An anti-freezing, anti-pollution, self-healing multi-crosslinking hydrogel, and a preparation method and application thereof

Abstract

This invention discloses a multi-crosslinked hydrogel with antifreeze properties, anti-fouling properties, and self-healing, as well as its preparation method and applications. The hydrogel employs a synergistic reinforcement strategy of an interpenetrating network framework and a core-shell conductive filler. A dual-network framework is constructed using a polyvinyl alcohol physical network and an N-hydroxyethylacrylamide-carboxybetaine copolymer chemical network. MXene@PDA serves as the core-shell conductive filler. The introduction of a deep eutectic solvent and a carboxybetaine hydration layer endows the hydrogel with dual-mechanism synergistic antifreeze properties. The electronic conductivity of MXene@PDA and the ionic conductivity of lithium chloride form a dual-conductivity synergistic reinforcement mechanism. Simultaneously, based on the synergistic effect of dynamic borate ester bonds and intermolecular hydrogen bonds, dual-mechanism self-healing is achieved. The hydrogel of this invention maintains high tensile strength, stable conductivity, excellent resistance to protein contamination, and efficient self-healing properties even in low-temperature environments below −40°C, effectively solving the technical problems of low-temperature signal attenuation, easy contamination, and lack of self-healing function in existing antifreeze hydrogels.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensing materials and biomedical engineering, specifically relating to a multi-crosslinked hydrogel that is antifreeze, anti-pollution, and self-healing, as well as its preparation method and application. Background Technology

[0002] Hydrogels, as polymer materials with a three-dimensional network structure, have shown broad application prospects in fields such as flexible sensors, wearable devices, biomedical electrodes, and human-computer interfaces due to their excellent flexibility, biocompatibility, and tunable physicochemical properties. However, traditional hydrogels face several key technical bottlenecks in practical applications, which restrict their further commercial development.

[0003] First, traditional hydrogels suffer from insufficient antifreeze properties. Traditional hydrogels use water as the dispersion medium; in sub-zero temperatures, the water freezes, causing the material to become brittle, lose flexibility and conductivity, severely limiting its application in cold regions and winter outdoor environments. To address this issue, researchers have attempted to introduce antifreeze components such as polyols, salts, or deep eutectic solvents; however, existing methods often struggle to maintain both high tensile strength and stable conductivity simultaneously in extreme low-temperature environments below −20°C.

[0004] Secondly, traditional hydrogels lack antifouling properties. In biomedical and wearable applications, hydrogels easily adsorb proteins and microorganisms, leading to signal drift, biofouling, and device failure. Existing antifouling strategies mainly rely on surface grafting of hydrophilic polymer brushes or zwitterionic materials (such as sulfobetaine and carboxybetaine), but such modifications are usually limited to the material surface and are difficult to achieve long-term antifouling properties in the bulk material.

[0005] Third, traditional hydrogels lack effective self-healing capabilities. During use, hydrogels inevitably suffer mechanical damage (such as stretching, cutting, and puncture), leading to interruptions in conductive pathways and device failure. In recent years, self-healing hydrogels based on dynamic covalent bonds (such as borate ester bonds) or non-covalent bonds (such as hydrogen bonds) have been extensively studied; however, the self-healing efficiency of most systems decreases significantly at low temperatures, making it difficult to meet practical application requirements.

[0006] Fourth, traditional conductive hydrogels suffer from a single conductivity mechanism and poor filler dispersion. The conductivity mechanisms of conductive hydrogels are typically categorized into electronic conductivity (e.g., the addition of conductive fillers such as carbon nanotubes, graphene, and MXene) and ionic conductivity (e.g., the introduction of salt ions or ionic liquids). However, a single conductivity mechanism often fails to simultaneously achieve high conductivity, low-temperature stability, and biocompatibility. Furthermore, two-dimensional conductive fillers such as MXene tend to aggregate and disperse poorly in the hydrogel matrix, further limiting the uniformity and stability of the conductive network.

[0007] To address the aforementioned issues, some improvement solutions have been reported in existing research. For example, Chinese patent CN108329497B discloses a moisturizing and antifreeze hydrogel and its preparation method, which achieves antifreeze performance at −20°C by introducing a glycerol antifreeze agent. However, the lower limit of the antifreeze temperature of this system is limited, and it lacks self-healing and anti-fouling functions. Another example is Chinese patent CN119708544B, which discloses a polyethyleneimine-functionalized polyvinyl alcohol / cellulose / MXene hydrophobic conductive hydrogel and its preparation method. However, this gel has insufficient conductivity stability at low temperatures and does not solve the problem of protein adsorption. The above-mentioned existing technologies have improved hydrogels from single dimensions such as antifreeze or conductivity. However, how to simultaneously overcome the three major technical challenges of antifreeze, antifouling, and self-healing in the same material system, especially to achieve a conductive hydrogel with multi-mechanism synergistic enhancement in extreme low-temperature environments below −40°C, has not yet been reported. Therefore, developing a hydrogel material that combines anti-protein contamination, self-healing, high tensile strength, and stable conductivity in low-temperature environments below −40°C has significant scientific and application value. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies and provide a multi-crosslinked hydrogel that is antifreeze, anti-pollution, and self-healing, as well as its preparation method and applications. Specifically, this invention aims to solve the following key technical problems: (1) Low-temperature signal attenuation problem: Solving the technical problem that existing antifreeze hydrogels become brittle, lose flexibility, and significantly reduce conductivity due to water freezing in extreme low-temperature environments below −20°C (especially below −40°C). (2) Surface contamination problem: Solving the problem that hydrogels easily adsorb proteins and microorganisms in biomedical and wearable applications, leading to signal drift, biological contamination, and device failure. (3) Damage failure problem: Solving the problem that the conductive pathway is interrupted and the device fails after the hydrogel suffers mechanical damage (such as stretching, cutting, puncture) during use, and that the healing efficiency of existing self-healing systems decreases significantly in low-temperature environments. (4) Single conductivity mechanism and filler dispersion problem: Solving the problem that a single conductivity mechanism (electronic conductivity or ionic conductivity) is difficult to balance high conductivity, low-temperature stability, and biocompatibility, as well as the problem that two-dimensional conductive fillers such as MXene are prone to agglomeration and poor dispersion in the hydrogel matrix.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for preparing a multi-crosslinked hydrogel that is antifreeze, anti-pollution, and self-healing, characterized by comprising the following steps:

[0011] 1) Mix the deep eutectic solvent with deionized water, add polyvinyl alcohol, heat to 90-95°C, and stir until completely dissolved to obtain mixture A;

[0012] 2) Cool mixture A to 40-50°C, add borax, stir to dissolve, and obtain mixture B;

[0013] 3) Cool the mixture B to 25-30°C, then add N-hydroxyethylacrylamide, carboxybetaine, lithium chloride and MXene@PDA in sequence, and stir to mix evenly to obtain mixture C;

[0014] 4) Adjust the pH of mixture C to 8.0-8.5, add initiator, stir evenly, pour into mold, and let stand at room temperature to polymerize to obtain the initial hydrogel product;

[0015] 5) Demold the initial hydrogel product and immerse it in the soaking solution for 20-28 hours to obtain the antifreeze, anti-pollution, and self-healing hydrogel.

[0016] The antifreeze, anti-pollution, and self-healing hydrogel prepared by this invention comprises an interpenetrating polymer network, a core-shell conductive filler, and a dual-mechanism antifreeze, dual-mechanism conductivity, and dual-mechanism self-healing system. The interpenetrating polymer network is formed by the interpenetration of a polyvinyl alcohol physical network and an N-hydroxyethylacrylamide-carboxybetaine copolymer chemical network. The core-shell conductive filler is MXene@PDA (polydopamine-coated MXene). The hydration layer provided by the deep eutectic solvent and carboxybetaine synergistically endows the hydrogel with the ability to maintain high tensile strength and stable conductivity in low-temperature environments below −40°C. The electronic conductivity provided by MXene@PDA and the ionic conductivity provided by lithium chloride synergistically enhance the conductive stability of the hydrogel. The synergistic self-healing ability is composed of dynamic borate ester bonds and hydrogen bonds.

[0017] Furthermore, the raw materials for preparing the hydrogel are as follows by weight: 60-80 parts of deep eutectic solvent, 15-25 parts of polyvinyl alcohol, 1.5-2.5 parts of borax, 5-12 parts of N-hydroxyethyl acrylamide, 8-18 parts of carboxybetaine, 3-8 parts of lithium chloride, 1-3 parts of MXene@PDA, and 0.2-0.4 parts of initiator.

[0018] Further, the deep eutectic solvent is prepared by mixing choline chloride (a hydrogen bond acceptor) with a hydrogen bond donor in a molar ratio of 1:1 to 1:3, heating and stirring at 80-90°C until a transparent homogeneous liquid is formed, and then cooling to obtain the deep eutectic solvent. Further, the hydrogen bond donor is at least one of ethylene glycol, urea, and glycerol.

[0019] Further, the preparation method of MXene@PDA is as follows: MXene powder is dispersed in deionized water, the pH is adjusted to 8.0-9.0, dopamine hydrochloride is added, and the mixture is stirred at room temperature for 12-24 hours. After centrifugation, washing, and freeze-drying, MXene@PDA is obtained. In the MXene@PDA, polydopamine is coated on the surface of MXene nanosheets in a core-shell form. The thickness of the MXene nanosheets is 1-5 nm, and the lateral dimension is 0.5-5 μm.

[0020] Furthermore, the initiator is ammonium persulfate.

[0021] In step 1), the volume ratio of deep eutectic solvent to deionized water is 5:5-9:1; preferably 7:3-8:2.

[0022] In step 4), the polymerization temperature is 20-30°C and the polymerization time is 4-6 hours.

[0023] In step 5), the soaking solution is a mixture of deep eutectic solvent and water in a mass ratio of 7:3.

[0024] The antifreeze, anti-fouling, and self-healing hydrogel described herein satisfies at least one of the following performance characteristics: (a) the conductivity at −40°C is maintained at more than 80% of the conductivity at room temperature; (b) the adsorption amount of bovine serum albumin is less than 10 μg / cm²; (c) the self-healing efficiency after 24 hours of self-healing at 25°C is greater than 85%; (d) the elongation at break is greater than 500%; and (e) the glass transition temperature is less than −70°C.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The hydrogel exhibits excellent low-temperature antifreeze properties.

[0027] This invention introduces a dual-mechanism synergistic antifreeze system by combining a deep eutectic solvent with a carboxybetaine hydration layer. The synergistic effect of the deep eutectic solvent and carboxybetaine significantly reduces the glass transition temperature of the hydrogel (below −70°C), enabling the hydrogel to maintain high tensile strength (elongation at break greater than 500%) and stable conductivity (conductivity retention rate of more than 80% of room temperature conductivity) even in extreme low-temperature environments below −40°C. This effectively solves the technical problem of low-temperature signal attenuation in existing antifreeze hydrogels.

[0028] 2. The hydrogel exhibits excellent resistance to protein contamination.

[0029] This invention utilizes the strong hydration layer effect provided by carboxybetaine to endow the hydrogel with excellent anti-protein contamination properties. The zwitterionic structure of carboxybetaine binds water molecules through electrostatic interactions, forming a dense hydration layer on the material surface, effectively blocking protein adsorption. Experiments show that the hydrogel of this invention adsorbs less than 10 μg / cm² of bovine serum albumin, significantly better than traditional hydrogels.

[0030] 3. The hydrogel possesses highly efficient dual-mechanism self-healing properties.

[0031] This invention utilizes both dynamic borate ester bonds (dynamic covalent bonds) and hydrogen bonds (non-covalent bonds) to construct a dual-mechanism self-healing system. Dynamic borate ester bonds provide rapid healing capability, while hydrogen bonds enhance the reversible crosslinking density of the network. The synergistic effect of these two mechanisms enables the hydrogel to achieve a self-healing efficiency of over 85% after 24 hours of self-healing at 25°C.

[0032] 4. The hydrogel possesses a stable and reliable dual conductivity mechanism.

[0033] This invention employs a dual synergistic conductivity strategy combining electronic conductivity from MXene@PDA and ionic conductivity from lithium chloride. The core-shell structure of MXene@PDA effectively prevents the aggregation of MXene nanosheets, forming a uniform electronic conductivity network. Simultaneously, the ionic conductivity provided by lithium chloride remains stable at low temperatures, complementing the electronic conductivity. The synergistic effect of this dual conductivity mechanism ensures that the hydrogel maintains stable and reliable conductivity across a wide temperature range (room temperature to −40°C).

[0034] 5. The overall advantages of multi-mechanism synergy.

[0035] This invention integrates an interpenetrating polymer network, a core-shell conductive filler, an antifreeze mechanism, a conductive mechanism, and a self-healing mechanism, with each mechanism synergistically reinforcing the others. For example, the deep eutectic solvent not only imparts antifreeze properties to the hydrogel but also acts as a plasticizer for polyvinyl alcohol, enhancing its flexibility; carboxybetaine not only provides an antifouling hydration layer but also participates in the construction of a chemically cross-linked network; the formation of dynamic borate ester bonds depends on the reaction of polyvinyl alcohol with borax, deeply integrating with both the physical and chemical networks. This multi-mechanism synergistic enhancement strategy enables the hydrogel of this invention to possess high tensile strength, stable conductivity, antifouling properties, and self-healing capabilities even under extreme low-temperature environments, exhibiting significantly superior overall performance compared to existing technologies.

[0036] 6. This invention has broad application prospects.

[0037] The comprehensive properties of the hydrogel of this invention enable it to be widely used in fields such as flexible sensors, wearable devices, biomedical electrodes, and human-computer interaction interfaces, and it is particularly suitable for long-term stable use in cold regions, winter outdoor environments, and biomedical scenarios. Attached Figure Description

[0038] Figure 1 This is a comparison chart of the elongation at break of the hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0039] Figure 2 This is a comparison diagram of the fracture strength of the hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0040] Figure 3 This is a comparison chart of the room temperature conductivity of the hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0041] Figure 4 This is a comparison chart of the conductivity retention rate of the hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention at different temperatures (−20°C, −40°C).

[0042] Figure 5 This is a comparison chart of the bovine serum albumin adsorption capacity of the hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0043] Figure 6 This is a comparison chart of the self-healing efficiency of the hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention after healing at 25°C for 24 hours.

[0044] Figure 7 The results are the electrical signals of the hydrogel prepared in Example 1 of this invention, which tracked finger movements at room temperature.

[0045] Figure 8 The results are the electrical signal results of tracking finger movements at −40°C using the hydrogel prepared in Example 1 of this invention.

[0046] Figure 9 The results are the electrical signals obtained by 300 cycles of stretching-release under 50% strain on the hydrogel prepared in Example 1 of this invention. Detailed Implementation

[0047] The present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited thereto.

[0048] Table 1 Gel Material Formulation

[0049] Serial Number PVA(g) HEAA(g) CBMA(g) DES(g) <![CDATA[H2O(g)]]> LiCl(g) MXene@PDA(g) Borax(g) APS(g) Example 1 20 10 10 60 20 5 2 2 0.3 Example 2 20 8 12 70 10 8 3 2 0.4 Example 3 15 8 15 65 15 6 2.5 2 0.3 Comparative Example 1 20 10 0 60 30 5 2 2 0.3 Comparative Example 2 20 10 10 60 20 5 0 2 0.3 Comparative Example 3 20 10 10 60 20 0 2 2 0.3

[0050] In Table 1, PVA: polyvinyl alcohol; HEAA: N-hydroxyethyl acrylamide; CBMA: carboxybetaine; DES: deep eutectic solvent; Borax: boric acid; APS: ammonium persulfate.

[0051] Example 1

[0052] This embodiment provides a method for preparing an antifreeze, anti-pollution, and self-healing hydrogel.

[0053] First, weigh 139.6 g (1 mol) of choline chloride and 124.2 g (2 mol) of ethylene glycol, add them to a 500 mL round-bottom flask, heat and stir in an oil bath at 85°C (300 rpm) for 2 hours, observe the solution change from suspension to transparent homogeneous liquid, cool to room temperature, seal and store for later use, and obtain choline chloride-ethylene glycol deep eutectic solvent (DES).

[0054] Subsequently, 100 mg of MXene powder was weighed and added to 50 mL of deionized water. The mixture was sonicated in an ice-water bath for 30 minutes (300 W) to obtain a uniform dispersion. The pH was adjusted to 8.5 with Tris buffer. 100 mg of dopamine hydrochloride was weighed and slowly added to the dispersion. The mixture was stirred at room temperature for 24 hours (200 rpm). The reaction solution was transferred to a centrifuge tube and centrifuged at 10,000 rpm for 15 minutes. The supernatant was discarded, and the mixture was washed with deionized water, repeating the process three times. The precipitate was freeze-dried at −50°C for 24 hours to obtain MXene@PDA powder.

[0055] The components of the hydrogel are shown in Table 1, Example 1. The preparation steps of the hydrogel are as follows: DES and deionized water were mixed at a volume ratio of 3:1, PVA was added, and the mixture was allowed to swell fully at room temperature for 10 minutes. Then, the mixture was heated to 95°C and stirred for 1-2 hours until the PVA was completely dissolved, resulting in a transparent homogeneous solution. Next, the mixture was allowed to cool naturally to 45°C, borax was added, and the mixture was stirred for 10 minutes (200 rpm) until completely dissolved. Then, the mixture was allowed to cool naturally to 25°C, and HEAA, CBMA, LiCl, and MXene@PDA were added sequentially, stirring thoroughly after each addition and stirring for 15 minutes until homogeneous. Finally, the pH was adjusted to 8.5 with 1M NaOH, and APS was added, followed by rapid stirring for 1 minute until homogeneous. Finally, the mixture was injected into a polytetrafluoroethylene mold, allowed to stand for polymerization at room temperature (25°C) for 5 hours, and then demolded. The resulting hydrogel was then immersed in a soaking solution with a DES to water mass ratio of 7:3 for 24 hours to achieve equilibration, thus obtaining the antifreeze, anti-pollution, and self-healing hydrogel of Example 1.

[0056] Example 2

[0057] This embodiment provides a highly conductive, antifreeze, anti-pollution, and self-healing hydrogel.

[0058] First, weigh 139.6 g (1 mol) of choline chloride and 120.1 g (2 mol) of urea, add them to a 500 mL round-bottom flask, heat and stir in an 80°C oil bath (300 rpm) until a transparent homogeneous liquid is formed, cool to room temperature, seal and store for later use, and obtain the choline chloride-urea deep eutectic solvent.

[0059] Then, MXene@PDA core-shell packing material was prepared using the same method as in Example 1.

[0060] Finally, the hydrogel was prepared using the same procedures as in Example 1, with the polymerization time set to 4 hours.

[0061] Example 3

[0062] This embodiment provides a highly anti-pollution, antifreeze, anti-pollution, and self-healing hydrogel.

[0063] First, weigh 139.6 g (1 mol) of choline chloride and 184.2 g (2 mol) of glycerol, add them to a 500 mL round-bottom flask, heat and stir in an oil bath at 85°C (300 rpm) for 3-4 hours until a transparent homogeneous liquid is formed, cool to room temperature, seal and store for later use, and obtain a choline chloride-glycerol deep eutectic solvent.

[0064] Then, MXene@PDA core-shell packing material was prepared using the same method as in Example 1.

[0065] Finally, the hydrogel was prepared using the same procedures as in Example 1, with the polymerization time set to 5 hours.

[0066] Comparative Example 1

[0067] This comparative example provides a CBMA-free hydrogel for comparison with Example 1. The preparation steps for the deep eutectic solvent (DES), MXene@PDA core-shell filler, and hydrogel are the same as in Example 1.

[0068] Comparative Example 2

[0069] This comparative example does not contain MXene@PDA, and the other components are the same as in Example 1. The preparation steps are the same as in Example 1.

[0070] Comparative Example 3

[0071] This comparative example does not contain LiCl, and the other components are the same as in Example 1. The preparation steps are the same as in Example 1.

[0072] Performance testing

[0073] The hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests.

[0074] (1) Cut the hydrogel into dumbbell-shaped standard specimens and perform tensile testing using a universal testing machine at a tensile rate of 50 mm / min. Record the elongation and maximum stress at break, which are respectively used as the elongation at break and the breaking strength.

[0075] like Figure 1-2 As shown, the hydrogels of Examples 1-3 of the present invention all have excellent mechanical properties, with elongation at break greater than 500% and tensile strength greater than 0.7 MPa, which can meet the mechanical requirements of flexible sensing and wearable devices.

[0076] (2) The conductivity of the hydrogel was tested by linear scanning voltammetry using an electrochemical workstation. The formula for calculating the conductivity of the hydrogel is as follows: σ = l / (R×A), where σ is the ionic conductivity of the hydrogel, l and A are the distance between the two electrodes and the cross-sectional area of ​​the hydrogel, respectively, and R is the resistance of the hydrogel.

[0077] like Figure 3 As shown, the trend of room temperature conductivity indicates that lithium chloride is the main contributor to conductivity, while electronic conductivity (MXene@PDA) is a minor but significant contributor. Figure 4 As shown, the hydrogels of Examples 1-3 all maintained a conductivity of over 80% at −40°C, which is far superior to Comparative Example 2 without MXene@PDA and Comparative Example 3 without LiCl, demonstrating the synergistic effect of the dual mechanisms of electronic conductivity of MXene@PDA and ionic conductivity of LiCl.

[0078] (3) Cut the hydrogel sample into equal areas and immerse it in a 1 mg / mL BSA solution. Incubate at 37°C for 2 hours. After removal, gently rinse three times with PBS buffer. Then, use a BCA protein assay kit to determine the amount of BSA adsorbed on the gel surface and calculate the adsorption amount per unit area (μg / cm²).

[0079] like Figure 5 As shown, the hydrogels of Examples 1-3 of this invention all exhibited BSA adsorption capacities below 10 μg / cm², with Example 3 showing an adsorption capacity as low as 5.8 μg / cm², demonstrating excellent anti-protein contamination ability. In contrast, Comparative Example 1 showed an adsorption capacity as high as 52.0 μg / cm², indicating that carboxybetaine is the key component imparting the anti-fouling properties to the hydrogel.

[0080] (4) The elongation at break is used as the evaluation index for self-healing performance. The hydrogel is cut into dumbbell-shaped specimens. The elongation at break (ε0) of the original specimen is first tested using a universal testing machine. Then, the specimen is completely cut in half, and the fracture surfaces are allowed to come into close contact and heal at room temperature for a certain period of time. The elongation at break (ε) of the healed specimen is then tested. The self-healing efficiency is calculated as η = ε / ε0 ×100%.

[0081] like Figure 6 As shown, the self-healing efficiency of the hydrogels in Examples 1-3 of the present invention is all above 85%, with Example 1 reaching as high as 90.0%, demonstrating excellent self-healing performance.

[0082] (5) To study the application of hydrogels in human motion detection, a hydrogel-based strain sensor was attached to a volunteer's finger and its two ends were connected to an electrochemical workstation. By recording and analyzing the resistance change data during finger bending, human motion can be detected. In addition, using the electrochemical workstation and a tensile testing machine, the hydrogel-based sensor was subjected to 300 stretch-release cycles under a fixed strain of 50%, and its resistance change was recorded to evaluate the cyclic stability of the sensor.

[0083] like Figure 7-9 As shown, the hydrogel-based sensor based on Example 1 is able to track limb movement at both room temperature and low temperature, and exhibits excellent cyclic stability.

Claims

1. A method for preparing a multi-crosslinked hydrogel that is antifreeze, anti-pollution, and self-healing, characterized in that, Includes the following steps: 1) Mix the deep eutectic solvent with water and polyvinyl alcohol, heat to 90-95°C, and stir until completely dissolved to obtain mixture A; 2) Cool mixture A to 40-50°C, add borax, stir to dissolve, and obtain mixture B; 3) Cool the mixture B to 25-30°C, add N-hydroxyethylacrylamide, carboxybetaine, lithium chloride and MXene@PDA, stir and mix evenly to obtain mixture C; 4) Adjust the pH of mixture C to 8.0-8.5, add initiator, stir evenly, pour into mold, and let stand at room temperature to polymerize to obtain the initial hydrogel product; 5) Demold the initial hydrogel product and immerse it in the soaking solution for 20-28 hours to obtain the antifreeze, anti-pollution, and self-healing hydrogel.

2. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 1, characterized in that, The raw materials for preparing the hydrogel are as follows by weight: 60-80 parts deep eutectic solvent, 15-25 parts polyvinyl alcohol, 1.5-2.5 parts borax, 5-12 parts N-hydroxyethyl acrylamide, 8-18 parts carboxybetaine, 3-8 parts lithium chloride, 1-3 parts MXene@PDA, and 0.2-0.4 parts initiator.

3. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 1, characterized in that, The deep eutectic solvent is prepared by mixing hydrogen bond acceptors and hydrogen bond donors in a molar ratio of 1:1 to 1:3, heating and stirring at 80-90°C until a transparent homogeneous liquid is formed, and then cooling to obtain the deep eutectic solvent. The preparation method of MXene@PDA is as follows: MXene powder is dispersed in water, the pH is adjusted to 8.0-9.0, dopamine hydrochloride is added, the mixture is stirred at room temperature for 12-24 hours, and after centrifugation, washing, and freeze-drying, MXene@PDA is obtained.

4. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 3, characterized in that, The hydrogen bond acceptor of the deep eutectic solvent is choline chloride, and the hydrogen bond donor is at least one of ethylene glycol, urea, and glycerol; in the MXene@PDA, polydopamine is coated on the surface of MXene nanosheets in a core-shell form, and the thickness of the MXene nanosheets is 1-5 nm, and the lateral dimension is 0.5-5 μm.

5. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 1, characterized in that, In step 1), the volume ratio of deep eutectic solvent to water is 5:5-9:

1.

6. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 1, characterized in that, In step 4), the polymerization temperature is 20-30°C and the polymerization time is 4-6 hours.

7. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 1, characterized in that, The initiator in step 4) is ammonium persulfate, and the soaking solution in step 5) is a mixture of deep eutectic solvent and water in a mass ratio of 7:

3.

8. The antifreeze, anti-pollution, and self-healing multi-crosslinked hydrogel obtained by the preparation method according to any one of claims 1-7.

9. The method for preparing a multi-crosslinked hydrogel with antifreeze, anti-pollution, and self-healing properties according to claim 8, characterized in that, The antifreeze, anti-fouling, and self-healing hydrogel described herein satisfies at least one of the following performance characteristics: (a) the conductivity at −40°C is maintained at more than 80% of the conductivity at room temperature; (b) the adsorption amount of bovine serum albumin is less than 10 μg / cm²; (c) the self-healing efficiency after 24 hours of self-healing at 25°C is greater than 85%; (d) the elongation at break is greater than 500%; and (e) the glass transition temperature is less than −70°C.

10. The application of the antifreeze, anti-pollution, and self-healing hydrogel as described in claim 8 in flexible sensors, wearable devices, biomedical electrodes, or human-computer interaction interfaces.

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