Composite hydrogel with two-stage pore structure as well as preparation method and application of composite hydrogel

Abstract

The invention relates to the technical field of multifunctional composite materials, and discloses composite hydrogel with a two-stage pore structure as well as a preparation method and application of the composite hydrogel. The composite hydrogel with the two-stage pore structure is prepared by carrying out synergistic pre-assembly on liquid metal nanoparticles and MXene nanosheets and then carrying out in-situ polymerization with an acrylic monomer; a two-stage pore structure which is formed in situ in one step through polymerization heat release is arranged in the porous material. In the hydrogel disclosed by the invention, the liquid metal exerts multiple functions of hydrophobic modification, pore forming and electric conduction, and generates a synergistic enhancement effect of '1 + 1gt, 2' with the MXene; through the synergistic effect of a hydrophobic area introduced by the liquid metal and a two-stage pore structure, the swelling resistance of the hydrogel is fundamentally improved, so that the hydrogel can adapt to harsh water environments and chemical environments. Based on the synergistic effect, the composite hydrogel with the two-stage pore structure has excellent broadband electromagnetic shielding performance (covering GHz and THz wave bands), infrared thermal camouflage capability, ultraviolet shielding function and long-term anti-swelling stability in a harsh liquid phase environment.

Description

Technical Field

[0001] This application relates to the field of multifunctional composite materials technology, specifically to a bi-porous composite hydrogel, its preparation method, and its application. Background Technology

[0002] With the development of flexible electronics and modern communication technologies, the requirements for electromagnetic shielding materials have gone beyond single-function applications, evolving towards broadband, multi-spectral defense (such as microwaves, terahertz waves, infrared, and ultraviolet) and good environmental adaptability. Hydrogels, due to their unique flexibility and biocompatibility, are considered one of the ideal matrices for electromagnetic shielding materials. However, existing hydrogel-based electromagnetic shielding materials generally face the following technical bottlenecks: First, their high-conductivity filler load often leads to gel brittleness; second, their single function makes it difficult to achieve effective defense across a wide electromagnetic spectrum; furthermore, traditional hydrophilic gel networks are prone to swelling or degradation in water, acid, and alkali environments, leading to three-dimensional structural damage and functional loss.

[0003] Although MXene or liquid metals have been used alone to prepare functional hydrogels, their applications are limited by the inherent defects of the materials themselves and the complex construction process. Because MXene is prone to stacking and liquid metal is prone to agglomeration, traditional construction methods require the addition of external initiators or cumbersome post-processing, making it difficult to achieve precise control of the pore structure.

[0004] Therefore, developing a preparation strategy for hydrogels that can spontaneously and in-situ form a stable bipolar porous structure without relying on external initiators, solely through material synergy, is of great significance for expanding the application range of hydrogel-based electromagnetic shielding materials. Summary of the Invention

[0005] This application provides a bi-level porous composite hydrogel, its preparation method, and its application, aiming to solve the technical problems of poor long-term environmental stability, narrow electromagnetic shielding frequency band, and poor multi-spectral defense effect of hydrogels caused by the reliance on external initiators or cumbersome post-processing, which makes it difficult to achieve precise control of pore structure.

[0006] To achieve the above objectives, the present application adopts the following technical solution.

[0007] In a first aspect, this application provides a bipolar porous composite hydrogel, which is prepared by synergistic pre-assembly of liquid metal nanoparticles and MXene nanosheets, followed by in-situ polymerization with acrylic monomers.

[0008] Its interior has a bilevel porous structure formed in situ in one step through exothermic polymerization.

[0009] Preferably, the bi-level pore structure includes primary macropores induced by liquid metal nanoparticles as sacrificial templates, and secondary micropores formed by MXene regulation.

[0010] More preferably, the average pore size of the primary macropore is 100~1000μm; and the average pore size of the secondary micropore is 1~100μm.

[0011] Preferably, the liquid metal nanoparticles comprise a gallium-indium alloy or a gallium-indium-tin alloy;

[0012] The MXene is Ti3C2T x .

[0013] Preferably, in the bipolar porous composite hydrogel, the mass percentage of liquid metal nanoparticles is 1.4~1.6 wt%.

[0014] The MXene nanosheets account for 0.15~0.3wt% of the total mass.

[0015] More preferably, in the bipolar porous composite hydrogel, the mass percentage of liquid metal nanoparticles is 1.5 wt%; and the mass percentage of MXene nanosheets is 0.3 wt%.

[0016] A second aspect of this application provides a method for preparing the above-mentioned bilevel porous composite hydrogel, comprising:

[0017] S1, Liquid metal nanoparticle dispersion and MXene nanosheet dispersion are mixed and synergistically pre-assembled to obtain composite conductive paste;

[0018] S2, the composite conductive paste is mixed with acrylic monomers, and the in-situ polymerization of acrylic monomers is initiated at 20~80°C to obtain a bipolar porous composite hydrogel.

[0019] Preferably, the reaction time for in-situ polymerization is 1 to 72 hours.

[0020] Preferably, the liquid metal nanoparticle dispersion is an aqueous dispersion of liquid metal nanoparticles; and the MXene nanosheet dispersion is an aqueous dispersion of MXene nanosheets.

[0021] A third aspect of this application provides the application of the above-mentioned bi-porous composite hydrogel in flexible electromagnetic shielding devices, infrared stealth materials, or ultraviolet protection materials.

[0022] Compared with the prior art, the beneficial effects of this application are as follows:

[0023] This application pre-assembles liquid metal nanoparticles with MXene nanosheets, and autonomously initiates the acrylic acid polymerization reaction by relying on the built-in initiation function of the composite system. Then, with the help of the intense exothermic effect released during the polymerization process, dynamic phase separation is initiated in the system, thereby spontaneously constructing a bi-level porous structure in one step. The endogenous pore-forming strategy of this application has a simple process and fast gelation speed, which is conducive to large-scale production.

[0024] In the hydrogel of this application, the liquid metal plays multiple roles in hydrophobic modification, pore formation, and conductivity, producing a synergistic enhancement effect with MXene, where "1+1>2". Through the synergistic effect of the hydrophobic water area introduced by the liquid metal and the bipolar porous structure, the swelling resistance of the hydrogel is fundamentally improved, enabling it to adapt to harsh aquatic and chemical environments. Based on the above synergistic effect, the bipolar porous composite hydrogel of this application exhibits excellent broadband electromagnetic shielding performance (covering GHz and THz bands), infrared thermal camouflage capability, ultraviolet shielding function, and long-term swelling stability in harsh liquid environments, making it suitable for multi-spectral electromagnetic protection applications requiring high flexibility and environmental durability. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram and a scanning electron microscope image of the bilevel porous composite hydrogel of this application.

[0027] Figure 2 The images show the hydrogels before and after stability testing in the embodiments and comparative examples of this application.

[0028] Figure 3 This is a scanning electron microscope image of the bilevel porous composite hydrogel of this application;

[0029] Figure 4 Images of the hydrogel from Example 2 before and after stability testing;

[0030] Figure 5 The graph shows the performance test results of the hydrogel in Example 2 at different frequency bands.

[0031] Figure 6 This is a UV shielding test result of the hydrogel in Example 2;

[0032] Figure 7 The image shows an infrared thermographic test of the hydrogel in Example 2 under a 100°C hot stage. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0034] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.

[0035] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0037] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0038] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0039] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood as each intermediate value between the upper and lower limits of the specifically disclosed range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] In the first aspect, this application provides a bi-porous composite hydrogel, which is prepared by synergistic pre-assembly of liquid metal nanoparticles and MXene nanosheets, followed by in-situ polymerization with acrylic monomers.

[0042] like Figure 1 As shown, the bi-level porous composite hydrogel of this application has a bi-level porous structure formed in situ in one step through exothermic polymerization; the bi-level porous structure includes primary macropores and secondary micropores, wherein the average pore diameter of the primary macropores is 100~1000μm; and the average pore diameter of the secondary micropores is 1~100μm.

[0043] In this application, the liquid metal nanoparticles serve as hydrophobic modifiers, pore-forming agents, and conductive fillers, improving the hydrophobicity and conductivity of the hydrogel and forming a macroporous structure. Specifically, the liquid metal nanoparticles induce macropore formation in the hydrogel through the template effect during gas generation at the reaction interface and phase separation. The liquid metal nanoparticles in this application include any one of gallium-indium alloy or gallium-indium-tin alloy.

[0044] In this application, the gas-generating behavior of MXene nanosheets under acidic conditions and their interaction with polymers form secondary micropores in the hydrogel. Specifically, the MXene is preferably Ti3C2T. x .

[0045] In the bipolar porous composite hydrogel of this application, the mass percentage of liquid metal nanoparticles is preferably 1.4~1.6wt%, more preferably 1.5wt%; the mass percentage of MXene nanosheets is preferably 0.15~0.3wt%, more preferably 0.3wt%.

[0046] This application pre-assembles liquid metal nanoparticles with MXene nanosheets, leveraging the built-in initiation function of this composite system to autonomously initiate the acrylic acid polymerization reaction. Then, utilizing the intense exothermic effect released during polymerization, dynamic phase separation occurs, thus spontaneously constructing a bipolar porous structure in one step. This endogenous pore-forming strategy is simple to implement and exhibits rapid gelation, which is beneficial for large-scale production.

[0047] In the hydrogel of this application, the liquid metal plays multiple functions of hydrophobic modification, pore formation and conductivity, and produces a synergistic enhancement effect of "1+1>2" with MXene; through the synergistic effect of the hydrophobic water area introduced by the liquid metal and the bilevel pore structure, the swelling resistance of the hydrogel is fundamentally improved, enabling it to adapt to harsh aquatic and chemical environments.

[0048] Based on the above synergistic effect, the bipolar porous composite hydrogel of this application has excellent broadband electromagnetic shielding performance (covering GHz and THz bands), infrared thermal camouflage capability, ultraviolet shielding function, and long-term anti-swelling stability in harsh liquid environment, making it suitable for multi-spectral electromagnetic protection fields with high requirements for flexibility and environmental durability.

[0049] The method for preparing the bi-porous composite hydrogel of this application includes:

[0050] S1, Liquid metal nanoparticle dispersion and MXene nanosheet dispersion are mixed and synergistically pre-assembled to obtain composite conductive paste;

[0051] Wherein, the liquid metal nanoparticle dispersion is an aqueous dispersion of liquid metal nanoparticles; and the MXene nanosheet dispersion is an aqueous dispersion of MXene nanosheets.

[0052] S2, the composite conductive paste is mixed with acrylic monomer, and the in-situ polymerization reaction of acrylic monomer is initiated at 20~80°C for 1~72h to obtain a bipolar porous composite hydrogel.

[0053] In this application, the in-situ polymerization reaction exothermically induces dynamic phase separation and gelation in the system, forming a bilevel porous structure; specifically, liquid metal nanoparticles induce the formation of macropores in the hydrogel through gas generation at the reaction interface and the template effect during the phase separation process; MXene nanosheets form secondary micropores in the hydrogel through gas generation behavior in an acidic environment and their interaction with the polymer.

[0054] The hydrogel of this application achieves broadband electromagnetic shielding, exhibiting effective electromagnetic shielding performance in both the 8.2–40 GHz microwave band and the 0.1–2.0 THz terahertz band. Furthermore, the hydrogel possesses excellent infrared thermal camouflage capabilities, significantly reducing the thermal radiation signal of target objects; it also exhibits extremely strong absorption of ultraviolet light in the 200–400 nm band with extremely low transmittance, achieving multi-spectral compatible defense. It can be used as a flexible electromagnetic shielding device, infrared stealth material, or ultraviolet protective material.

[0055] The present application will be further illustrated by the following examples.

[0056] Example 1

[0057] This embodiment provides a bilevel porous composite hydrogel, the preparation method of which includes:

[0058] S1, 60mg of Ti3C2T x -MXene was dispersed in 6 mL of water to prepare a dispersion; 280 mg of gallium indium liquid metal nanoparticles were dispersed in 10 mL of water to prepare a dispersion.

[0059] Add 6 mL of Ti3C2T x -MXene aqueous dispersion was mixed with 10 mL of gallium indium liquid metal nanoparticle aqueous dispersion and magnetically stirred for 30 min at room temperature to obtain composite conductive slurry;

[0060] S2, 3.64g of acrylic monomer was added to the above composite conductive slurry, and after being vortexed and homogenized, it was transferred to a mold and placed in a 40°C oven for polymerization reaction for 24h to obtain a bipolar porous composite hydrogel.

[0061] Example 2

[0062] This embodiment provides a bilevel porous composite hydrogel, the preparation method of which includes:

[0063] S1, 60mg of Ti3C2T x -MXene was dispersed in 6 mL of water to prepare a dispersion; 300 mg of gallium indium liquid metal nanoparticles were dispersed in 10 mL of water to prepare a dispersion.

[0064] Add 6 mL of Ti3C2T x -MXene aqueous dispersion was mixed with 10 mL of gallium indium liquid metal nanoparticle aqueous dispersion and magnetically stirred for 30 min at room temperature to obtain composite conductive slurry;

[0065] S2, 3.64g of acrylic monomer was added to the above composite conductive slurry, and after being vortexed and homogenized, it was transferred to a mold and placed in a 40°C oven for polymerization reaction for 24h to obtain a bipolar porous composite hydrogel.

[0066] Example 3

[0067] This embodiment provides a bilevel porous composite hydrogel, the preparation method of which includes:

[0068] S1, 60mg of Ti3C2T x -MXene was dispersed in 6 mL of water to prepare a dispersion; 320 mg of gallium indium liquid metal nanoparticles were dispersed in 10 mL of water to prepare a dispersion.

[0069] Add 6 mL of Ti3C2T x -MXene aqueous dispersion was mixed with 10 mL of gallium indium liquid metal nanoparticle aqueous dispersion and magnetically stirred for 30 min at room temperature to obtain composite conductive slurry;

[0070] S2, 3.64g of acrylic monomer was added to the above composite conductive slurry, and after being vortexed and homogenized, it was transferred to a mold and placed in a 40°C oven for polymerization reaction for 24h to obtain a bipolar porous composite hydrogel.

[0071] Example 4

[0072] This embodiment provides a bilevel porous composite hydrogel, the preparation method of which includes:

[0073] S1, 30mg of Ti3C2T x -MXene was dispersed in 6 mL of water to prepare a dispersion; 300 mg of gallium indium liquid metal nanoparticles were dispersed in 10 mL of water to prepare a dispersion.

[0074] Add 6 mL of Ti3C2T x -MXene aqueous dispersion was mixed with 10 mL of gallium indium liquid metal nanoparticle aqueous dispersion and magnetically stirred for 30 min at room temperature to obtain composite conductive slurry;

[0075] S2, 3.64g of acrylic monomer was added to the above composite conductive slurry, and after being vortexed and homogenized, it was transferred to a mold and placed in a 40°C oven for polymerization reaction for 24h to obtain a bipolar porous composite hydrogel.

[0076] Comparative Example 1

[0077] The difference between Comparative Example 1 and Example 2 is that there are no gallium indium liquid metal nanoparticles; otherwise, they are the same as in Example 1.

[0078] Comparative Example 2

[0079] The difference between Comparative Example 2 and Example 2 is that there is no Ti3C2T. x -MXene, the rest are the same as in Example 2.

[0080] Comparative Example 3

[0081] This embodiment provides a bilevel porous composite hydrogel, the preparation method of which includes:

[0082] S1, 60mg of Ti3C2T x -MXene was dispersed in 6 mL of water to prepare a dispersion; 200 mg of gallium indium liquid metal nanoparticles were dispersed in 10 mL of water to prepare a dispersion.

[0083] Add 6 mL of Ti3C2T x -MXene aqueous dispersion was mixed with 10 mL of gallium indium liquid metal nanoparticle aqueous dispersion and magnetically stirred for 30 min at room temperature to obtain composite conductive slurry;

[0084] S2, 3.64g of acrylic monomer was added to the above composite conductive slurry, and after being vortexed and homogenized, it was transferred to a mold and placed in a 40°C oven for polymerization reaction for 24h to obtain a bipolar porous composite hydrogel.

[0085] Comparative Example 4

[0086] This embodiment provides a bilevel porous composite hydrogel, the preparation method of which includes:

[0087] S1, 60mg of Ti3C2T x -MXene was dispersed in 6 mL of water to prepare a dispersion; 400 mg of gallium indium liquid metal nanoparticles were dispersed in 10 mL of water to prepare a dispersion.

[0088] Add 6 mL of Ti3C2T x -MXene aqueous dispersion was mixed with 10 mL of gallium indium liquid metal nanoparticle aqueous dispersion and magnetically stirred for 30 min at room temperature to obtain composite conductive slurry;

[0089] S2, 2.4g of acrylic monomer was added to the above composite conductive slurry, and after being vortexed and homogenized, it was transferred to a mold and placed in a 40°C oven for polymerization reaction for 24h to obtain a bipolar porous composite hydrogel.

[0090] The anti-swelling properties of the hydrogels prepared in the examples and comparative examples were evaluated to assess their long-term stability. Specifically, the hydrogels were immersed in deionized water for 7 days, and their morphology was observed. The test results are shown in Table 1 and... Figure 2 As shown.

[0091] Table 1. Stability test results of hydrogels

[0092]

[0093] From Table 1 and Figure 2 It can be seen that in Ti3C2T x With a constant MXene content, the hydrogel exhibits significant swelling when the content of gallium indium liquid metal nanoparticles is 0 wt%; dissolution occurs when the content is 1 wt%; the hydrogel remains stable in water for extended periods when the content is 1.4–1.6 wt%; and significant shrinkage occurs when the content is 2 wt%. Notably, the hydrogel with a gallium indium liquid metal nanoparticle content of 1.5 wt% remains stable in water for a long period, achieving an ideal swelling equilibrium.

[0094] The secondary micropore morphology of the hydrogels prepared in the examples and comparative examples was evaluated by scanning electron microscopy, and the test results are shown in Table 2 and 3. Figure 3 As shown.

[0095] Table 2. Micropore morphology test results of hydrogels

[0096]

[0097] Test results show that Ti3C2T x When the MXene content is 0, the hydrogel has no secondary microporous structure; when the Ti3C2T content is 0, the hydrogel has no secondary microporous structure. x When the MXene content is 0.15wt%, closed secondary micropores begin to form; when Ti3C2T x When the MXene content increases to 0.3wt%, the secondary microporous structure becomes more developed and evolves into semi-open pores.

[0098] In this application, the content of gallium indium liquid metal nanoparticles in Example 2 is 1.5 wt%, and Ti3C2T x When the MXene content was 0.3 wt%, the prepared hydrogel successfully constructed an ideal hierarchical porous structure. The structure is characterized by: primary macropores with a size of approximately several hundred micrometers, secondary micropores with a size of approximately tens of micrometers, and the two levels of pores being interconnected to form a complete hierarchical porous network.

[0099] The hydrogel prepared in Example 2 was subjected to stability testing. The testing method was as follows: it was immersed in hydrochloric acid solution (pH=3), NaOH solution (pH=10), and NaCl solution (3.5% concentration), respectively. Samples were periodically removed, and their size and weight changes were measured. After immersion for 30 days, the hydrogel sample was removed, and the actual image of the hydrogel is shown below. Figure 4 As shown.

[0100] from Figure 4 It was found that after 30 days of soaking, none of the hydrogels dissolved, and the volume change rate in various media was less than 5%, demonstrating excellent dimensional stability. This hydrogel maintained its structural and functional integrity for a long period in water environments with different pH levels and salinity.

[0101] The performance of the hydrogel in Example 2 was tested at different frequency bands, and the results are as follows: Figure 5 As shown, the specific test is as follows:

[0102] The hydrogel sample of Example 2 was tested using a vector network analyzer, and the test results are as follows: Figure 5 As shown in the middle left figure, the test results show that the average electromagnetic shielding effectiveness is higher than 20dB in the ultra-wideband range of 8.2–40GHz; and in the X-band (8.2–12.4GHz), the average shielding effectiveness exceeds 70dB.

[0103] Test results of the terahertz time-domain spectroscopy system are as follows Figure 5 As shown in the middle right figure, this hydrogel maintains excellent shielding capabilities in the 0.1–2.0 THz frequency band, with an average shielding effectiveness greater than 50 dB.

[0104] Figure 6 The UV-Vis spectral test results of the hydrogel in Example 2 show that the ultraviolet light transmittance of the hydrogel is close to zero in the wavelength range of 200–400 nm, indicating that it has almost complete ultraviolet shielding capability.

[0105] The hydrogel from Example 2 was placed on a 100°C hot stage and observed using an infrared thermal imager. The test results are as follows: Figure 7 As shown, its surface temperature differs from the hot stage temperature by 70°C, demonstrating excellent thermal infrared stealth capabilities.

[0106] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A bipolar porous composite hydrogel, characterized in that, It is prepared by synergistic pre-assembly of liquid metal nanoparticles and MXene nanosheets, followed by in-situ polymerization with acrylic acid monomers; Its interior has a bilevel porous structure formed in situ in one step through exothermic polymerization.

2. The bi-level porous composite hydrogel according to claim 1, characterized in that, The bilevel pore structure includes primary macropores induced by liquid metal nanoparticles as sacrificial templates, and secondary micropores formed by MXene regulation.

3. The bi-level porous composite hydrogel according to claim 2, characterized in that, The average pore size of the primary macropores is 100~1000μm; the average pore size of the secondary micropores is 1~100μm.

4. The bi-level porous composite hydrogel according to claim 1, characterized in that, The liquid metal nanoparticles include gallium indium alloy or gallium indium tin alloy; The MXene is Ti3C2T x .

5. The bi-porous composite hydrogel according to claim 1, characterized in that, In the bipolar porous composite hydrogel, the mass percentage of liquid metal nanoparticles is 1.4~1.6 wt%. The MXene nanosheets account for 0.15~0.3wt% of the total mass.

6. The bi-level porous composite hydrogel according to claim 5, characterized in that, In the bipolar porous composite hydrogel, the mass percentage of liquid metal nanoparticles is 1.5 wt%; and the mass percentage of MXene nanosheets is 0.3 wt%.

7. The method for preparing the bi-level porous composite hydrogel according to claim 1, characterized in that, include: S1, Liquid metal nanoparticle dispersion and MXene nanosheet dispersion are mixed and synergistically pre-assembled to obtain composite conductive paste; S2, the composite conductive paste is mixed with acrylic monomers, and the in-situ polymerization of acrylic monomers is initiated at 20~80°C to obtain a bipolar porous composite hydrogel.

8. The preparation method according to claim 7, characterized in that, The reaction time for in-situ polymerization is 1~72h.

9. The preparation method according to claim 7, characterized in that, The liquid metal nanoparticle dispersion is an aqueous dispersion; The MXene nanosheet dispersion is an aqueous dispersion.

10. The application of the bi-porous composite hydrogel according to any one of claims 1-6 in flexible electromagnetic shielding devices, infrared stealth materials or ultraviolet protection materials.

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