Preparation method of multifunctional conductive gel based on metal salt ionic liquid
By introducing zwitterionic structures into metal acid salt ionic liquids to form covalent/non-covalent cross-linked networks, conductive gels were prepared, solving the problems of hydrogel freezing at low temperatures and poor mechanical properties, and enabling multifunctional applications in extreme environments.
Patent Information
- Application Number
- CN202411652126.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2044-11-19
AI Technical Summary
Traditional hydrogels freeze at low temperatures, resulting in reduced flexibility and conductivity. Furthermore, zwitterionic hydrogels exhibit poor mechanical properties and insufficient responsiveness, limiting their application in extreme environments and flexible electronic devices.
Conductive gels based on metal acid salt ionic liquids were prepared by introducing zwitterionic structures into metal acid salt ionic liquids containing unsaturated double bonds and forming covalent/non-covalent crosslinked networks through free radical polymerization and crosslinking reactions.
The obtained conductive gel has good conductivity, flexibility, freeze resistance and water retention properties, making it suitable for flexible wearable electronic devices. It has multifunctional features and is suitable for industrial production.
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Figure CN119390891B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of composite gel materials, and more particularly relates to a preparation method of a multifunctional conductive gel based on a metal salt ionic liquid. BACKGROUND
[0002] Hydrogels are soft materials composed of three-dimensional cross-linked networks and a large amount of water. Due to their high flexibility, structural designability and good biocompatibility, hydrogels are widely used as functional smart materials in wearable electronic devices and other fields. However, the traditional hydrogels inevitably freeze at low temperatures, and their flexibility and conductivity will be significantly reduced, which seriously affects their application in extreme environments (often freezing at the freezing point of water, losing flexibility and failing to be applied in the sensing field). Even at room temperature, hydrogels will lose a large amount of water in a few hours (for example, see: X. Sui, H. Guo, C. Cai, Q. Li, C. Wen, X. Zhang, X. Wang, J. Yang, L. Zhang, Ionic conductive hydrogels with long-lasting antifreezing, water retention and self-regeneration abilities, Chemical Engineering Journal 419 (2021) 129478.), which limits their long-term stability and operational durability. Therefore, it is necessary to develop hydrogels with excellent antifreezing and water retention properties.
[0003] Monomer compounds or polymers thereof with zwitterionic structures, where the zwitterionic structure is a dipolar ion with both positive and negative charges on the same molecule, zwitterionic hydrogels are of great concern in the field of flexible electronic devices due to their unique structure, excellent anti-freezing properties, water retention, conductivity, adhesion and biocompatibility. However, zwitterionic-based hydrogels have a strong affinity for water, which leads to poor mechanical properties (see: H. Wang, B. Liu, D. Chen, Z. Wang, H. Wang, S. Bao, P. Zhang, J. Yang, W. Liu, Low hysteresis zwitterionic supramolecular polymer ion-conductive elastomers with anti-freezing properties, high stretchability, and self-adhesion for flexible electronic devices, Materials Horizons 11(11) (2024) 2628-2642.). In addition, the single network and toughening mechanism of zwitterionic hydrogels makes them have low elasticity and poor responsiveness to various deformations (see: Y. Liu, Q. Liu, L. Zhong, C. Chen, Z. Xu, Tough, antifreezing, and conductive double network zwitterionic-based hydrogel for flexible sensors, Chemical Engineering Journal 452 (2023) 139314.), which greatly limits their practical application. SUMMARY
[0004] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide a preparation method of multifunctional conductive gel based on metal salt ionic liquid, wherein by improving the specific composition and corresponding preparation method of the conductive gel, the zwitterionic structure is used to jointly construct the conductive gel based on metal salt ionic liquid with the participation of metal salt ionic liquid containing unsaturated double bond, and the obtained hydrogel has good conductivity, good flexibility, excellent anti-freezing properties and water retention performance, excellent performance, great application prospect in the field of flexible wearable electronic devices, and multifunctional characteristics. The method of the present application is simple and effective, the reaction conditions are mild, the operation is simple, and it is suitable for industrial production.
[0005] To achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of conductive gel based on metal salt ionic liquid is provided, comprising the following steps:
[0006] (1) uniformly dissolving a metal halide in an ionic liquid containing unsaturated double bond, stirring and mixing uniformly to obtain a metal acid salt ionic liquid containing unsaturated double bond;
[0007] (2) using a monomer compound having zwitterionic structure and / or a polymer thereof as a zwitterionic raw material, uniformly dissolving and dispersing the zwitterionic raw material and a crosslinking agent in deionized water together with the metal acid salt ionic liquid containing unsaturated double bond to obtain a mixed system;
[0008] (3) allowing the mixed system to undergo a free radical polymerization reaction and a crosslinking reaction, thereby obtaining a metal acid salt ionic liquid-based conductive gel.
[0009] As a further preferred embodiment of the present application, in step (2), the molar ratio of the metal acid salt ionic liquid containing unsaturated double bond to the zwitterionic structure contained in the zwitterionic raw material is (0.01-2):1, preferably (0.1-1):1.
[0010] As a further preferred embodiment of the present application, in step (1), the molar ratio of the ionic liquid containing unsaturated double bond to the metal halide is (0.01-20):1, preferably (0.5-10):1.
[0011] As a further preferred embodiment of the present application, in step (1), the metal element in the metal halide is one or more of Zn, Zr, Al, Ga, In, Fe, and Cu, and the halogen is one or more of F, Cl, Br, and I.
[0012] The anion of the ionic liquid containing unsaturated double bond is one or more of F, Cl, Br, and I.
[0013] The ionic liquid containing unsaturated double bond is at least one of an imidazole salt ionic liquid containing unsaturated double bond, a quaternary ammonium salt ionic liquid containing unsaturated double bond, a pyridine salt ionic liquid containing unsaturated double bond, and a quaternary phosphonium salt ionic liquid containing unsaturated double bond.
[0014] Preferably, the ionic liquid containing unsaturated double bond is an imidazole salt ionic liquid containing unsaturated double bond, and the length of the alkyl carbon chain is 1-12 carbon atoms.
[0015] As a further preferred embodiment of the present application, in step (2), the monomer compound having zwitterionic structure is preferably betaine or a derivative thereof.
[0016] The concentration of the crosslinking agent in the mixed system is 0.001M to 0.5M.
[0017] The crosslinking agent is preferably N,N-methylenebisacrylamide.
[0018] As a further preferred embodiment of the present application, in step (1), the stirring and mixing are performed at 20-80℃ for 2-12h.
[0019] In step (2), the uniform dispersion is achieved by ultrasonic dispersion.
[0020] As a further preferred embodiment of the present application, in step (3), the radical polymerization and cross-linking reaction are preferably induced by ionizing radiation treatment.
[0021] The ionizing radiation treatment is preferably performed by irradiation with electron beam, gamma ray or X-ray; and the absorbed dose of the ionizing radiation is 1-200KGy, preferably 10-50KGy.
[0022] According to another aspect of the present application, the present application provides a metalate-based ionic liquid conductive gel prepared by the above method.
[0023] According to still another aspect of the present application, the present application provides a use of the above metalate-based ionic liquid conductive gel as a sensing material in a flexible strain sensor.
[0024] As a further preferred embodiment of the present application, the flexible strain sensor is a wearable device, which utilizes the change of the resistance and / or conductivity of the metalate-based ionic liquid conductive gel to sense the strain.
[0025] Preferably, the application is used in an environment with a temperature of -60℃ or above.
[0026] Compared with the prior art, the metalate-based ionic liquid containing unsaturated double bonds is a functional ionic liquid composed of an anion group formed by complexing an organic cation, a metal ion and a halogen ion. The metalate-based ionic liquid containing unsaturated double bonds combines the unique properties of ionic liquids and metal ions, effectively disperses stress and dissipates energy through the interaction of rich reversible bonds (hydrogen bonds, coordination bonds, etc.) and zwitterionic structures, and improves the mechanical strength and elasticity of the gel. The obtained hydrogel has good conductivity, good flexibility, excellent frost resistance and water retention performance, and other multifunctional characteristics, and can be particularly applied in the field of flexible electronics.
[0027] Specifically, the present application can achieve the following beneficial effects:
[0028] (1) The present application utilizes the zwitterionic structure to jointly construct a metalate ionic liquid-based conductive gel with the participation of a metalate ionic liquid containing an unsaturated double bond. The obtained hydrogel has good conductivity, good flexibility, excellent frost resistance and water retention performance, excellent performance, great application prospects in the field of flexible wearable electronic devices, and multi-functional characteristics. Moreover, the preparation method can particularly use ionizing radiation technology to induce free radical polymerization and crosslinking reaction. The preparation method involved has the advantages of being carried out at room temperature, free of initiators, green and environmentally friendly, and large-scale industrial production.
[0029] (2) The synergistic effect of covalent and various non-covalent interactions endows the hydrogel with excellent mechanical tensile properties, high compressive strength, ultra-fast response time, water retention and frost resistance. Based on its excellent performance, the conductive hydrogel is used as a multifunctional flexible sensor to reliably and timely detect large-scale and small-scale movements of the human body. As shown in the examples below, it can also transmit Morse code information through finger movements.
[0030] (3) The multifunctional conductive hydrogel prepared by the present application has broad application prospects in the fields of wearable devices, electronic skin and intelligent information encryption transmission.
[0031] Considering the higher bond energy and broader spectrum of binding strength of coordination bonds, its controllable structure is essential for hydrogels. Previous studies on the synthesis of metal coordination complexes involve the use of organic solvents and complex processes (see: X. Guan, Y. Zhu, B. Zhang, X. Sun, M. A. Abosheasha, C. Gong, S. Zheng, D. Li, Q. Han, M. An, M. Ueda, Y. Ito, Shutters-Inspired metal ions coordination hydrogel Strain / Pressure sensor for joint behavior evaluation and flatfeet correction, Chemical Engineering Journal 489 (2024) 151353.) while the present invention innovatively introduces metal halides into ionic liquids containing unsaturated double bonds by a simple method, forms metal salt ionic liquids, and forms a covalent / non-covalent crosslinking network with zwitterions through free radical polymerization to form conductive gels. Moreover, most of the metal salt ionic liquids reported in the prior art are used as solvents, while the present invention uses metal salt ionic liquids containing unsaturated double bonds, which not only provide a large number of coordination sites, but also form polyionic liquid chains through free radical polymerization. During the gel formation process, the formed polyionic liquid segments are more easily enhanced through non-covalent interaction and entanglement with zwitterion segments to form gels. BRIEF DESCRIPTION OF DRAWINGS
[0032] Figure 1 The infrared spectra of [ABIm]Cl, anhydrous ZnCl2, [ABIm][Zn x Cl y ](1:1) and [ABIm][Zn x Cl y ](3:1).
[0033] Figure 2 The infrared spectra of [ABIm]Cl, anhydrous ZnCl2, [ABIm][Zn x Cl y ](1:1) and [ABIm][Zn x Cl y ](3:1).
[0034] Figure 3 The stability test results of the PI6Z6 hydrogel in Example 1; wherein, Figure 3 a in the differential scanning calorimetric graph of the PI6Z6 hydrogel in Example 1; Figure 3 b in the weight retention rate change of the PI6Z6 hydrogel in Example 1 placed in an open environment at room temperature.
[0035] Figure 4 Mechanical tensile curve of the hydrogel prepared in Example 1 and Example 3.
[0036] Figure 5 Mechanical tensile curve of the hydrogel prepared in Example 4.
[0037] Figure 6 Mechanical tensile curve of the hydrogel prepared in Comparative Example 2.
[0038] Figure 7 Compression curve of the PI6Z6 hydrogel in Example 1.
[0039] Figure 8 Response and recovery time of the PI6Z6 hydrogel in Example 1 during the stretching process.
[0040] Figure 9 Signal response curve of the PI6Z6 hydrogel in Example 1 to different movements of the human body. Among them, Figure 9 a in the above formula is finger bending (at this time the PI6Z6 hydrogel is located at the finger), Figure 9 b in the above formula is wrist bending (at this time the PI6Z6 hydrogel is located at the wrist), Figure 9 c in the above formula is volunteer coughing (at this time the PI6Z6 hydrogel is located at the throat).
[0041] Figure 10 Application example of the PI6Z6 hydrogel prepared in Example 1 in information encryption transmission; among them, Figure 10 a in the above formula is the Morse code table, Figure 10 b and Figure 10 c in the above formula are the response signals of the PI6Z6 hydrogel to "HUST" and "HELP" according to the Morse code table. DETAILED DESCRIPTION
[0042] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.
[0043] The metal acid salt ionic liquid is first prepared in the embodiment of the present application. The following examples use the metal acid salt ionic liquid prepared by the following preparation method using commercially available raw materials as raw materials.
[0044] 1-allyl-3-butylimidazole chloride ([ABIm]Cl) and anhydrous ZnCl2 were stirred at 50℃ for 8h to synthesize the metal acid salt ionic liquid ([ABIm][Zn x Cly ]) to give a clear and homogeneous solution, as shown in Figure 1 The metal salt ionic liquids prepared according to the molar ratio of [ABIm]Cl to anhydrous ZnCl2 of 3:1 and 1:1 are named as [ABIm][Zn x Cl y ](3:1) and [ABIm][Zn x Cl y ](1:1), respectively. As a supplementary note: the molar mass of [ABIm][Zn x Cl y ](3:1) is calculated by (3*molar mass of [ABIm]Cl + molar mass of ZnCl2) / 4; the molar mass of [ABIm][Zn x Cl y ](1:1) is calculated by ([ABIm]Cl + ZnCl2) / 2.
[0045] Example 1
[0046] A mixture system is prepared, in which the molar concentration of [ABIm][Zn x Cl y ](3:1) is 6M, the molar concentration of sulfobetaine methacrylate (SBMA) is 6M, and the molar concentration of N,N-methylenebisacrylamide is 0.012M (the mixture system is specifically obtained by dissolving [ABIm][Zn x Cl y ](3:1), SBMA and N,N-methylenebisacrylamide in 2ml of deionized water and ultrasonic dispersion), and then the mixture system is irradiated under an electron beam, to obtain a PI6Z6 hydrogel. The absorbed dose of the electron beam irradiation is 20KGy.
[0047] Example 2
[0048] In this example, the same method as in Example 1 is used to prepare a multifunctional conductive hydrogel, except that the concentration of SBMA is 5M, and the synthesized gel is named as PI6Z5 hydrogel.
[0049] Example 3
[0050] In this example, the same method as in Example 1 is used to prepare a multifunctional conductive hydrogel, except that the concentration of SBMA is 7M, and the synthesized gel is named as PI6Z7 hydrogel.
[0051] Example 4
[0052] A mixture system is prepared, in which the molar concentration of [ABIm][Zn -1 Cly The molar concentration of [ABIm][Zn](1:1) is 6M, the molar concentration of sulfonate betaine methacrylate (SBMA) is 6M, and the molar concentration of N,N-methylenebisacrylamide is 0.012M (this mixture specifically consists of [ABIm][Zn]). x Cl y The PI6Z6(1:1) hydrogel was obtained by dissolving SBMA and N,N-methylenebisacrylamide in 2 ml of deionized water and ultrasonically dispersing them evenly. The mixture was then irradiated with an electron beam to obtain the PI6Z6(1:1) hydrogel. The absorbed dose of the electron beam irradiation was 20 kGy.
[0053] Comparative Example 1
[0054] A mixture was prepared in which the molar concentrations of [ABIm]Cl, sulfonated betaine methacrylate (SBMA), and N,N-methylenebisacrylamide were 6 M and 0.012 M respectively (the mixture was prepared by dissolving [ABIm]Cl, SBMA, and N,N-methylenebisacrylamide in 2 ml of deionized water and then ultrasonically dispersing them evenly). The mixture was then irradiated with an electron beam at an absorbed dose of 20 kGy.
[0055] Comparative Example 2
[0056] A mixture was prepared in which the molar concentration of [ABIm]Cl was 4.5 M, the molar concentration of anhydrous ZnCl2 powder was 1.5 M, the molar concentration of sulfonate betaine methacrylate (SBMA) was 6 M, and the molar concentration of N,N-methylenebisacrylamide was 0.012 M (the mixture was specifically prepared by dissolving [ABIm]Cl, anhydrous ZnCl2, SBMA, and N,N-methylenebisacrylamide in 2 ml of deionized water and ultrasonically dispersing them evenly). The mixture was then irradiated with an electron beam at an absorbed dose of 20 kGy.
[0057] Performance testing:
[0058] The synthesized metal acid salt ionic liquid was subjected to Fourier transform infrared (FTIR) testing, such as... Figure 2 As shown. Compared to pure [ABIm]Cl, when the molar ratio of [ABIm]Cl to ZnCl2 is 3:1, 3049 cm⁻¹ -1 (=CH stretching vibration) and 3136cm -1 The peak at (CH stretching vibration) points to a higher wavenumber (3072cm). -1 and 3142cm -1) shifted. When the molar ratio of [ABIm]Cl to ZnCl2was changed to 1:1, the stretching peak of [ABIm][Zn x Cl y ](1:1) shifted to higher wavenumber. The above results proved the successful synthesis of metalate ionic liquids, indicating that the addition of metal halide weakened the influence of halide ion on imidazolium cation.
[0059] The conductivity of PI6Z6 hydrogel obtained in Example 1 was tested, and the result showed that the conductivity of PI6Z6 hydrogel was 1.36 mS cm -1 at room temperature, and it also had conductivity at -60°C.
[0060] In terms of stability, the PI6Z6 hydrogel obtained in Example 1 was further proved to have good anti-freezing property by differential scanning calorimetry (DSC), as shown in a of Figure 3 In addition, the PI6Z6 hydrogel could still maintain 86.4% of the original weight after being placed in an open environment at room temperature for 30 days, as shown in b of Figure 3
[0061] Figure 4 The mechanical properties of the hydrogels prepared in Example 1 and Example 3 were compared. The results showed that the hydrogels obtained whether the SBMA concentration was 6M or 7M had good mechanical properties (of course, the PI6Z6 hydrogel obtained in Example 1 had the best comprehensive strength and strain properties).
[0062] Figure 5 The mechanical properties of the hydrogel prepared in Example 4 were shown. Compared with the PI6Z6 hydrogel prepared in Example 1, the PI6Z6(1:1) hydrogel prepared in Example 4 had reduced strain and increased stress, and also had good mechanical properties.
[0063] The hydrogel obtained in Comparative Example 1 was very soft and had low stress, so it was difficult to take out the complete shape for subsequent mechanical testing. The addition of ZnCl2powder improved the strength of the gel prepared in Comparative Example 2, but it was still very weak. As shown in Figure 6 As shown, the strength of the obtained gel (10 kPa) is much lower than that of the PI6Z6 hydrogel (57 kPa) prepared in Example 1. This result further confirms the important role of the metal salt ionic liquid, which can enhance the SMBA hydrogel. That is, using the ordinary ionic liquid 1-allyl-3-butyl imidazole chloride ([ABIm]Cl) to modify sulfobetaine methacrylate (SBMA), the obtained hydrogel is very soft and has low stress, so it is difficult to take out the complete shape for subsequent mechanical testing; adding ZnCl2 powder in the above system, the strength of the gel is improved, but it is still very weak, the strength of the obtained gel (10 kPa) is much lower than that of the PI6Z6 hydrogel (57 kPa) prepared by the metal salt ionic liquid; these results confirm that the metal salt ionic liquid can enhance the zwitterionic hydrogel.
[0064] The PI6Z6 hydrogel prepared in Example 1 has good compressive resistance, as shown in Figure 7 The obtained hydrogel has a compressive strength of up to 820 kPa at 90% strain.
[0065] The PI6Z6 hydrogel prepared in Example 1 was deformed by a tensile machine, and the deformation was applied at 0.14 s and maintained until 1.34 s when it was removed, and the change in resistance was as shown in Figure 8 As can be seen from the figure, the response and recovery time of the PI6Z6 hydrogel prepared in Example 1 is 0.14 s, which indicates that it can sensitively perceive external stimuli and quickly provide corresponding real-time electrical signals.
[0066] The PI6Z6 hydrogel sensor prepared in Example 1 can quickly and accurately detect the movement of the finger at different bending angles Figure 9 As shown in b of Figure 9 The hydrogel sensor can also be attached to the wrist to monitor the movement of the wrist in the bending process in real time by collecting electrical signals. In addition, the hydrogel sensor attached to the throat can also accurately detect the repeated signals of the volunteer's cough Figure 9 (c) of
[0067] The hydrogel sensor can be used to transmit information in real time by Morse code, which is an effective real-time coding system that uses a series of dots and lines to represent English letters, as shown in a of Figure 10 The PI6Z6 hydrogel prepared in Example 1 is attached to the finger, the bending and holding time of the finger is controlled, and the peak and platform peak are generated, and the corresponding "HUST", "HELP" and other electrical signals are detected and transmitted in real time Figure 10 (b, Figure 10 (c) of
[0068] The metal element in the metal salt ionic liquid can also be one or more of Zn, Zr, Al, Ga, In, Fe, and Cu, and the halogen in the anion group in the metal salt ionic liquid can also be one or more of F, Cl, Br, and I. For another example, the free radical polymerization reaction can also be induced by using other ways known in the prior art, such as photo initiation and thermal initiation.
[0069] Those skilled in the art can understand that the above description is only preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims
1. A method for preparing a metalate ionic liquid based conductive gel, characterized in that, The method comprises the following steps: (1) uniformly dissolving metal halide in ionic liquid containing unsaturated double bond to obtain metal salt ionic liquid containing unsaturated double bond; (2) using monomer compound with zwitterionic structure and / or polymer thereof as zwitterionic raw material, uniformly dissolving and dispersing the zwitterionic raw material, crosslinking agent and the metal salt ionic liquid containing unsaturated double bond in deionized water to obtain a mixed system; (3) inducing free radical polymerization and crosslinking reaction of the mixed system to obtain metal salt ionic liquid-based conductive gel.
2. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of the metal salt ionic liquid containing unsaturated double bond to the zwitterionic structure contained in the zwitterionic raw material is (0.01-2):
1.
3. The preparation method according to claim 2, characterized in that, In step (2), the molar ratio of the metal salt ionic liquid containing unsaturated double bond to the zwitterionic structure contained in the zwitterionic raw material is (0.1-1):
1.
4. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of the ionic liquid containing unsaturated double bond to the metal halide is (0.01-20):
1.
5. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of the ionic liquid containing unsaturated double bond to the metal halide is (0.5-10):
1.
6. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (1), the metal element in the metal halide is one or more of Zn, Zr, Al, Ga, In, Fe and Cu, and the halogen is one or more of F, Cl, Br and I. The anion of the ionic liquid containing unsaturated double bond is one or more of F, Cl, Br and I. The ionic liquid containing unsaturated double bond is at least one of imidazole salt ionic liquid containing unsaturated double bond, quaternary ammonium salt ionic liquid containing unsaturated double bond, pyridine salt ionic liquid containing unsaturated double bond and quaternary phosphonium salt ionic liquid containing unsaturated double bond.
7. The preparation method according to claim 6, characterized in that, The ionic liquid containing unsaturated double bond is imidazole salt ionic liquid containing unsaturated double bond, and the alkyl carbon chain length is 1-12 carbon atoms.
8. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (2), the monomer compound with zwitterionic structure is betaine or its derivative. The concentration of the crosslinking agent in the mixed system is 0.001M to 0.5M. The crosslinking agent is N,N-methylenebisacrylamide.
9. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (1), the stirring and mixing are performed at 20-80°C for 2-12h. In step (2), the uniform dispersion is performed by ultrasonic dispersion.
10. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (3), the free radical polymerization and crosslinking reaction are induced by ionizing radiation treatment. The ionizing radiation treatment is performed by irradiation treatment using any one of electron beam, gamma ray or X-ray; and the absorbed dose of the ionizing radiation is 1-200KGy.
11. The method of claim 10, wherein the step of preparing is characterized by, The absorbed dose of the ionizing radiation is 10-50KGy.
12. Metal salt ionic liquid-based conductive gel prepared by the method of any one of claims 1-11.
13. Application of the metal salt ionic liquid-based conductive gel of claim 12 as sensing material in flexible strain sensor.
14. The use according to claim 13, wherein the compound is ###0002### The flexible strain sensor is a wearable device, which utilizes the change of resistance and / or conductivity of the metal salt ionic liquid-based conductive gel to sense strain.
15. The use according to claim 14, wherein the compound is ###00010### or a pharmaceutically acceptable salt thereof. The application is used in an environment with a temperature of -60 DEG C or above.