High-toughness deep eutectic gel as well as preparation method and application thereof

Abstract

The invention discloses high-toughness deep eutectic gel as well as a preparation method and application thereof. According to the method, a PVA aqueous solution is soaked in a deep eutectic solvent, and after water in the PVA aqueous solution is completely replaced by the deep eutectic solvent, the deep eutectic gel is prepared. According to the invention, the mechanical property of the deep eutectic gel is regulated and controlled by regulating a hydrogen bond network structure in PVA molecular chains and between the PVA molecular chains, the regulating range of the tensile strength is 8.19 MPa-31.53 MPa, the regulating range of the toughness is 69.84 MJ m <-3 >-203.38 MJ m <-3 >, and the regulating range of the elastic modulus is 3.38 MPa-1301 MPa. The deep eutectic gel with high strength and high toughness has good electrical conductivity and environmental stability at the same time, and has wide application prospects in the field of flexible electronic devices.

Description

Technical Field

[0001] The invention belongs to the field of gel electrolytes and relates to a high-strength and tough deep eutectic gel and a preparation method and application thereof. Background Art

[0002] In recent years, with the booming research in the fields of human-computer interaction such as cloud computing, metaverse, and advanced medicine and biology, the demand for flexible electronic products such as personalized smart wearable devices, soft robots, and electronic skin is increasing. Most flexible electronic devices are composed of two layers of flexible electrodes wrapped with a gel electrolyte in the middle. At present, traditional gel electrolytes with water, organic solvents or ionic liquids as the continuous phase have problems such as poor temperature resistance, low conductivity, bio-incompatibility, and high cost, which hinder their practical application.

[0003] Deep eutectic gel is a new type of gel electrolyte that has emerged in recent years. Thanks to the inherent high conductivity, weak volatility, and high environmental stability of deep eutectic solvents (DESs), deep eutectic gel has broad application prospects in energy, electronics, and environmental science. However, the practical application of deep eutectic gel is often limited by its insufficient strength and toughness (usually strength <30MPa, toughness <100MJ m -3 ) and is restricted (Adv. Mater., 2024, 36, 2309576; Adv. Funct. Mater., 2022, 32, 2206305). Summary of the invention

[0004] The purpose of the present invention is to provide a high-strength and tough deep eutectic gel and its preparation method and application. The present invention adjusts the hydrogen bond network structure of the deep eutectic solvent by regulating the number and type of hydrogen bond functional groups in the deep eutectic solvent, and the change of the hydrogen bond network structure can effectively regulate the aggregation state of the polymer chains in the deep eutectic solvent, thereby significantly affecting the mechanical properties of the deep eutectic gel. The prepared deep eutectic gel exhibits excellent mechanical properties, including record strength (31.53MPa) and toughness (203.38MJ m -3 ).

[0005] The technical solution for achieving the purpose of the present invention is as follows:

[0006] The method for preparing high-strength and high-toughness deep eutectic gel comprises the following steps:

[0007] (1) Choline chloride is used as a hydrogen bond acceptor and a compound containing a hydrogen bond functional group is used as a hydrogen bond donor, the two are mixed and heated in a water bath with stirring until they are melted, and then degassed to form a uniform deep eutectic solvent;

[0008] (2) Pour a polyvinyl alcohol (PVA) aqueous solution into a mold and immerse it in a deep eutectic solvent until the water in the PVA aqueous solution is completely replaced by the deep eutectic solvent to obtain a deep eutectic gel.

[0009] Furthermore, in step (1), the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:4, preferably 1:2.

[0010] Furthermore, in step (1), the compound containing a hydrogen bonding functional group includes but is not limited to ethylene glycol, glycerol, urea, malic acid, etc.

[0011] Furthermore, in step (1), the water bath heating temperature is above the melting points of the hydrogen bond acceptor and the hydrogen bond donor.

[0012] Furthermore, in step (1), the degassing method is ultrasonic treatment, and the degassing time is 30 to 40 minutes.

[0013] Furthermore, in step (2), the mass fraction of PVA in the PVA aqueous solution is 10 to 20 wt %, more preferably 20%.

[0014] Furthermore, in step (2), the soaking process is as follows: the PVA aqueous solution is soaked in the deep eutectic solvent for 24 hours, and the deep eutectic solvent is replaced every 6 hours to ensure that the water in the PVA aqueous solution is completely replaced.

[0015] The present invention provides a high-strength and tough deep eutectic gel prepared by the preparation method.

[0016] Furthermore, the present invention provides the use of the high-strength and tough deep eutectic gel as an electrolyte in the preparation of flexible and stretchable electronic devices.

[0017] Furthermore, flexible and stretchable electronic devices include but are not limited to flexible wearable sensors, etc.

[0018] Furthermore, the flexible wearable sensor is composed of a deep eutectic gel and copper sheet electrodes and tapes attached to both sides of the gel.

[0019] Preferably, the tape is made of VHB tape.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present invention proposes a new strategy to regulate the mechanical properties of deep eutectic gels by utilizing the unique hydrogen bond network of deep eutectic solvents. The deep eutectic gels of the present invention exhibit excellent mechanical properties, including record-breaking strength (31.53 MPa) and toughness (203.38 MJ m -3), which not only surpasses the strongest eutectic gel reported so far, but is also superior to synthetic polymers such as PDMS, synthetic rubber, and natural spider silk.

[0022] (2) The present invention can adjust the hydrogen bond network structure of the deep eutectic solvent by selecting the number and type of hydrogen bond functional groups in the deep eutectic solvent, thereby further accurately regulating the mechanical properties of the deep eutectic gel in a wide range. Specifically, the tensile strength can be adjusted within the range of 8.19MPa to 31.53MPa, and the toughness can be adjusted within the range of 69.84MJ m -3 to 203.38MJ m -3 The elastic modulus can be adjusted within the range of 3.38MPa to 13.01MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a comparison chart of the strength and toughness of the choline chloride-malic acid-PVA high-strength and tough deep eutectic gel and other gels;

[0024] Figure 2 The stress-strain curves of choline chloride-ethylene glycol deep eutectic gel based on three PVA concentrations;

[0025] Figure 3 The bar graphs are the modulus and toughness of choline chloride-ethylene glycol co-gels based on three PVA concentrations;

[0026] Figure 4 is the stress-strain curve of the deep eutectic gel prepared based on Examples 3, 5, 6, and 7;

[0027] Figure 5 is a bar graph of the modulus and toughness of the deep eutectic gels prepared based on Examples 3, 5, 6, and 7;

[0028] Figure 6 is the mass retention rate of the deep eutectic gel prepared based on Examples 3, 5, 6 and 7 after being placed under 25°C / 50°C and 50% humidity conditions for 7 days;

[0029] Figure 7 The tensile curves of the deep eutectic gel prepared in Example 7 placed at room temperature for 3 days and 7 days;

[0030] Figure 8 The impedance spectroscopy (EIS) of the deep eutectic gel prepared based on Examples 3, 5, 6, and 7;

[0031] Fig. 9 is a conductivity bar graph of the deep eutectic gel prepared based on Examples 3, 5, 6, and 7;

[0032] Fig.10are the tensile curves of the original and recycled choline chloride-ethylene glycol deep eutectic gels prepared in Example 3;

[0033] Fig.11 is a bar graph showing the conductivity of the original and recovered choline chloride-ethylene glycol deep eutectic gels prepared in Example 3;

[0034] Fig.12 The resistance-strain curve and the corresponding sensitivity coefficient of the flexible resistive sensor based on the choline chloride-malic acid deep eutectic gel electrolyte prepared in Example 7 within a strain range of 500%;

[0035] Fig.13 Response diagram of the flexible resistive sensor based on the choline chloride-malic acid deep eutectic gel electrolyte prepared in Example 7 to pressing stimulation under cyclic small strain (0-90%) and large strain (100-500%);

[0036] Fig.14 This is a response diagram of a flexible resistive sensor based on the choline chloride-ethylene glycol deep eutectic gel electrolyte prepared in Example 3 to a stretching stimulus at -20°C;

[0037] Fig.15 Response diagram of the flexible resistive sensor based on the choline chloride-ethylene glycol deep eutectic gel electrolyte prepared in Example 3 to stretching stimulation at 50°C;

[0038] Fig.16 Response diagram of the flexible resistive sensor based on the choline chloride-ethylene glycol deep eutectic gel electrolyte prepared in Example 3 to stretching stimulation before and after being placed for one week;

[0039] Fig.17 This is a response diagram of the flexible resistive sensor based on the choline chloride-malic acid deep eutectic gel electrolyte prepared in Example 7 to basic human activities;

[0040] Fig.18 This is a graph showing the monitoring of human electrocardiogram signals by a resistive sensor based on the choline chloride-malic acid deep eutectic gel electrolyte prepared in Example 7;

[0041] Fig.19 This is a graph showing the monitoring of human eye electroocular signals by a resistive sensor based on the choline chloride-malic acid deep eutectic gel electrolyte prepared in Example 7. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below in conjunction with the embodiments and drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0043] Example 1: Preparation of deep eutectic gel (PVA mass fraction is 10%, hydrogen bond donor is ethylene glycol)

[0044] (1) a certain amount of choline chloride (hydrogen bond acceptor) and ethylene glycol (hydrogen bond donor) were respectively measured to make the molar ratio of 1:2, stirred evenly in a water bath at 90° C., and then ultrasonicated for 30 min to remove bubbles to obtain a deep eutectic solvent;

[0045] (2) 0.3 g of PVA powder was weighed and dissolved in 2.7 g of deionized water at 95° C. and stirred for 3 hours until a PVA aqueous solution was formed. The PVA aqueous solution was then ultrasonicated for 1 hour to remove bubbles.

[0046] (3) Pour the defoamed PVA solution into a glass mold and soak it in a deep eutectic solvent for 24 hours. Replace the deep eutectic solvent every 6 hours to obtain a deep eutectic gel DESs-PVA 10 .

[0047] Example 2: Preparation of deep eutectic gel (PVA mass fraction is 15%, hydrogen bond donor is ethylene glycol)

[0048] (1) a certain amount of choline chloride (hydrogen bond acceptor) and ethylene glycol (hydrogen bond donor) were respectively measured to make the molar ratio of 1:2, stirred evenly in a water bath at 90° C., and then ultrasonicated for 30 min to remove bubbles, thereby obtaining a deep eutectic solvent;

[0049] (2) Weigh 0.45 g of PVA powder and dissolve it in 2.55 g of deionized water at 95° C. and stir for 3 hours until a PVA aqueous solution is formed. Then, the PVA aqueous solution is ultrasonicated for 1 hour to remove bubbles.

[0050] (3) Pour the defoamed PVA solution into a glass mold and soak it in a deep eutectic solvent for 24 hours. Replace the deep eutectic solvent every 6 hours to obtain a deep eutectic gel DESs-PVA 15 .

[0051] Example 3: Preparation of deep eutectic gel (PVA mass fraction is 20%, hydrogen bond donor is ethylene glycol)

[0052] (1) a certain amount of choline chloride (hydrogen bond acceptor) and ethylene glycol (hydrogen bond donor) were respectively measured to make the molar ratio of 1:2, stirred evenly in a water bath at 90° C., and then ultrasonicated for 30 min to remove bubbles, thereby obtaining a deep eutectic solvent;

[0053] (2) Weigh 0.6 g of PVA powder and dissolve it in 2.4 g of deionized water at 95° C. and stir for 3 hours until a PVA aqueous solution is formed. Then, the PVA aqueous solution is sonicated to remove bubbles.

[0054] (3) Pour the defoamed PVA solution into a mold and soak it in a deep eutectic solvent for 24 hours, replacing the deep eutectic solvent every 6 hours to obtain a deep eutectic gel DESs-PVA 20 .

[0055] Example 4: Mechanical properties test of deep eutectic gel

[0056] The deep eutectic gels prepared in Examples 1 to 3 were subjected to mechanical property tests. The stress-strain curves of different PVA mass fractions are shown in FIG. Figure 2 DESs-PVA 10 The stress of DESs-PVA is 2.04MPa and the strain is 6.57 times. When the PVA content increases to 15wt% and 20wt%, 15 and DESs-PVA 20 The ultimate stress and strain reached 4.9MPa, 9.68 times and 8.19MPa, 12.88 times, respectively. With the increase of polymer concentration in the deep eutectic gel precursor solution, the spatial network becomes denser, more PVA molecular chains participate in dissipating energy, and the mechanical properties continue to increase. It can be seen from the stress-strain curve that the DESs-PVA deep eutectic gel has two different strain zones during the stretching process. At a strain below 50%, the mechanical characteristics of DESs-PVA are elastic deformation, and the small-scale tightly entangled PVA molecular chains move. When the strain is greater than 50%, the rearrangement of the polymer molecules in the shear transition zone is restricted, and strain hardening occurs, resulting in a rapid increase in strain and stress. In addition, the Young's modulus and toughness curves corresponding to the PVA content are shown in the following figure. Figure 3 The Young's modulus and toughness of DESs-PVA20 reached 3.37MPa and 69.84MJ m -3 , which are 3 and 7.6 times that of DESs-PVA10 (1.12 MPa and 9.18 MJ m -3 ). Comprehensively considered, the deep eutectic gel corresponding to the PVA mass fraction of 20wt% has the best mechanical properties, with high tensile strength (8.19MPa) and high toughness (69.84MJ m -3 ), so this quality score was selected for subsequent testing.

[0057] Example 5: Preparation of deep eutectic gel (PVA mass fraction is 20%, hydrogen bond donor is glycerol)

[0058] (1) a certain amount of choline chloride (hydrogen bond acceptor) and glycerol (hydrogen bond donor) were respectively measured to make the molar ratio of 1:2, stirred evenly in a water bath at 90° C., and then ultrasonicated for 30 min to remove bubbles, thereby obtaining a deep eutectic solvent;

[0059] (2) 0.6 g of PVA powder was weighed and dissolved in 2.4 g of deionized water at 95° C. and stirred for 3 hours until a PVA aqueous solution was formed. The PVA aqueous solution was then ultrasonicated for 1 hour to remove bubbles.

[0060] (3) Pour the defoamed PVA solution into a glass mold and soak it in a deep eutectic solvent for 24 hours, replacing the deep eutectic solvent every 6 hours to obtain a deep eutectic gel.

[0061] Example 6: Preparation of deep eutectic gel (PVA mass fraction is 20%, hydrogen bond donor is urea)

[0062] (1) a certain amount of choline chloride (hydrogen bond acceptor) and urea (hydrogen bond donor) were measured respectively to make the molar ratio of 1:2, stirred evenly in a water bath at 90°C, and then ultrasonicated for 30 minutes to remove bubbles, thereby obtaining a deep eutectic solvent;

[0063] (2) 0.6 g of PVA powder was weighed and dissolved in 2.4 g of deionized water at 95° C. and stirred for 3 hours until a PVA aqueous solution was formed. The PVA aqueous solution was then ultrasonicated for 1 hour to remove bubbles.

[0064] (3) Pour the defoamed PVA solution into a glass mold and soak it in a deep eutectic solvent for 24 hours, replacing the deep eutectic solvent every 6 hours to obtain a deep eutectic gel.

[0065] Example 7: Preparation of deep eutectic gel (PVA mass fraction is 20%, hydrogen bond donor is malic acid)

[0066] (1) a certain amount of choline chloride (hydrogen bond acceptor) and malic acid (hydrogen bond donor) were respectively measured to make the molar ratio of 1:2, stirred evenly in a water bath at 90° C., and then ultrasonicated for 30 min to remove bubbles, thereby obtaining a deep eutectic solvent;

[0067] (2) 0.6 g of PVA powder was weighed and dissolved in 2.4 g of deionized water at 95° C. and stirred for 3 hours until a PVA aqueous solution was formed. The PVA aqueous solution was then ultrasonicated for 1 hour to remove bubbles.

[0068] (3) Pour the defoamed PVA solution into a glass mold and soak it in a deep eutectic solvent for 24 hours, replacing the deep eutectic solvent every 6 hours to obtain a deep eutectic gel.

[0069] Example 8: Mechanical properties test of deep eutectic gel

[0070] The mechanical properties of the deep eutectic gels prepared in Examples 3, 5, 6, and 7 were tested. The stress-strain curves corresponding to different deep eutectic solvents are shown in Figure 2. Figure 4As shown in the figure, in the system of choline chloride and ethylene glycol, glycerol, and urea, it was found that as the affinity of the deep eutectic solvent to PVA decreased, the stress and strain of the PVA deep eutectic gel increased linearly, and the ultimate stress and maximum strain increased from 8.19 MPa to 13.55 MPa, and from 12.88 times to 18.79 times, respectively. The modulus and toughness also showed a similar trend, such as Figure 5 As shown in the figure, the pressure increased from 3.37MPa to 8.61MPa and from 69.84MJ m -3 Increased to 179.46MJ m -3 The fracture strength, elastic modulus and fracture energy of choline chloride-malic acid deep eutectic gel far exceed the first three, with an ultimate stress of 31.53MPa and a modulus of 13.01MPa. Although the increase in strength loses some tensile properties (10.91 times), it does not lose toughness. Its fracture energy is as high as 203.38MJ m -3 Taking all factors into consideration, the deep eutectic gel with malic acid as the hydrogen bond donor has the best mechanical properties, with high strength (31.53 MPa) and high toughness (203.38 MJ m -3 ).

[0071] Example 9: Environmental stability test of deep eutectic gel

[0072] The deep eutectic gels prepared in Examples 3, 5, 6, and 7 were placed in an air environment with a humidity of 25% and 50% for 7 days, and their mass changes were measured respectively. Figure 6 As shown in the figure, after 7 days of storage, the mass of the choline chloride-malic acid deep eutectic gel increased slightly by about 5%, which is related to the hygroscopicity of malic acid itself. The other three deep eutectic gels all had different degrees of mass reduction. The choline chloride-ethylene glycol deep eutectic gel with the most solvent evaporation still had a mass retention rate of more than 80%. The choline chloride-malic acid deep eutectic gel was then placed at room temperature for a period of time and then tensile tested to evaluate the degree of degradation of its mechanical properties. The stress-strain curves after being placed at room temperature for 3 days and 7 days are shown in the figure. Figure 7 As shown. The tensile strength of the gel slightly declined from about 31MPa to 24MPa, and the elongation at break increased from 1090% to 1280%, and the mechanical properties remained good. These changes should be related to the water absorption behavior mentioned above. Overall, the choline chloride-malic acid deep eutectic gel has excellent anti-drying properties and exhibits good environmental stability.

[0073] Example 10: Conductive property test of deep eutectic gel

[0074] The deep eutectic gels prepared in Examples 3, 5, 6 and 7 were cut into discs and placed in an electrolyte impedance test fixture to test their impedance in the frequency range of 100 kHz to 1 Hz, and an impedance spectrum (EIS) was obtained as shown below: Figure 8As shown in the figure, it can be seen that the impedance values ​​of each sample are orders of magnitude different. The ionic conductivity of different deep eutectic gels can be calculated from the impedance of each sample, such as Fig. 9 As shown in Figure 2, it can be found that the ionic conductivity shows a decreasing trend with the improvement of mechanical properties, from 5.6Scm -1 Down to 0.01S cm -1 The difference is two orders of magnitude. The better the mechanical properties, the lower the solvent content of the gel, which drops from 60.66% of the choline chloride-ethylene glycol deep eutectic gel to 48.89% of the choline chloride-malic acid deep eutectic gel. The difference in solvent content and the difference in ion migration ability determine the conductive properties of deep eutectic gels of different systems.

[0075] Example 11: Recyclability test of deep eutectic gel

[0076] The deep eutectic gel prepared in Example 3 was broken into several small pieces, dissolved into a PVA aqueous solution by soaking in water, and then repaired by adding the same deep eutectic solvent for gelation. Finally, the mechanical properties and conductive properties of the gel before and after repair were tested. The stress-strain curves of the original and recovered gels are shown in Figure 2. Fig.10 As shown in Figure 2, the tensile strength and elongation at break of the gel were almost unchanged. The conductivity images of the original and recycled gels are shown in Figure 2. Fig.11 As shown in Figure 2, the conductivity of the gel decreased from 56.1 mS m-1 to 49.5 mS m -1 , which only decreased by 11.8%. Overall, the mechanical properties and electrical conductivity of the deep eutectic gel were well maintained before and after recycling, reflecting good recyclability.

[0077] Application Example 1: Preparation of flexible sensors and testing of their mechanical sensing performance

[0078] Copper wire electrodes were attached to both sides of the deep eutectic gel prepared in Example 7, and VHB dielectric elastomer was attached to both sides of the gel to form a "sandwich" structure, which was packaged into a flexible stretchable sensor. The response of the flexible stretchable sensor to different compression and stretching stimulation signals was tested. Fig.12 , 13 As shown, it means that the continuous pressing and stretching tests with the same force are carried out at room temperature for multiple times, and the changes in the relative resistance change rate and the response sensitivity are observed. It can be seen that the resistive strain sensor has a stable and accurate response to different degrees of pressing and stretching stimulation, and the continuous stimulation does not cause the sensor's response to different degrees of the same force to decay, indicating that the sensor has excellent anti-fatigue performance for mechanical stimulation. Under small-range stretching (0-90%) and large-scale stretching (100-500%), the flexible strain sensor has a high sensitivity coefficient (GF) and maintains a high degree of fit with the relative resistance change rate.

[0079] Application Example 2: Environmental stability performance test of flexible sensors

[0080] Copper wire electrodes were attached to both sides of the deep eutectic gel prepared in Example 3, and VHB dielectric elastomer was attached to both sides of the gel to form a "sandwich" structure, which was packaged into a flexible stretchable sensor. The relative resistance change rate of the above-mentioned flexible stretchable sensor was tested at different temperatures and before and after being placed for one week. Fig.14 , 15 As shown, the flexible stretchable sensor is subjected to stretching cycles at different temperatures, and the change in its relative resistance change rate is observed. It can be seen that the flexible sensor has a good response to changes in a wide range of temperatures. Fig.16 As shown, the flexible stretchable sensor placed for one week or so can still output stable electrical signals and has good environmental stability after being subjected to multiple stretching cycles.

[0081] Application Example 3: Preparation of flexible wearable sensors and their monitoring of human activities

[0082] Copper wire electrodes were attached to both sides of the deep eutectic gel prepared in Example 7, and VHB dielectric elastomer was attached to both sides of the gel to form a "sandwich" structure, which was packaged into a flexible wearable sensor. The response of the above-mentioned flexible wearable sensor to knee joint movement was tested. Fig.17 As shown in the figure, the sensor can still respond well after a stretching cycle of up to 20 minutes. This excellent sensing performance is expected to expand the application of wearable sensors in the field of sports monitoring.

[0083] Application Example 4: Preparation of flexible wearable sensors and their monitoring of human physiological signals

[0084] Copper wire electrodes were attached to both sides of the deep eutectic gel prepared in Example 7, and VHB dielectric elastomer was attached to both sides of the gel to form a "sandwich" structure, which was packaged into a flexible wearable sensor. The responses of the above-mentioned flexible wearable sensors to human physiological signals were tested respectively. Fig.18 , 19 As shown in the figure, the human body's ECG and EOG are tested to observe the change in resistance change rate. It can be seen that the ECG and EOG signals of the flexible wearable sensor before and after human exercise in a narrow temperature range have stable and accurate responses. This unique and excellent sensing performance is expected to further expand the application of wearable sensors in the field of human health monitoring.

[0085] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a high-strength and high-toughness deep eutectic gel, characterized in that: The following steps are involved: (1) Choline chloride is used as a hydrogen bond acceptor and a compound containing a hydrogen bond functional group is used as a hydrogen bond donor. The two are mixed and heated in a water bath and stirred until they are melted, and then degassed to form a uniform deep eutectic solvent; (2) Pour the PVA aqueous solution into a mold and soak it in a deep eutectic solvent until the water in the PVA aqueous solution is completely replaced by the deep eutectic solvent to obtain a deep eutectic gel.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:

4.

3. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:

2.

4. The preparation method according to claim 1, characterized in that: In step (1), the compound containing a hydrogen bonding functional group is ethylene glycol, glycerol, urea or malic acid.

5. The preparation method according to claim 1, characterized in that: In step (1), the water bath heating temperature is above the melting point of the hydrogen bond acceptor and the hydrogen bond donor; the degassing method is ultrasonic treatment, and the degassing time is 30 to 40 minutes.

6. The preparation method according to claim 1, characterized in that: In step (2), the mass fraction of PVA in the PVA aqueous solution is 10-20 wt%.

7. The preparation method according to claim 1, characterized in that: In step (2), the soaking process is as follows: the PVA aqueous solution is soaked in the deep eutectic solvent for 24 hours, and the deep eutectic solvent is replaced every 6 hours to ensure that the water in the PVA aqueous solution is completely replaced.

8. A high-strength and tough deep eutectic gel prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the high-strength and tough deep eutectic gel according to claim 8 as an electrolyte in the preparation of flexible and stretchable electronic devices.

10. The use according to claim 9, characterized in that: The flexible stretchable electronic device is a flexible wearable sensor, which consists of a deep eutectic gel and copper sheet electrodes and tape attached to both sides of the gel, and the tape is made of VHB tape.

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