Ionic polyurethane gel as well as preparation method and application thereof

Abstract

The invention discloses ionic polyurethane gel as well as a preparation method and application thereof, the method comprises the following steps: mixing formaldehyde, glyoxal and 1, 4-butanediamine, stirring and reacting to obtain polyionic liquid; the preparation method comprises the following steps: carrying out prepolymerization reaction on polypropylene glycol bis (2-aminopropyl ether) and isophorone diisocyanate in a nitrogen atmosphere to obtain an isocyanate-terminated prepolymer solution; adding adipic dihydrazide into the prepolymer solution, carrying out a first chain extension reaction, then adding a polyion liquid, and carrying out a second chain extension reaction to obtain a PIM / ADH-coated PU solution; after the PIM / ADH coated PU is dried, a PIM / ADH coated PU film is obtained; and dissolving the PIM / ADH coated PU film, then adding 1-butyl-3-methylimidazole bis (trifluoromethylsulfonyl) imide, stirring to obtain a mixed solution, and drying to obtain the ionic polyurethane gel. The ionic polyurethane gel has self-repairing capability and stable ionic liquid bonding performance.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics, specifically to ionic polyurethane gels, their preparation methods, and applications. Background Technology

[0002] With the development of flexible electronics technology, biomimetic ion skin has attracted widespread attention due to its ability to simulate the mechanical properties and ion conduction sensing characteristics of real skin. These materials have significant potential in intelligent sensing applications such as human motion monitoring and body temperature detection, especially given the need for adaptability to a wide temperature range. Polyurethane (PU), with its soft segments providing elasticity, hard segments forming a microphase separation structure, and multiple hydrogen bonding interactions, combines mechanical strength and toughness, making it an ideal matrix material for flexible devices.

[0003] Traditional flexible electronic conductors, such as polymers doped with conductive fillers, exhibit excellent conductivity. However, under large mechanical deformations, the separation between the conductive filler and the substrate often disrupts the conductive pathway, leading to a significant decrease in conductivity and limiting their practical applications. In contrast, flexible ionic conductors promote charge transport through ion migration, thus better adapting to various deformations and complex environments. Therefore, they are considered core materials for next-generation flexible electronic devices. By introducing ionic liquids (ILs) into blends with polyurethane (PU), ionic gels can be prepared, which not only endow the material with conductivity but also enhance its low-temperature resistance, making it suitable for sub-zero environments. The conductivity of this material enables it to convert mechanical strain (such as human movement) and temperature changes into resistance signals, realizing motion monitoring and body temperature sensing.

[0004] Iongel sensors fabricated using ionic liquids mixed with polyurethane often suffer from ionic liquid leakage during use. To prevent this leakage, polyionic liquids (PILs) are directly polymerized to create conductive materials. Polyionic liquids (PILs) are composed of a polymer backbone and repeating ionic liquid (IL) units. They have attracted widespread attention due to their low volatility, thermal stability, and excellent mechanical durability. However, the movement of these ions is restricted, limiting conductivity, sensitivity, and tensile strength. This also limits their use in sensing electronics. Furthermore, ionic gels inevitably suffer mechanical damage during everyday use, and compatibility issues between the ionic liquid and the polyurethane matrix can lead to ionic liquid leakage. Therefore, developing ionic polyurethane elastomers with both self-healing capabilities and stable ionic liquid binding properties is a key research direction for improving the reliability and stability of flexible sensors. Summary of the Invention

[0005] The purpose of this invention is to provide an ionic polyurethane gel, its preparation method and application, which has both self-healing ability and stable ionic liquid binding performance.

[0006] In one aspect of the invention, a method for preparing ionic polyurethane gel is provided. According to an embodiment of the invention, the method includes the following steps:

[0007] (1) Formaldehyde, glyoxal and 1,4-butanediamine were mixed and stirred to react. The product was dried and dialyzed, and then dried to obtain a polyionic liquid.

[0008] (2) Polypropylene glycol bis(2-aminopropyl ether) and isoflurane diisocyanate were subjected to a prepolymerization reaction under a nitrogen atmosphere to obtain an isocyanate-terminated prepolymer solution.

[0009] (3) Add adipic acid dihydrazide to the prepolymer solution and carry out the first chain extension reaction under a nitrogen atmosphere. Then add polyionic liquid and carry out the second chain extension reaction under a nitrogen atmosphere to obtain PIM / ADH@PU solution.

[0010] (4) Pour the PIM / ADH@PU solution into a mold and dry it to obtain a PIM / ADH@PU film;

[0011] (5) Dissolve the PIM / ADH@PU film, then add 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, stir to obtain a mixed solution, pour the mixed solution into a mold, and dry to obtain an ionic polyurethane gel.

[0012] In addition, the preparation method of the ionic polyurethane gel according to the above embodiments of the present invention may also have the following additional technical features:

[0013] In some embodiments of the present invention, in step (1), the mass ratio of formaldehyde, glyoxal, and 1,4-butanediamine is 1:1.5-2:2.5-3; the reaction temperature is 25-60°C, and the reaction time is 24-36 h; the dialysis uses a regenerated cellulose membrane to dialyze in deionized water for 36-72 h. Formaldehyde is used to provide the C2 bond of the imidazole ring, glyoxal is used to provide the C4-C5 bond of the imidazole ring, and 1,4-butanediamine is used to provide the nitrogen atoms at the N1 and N3 positions of the imidazole ring, and determines the structure of the polymer chain.

[0014] The synthetic route in step (1) is as follows:

[0015]

[0016] In some embodiments of the present invention, in step (2), the polypropylene glycol bis(2-aminopropyl ether) is heated to remove moisture before the reaction; the isoflurane diisocyanate is dissolved in N,N-dimethylformamide before the reaction. The heating temperature for removing moisture is 80-120°C, and the time is 0.5-1 h; the temperature for the prepolymerization reaction is 25-60°C, and the time is 3-6 h. Polypropylene glycol bis(2-aminopropyl ether) is the soft segment, providing the elastic portion of the elastomer. Isoflurane diisocyanate, as the hard segment, provides a rigid structure that enhances its performance.

[0017] The synthetic route in step (2) is as follows:

[0018]

[0019] In some embodiments of the present invention, in step (3), the temperature of the first chain extension reaction is 40-60°C and the reaction time is 12-36h; the temperature of the second chain extension reaction is 40-60°C and the reaction time is 8-24h.

[0020] This invention synthesizes an ionic polyurethane (PIM / ADH@PU) by polymerizing a polyionic liquid chain extender with polypropylene glycol bis(2-aminopropyl ether) (Mn = 2000), isophorone diisocyanate (IPDI), and adipate dihydrazide (ADH). The resulting IPU is then further composited with the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM[TFSI]) to form an ionic gel. The addition of adipate dihydrazide (ADH) introduces multiple hydrogen bond structures into the ionic gel polymer network, significantly enhancing the mechanical properties of the material and forming multiple hydrogen bonds with the ionic liquid, achieving a self-healing effect.

[0021] The synthetic route in step (3) is as follows:

[0022]

[0023] In some embodiments of the present invention, the molar ratio of polypropylene glycol bis(2-aminopropyl ether), isophorone diisocyanate, adipic acid dihydrazide, and polyionic liquid is 1-1.5:2.4-3.8:1-1.5:0.4-0.8.

[0024] In some embodiments of the present invention, in step (4), the drying is first performed at 60-80°C for 12-36 hours, and then vacuum dried at 60-80°C for 24-48 hours.

[0025] In some embodiments of the present invention, in step (5), the PIM / ADH@PU film is dissolved in N,N-dimethylformamide.

[0026] In some embodiments of the present invention, in step (5), the mass ratio of the PIM / ADH@PU film, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and N,N-dimethylformamide is 1:0.1-1:2.5-5; the stirring temperature is 25-60℃, the stirring time is 0.5-1.5h, and then the mixture is dried in a polytetrafluoroethylene mold at 60-80℃ for 48-96h. The 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM[TFSI]) ionic liquid provides conductivity. The ionic liquid also has a high boiling point and stable properties. The introduction of ionic polyurethane PIM / ADH@PU as an elastomer matrix gives the ionic gel excellent elasticity and toughness.

[0027] In another aspect of the present invention, the present invention provides a method for preparing ionic polyurethane gels.

[0028] In another aspect of the invention, the invention proposes the application of ionic polyurethane gels for the fabrication of flexible sensors.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1) This invention synthesizes a polyionic liquid chain extender with a large number of imidazole groups in the main chain via a Poly-Radziszewski reaction. This reaction method is simple, can be used in a one-step process, and has a high yield with simple post-processing. The polyionic liquid chain extender with amino groups at both ends, introduced into the ionic polyurethane PIM / ADH@PU, can serve as binding sites for electrostatic forces. The introduction of ionic groups on the main chain increases the compatibility between the ionic polyurea and the ionic liquid, preventing leakage of the ionic liquid without hindering its migration. Then, through a simple mixing step, the ionic polyurethane elastomer is dissolved in an organic solvent and the ionic liquid is added to prepare the ionic gel PIM / ADH / IL. n @PU (n = 0.1-0.6) has excellent self-healing properties through electrostatic interactions between ionic bonds.

[0031] 2) The ionic groups on the main chain of ionic polyurethane (IPU) establish electrostatic and ionic dipole interactions with the ionic groups on polyionic liquid (PIM), increasing the compatibility between the ionic polyurethane and the ionic liquid, promoting the uniform dispersion of the ionic liquid, and locking the ionic liquid in place, thus preventing leakage. The synergistic integration of PIM and ionic liquid not only establishes dynamic ionic bonds, endowing the ionic gel with self-healing capabilities, but also utilizes the inherent antibacterial properties of imidazole cations. This multifunctional design of the ionic gel combines leak-proof, self-healing, and antibacterial activity, providing a promising strategy for the development of advanced ionic gels.

[0032] 3) The ionic polyurethane gel provided by this invention belongs to thermoplastic polyurethane elastomers. It is based on a novel polyurethane elastomer containing hydrogen bonds and ionic bonds. Firstly, an adipic acid dihydrazide chain extender containing multiple hydrogen bond sites is introduced. This not only significantly enhances the mechanical strength of the ionic polyurethane as a matrix but also forms hydrogen bonds with the ionic liquid when mixed, promoting the formation of PIM / ADH / IL ionic gel. n Self-healing of @PU(n=0.1-0.6).

[0033] 4) Ionic polyurethane gels, used as flexible sensors, exhibit a wide strain sensing range (0.1–300%) and high sensitivity (GF = 3.02), enabling precise acquisition of human motion sensing signals. They also reliably function as temperature sensors, achieving high sensitivity (-2.14℃ / %) and accuracy (0.2℃ resolution). This work establishes a multifunctional platform for ionic gels in flexible dual-mode sensing systems, enhancing their potential in skin-inspired electronics for next-generation wearable devices.

[0034] 5) The ionic polyurethane gel of the present invention has good biocompatibility and abundant imidazole positive charges on the main chain. The imidazole ring will interact electrostatically with the microbial cell membrane. The multifunctional design of this ionic gel combines leak-proof, self-healing and antibacterial activities, providing a promising strategy for the development of advanced ionic gels. Attached Figure Description

[0035] Figure 1 The above is the hydrogen nuclear magnetic resonance spectrum of PIM in Example 1 of this invention;

[0036] Figure 2 This is the gel permeation chromatogram of PIM in Example 1 of the present invention;

[0037] Figure 3 The ionic polyurethane PIM / ADH@PU in Example 1 of this invention and the ionic polyurethane gel PIM / ADH / IL in Examples 1-6 are examples of this invention. nFT-IR spectra of @PU(n=0.1-0.6);

[0038] Figure 4 The ionic polyurethane PIM / ADH@PU in Example 1 of this invention and the ionic polyurethane gel PIM / ADH / IL in Examples 1-6 are examples of this invention. n XRD pattern of @PU(n=0.1-0.6);

[0039] Figure 5 The ionic polyurethane PIM / ADH@PU in Example 1 of this invention and the ionic polyurethane gel PIM / ADH / IL in Examples 1-6 are examples of this invention. n Transmittance plot of @PU(n=0.1-0.6);

[0040] Figure 6 The ionic polyurethane PIM / ADH@PU in Example 1 of this invention and the ionic polyurethane gel PIM / ADH / IL in Examples 1-6 n The glass transition temperature of @PU(n=0.1-0.6);

[0041] Figure 7 The ionic polyurethane PIM / ADH@PU in Example 1 of this invention and the ionic polyurethane gel PIM / ADH / IL in Examples 1-6 n Thermogravimetric curves of @PU(n=0.1-0.6);

[0042] Figure 8 This is a contact angle diagram between the ionic polyurethane PIM / ADH@PU and the ionic liquid in Embodiment 1 of the present invention;

[0043] Figure 9 The ionic polyurethane PIM / ADH@PU in Example 1 of this invention and the ionic polyurethane gel PIM / ADH / IL in Examples 1-6 are examples of this invention. n Mechanical property diagram of @PU(n=0.1-0.6);

[0044] Figure 10 The ionic polyurethane gel PIM / ADH / IL in Application Example 1 of this invention 0.5 @Self-healing image of PU under an optical microscope; a, e, are ionogels PM / ADH / IL in order. 0.5 Light micrographs of @PU self-healing at 33℃ for 0h, 3h, 6h, 9h, and 12h.

[0045] Figure 11 The ionic polyurethane gel PIM / ADH / IL in Application Example 1 of this invention 0.5 @Mechanical properties of PU at room temperature self-healing;

[0046] Figure 12 The ionic polyurethane gel PIM / ADH / IL in Application Example 1 of this invention 0.5 @PU self-healing process diagram at high temperature;

[0047] Figure 13 In Example 1 of this invention, PIM / ADH / IL were observed before and after self-healing under different tensile strains. 0.5 Graph showing the resistance signal variation of PU ionic polyurethane gel;

[0048] Figure 14 In Example 1 of this invention, the PIM / ADH / IL before and after self-healing under 100%-300% strain are shown. 0.5 Changes in the resistance signal of PU ionic polyurethane gel;

[0049] Figure 15 In Example 1 of the application of this invention, PIM / ADH / IL 0.5 The excellent tensile properties of ionic polyurethane gel enable it to perform sensing functions over a wide strain range.

[0050] Figure 16 In Example 1 of this invention, PIM / ADH / IL are measured at different angles of finger bending. 0.5 Graph showing the resistance signal variation of PU ionic polyurethane gel;

[0051] Figure 17 In Example 1 of the application of this invention, PIM / ADH / IL 0.5 Conductivity graph of PU ionic polyurethane gel at different temperatures;

[0052] Figure 18 The ionic polyurethane gel PIM / ADH / IL in Application Example 1 of this invention 0.5 It can detect sensor signals at different temperatures;

[0053] Figure 19 Example 1 of this invention describes the application of ionic polyurethane gel PIM / ADH / IL. 0.5 The results of 5 cycles at 30-40℃ are shown in the figure.

[0054] Figure 20 The ion gel sensor PIM / ADH / IL in Application Example 1 of this invention 0.5 A graph showing the change in sensor signal between exhalation and inhalation during deep breathing in a human body when used as a temperature sensor;

[0055] Figure 21 This is a graph showing the change in the sensing signal between exhalation and inhalation during normal human breathing when the ionogel sensor PIM / ADH / IL0.5 is used as a temperature sensor in Application Example 1 of this invention.

[0056] Figure 22 The ionic polyurethane gel PIM / ADH / IL in Application Example 1 of this invention 0.5 Antibacterial diagrams against Escherichia coli and Staphylococcus aureus;

[0057] Figure 23 This is a flowchart of the preparation process of step (5) in Embodiment 1 of the present invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0059] Example 1

[0060] A method for preparing ionic polyurethane gel includes the following steps:

[0061] (1) Synthesis of PIM: 0.88 g of 1,4-butanediamine was dissolved in 75 mL of acetic acid and cooled in an ice bath. 0.81 g of 37% formaldehyde solution and 1.45 g of 40% glyoxal solution were dissolved in 37.5 mL of deionized water, and the mixture was added dropwise to the 1,4-butanediamine solution. The resulting mixture was stirred at 25 °C for 24 h, and then the solvent was evaporated using a rotary evaporator. The dried product was redissolved in deionized water, dialyzed against a regenerated cellulose membrane (MWCO 1 kDa) for 72 h, and then freeze-dried to obtain polyimide (PIM). Acetic acid served as both a catalyst and solvent, providing an acidic reaction environment, accelerating the cyclization reaction, and inhibiting side reactions.

[0062] like Figure 1 As shown, the successful synthesis of product PIM is confirmed by the appearance of peaks such as the newly formed imidazole ring (δ = 9.8, 7.8 ppm) in deuterated dimethyl sulfoxide (DMSO-d6) NMR. Figure 2 As shown, the molecular weight of PIM is Mn = 3000, and PDI = 2.14.

[0063] (2) Prepolymer Solution: First, 8.0 g of polypropylene glycol bis(2-aminopropyl ether) was added to a 500 mL three-necked flask and heated in a vacuum oven at 120 °C for 1 h to remove moisture. After cooling to 60 °C, 2.52 g of isoflurane diisocyanate (IPDI) was dissolved in 5 mL of ultra-dry N,N-dimethylformamide (DMF) and added to the three-necked flask. The mixture was reacted at 60 °C for 3 h under a nitrogen atmosphere. After the reaction, an isocyanate-terminated prepolymer solution was successfully obtained.

[0064] (3) PIM / ADH@PU solution: 0.96 g of adipate dihydrazide (ADH) was dissolved in 20 mL of ultra-dry N,N-dimethylformamide (DMF) at 60 °C, and then added to the prepolymer solution. The reaction was carried out at 60 °C for 24 h under a nitrogen atmosphere. After the chain extension reaction was completed, the temperature was lowered to 45 °C. 2.4 g of polyimide (PIM) was dissolved in 10 mL of ultra-dry N,N-dimethylformamide (DMF) at 80 °C and added to the reaction solution. The mixture was reacted at 45 °C under a nitrogen atmosphere for 8 h.

[0065] (4) Preparation of PIM / ADH@PU film: PIM / ADH@PU solution was poured into a polytetrafluoroethylene (PTFE) mold. After drying at 80℃ for 12h, and then vacuum drying at 60℃ for 24h, PIM / ADH@PU film was successfully obtained.

[0066] like Figure 8 As shown, due to the introduction of the polyionic liquid, PIM / ADH@PU forms an electrostatic interaction with the small molecules of the ionic liquid, resulting in a low contact angle and good compatibility. Furthermore, over time, the contact angle between the ionic polyurethane PIM / ADH@PU and the ionic liquid remains stable after 9 days, further demonstrating the excellent compatibility between ionic polyurethane and ionic liquid.

[0067] (5) PIM / ADH / IL 0.1 Preparation of ionic polyurethane gels, such as Figure 23 As shown: 2.0 g of PIM / ADH@PU film was dissolved in 10 mL of N,N-dimethylformamide (DMF), and then 0.22 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM]TFSI) was added. After stirring for 1 h, the mixture was poured into a polytetrafluoroethylene (PTFE) mold and evaporated at 60 °C for 48 h. Ionic polyurethane gel was obtained by further drying in a vacuum oven at 60 °C for 24 h. A 10% PIM / ADH / IL film was prepared. 0.1 Ionic polyurethane gel.

[0068] Example 2

[0069] A method for preparing ionic polyurethane gel includes the following steps:

[0070] (1) Synthesis of PIM: 0.88 g of 1,4-butanediamine was dissolved in 75 mL of acetic acid and cooled in an ice bath. 0.81 g of 37% formaldehyde solution and 1.45 g of 40% glyoxal solution were dissolved in 37.5 mL of deionized water, and the mixture was added dropwise to the 1,4-butanediamine solution. The resulting mixture was stirred at 25 °C for 24 h, and then the solvent was evaporated using a rotary evaporator. The dried product was redissolved in deionized water, dialyzed against a regenerated cellulose membrane (MWCO 1 kDa) for 72 h, and then freeze-dried to obtain polyimide (PIM).

[0071] (2) Prepolymer Solution: First, 8.0 g of polypropylene glycol bis(2-aminopropyl ether) was added to a 500 mL three-necked flask and heated in a vacuum oven at 120 °C for 1 h to remove moisture. After cooling to 60 °C, 2.52 g of isoflurane diisocyanate (IPDI) was dissolved in 5 mL of ultra-dry N,N-dimethylformamide (DMF) and added to the three-necked flask. The mixture was reacted at 60 °C for 3 h under a nitrogen atmosphere. After the reaction, an isocyanate-terminated prepolymer solution was successfully obtained.

[0072] (3) PIM / ADH@PU solution: Dissolve 0.96 g of adipate dihydrazide (ADH) in 20-40 mL of ultra-dry N,N-dimethylformamide (DMF) at 60 °C, and then add it to the prepolymer solution. React at 60 °C for 24 h under a nitrogen atmosphere. After the chain extension reaction is completed, lower the temperature to 45 °C. Dissolve 2.4 g of polyionic liquid (PIM) in 10 mL of ultra-dry N,N-dimethylformamide (DMF) at 80 °C and add it to the reaction solution. React the mixture at 45 °C under a nitrogen atmosphere for 8 h.

[0073] (4) Preparation of PIM / ADH@PU film: PIM / ADH@PU solution was poured into a polytetrafluoroethylene (PTFE) mold. After drying at 80℃ for 12h, and then vacuum drying at 60℃ for 24h, PIM / ADH@PU film was successfully obtained.

[0074] (5) PIM / ADH / IL 0.2Preparation of ionic polyurethane gel: 2.0 g of PIM / ADH@PU film was dissolved in 10-15 mL of N,N-dimethylformamide (DMF), and then 0.5 g of [BMIM]TFSI was added. After stirring for 30 minutes, the mixture was poured into a polytetrafluoroethylene (PTFE) mold. The mixture was then evaporated at 60 °C for 48 h. Ionic polyurethane gel was obtained by further drying in a vacuum oven at 60 °C for 24 h. A 20% PIM / ADH / IL gel was prepared. 0.2 Ionic polyurethane gel.

[0075] Example 3

[0076] A method for preparing ionic polyurethane gel includes the following steps:

[0077] (1) Synthesis of PIM: 0.88 g of 1,4-butanediamine was dissolved in 75 mL of acetic acid and cooled in an ice bath. 0.81 g of 37% formaldehyde solution and 1.45 g of 40% glyoxal solution were dissolved in 37.5 mL of deionized water, and the mixture was added dropwise to the 1,4-butanediamine solution. The resulting mixture was stirred at 25 °C for 24 h, and then the solvent was evaporated using a rotary evaporator. The dried product was redissolved in deionized water, dialyzed against a regenerated cellulose membrane (MWCO 1 kDa) for 72 h, and then freeze-dried to obtain polyimide (PIM).

[0078] (2) Prepolymer Solution: First, 8.0 g of polypropylene glycol bis(2-aminopropyl ether) was added to a 500 mL three-necked flask and heated in a vacuum oven at 120 °C for 1 h to remove moisture. After cooling to 60 °C, 2.52 g of isoflurane diisocyanate (IPDI) was dissolved in 5 mL of ultra-dry N,N-dimethylformamide (DMF) and added to the three-necked flask. The mixture was reacted at 60 °C for 3 h under a nitrogen atmosphere. After the reaction, an isocyanate-terminated prepolymer solution was successfully obtained.

[0079] (3) PIM / ADH@PU solution: 0.96 g of adipate dihydrazide (ADH) was dissolved in 20 mL of ultra-dry N,N-dimethylformamide (DMF) at 60 °C, and then added to the prepolymer solution. The reaction was carried out at 60 °C for 24 h under a nitrogen atmosphere. After the chain extension reaction was completed, the temperature was lowered to 45 °C. 2.4 g of polyionic liquid (PIM) was dissolved in 10 mL of ultra-dry N,N-dimethylformamide (DMF) at 80 °C and added to the reaction solution. The mixture was reacted at 45 °C under a nitrogen atmosphere for 8 h.

[0080] (4) Preparation of PIM / ADH@PU film: The PIM / ADH@PU solution was poured into a polytetrafluoroethylene (PTFE) mold with dimensions of 4cm×4cm×0.1cm (length×width×thickness). After drying at 80℃ for 12h, and then vacuum drying at 60℃ for 24h, the PIM / ADH@PU film was successfully obtained.

[0081] (5) PIM / ADH / IL 0.3 Preparation of ionic polyurethane gel: 2.0 g of PIM / ADH@PU film was dissolved in 10.0 mL of N,N-dimethylformamide (DMF), and then 0.86 g of [BMIM]TFSI was added. After stirring for 30 minutes, the mixture solution was poured into a polytetrafluoroethylene (PTFE) mold. The mixture was then evaporated at 60 °C for 48 h. Ionic polyurethane gel was obtained by further drying in a vacuum oven at 60 °C for 24 h. A 30% (w / w) PIM / ADH / IL gel was prepared. 0.3 Ionic polyurethane gel.

[0082] Example 4

[0083] A method for preparing ionic polyurethane gel includes the following steps:

[0084] (1) Synthesis of PIM: 0.88 g of 1,4-butanediamine was dissolved in 75 mL of acetic acid and cooled in an ice bath. 0.81 g of 37% formaldehyde solution and 1.45 g of 40% glyoxal solution were dissolved in 37.5 mL of deionized water, and the mixture was added dropwise to the 1,4-butanediamine solution. The resulting mixture was stirred at 25 °C for 24 h, and then the solvent was evaporated using a rotary evaporator. The dried product was redissolved in deionized water, dialyzed against a regenerated cellulose membrane (MWCO 1 kDa) for 72 h, and then freeze-dried to obtain polyimide (PIM).

[0085] (2) Prepolymer Solution: First, 8.0 g of polypropylene glycol bis(2-aminopropyl ether) was added to a 500 mL three-necked flask and heated in a vacuum oven at 120 °C for 1 h to remove moisture. After cooling to 60 °C, 2.52 g of isoflurane diisocyanate (IPDI) was dissolved in 5 mL of ultra-dry N,N-dimethylformamide (DMF) and added to the three-necked flask. The mixture was reacted at 60 °C for 3 h under a nitrogen atmosphere. After the reaction, an isocyanate-terminated prepolymer solution was successfully obtained.

[0086] (3) PIM / ADH@PU solution: 0.96 g of adipate dihydrazide (ADH) was dissolved in 20 mL of ultra-dry N,N-dimethylformamide (DMF) at 60 °C, and then added to the prepolymer solution. The reaction was carried out at 60 °C for 24 h under a nitrogen atmosphere. After the chain extension reaction was completed, the temperature was lowered to 45 °C. 2.4 g of polyionic liquid (PIM) was dissolved in 10 mL of ultra-dry N,N-dimethylformamide (DMF) at 80 °C and added to the reaction solution. The mixture was reacted at 45 °C under a nitrogen atmosphere for 8 h.

[0087] (4) Preparation of PIM / ADH@PU film: PIM / ADH@PU solution was poured into a polytetrafluoroethylene (PTFE) mold. After drying at 80℃ for 12h, and then vacuum drying at 60℃ for 24h, PIM / ADH@PU film was successfully obtained.

[0088] (5) PIM / ADH / IL 0.4 Preparation of ionic polyurethane gel: 2.0 g of PIM / ADH@PU film was dissolved in 10.0 mL of N,N-dimethylformamide (DMF), and then 1.33 g of [BMIM]TFSI was added. After stirring for 30 minutes, the mixture was poured into a polytetrafluoroethylene (PTFE) mold. The mixture was then evaporated at 80 °C for 12 h. Ionic polyurethane gel was obtained by further drying in a vacuum oven at 60 °C for 24 h. A 40% PIM / ADH / IL gel was prepared. 0.4 Ionic polyurethane gel.

[0089] Example 5

[0090] A method for preparing ionic polyurethane gel includes the following steps:

[0091] (1) Synthesis of PIM: 0.88 g of 1,4-butanediamine was dissolved in 75 mL of acetic acid and cooled in an ice bath. 0.81 g of 37% formaldehyde solution and 1.45 g of 40% glyoxal solution were dissolved in 37.5 mL of deionized water, and the mixture was added dropwise to the 1,4-butanediamine solution. The resulting mixture was stirred at 25 °C for 24 h, and then the solvent was evaporated using a rotary evaporator. The dried product was redissolved in deionized water, dialyzed against a regenerated cellulose membrane (MWCO 1 kDa) for 72 h, and then freeze-dried to obtain polyimide (PIM).

[0092] (2) Prepolymer Solution: First, 8.0 g of polypropylene glycol bis(2-aminopropyl ether) was added to a 500 mL three-necked flask and heated in a vacuum oven at 120 °C for 1 h to remove moisture. After cooling to 60 °C, 2.52 g of isoflurane diisocyanate (IPDI) was dissolved in 5 mL of ultra-dry N,N-dimethylformamide (DMF) and added to the three-necked flask. The mixture was reacted at 60 °C for 3 h under a nitrogen atmosphere. After the reaction, an isocyanate-terminated prepolymer solution was successfully obtained.

[0093] (3) PIM / ADH@PU solution: 0.96 g of adipate dihydrazide (ADH) was dissolved in 20 mL of ultra-dry N,N-dimethylformamide (DMF) at 60 °C, and then added to the prepolymer solution. The reaction was carried out at 60 °C for 24 h under a nitrogen atmosphere. After the chain extension reaction was completed, the temperature was lowered to 45 °C. 2.4 g of polyionic liquid (PIM) was dissolved in 10 mL of ultra-dry N,N-dimethylformamide (DMF) at 80 °C and added to the reaction solution. The mixture was reacted at 45 °C under a nitrogen atmosphere for 8 h.

[0094] (4) Preparation of PIM / ADH@PU film: PIM / ADH@PU solution was poured into a polytetrafluoroethylene (PTFE) mold. After drying at 80℃ for 12h, and then vacuum drying at 60℃ for 24h, PIM / ADH@PU film was successfully obtained.

[0095] (5) PIM / ADH / IL 0.5 Preparation of ionic polyurethane gel: 2.0 g of PIM / ADH@PU film was dissolved in 10.0 mL of N,N-dimethylformamide (DMF), and then 2.0 g of [BMIM]TFSI was added. After stirring for 30 minutes, the mixture was poured into a polytetrafluoroethylene (PTFE) mold. The mixture was then evaporated at 60 °C for 48 h. Ionic polyurethane gel was obtained by further drying in a vacuum oven at 60 °C for 24 h. A 50% PIM film was prepared. / ADH / IL 0.5 Ionic polyurethane gel.

[0096] Example 6

[0097] A method for preparing ionic polyurethane gel includes the following steps:

[0098] (1) Synthesis of PIM: 0.88 g of 1,4-butanediamine was dissolved in 75 mL of acetic acid and cooled in an ice bath. 0.81 g of 37% formaldehyde solution and 1.45 g of 40% glyoxal solution were dissolved in 37.5 mL of deionized water, and the mixture was added dropwise to the 1,4-butanediamine solution. The resulting mixture was stirred at 25 °C for 24 h, and then the solvent was evaporated using a rotary evaporator. The dried product was redissolved in deionized water, dialyzed against a regenerated cellulose membrane (MWCO 1 kDa) for 72 h, and then freeze-dried to obtain polyimide (PIM).

[0099] (2) Prepolymer Solution: First, 8.0 g of polypropylene glycol bis(2-aminopropyl ether) was added to a 500 mL three-necked flask and heated in a vacuum oven at 120 °C for 1 h to remove moisture. After cooling to 60 °C, 2.52 g of isoflurane diisocyanate (IPDI) was dissolved in 5 mL of ultra-dry N,N-dimethylformamide (DMF) and added to the three-necked flask. The mixture was reacted at 60 °C for 3 h under a nitrogen atmosphere. After the reaction, an isocyanate-terminated prepolymer solution was successfully obtained.

[0100] (3) PIM / ADH@PU solution: 0.96 g of adipate dihydrazide (ADH) was dissolved in 20 mL of ultra-dry N,N-dimethylformamide (DMF) at 60 °C, and then added to the prepolymer solution. The reaction was carried out at 60 °C for 24 h under a nitrogen atmosphere. After the chain extension reaction was completed, the temperature was lowered to 45 °C. 2.4 g of polyionic liquid (PIM) was dissolved in 10 mL of ultra-dry N,N-dimethylformamide (DMF) at 80 °C and added to the reaction solution. The mixture was reacted at 45 °C under a nitrogen atmosphere for 8 h.

[0101] (4) Preparation of PIM / ADH@PU film: PIM / ADH@PU solution was poured into a polytetrafluoroethylene (PTFE) mold. After drying at 80℃ for 12h, and then vacuum drying at 60℃ for 24h, PIM / ADH@PU film was successfully obtained.

[0102] (5) PIM / ADH / IL 0.6 Preparation of ionic polyurethane gel: 2.0 g of PIM / ADH@PU film was dissolved in 10.0 mL of N,N-dimethylformamide (DMF), and then 3.0 g of [BMIM]TFSI was added. After stirring for 30 minutes, the mixture was poured into a polytetrafluoroethylene (PTFE) mold. The mixture was then evaporated at 60 °C for 48 h. Ionic polyurethane gel was obtained by further drying in a vacuum oven at 60 °C for 24 h. A 60% PIM film was prepared. / ADH / IL 0.6 Ionic polyurethane gel.

[0103] like Figure 3 As shown, by 2260cm -1 The absorption peak of -NCO at 1357 cm⁻¹ essentially disappeared, proving that -NCO and -NH₂ reacted almost completely in ionic polyurethane. In ionic polyurethane gels, the absorption peak at 1357 cm⁻¹... -1 and 1198cm -1 Attributable to the tensile vibration of the S=O bond, 1201.3 cm -1 and 1055cm -1 The tensile vibrations of CF and SNS bonds respectively indicate the successful synthesis of ionic polyurethane gel.

[0104] like Figure 4 As shown, all ionic polyurethane gels with different IL contents are amorphous at room temperature. As the content of ionic liquid increases, the ionic liquid will form hydrogen bonds with the soft segments, which will destroy the regularity of the original chain segments. This will lead to the destruction of hydrogen bonds in the ionic polyurethane, a reduction in the degree of microphase separation, and a continuous decrease in the intensity of the diffraction peaks of the ionic polyurethane gel.

[0105] like Figure 5 As shown, the UV-Vis spectra of the thin film and ionogel were recorded at ambient temperature using an Agilent (USA) CARY 5000UV-Vis-NIR instrument, with a wavelength range of 400-800 nm. With increasing ionic liquid content, hydrogen bonds are broken, leading to a decrease in crystallinity. Therefore, the transmittance of the ionotropic polyurethane gel continuously increases with increasing ionic liquid content. It also exhibits good transparency, making it well-suited for various everyday applications.

[0106] like Figure 6 As shown, differential scanning calorimetry (DSC) measurements were performed on a TADSC Q2000 thermal analysis system, with a temperature range of -80 to 120 °C. Heating and cooling rates were set to 10 °C / min, and nitrogen flow rate was set to 40 mL / min. The glass transition temperature (Tg) was... g The glass transition temperature was determined based on the median transition point recorded during the second heating process. Because the ionic liquid acts as a plasticizer, the chain segments move more easily as the ionic liquid content increases, and the glass transition temperature of the ionic polyurethane gel continuously decreases.

[0107] like Figure 7 As shown, thermogravimetric analysis (TGA) was performed on the dried film and ionogel samples using a TGA8000 thermogravimetric analyzer, with temperatures ranging from room temperature to 800 °C and a heating rate of 10 °C / min under a nitrogen flow. Due to the excellent thermal stability of ionic liquids, the ionotropic polyurethane gel exhibited excellent thermal stability.

[0108] like Figure 9 As shown, the tensile stress-strain curves of the ionomer gel were obtained at room temperature using a universal testing machine (CMT 4104, (Shenzhen) Laboratory Equipment Co., Ltd.). The stress showed a decreasing trend with the increase of ion liquid content. This is because the ion liquid forms hydrogen bonds with the ether bonds of the soft segment, which destroys the original hydrogen bonds in the system and reduces the degree of microphase separation, resulting in a continuous decrease in the mechanical properties of the ionomer polyurethane gel.

[0109] Application Example 1

[0110] Ionic polyurethane gels were used to fabricate flexible sensors, specifically the ionic polyurethane gels PIM / ADH / IL prepared in Examples 1-6. n @PU (n=0.1-0.6) and the ionic polyurethane PIM / ADH@PU prepared in Example 1.

[0111] like Figure 10 As shown, PIM / ADH / IL 0.5 @PU scratch self-healing experiment at room temperature: A blade with a width of 100 micrometers was used to puncture an iontophoresis gel with a thickness of approximately 0.25 mm. The puncture healing performance of the iontophoresis gel at 33°C was observed using an optical microscope. Figure ae shows optical microscope images of the self-healing process after 0, 3, 6, 9, and 12 hours. Due to the multiple hydrogen bonds and ionic bonds in the iontophoresis gel system, the iontophoresis gel can achieve complete self-healing within 6 hours.

[0112] like Figure 11 As shown, PIM / ADH / IL is selected. 0.5 @PU was used as a self-healing sample. The original film and the ionogel sample (70mm×10mm×1.2mm) were cut into two pieces. The two ends were then brought into full contact under appropriate pressure. The self-healing performance was then tested by heating in a 33℃ vacuum oven for different times. The samples were tested at a stretching rate of 30mm / min, and each sample was tested three times repeatedly. When the ionopolymer gel fractured, the ionic and hydrogen bonds at the interface broke preferentially. When the two broken parts of the gel reconnected, the ionic and hydrogen bonds quickly reconnected. Simultaneously, due to the good solubility of the ionic liquid soft segments and the good mobility of the soft segment chains in the gel, they could move between the two interfaces and re-entangle, thus achieving the self-healing process.

[0113] like Figure 12 As shown, PIM / ADH / IL is selected. 0.5@PU was used as a self-healing sample. The original film and the ionogel sample (70mm×10mm×1.2mm) were cut into two pieces. The two ends were then brought into full contact under appropriate pressure. The self-healing performance was then tested by heating in an 80℃ vacuum oven for different times. The samples were tested at a stretching rate of 30mm / min, and each sample was tested three times. Compared to room temperature, the healing time was shorter at higher temperatures. This is because the chain segments migrate more easily at higher temperatures, and hydrogen bonds recombine more quickly, allowing them to move and re-entangle between the two interfaces more rapidly, thus achieving the self-healing process.

[0114] like Figure 13 As shown, the relative resistance change (ΔR / R0) was calculated by monitoring the current at a constant voltage of 2.5V using a portable electrochemical workstation (HY-2550, Shenzhen). Two copper wires were connected to the testing device, with their other ends connected to the two ends of an ionomer gel (40mm×4mm×0.5mm). Cyclic tensile testing was performed using a tensile testing machine (CMT 4104), and the change in relative resistance signal with strain was recorded in real time. The testing conditions were room temperature (25℃). The formula for calculating ΔR / R0 is as follows:

[0115] ΔR / R0=(R-R0) / R0

[0116] In the formula, R represents the resistance after stretching, and R0 represents the original resistance.

[0117] Due to its excellent elasticity and durability, the original and cured PIM / ADH / IL 0.5 @PU ionic polyurethane gel sensors can generate clear and repeatable electrical signals under small strains, and can detect strains as low as 0.1%.

[0118] like Figure 14 As shown, due to its good elasticity and durability, the original and cured PIM / ADH / IL 0.5 @PU ionic polyurethane gel sensors can generate clear and repeatable electrical signals under large strain, and strain detection can detect 300% of the strain.

[0119] like Figure 15 As shown, the experimental steps are the same. Figure 13 Experimental procedure: GF=(ΔR / R0) / L, where R represents the resistance after stretching, R0 represents the original resistance, and L represents the stretching factor relative to the original length of the ionogel.

[0120] The GF values ​​were fitted in three parts: GF = 1.52 for the small strain range of 0 to 100%, GF = 2.158 for the medium strain range of 100% to 400%, and GF = 3.08 for the large strain range of 400% to 1000%. Ionic polyurethane gel exhibits excellent strain response as a strain sensor.

[0121] like Figure 16 As shown, a portable electrochemical workstation (HY-2550, Shenzhen) was used to monitor the current at a constant voltage of 2.5V to calculate the relative resistance change (ΔR / R0). Alligator clips from the electrochemical workstation were used to connect to both ends of the ionogel (40mm × 4mm × 0.5mm), and 3M insulating tape was used to fix the ionogel to the corresponding joint of the subject to sense joint movement and record changes in the relative resistance signal in real time. The ionogel generated a stable signal when the finger was bent at different angles, demonstrating its promising potential in detecting human movement.

[0122] like Figure 17 As shown, by using iontophoresis gel PIM / ADH / IL 0.5 The PIM / ADH / ILn@PU ionogel was fixed on a heating stage, and its ionic conductivity (σ) at different temperatures was measured using an electrochemical workstation (CHI660E, Chenhua). A voltage amplitude of 10 mV was applied to measure the impedance within a frequency range of 1 MHz to 0.1 Hz. The conductivity was calculated as follows:

[0123] σ=d / RA

[0124] Where d, R, and A represent the distance between the two electrodes, the resistivity, and the cross-sectional area of ​​the PIM / ADH / ILn@PU ion gel, respectively.

[0125] like Figure 18 As shown, when PIM / ADH / IL 0.5 When using @PU ionogel as a temperature sensor, it was cut into rectangles of 40mm × 10mm × 0.5mm, with copper wires connected at both ends as electrodes. A portable potentiometer (HY-2550, Shenzhen) was used to detect the change in relative resistance signal with temperature. It was then sealed with transparent tape to avoid unnecessary deformation. The temperature stimulus used for measurement was controlled by an INSTEC heating stage equipped with a liquid nitrogen-cooled mercury cadmium telluride (MCT) detector. The PIM / ADH / IL0.5@PU ionogel temperature sensor was placed on the heating stage, and the temperature was increased from 30℃ to 100℃ at a rate of 30℃ / min. The temperature coefficient of resistance (TCR) was calculated using the following formula:

[0126] TCR=(ΔR / R0) / ΔT

[0127] In the formula, R represents the resistance after heating, R0 represents the original resistance, and ΔT represents the temperature change of the ion gel.

[0128] PIM / ADH / IL 0.5 @PU ionic polyurethane gel exhibits excellent temperature sensing capabilities, showing a significant decreasing trend as the temperature increases from 30℃ to 100℃. The curve is non-linear within the measurement range, and piecewise fitting yields more accurate TCR values. The TCR1 is 2.14% / ℃ (30–60℃) and TCR2 is 0.53% / ℃ (70–100℃). These results demonstrate that ionic polyurethane gel possesses excellent thermal response.

[0129] like Figure 19 As shown, R0 and R represent the resistance values ​​of the sensor at the initial temperature and the measurement temperature, respectively, and ΔT represents the temperature difference. Five cycles of heating-cooling tests were conducted at a heating rate of 20℃ / min, ranging from 30℃ to 40℃.

[0130] Because PIM / ADH / IL 0.5 @PU ionic polyurethane gel is highly relevant to its practical application as ionic skin. The change in ΔR / R0 remains almost constant over five cycles of temperature switching between 30°C and 40°C, demonstrating the effectiveness of PIM / ADH / IL-based ionic skin gel. 0.5 The temperature sensor exhibits good repeatability.

[0131] like Figure 20-21 As shown, PIM / ADH / IL 0.5 @PU ionic polyurethane gel is applied under the nostrils and connected to a portable electrochemical workstation (HY-2550, Shenzhen) to detect changes in resistance during respiration at different breathing frequencies.

[0132] Because temperature sensors can detect minute temperature changes, it's worth noting that the sensor can clearly distinguish between a volunteer's normal breathing and deep breathing based on the temperature difference. There is a temperature difference of approximately 1.0–3.1°C between inhalation and exhalation, which causes variations. When the volunteer is breathing rapidly, there is a smaller temperature difference between inhalation and exhalation. However, when the volunteer is breathing slowly, there is a larger temperature difference between inhalation and exhalation. A larger temperature difference will produce a larger ΔR / R0 sensing signal.

[0133] like Figure 22As shown, the antibacterial experiment was conducted as follows: First, frozen Escherichia coli and Staphylococcus aureus were activated to prepare bacterial suspensions. Then, 20 μL of the bacterial suspension (OD600 = 0.01) was inoculated onto the sample surface (10 mm × 10 mm) and incubated at 37°C for 2 hours. Subsequently, the bacteria from the sample surface were collected into 2 mL of sterile culture medium; simultaneously, 20 μL of the bacterial suspension (OD600 = 0.01) was placed into 2 mL of sterile culture medium as a blank control. Finally, 20 μL of the bacterial suspension from each sample was inoculated onto agar plates using the spread plate method and incubated at 37°C for 24 hours. Each antibacterial experiment was repeated three times. The number of colonies was counted using the plate counting method, and the antibacterial rate was calculated using the following formula:

[0134] Bacterial survival rate(%)=C / B*100%

[0135] In the formula, B refers to the number of colonies in the blank control group, and C refers to the number of colonies in the experimental group.

[0136] Testing ion gel PIM / ADH / IL 0.5 The antibacterial properties of ionic polyurethane (PU) against *Escherichia coli* and *Staphylococcus aureus* are due to the presence of a large number of imidazole cations in the ionic gel. These cations originate from both the imidazole cations on the ionic polyurethane backbone and from the added ionic liquid. The antibacterial activity of imidazoles is primarily attributed to the cationic nature of the imidazole ring and the hydrophobic carbon chain. The imidazole ring interacts electrostatically with the microbial cell membrane, while the alkyl chain disrupts the lipid layer structure of the cell membrane, leading to leakage of intracellular substances and ultimately cell death.

[0137] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing ionic polyurethane gel, characterized in that, Includes the following steps: (1) Formaldehyde, glyoxal and 1,4-butanediamine were mixed and stirred to react. The product was dried and dialyzed, and then dried to obtain a polyionic liquid. (2) Polypropylene glycol bis(2-aminopropyl ether) and isoflurane diisocyanate were subjected to a prepolymerization reaction under a nitrogen atmosphere to obtain an isocyanate-terminated prepolymer solution. (3) Add adipic acid dihydrazide to the prepolymer solution and carry out the first chain extension reaction under a nitrogen atmosphere. Then add polyionic liquid and carry out the second chain extension reaction under a nitrogen atmosphere to obtain PIM / ADH@PU solution. (4) Pour the PIM / ADH@PU solution into a mold and dry it to obtain a PIM / ADH@PU film; (5) Dissolve the PIM / ADH@PU film, then add 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, stir to obtain a mixed solution, and dry to obtain the ionic polyurethane gel.

2. The method for preparing ionic polyurethane gel according to claim 1, characterized in that: In step (1), the mass ratio of formaldehyde, glyoxal, and 1,4-butanediamine is 1:1.5-2:2.5-3; the reaction temperature is 25-60℃ and the reaction time is 24-36h; the dialysis uses a regenerated cellulose membrane to dialyze in deionized water for 36-72h.

3. The method for preparing ionic polyurethane gel according to claim 1, characterized in that: In step (2), the polypropylene glycol bis(2-aminopropyl ether) is heated to remove moisture before the reaction; the heating temperature for removing moisture is 80-120℃ and the time is 0.5-1h; the isoflurane diisocyanate is dissolved in N,N-dimethylformamide before the reaction; the temperature of the prepolymerization reaction is 25-60℃ and the time is 3-6h.

4. The method for preparing ionic polyurethane gel according to claim 1, characterized in that: In step (3), the temperature of the first chain extension reaction is 40-60℃ and the reaction time is 12-36h; the temperature of the second chain extension reaction is 40-60℃ and the reaction time is 8-24h.

5. The method for preparing ionic polyurethane gel according to claim 1, characterized in that: The molar ratio of polypropylene glycol bis(2-aminopropyl ether), isophorone diisocyanate, adipic acid dihydrazide, and polyionic liquid is 1-1.5:2.4-3.8:1-1.5:0.4-0.

8.

6. The method for preparing ionic polyurethane gel according to claim 1, characterized in that: In step (4), the drying process involves first drying at 60-80℃ for 12-36 hours, and then vacuum drying at 60-80℃ for 24-48 hours.

7. The method for preparing ionic polyurethane gel according to claim 1, characterized in that: In step (5), the PIM / ADH@PU film is dissolved in N,N-dimethylformamide.

8. The method for preparing ionic polyurethane gel according to claim 7, characterized in that: In step (5), the mass ratio of the PIM / ADH@PU film, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and N,N-dimethylformamide is 1:0.1-1:2.5-5; the stirring temperature is 25-60℃ and the stirring time is 0.5-1.5h; then the film is dried in a mold at 60-80℃ for 48-96h.

9. An ionic polyurethane gel prepared by the method of any one of claims 1-8.

10. The application of the ionic polyurethane gel according to claim 9, characterized in that: The ionic polyurethane gel is used to fabricate flexible sensors.

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