An ionic liquid responsive to both temperature and co2 stimulation and a method of preparation thereof

Abstract

The application discloses a kind of double stimulation response ionic liquid to temperature and CO2 and preparation method thereof.The specific steps are: polyether amine and long-chain fatty acid are mixed with molar ratio 1:2, heated to 50~90 DEG C, and react for 0.5-12h;Reaction product;The reaction product is vacuum dried, and the double response ionic liquid to temperature and CO2 is obtained.The polyether amine fatty acid gemini ionic liquid of the application can be mixed with water to form a double liquid system with reversible low critical temperature solubility phase behavior, and in addition, the mixed system can realize the reversible conversion of the system between homogeneous phase and heterogeneous phase by alternately introducing and removing CO2.Temperature and CO2 have synergistic effect on the ionic liquid-water system, and when the system is stimulated by both, the sensitivity of the system phase transition can be improved.The ionic liquid prepared by the application has wide application prospect in the field of catalytic separation and stimulus response materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical engineering, and relates to an ionic liquid with double stimuli response to temperature and CO2 and a preparation method thereof. BACKGROUND

[0002] Stimuli-responsive materials refer to materials whose physical and chemical properties and the properties of related systems change sensitively when the external environment changes. Such materials have unique stimuli-responsive characteristics and can regulate the properties of the materials under external stimuli. Stimuli-responsive ionic liquids (ILs) are prepared by implanting stimuli-responsive groups in the cations or anions of ILs, and have the dual advantages of ILs and stimuli-responsive materials through careful design of the structure. External stimuli can change the structure and properties of stimuli-responsive ionic liquids, which can be further applied to many frontier fields, including extraction, catalysis, separation and material preparation.

[0003] The regulation of the behavior of stimuli-responsive IL-water phase is the basis for studying the responsiveness of stimuli-responsive ILs. However, most of the currently reported stimuli-responsive ILs only respond to a single external stimulus. For example, the hydroxyl-functionalized diisopropylamine imidazole [C4DIPA][Im] and water mixed system can be driven to undergo phase transition under CO2 stimulus, and the 1-butyl-3-methyl imidazole tetrachloro ferrate [Bmim][FeCl4] and water mixed system can be reversibly switched between homogeneous and heterogeneous phases under an external magnetic field. In addition, the IL-water mixed system also has temperature response characteristics through upper critical solution temperature and lower critical solution temperature phase behavior. At present, there are few reports on double stimuli-responsive ionic liquids. Tetrabutyl phosphonium N-trifluoromethanesulfonyl leucine ([P 4444 ][Tf-Leu]) and water mixed system has double stimuli response to CO2 and temperature, but the process synthesis steps are complex, requiring more than three steps of reaction, which limits the large-scale synthesis and application of stimuli-responsive ionic liquids. The double stimuli-responsive IL-water mixed system not only brings double response to the system, but also greatly improves the response performance of the system, so that the system can be widely, efficiently and flexibly applied. Therefore, it is necessary to explore a double stimuli-responsive ionic liquid with simple, recyclable and environmentally friendly phase separation behavior. However, so far, how to design double stimuli-responsive ionic liquids and their double response mechanism is still not clear. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the defects of the prior art and provide an ionic liquid with double stimuli response to temperature and CO2 and a preparation method thereof.

[0005] The present application provides an ionic liquid with double stimuli response to temperature and CO2, and the structural formula is as follows:

[0006]

[0007] Among them, n is 2.5, 6.1, and R is C7H 15 , C9H 19 , C 11 H 23 , C 13 H 27 , C 15 H 31 .

[0008] The present invention also provides a method for preparing the above-mentioned ionic liquid that responds to dual stimulations of temperature and CO2, which comprises the following steps:

[0009] Mixing polyetheramine and long-chain fatty acid in a molar ratio of 1:2, heating to 50°C to 90°C, and reacting for 0.5 to 12 hours to obtain a reactant;

[0010] The reactant is vacuum dried to obtain the ionic liquid having dual responses to temperature and CO2.

[0011] Furthermore, the present invention also provides applications of the ionic liquid having dual responses to temperature and CO2 in the fields of sensing and separation.

[0012] The present invention provides an ionic liquid that is dually responsive to temperature and CO₂. The ionic liquid forms a temperature-controllable system with water. A polyetheramine mixed with water exhibits reversible LCST phase behavior when the water content is between 30% and 96% by weight. This phase behavior also exhibits a reversible response to CO₂. Due to the excellent stability and reversibility of the ILs structure, the dual regulation of phase behavior by temperature and CO₂ exhibits excellent stability and can be cycled more than 10 times. Mechanistic studies have shown that the ionic liquid prepared by this method exhibits temperature and CO₂ response processes dominated by cations and anions, respectively. Furthermore, temperature and CO₂ act synergistically, and when these two stimulate the system together, the sensitivity of the system's phase transitions can be enhanced.

[0013] Compared with the conventional ionic liquid, the present application has the following characteristics: (1) the phase behavior of the ionic liquid-water system can be regulated by temperature and CO2; (2) the hydrophobic-hydrophilic transition of the ionic liquid can be switched by temperature and CO2 as simple and green stimuli; (3) the ionic liquid-water mixed system has reversible LCST phase behavior; (4) the phase behavior of the ionic liquid-water mixed system can be reversibly changed between liquid-liquid two-phase system and homogeneous single-phase system by adding or removing CO2 at normal temperature and pressure; (5) the regulation of temperature and CO2 on the phase behavior of the ionic liquid-water mixed system can be recycled more than 10 times; (6) the regulation of temperature and CO2 on the phase behavior of the ionic liquid-water mixed system has synergistic effect. Further, the preparation method of the temperature and CO2 double-responsive gemini polyether amine fatty acid ionic liquid has simple process, low cost, environmental friendliness and high yield. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a diagram of the phase behavior change of the ionic liquid-water mixed system prepared in Example 1 under the double regulation of temperature and CO2.

[0015] Figure 2 is the nuclear magnetic hydrogen spectrum of the temperature and CO2 double-responsive gemini polyether amine fatty acid ionic liquid [PEA 400 ][Oct] prepared in Example 2 compared with the raw material.

[0016] Figure 3 is the infrared spectrum of the temperature and CO2 double-responsive gemini polyether amine fatty acid ionic liquid [PEA 400 ][Oct] prepared in Example 2 compared with the raw material. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0018] The present application provides a temperature and CO2 double-stimulus responsive ionic liquid, which has the following structure:

[0019]

[0020] wherein n is 2.5, 6.1, R is C7H 15 , C9H 19 , C 11 H 23 , C 13 H 27 , C 15H 31 .

[0021] The embodiment of the present application also provides a preparation method of the above-mentioned ion liquid with dual response to temperature and CO2, which comprises the following steps:

[0022] S01: mixing polyether amine and long-chain fatty acid at a molar ratio of 1:2, heating to 50-90°C, and reacting for 0.5-12h; obtaining a reactant;

[0023] S02: vacuum drying the reactant to obtain the ion liquid with dual response to temperature and CO2.

[0024] Specifically, in step S01, the polyether amine is at least one of polyether amine D230, polyether amine D400 and polyether amine D2000, and the long-chain fatty acid is at least one of n-octanoic acid, n-decanoic acid, lauric acid, myristic acid and palmitic acid. Preferably, the heating is to 65-75°C.

[0025] In step S02, the vacuum drying is performed at a vacuum pressure of-0.1-0Mpa and a temperature of 40-60°C.

[0026] Further, the embodiment of the present application also provides application of the above-mentioned ion liquid with dual response to temperature and CO2 in the field of response sensing and extraction separation.

[0027] The ion liquid with dual response to temperature and CO2 is used for temperature and CO2 phase behavior regulation, the temperature range is 37-91°C, and the CO2 flow rate range is 10-100mL / min.

[0028] The response condition of the ion liquid with dual response to temperature and CO2 is that the mass concentration of the ion liquid is 30-96%.

[0029] Under the regulation of temperature and CO2, the phase behavior of the ion liquid with dual response to temperature and CO2 and the water mixed system can be reversibly switched between homogeneous and heterogeneous phases, and the particle size of the homogeneous system can also be precisely regulated between 6.5nm and 21.0nm. This has important potential application in preparation of intelligent response devices and nanomaterials with specific size.

[0030] The above-mentioned content of the present application is further described in detail through the following examples, but this should not be understood as the range of the above-mentioned subject matter of the present application being limited to the following examples only, and any technology realized based on the above-mentioned content of the present application belongs to the range of the present application.

[0031] Example 1

[0032] The polyetheramine D230 and lauric acid with a molar ratio of 1:2 were weighed and added into a 250 mL round-bottom flask, and stirred in an oil bath for 12 h. The ionic liquid [PEA 230 ][La] was obtained by drying at 50°C under a vacuum of -0.1 MPa for 48 h.

[0033] Example 2

[0034] The polyetheramine D400 and n-octanoic acid with a molar ratio of 1:2 were weighed and added into a 250 mL round-bottom flask, and stirred in an oil bath for 12 h. The ionic liquid [PEA 400 ][Oct] was obtained by drying at 50°C under a vacuum of -0.1 MPa for 48 h.

[0035] Example 3

[0036] The polyetheramine D2000 and n-decanoic acid with a molar ratio of 1:2 were weighed and added into a 250 mL round-bottom flask, and stirred in an oil bath for 12 h. The ionic liquid [PEA 2000 ][Dec] was obtained by drying at 50°C under a vacuum of -0.1 MPa for 48 h.

[0037] Example 4

[0038] The [PEA 230 ][La] prepared in Example 1 was added into a series of 10 mL glass test tubes at 25°C, and then different proportions of water were added. Since the ionic liquid is hydrophilic, a homogeneous solution system was formed. The glass test tubes were then inserted into a thermometer, and placed in a glass-jacketed water bath. The temperature of the water bath was then increased, and the temperature at which the system became turbid was recorded as the lower critical solution temperature of the system. After standing, the system was divided into two layers.

[0039] Example 5

[0040] The ionic liquid-water phase separation system at high temperature in Example 4 was gently shaken until it became turbid, and then cooled to room temperature. The system quickly returned to a clear homogeneous state.

[0041] Example 6

[0042] The lower critical solution temperature phase behavior of the ionic liquid-water system in Example 4 and 5 was reversible and could be cycled more than 10 times.

[0043] Example 7

[0044] In order to verify the accuracy of the data measured by the visual cloud point method, the [PEA 400] at 25°C. The light transmittance of the system at room temperature was 100%. The temperature at which the light transmittance of the system was reduced to 80% was defined as the lower critical solution temperature of the system. The data measured by the UV-Vis spectroscopy method were consistent with the data measured by the visual turbidity point method.

[0045] Example 8

[0046] At 25°C, different proportions of [PEA 2000 ] and water prepared in Example 3 were added to a series of 10 mL glass test tubes. Since the ionic liquid was more hydrophilic, a homogeneous solution system was formed. Then CO2 was blown into the glass test tube at a rate of 10 mL / min. After a period of time, the system changed from the original homogeneous solution state to a turbid state, and after standing, it could be divided into two phases.

[0047] Example 9

[0048] The [PEA 2000 ] - water - CO2 turbid system was heated to remove CO2 in the system, and after cooling to room temperature, the system could return to the original homogeneous state.

[0049] Example 10

[0050] The response of the phase behavior of such ionic liquid water systems to CO2 could be recycled more than 10 times.

[0051] Example 11

[0052] At 25°C, 35°C, 45°C, and 55°C, [PEA 400 ] - water systems prepared in Example 2 with water contents of 90%, 92%, and 94% were added to a series of 10 mL glass test tubes. Then CO2 was blown into the glass test tube at a rate of 10 mL / min. After a period of time, the system changed from the original homogeneous solution state to a turbid state, and after standing, it could be divided into two phases. At 25°C, 35°C, 45°C, and 55°C, the time required for the 90% [PEA 400 ] - water system to become turbid was 71 s, 43 s, 20 s, and 6 s, respectively. At 25°C, 35°C, and 45°C, the time required for the 92% [PEA 400 ] - water system to become turbid was 38 s, 22 s, and 12 s, respectively. At 25°C and 35°C, the time required for the 94% [PEA 400 ] - water system to become turbid was 13 s and 5 s, respectively.

[0053] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An ionic liquid that responds to dual stimuli of temperature and CO2, characterized in that: The structural formula of ionic liquid is shown below: Among them, n is 6.1, R is C7H 15 , C9H 19 , C 11 H 23 , C 13 H 27 , C 15 H 31 .

2. A method for preparing an ionic liquid that responds to dual stimulations of temperature and CO2 as claimed in claim 1, characterized in that: The steps include: Mixing polyetheramine and long-chain fatty acid in a molar ratio of 1:2, heating to 50°C to 90°C, and reacting for 0.5 to 12 hours to obtain a reactant; The reactant is vacuum dried to obtain the ionic liquid having dual responses to temperature and CO2; The vacuum pressure range of the vacuum drying is -0.1 to 0 MPa; The polyetheramine is polyetheramine D400, and the long-chain fatty acid is at least one of n-octanoic acid, n-decanoic acid, lauric acid, myristic acid, and palmitic acid.

3. The method for preparing an ionic liquid that responds to dual stimulations of temperature and CO2 according to claim 2, characterized in that: The temperature is raised to 65°C to 75°C.

4. The method for preparing an ionic liquid that responds to dual stimulations of temperature and CO2 according to claim 2, characterized in that: This type of ionic liquid has a temperature-responsive polyetheramine cation and a CO2-responsive long-chain fatty acid anion.

5. An application of the ionic liquid responsive to dual stimulations of temperature and CO2 as claimed in claim 1 in the fields of responsive sensing and extraction separation.

6. The use of the ionic liquid responsive to dual stimulations of temperature and CO2 according to claim 5 in the field of responsive sensing and extraction separation, characterized in that: The application temperature range is 10℃-92℃, and the amount of CO2 is 0.5mL-30mL.

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