Dual stimuli-responsive phase transition of an ionic liquid/water mixture

Kohno, Yuki; Arai, Hiroki; Ohno, Hiroyuki

doi:10.1039/c1cc10613a

Cited by 44 publications

(40 citation statements)

References 27 publications

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“…[27] In the case of [P 4444 ][Tf-Leu], the carboxylic group on [Tf-Leu] À was partially dissociated in water, and the dissociation of the carboxylic group was found to be suppressed by heating. [27] These results suggested that the dissociation state of the carboxylic group was one of important factors to show the LCST-type phase transition. However, there was no guarantee that the dissociation degree of the carboxylic acid group is the only factor to govern the LCST behaviour of IL/water mixtures.…”

Section: Introductionmentioning

confidence: 96%

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

et al. 2011

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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 (T c ) 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 (m water ) 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 m water depended on the ion structure, especially on the hydrophobicity, the T c was accurately set out by suitably mixing two ILs with different hydrophobicity.

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Section: Introductionmentioning

confidence: 96%

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

et al. 2011

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“…[8] Nevertheless,e fficient coupling of reaction, separation, and recyclability in conventional ILs remains amajor challenge.Unlike the ordinary solvents,their very high boiling point often precludes recovery of ILs by distillation under ambient conditions.A lso,t heir very strong solubilization capacity makes it extremely difficult to separate the products and to reuse the ILs.T he groups of Leitner and of Cheng [9] found that supercritical carbon dioxide (ScCO 2 )/ IL systems could be used to realize the coupling of reaction, separation, and recyclability by varying the pressure of CO 2 . Ohno et al [10] recently developed an IL, tetrabutylphosphonium N-trifluoromethanesulfonyleucine,4 0wt% of which was completely miscible with 60 wt %ofwater at 20 8 8Cinthe absence of CO 2 , but they were partially miscible in the presence of CO 2 . Ohno et al [10] recently developed an IL, tetrabutylphosphonium N-trifluoromethanesulfonyleucine,4 0wt% of which was completely miscible with 60 wt %ofwater at 20 8 8Cinthe absence of CO 2 , but they were partially miscible in the presence of CO 2 .…”

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confidence: 99%

Reversible Hydrophobic–Hydrophilic Transition of Ionic Liquids Driven by Carbon Dioxide

Xiong¹,

Cui²,

Wang³

et al. 2015

Angew Chem Int Ed

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Ionic liquids (ILs) with a reversible hydrophobic-hydrophilic transition were developed, and they exhibited unique phase behavior with H2O: monophase in the presence of CO2, but biphase upon removal of CO2 at room temperature and atmospheric pressure. Thus, coupling of reaction, separation, and recovery steps in sustainable chemical processes could be realized by a reversible liquid-liquid phase transition of such IL-H2O mixtures. Spectroscopic investigations and DFT calculations showed that the mechanism behind hydrophobic-hydrophilic transition involved reversible reaction of CO2 with anion of the ILs and formation of hydrophilic ammonium salts. These unique IL-H2O systems were successfully utilized for facile one-step synthesis of Au porous films by bubbling CO2 under ambient conditions. The Au porous films and the ILs were then separated simultaneously from aqueous solutions by bubbling N2, and recovered ILs could be directly reused in the next process.

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“…It is known that the physicochemical properties of ILs can be tuned towards specific tasks by exploiting the diversities of the component organic ions . The hydrophilic/hydrophobic balance of the component ions of an IL in an IL–water mixture is also an important physicochemical parameter that governs their thermoresponsive properties to either upper critical solution temperature (UCST)‐type and/or lower critical solution temperature (LCST)‐type materials . There are several reports on LCST‐type thermomorphic behaviours of IL–water mixtures .…”

Section: Introductionmentioning

confidence: 99%

“…[8,23,24] The hydrophilic/hydrophobic balance of the component ions of an IL in an IL-water mixture is also an important physicochemical parametert hat governs their thermoresponsive properties to either upper critical solution temperature (UCST)-type [25][26][27] and/orl ower critical solution temperature (LCST)-type materials. [28][29][30] There are severalr eports on LCST-type thermomorphic behaviours of IL-water mixtures. [1] Ohno and co-workersi nvestigated LCST-type phase behaviours of many different ILs in water, [22,29,31,32] with different cloud points (T cp s) depending on the counter anions, such as 4-styrenesulfonate, [33] trifluoroacetate [31] etc.…”

Section: Introductionmentioning

confidence: 99%

“…[28][29][30] There are severalr eports on LCST-type thermomorphic behaviours of IL-water mixtures. [1] Ohno and co-workersi nvestigated LCST-type phase behaviours of many different ILs in water, [22,29,31,32] with different cloud points (T cp s) depending on the counter anions, such as 4-styrenesulfonate, [33] trifluoroacetate [31] etc. In addition to these studies, Ohno et al also described ad etailed study of a list of existing LCST-type ILs in ar ecent reviews.…”

Section: Introductionmentioning

confidence: 99%

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Chemical Tuning of Zwitterionic Ionic Liquids for Variable Thermophysical Behaviours, Nanostructured Aggregates and Dual‐Stimuli Responsiveness

Biswas

Ghosh

Mandal

2018

Chemistry A European J

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The design and synthesis of a series of zwitterionic ionic liquids (ZILs) to understand the structure-property relationship towards an increase of the thermal stability, a variation of the glass transition temperature, the shape-tuning of nanostructured aggregates and the tuning of the stimuli responsiveness are demonstrated. The substitution reaction of imidazole with various aliphatic and aromatic bromides followed by the reaction of the corresponding substituted imidazoles with bromoalkyl carboxylic acids of varying spacer length produces the ZILs. In aqueous solution, a ZIL molecule either exist in its ionic liquid (substituted imidazolium bromide) form or its zwitterionic (substituted imidazolium alkyl carboxylate) form with an isoelectric point (pI) depending on the pH value of the solution. Upon changing the pH to near or above the pI, the aqueous ZIL solution undergoes transition from a transparent to a turbid phase due to the formation of insoluble hierarchical nanostructured aggregates of various morphologies, such as spheres, tripods, tetrapods, fern-like, flower-like, dendrites etc. depending on the pH of the solution and the nature of the alkyl/vinyl/aryl substituents. Upon heating the solution a phase transition occurs from turbid to transparent, exhibiting a distinct reversible upper critical solution temperature (UCST)-type cloud point (T ). It is observed that the cloud point varies with the nature of the substituent, an increase of the concentration of the ZIL as well as with changes of the pH of the solution.

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Dual stimuli-responsive phase transition of an ionic liquid/water mixture

Abstract: A mixture of tetrabutylphosphonium N-trifluoromethanesulfonyl leucine and water showed a reversible change between a homogeneous phase and separated liquid-liquid phase by bubbling CO(2) gas or N(2) gas at atmospheric pressure as well as a small temperature change.

Cited by 44 publications

References 27 publications

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

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

Reversible Hydrophobic–Hydrophilic Transition of Ionic Liquids Driven by Carbon Dioxide

Chemical Tuning of Zwitterionic Ionic Liquids for Variable Thermophysical Behaviours, Nanostructured Aggregates and Dual‐Stimuli Responsiveness

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