuli such as shear stress.

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Combinatorial discovery of small-molecule 1,2,3-triazolium ionic liquids exhibiting lower critical solution temperature phase transition

Scientific Reports ◽

10.1038/s41598-020-75392-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yen-Ho Chu ◽

Mou-Fu Cheng ◽

Yung-Hsin Chiang

Keyword(s):

Phase Transition ◽

Ionic Liquid ◽

Ionic Liquids ◽

Phase Transitions ◽

Small Molecule ◽

Room Temperature ◽

Solution Temperature ◽

Temperature Phase ◽

Critical Solution Temperature ◽

True Value

Abstract Both lower and upper critical solution temperature (LCST and UCST) systems are two typical phase behaviors of thermoresponsive materials with solvents, in which LCST is far less common than UCST. Recent studies on ionic liquids carrying LCST phase transitions have predominantly focused on quaternary ammonium- and phosphonium-based ionic salts. Based on the 1,2,3-triazole core structure assemblable by azide-alkyne cycloaddition click reaction, this work reports the combinatorial synthesis of 1,3,4-trialkylated 1,2,3-triazolium ionic liquids in three libraries with a total of 160 ionic liquids and demonstrates, for the first time, their values in temperature-switchable phase transition with water. In this work, the successful discovery of a new thermoresponsive ionic liquid b26, based on the structure-and-phase separation study of b8 and b9, perfectly exemplified the true value of the tunability of ionic liquid fine structures. For all 160 ionic liquids synthesized, 155 are liquid at room temperature and 22 room-temperature ionic liquids were found to exhibit thermoresponsive phase transitions having low Tc values in water. To the best of our knowledge, this comprehensive study is the first report of small-molecule 1,2,3-triazolium ionic liquids that exhibit LCST property in water.

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Homogeneous liquid–liquid extraction of metal ions with non-fluorinated bis(2-ethylhexyl)phosphate ionic liquids having a lower critical solution temperature in combination with water

Chemical Communications ◽

10.1039/c5cc05649g ◽

2015 ◽

Vol 51 (75) ◽

pp. 14183-14186 ◽

Cited By ~ 21

Author(s):

Daphne Depuydt ◽

Liwang Liu ◽

Christ Glorieux ◽

Wim Dehaen ◽

Koen Binnemans

Keyword(s):

Ionic Liquids ◽

Metal Ions ◽

Transition Metal Ions ◽

Liquid Extraction ◽

Phase Behaviour ◽

Solution Temperature ◽

Temperature Dependent ◽

Critical Solution Temperature ◽

Homogeneous Liquid ◽

Liquid Liquid Extraction

Bis(2-ethylhexyl)phosphate ionic liquids show a temperature-dependent phase behaviour of the LCST-type and can extract transition metal ions very efficiently via homogeneous liquid–liquid extraction.

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A thermoresponsive poly(ionic liquid) membrane enables concentration of proteins from aqueous media

Chemical Communications ◽

10.1039/c6cc02703b ◽

2016 ◽

Vol 52 (47) ◽

pp. 7497-7500 ◽

Cited By ~ 15

Author(s):

Yuki Kohno ◽

Douglas L. Gin ◽

Richard D. Noble ◽

Hiroyuki Ohno

Keyword(s):

Ionic Liquid ◽

Lower Critical Solution Temperature ◽

Liquid Membrane ◽

Aqueous Media ◽

Water Soluble ◽

Phase Behaviour ◽

Solution Temperature ◽

Critical Solution Temperature ◽

New Type ◽

Poly Ionic Liquid

A new type of poly(ionic liquid) membrane, which shows switchable hydrated states via lower critical solution temperature-type phase behaviour, enables concentration of some water-soluble proteins from aqueous media.

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Material design of ionic liquids to show temperature-sensitive LCST-type phase transition after mixing with water

Australian Journal of Chemistry ◽

10.1071/ch11278 ◽

2011 ◽

Vol 64 (12) ◽

pp. 1560 ◽

Cited By ~ 62

Author(s):

Yuki Kohno ◽

Hiroki Arai ◽

Shohei Saita ◽

Hiroyuki Ohno

Keyword(s):

Phase Transition ◽

Ionic Liquids ◽

Material Design ◽

Phase Behaviour ◽

Solution Temperature ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Alkyl Chains ◽

Type Phase ◽

Separation Temperature

Phosphonium cations bearing different alkyl chains were coupled with several common anions so as to prepare ionic liquids (ILs) with diverse hydrophobicity. A temperature-driven phase behaviour of the mixture of various ILs and water has been examined. A few ILs were found to exhibit temperature-sensitive lower critical solution temperature (LCST)-type phase transition after mixing with water. The phase separation temperature (Tc) of the IL/water mixtures depended strongly on the hydrophobicity of the component ions as well as mixing ratio. The number of water molecules per ion pair in the IL phase (mwater) increased dramatically upon cooling. The temperature dependence of this parameter was found to be useful to predict the possibility of the ILs to show the LCST-type phase behaviour after mixing with water. Since the value of mwater depended on the ion structure, especially on the hydrophobicity, the Tc was accurately set out by suitably mixing two ILs with different hydrophobicity.

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Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

10.26434/chemrxiv.13239059.v1 ◽

2020 ◽

Author(s):

Swati Arora ◽

Julisa Rozon ◽

Jennifer Laaser

Keyword(s):

Dielectric Constant ◽

Ionic Liquid ◽

Ionic Liquids ◽

Ion Pairs ◽

Polymer Chains ◽

Ion Motion ◽

Charged Species ◽

Broadband Dielectric Spectroscopy ◽

Covalently Linked ◽

Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

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