Hydrogel with both strength and electromagnetic wave absorption and preparation method thereof

Abstract

The invention relates to a hydrogel with both strength and electromagnetic wave absorption and a preparation method thereof. The preparation method of the hydrogel material comprises the following steps: S1, carrying out amination treatment on Fe3O4; s2, adding Fe3O4-NH2 and GO in the step S1 into deionized water, and carrying out ultrasonic dispersion; s3, adding polyethylene glycol methyl ether acrylate-480 and acryloyl morpholine into the dispersion liquid in the S2, and dissolving the polyethylene glycol methyl ether acrylate-480 and the acryloyl morpholine to obtain a mixed liquid; s4, removing dissolved oxygen in the mixed solution in S3, sealing the container, and stirring under an ice bath condition; s5, adding potassium persulfate and N, N, N ', N'-tetramethylethylenediamine into the mixed solution stirred in the step S4, and closing the container again; s6, the container is subjected to a polymerization reaction at the temperature of 60 DEG C, and hydrogel is obtained. Compared with the prior art, when the thickness of the hydrogel material is 2.07 mm, strong broadband microwave absorption is achieved, RLmin is-57.0 dB, EABmax is 6.4 GHz, meanwhile, excellent flexibility is kept, and the work provides a new view angle for developing a high-flexibility and efficient electromagnetic wave absorber.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, and specifically relates to a hydrogel that balances strength and electromagnetic wave absorption, and its preparation method. Background Technology

[0002] The proliferation of advanced electronic devices has exacerbated the challenges associated with electromagnetic pollution. To mitigate these problems, microwave absorbing materials, renowned for their effective electromagnetic dissipation, have been widely adopted as a key solution. Typically, the best microwave absorbers must inherently combine key properties: minimal thickness, low density, high absorption intensity, and wide absorption bandwidth. This comprehensive absorption capability is crucial for effectively suppressing diverse electromagnetic waves, thereby improving device functionality and operational stability.

[0003] Among various microwave absorbers, hydrogels stand out due to their inherent advantages, such as low density, good flexibility, and tunable water content and pore structure. These properties collectively enhance electromagnetic wave dissipation, enabling lightweight and efficient microwave absorption. Thanks to these unique properties, hydrogels have been widely developed for microwave absorption applications. Although the water in hydrogels can effectively dissipate electromagnetic waves through dielectric polarization, their relatively high dielectric constant often limits absorption intensity and frequency coverage. Therefore, various conductive or magnetic materials are typically incorporated into hydrogels as fillers to enhance their electromagnetic wave dissipation mechanism and optimize impedance matching. However, pursuing such high electromagnetic performance often compromises mechanical properties. Adding traditional rigid fillers often reduces the elongation at fracture, leading to decreased structural robustness. Therefore, combining excellent microwave absorption with high mechanical strength and flexibility in hydrogel-based materials remains a key challenge. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a hydrogel that balances strength and electromagnetic wave absorption and its preparation method, mainly solving the technical problem that it is difficult to achieve both strength and toughness of hydrogels and microwave absorption performance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A hydrogel that balances strength and electromagnetic wave absorption is described. The hydrogel is an interpenetrating network structure composed of polymer chains / GO / Fe3O4-NH2, wherein the polymer chains form a continuous network structure, GO sheets are dispersed therein as a rigid framework, and Fe3O4-NH2 consists of amination Fe3O4 nanoparticles uniformly loaded on the GO surface or between the polymer chains. Amino groups form hydrogen bonds with oxygen-containing functional groups on the polymer chains and GO sheets, connecting the oxygen-containing groups of GO, Fe3O4-NH2 and the polymer matrix.

[0006] In one embodiment, the polymer chain is formed by cross-linking polyethylene glycol methyl ether acrylate-480 and acryloylmorpholine.

[0007] In one embodiment, the ratio of GO to Fe3O4-NH2 by weight is 20:(10~40).

[0008] In one embodiment, the weight ratio of GO to Fe3O4-NH2 is 20:30, the thickness of the hydrogel is 2.07 mm, and the minimum reflection loss RL is... min The maximum effective absorption bandwidth is -57.0 dB, EAB. max It is 6.4 GHz.

[0009] The present invention also provides a method for preparing the hydrogel that balances strength and electromagnetic wave absorption, comprising the following steps: S1. Amination of Fe3O4 yields Fe3O4-NH2; S2. Add the Fe3O4-NH2 and GO to deionized water and disperse them by ultrasonication to obtain a dispersion. S3. Add polyethylene glycol methyl ether acrylate-480 and acrylamide to the dispersion and dissolve them to obtain a mixture; S4. Remove dissolved oxygen from the mixture, seal the container, and stir under ice bath conditions; S5. Add the thermal initiator and accelerator to the stirred mixture, and seal the container again to obtain the hydrogel after the polymerization reaction is completed.

[0010] In one embodiment, the S1, Fe3O4 amination treatment is implemented as follows: Fe3O4 was added to a mixture of ethanol and deionized water and heated to react; then a silane coupling agent was added and heated to react again; the solid was then separated and dried to obtain Fe3O4-NH2.

[0011] In one embodiment, the first heating reaction is carried out under the following conditions: oil bath at 50~70℃, with continuous stirring for 30 min; the second heating reaction is carried out under the following conditions: oil bath at 50~70℃, with continuous stirring for 60 min; and the drying is carried out under the following conditions: vacuum drying at 60℃ for 12 h.

[0012] In one embodiment, in step S2, 10-40 mg of Fe3O4-NH2 and 20 mg of GO are added to deionized water and ultrasonically dispersed; in step S3, 2.6-2.68 mL of polyethylene glycol methyl ether acrylate-480 and 2.35-2.45 mL of acryloylmorpholine are added to the dispersion; in step S5, 0.1-0.3 g of thermal initiator and 15-25 μL of accelerator are added to the stirred mixture. For example, the thermal initiator is potassium persulfate and the accelerator is N,N,N',N'-tetramethylethylenediamine.

[0013] In one embodiment, the stirring conditions in step S4 are: stirring at a speed of 400-600 r / min for 10-30 min.

[0014] In one embodiment, step S5 involves completing the polymerization reaction in an oven under the following conditions: 50-70 °C for 10-14 hours.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention introduces GO and amination Fe3O4-NH2 nanoparticles into the network architecture of polymer chains to form a composite hydrogel that effectively balances mechanical robustness and microwave absorption performance. By optimizing the Fe3O4-NH2 content, surface amino groups form hydrogen bonds with oxygen-containing functional groups on the polymer chains and polymer matrix, connecting the oxygen-containing groups of GO, Fe3O4-NH2, and the polymer matrix through a three-dimensional hydrogen bond network. This integrated network structure not only simultaneously enhances the tensile strength, fracture strain, and toughness of the hydrogel, but also promotes impedance matching and activates synergistic dielectric and magnetic loss mechanisms. In a specific embodiment, the GF-30 hydrogel, with a thickness of 2.07 mm, achieved extremely strong broadband microwave absorption, RL min -57.0 dB, EAB max The circuit achieves a current of 6.4 GHz while maintaining excellent flexibility. This work provides a practical and effective strategy for developing high-performance flexible absorbers with good mechanical and electromagnetic properties. Attached Figure Description

[0016] Figure 1 The images show actual photos of the hydrogels provided in Examples 1-4 and Comparative Example 1 of this invention.

[0017] Figure 2 This is a microscopic morphology diagram of the hydrogel provided in Comparative Example 1 of the present invention.

[0018] Figure 3 This is a microscopic morphology diagram of the hydrogel provided in Example 1 of the present invention.

[0019] Figure 4This is a microscopic morphology diagram of the hydrogel provided in Example 2 of the present invention.

[0020] Figure 5 This is a microscopic morphology diagram of the hydrogel provided in Example 3 of the present invention.

[0021] Figure 6 This is a microscopic morphology diagram of the hydrogel provided in Example 4 of the present invention.

[0022] Figure 7 The stress-strain curves of the hydrogels provided in Examples 1-4 and Comparative Example 1 of this invention are shown.

[0023] Figure 8 This is a reflection loss diagram of the hydrogel provided in Comparative Example 1 of the present invention.

[0024] Figure 9 The image shows the reflection loss of the hydrogel provided in Embodiment 1 of the present invention.

[0025] Figure 10 The image shows the reflection loss of the hydrogel provided in Embodiment 2 of the present invention.

[0026] Figure 11 The image shows the reflection loss of the hydrogel provided in Embodiment 3 of the present invention.

[0027] Figure 12 The image shows the reflection loss of the hydrogel provided in Embodiment 4 of the present invention. Detailed Implementation

[0028] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0029] The present invention comprises two parts: the design of the hydrogel composition and the preparation method.

[0030] (1) Hydrogel composition design.

[0031] The hydrogel of this invention is an interpenetrating network structure of polymer chains / GO / Fe3O4-NH2 composite, comprising three core components: the polymer chains refer to the main polymers that construct the three-dimensional network of the hydrogel, forming a continuous network structure and constituting the matrix of the entire hydrogel. GO sheets are dispersed within it as a rigid framework, forming one of the frameworks of the composite network. Fe3O4-NH2 consists of amination Fe3O4 nanoparticles, i.e., the surface of the Fe3O4 nanoparticles has been modified and grafted with amino (-NH2) functional groups, which are uniformly loaded on the GO surface or between the polymer chains. The three core components are physically cross-linked through dense hydrogen bonds, forming a multi-scale composite network. Preferably, the weight ratio of GO to Fe3O4-NH2 is 20:(10~40).

[0032] Specifically, the amino group (-NH2) forms hydrogen bonds with oxygen-containing functional groups (such as hydroxyl, epoxy, carboxyl and carbonyl) on the polymer chain and GO sheets. The dense hydrogen bonds formed between the amino group (-NH2) and the functional groups of the polymer chain itself constitute a three-dimensional hydrogen bond network, connecting the oxygen-containing groups of GO, Fe3O4-NH2 and the polymer matrix.

[0033] In this invention, the polymer chain is formed by the cross-linking of two monomers, mPEG-Ac and ACMO.

[0034] In the components of this invention: Graphene oxide (GO) provides a dielectric loss mechanism and is one of the key components for microwave absorption. Its surface oxygen-containing functional groups (such as hydroxyl and carboxyl groups) can form hydrogen bonds with the amino groups of Fe3O4-NH2, participating in the construction of a three-dimensional network that enhances mechanical properties.

[0035] Iron oxide (Fe3O4) provides a magnetic loss mechanism, synergistically achieving excellent microwave absorption performance with GO. After amination treatment, the amino groups on its surface become a "bridge" connecting GO and the polymer matrix.

[0036] Polyethylene glycol methyl ether acrylate-480 (mPEG-Ac) is one of the main monomers, and its long-chain polyethylene glycol structure endows the hydrogel with good flexibility and biocompatibility.

[0037] Acryloylmorpholine (ACMO) is one of the main monomers. Its morpholine ring structure provides rigidity and works synergistically with mPEG-Ac to construct the polymer network framework of the hydrogel, balancing toughness and strength.

[0038] This invention utilizes the core strategy of constructing a three-dimensional hydrogen bond network to prepare a composite hydrogel that successfully overcomes the problem of achieving both mechanical strength and microwave absorption performance in traditional materials.

[0039] (2) Preparation method of hydrogel.

[0040] This invention provides a hydrogel that balances strength and electromagnetic wave absorption, and its preparation method. Fe3O4 is amination-treated and added to a solution. The solution is thoroughly mixed, nitrogen is purged to remove oxygen, and the mixture is stirred in an ice bath before being placed in an oven for polymerization. The required raw materials include: deionized water, polyethylene glycol methyl ether acrylate-480 (mPEG-Ac), acryloylmorpholine (ACMO), potassium persulfate (KPS), N,N,N',N'-tetramethylethylenediamine (TEMED), aminopropyltriethoxysilane (APTES), ethanol, graphene oxide (GO), and Fe3O4. The specific steps are as follows: 1) Amination treatment of Fe3O4.

[0041] Specifically, 100 mg of Fe3O4 was added to a mixture of 5 mL ethanol and 5 mL deionized water, and the mixture was continuously stirred in an oil bath at 50–70 °C (preferably 60 °C) for 30 min. Then, 0.5 mL of APTES was added, and the mixture was stirred at 50–70 °C (preferably 60 °C) for 1 h. After the reaction, the mixture was centrifuged at 8000 r / min for 5 min to separate the solid. Finally, amination Fe3O4 (Fe3O4-NH2) was obtained by vacuum drying at 60 °C for 12 h. This invention achieves multiple key functions by amination of Fe3O4, grafting active amino functional groups onto Fe3O4: First, by utilizing the steric hindrance and electrostatic repulsion effect of amino groups, the magnetic and van der Waals forces of nanoparticles are effectively suppressed, promoting uniform dispersion of nanoparticles in the polymer matrix and graphene oxide sheets, thereby fully leveraging their nano-reinforcing effect; Second, amino groups, acting as "molecular bridges," can form a dense hydrogen bond network with the abundant oxygen-containing functional groups (such as hydroxyl and carboxyl groups) of graphene oxide and the polymer matrix, thus firmly "stitching" inorganic nanoparticles, two-dimensional nanosheets, and organic polymer chains together, greatly enhancing interfacial bonding, achieving efficient stress transfer, and ultimately synergistically improving the mechanical strength and electromagnetic wave absorption performance of the composite material.

[0042] 2) Preparation of reaction solution.

[0043] Specifically, a certain amount of Fe3O4-NH2 (10~40 mg) and 20 mg GO were added to 20 mL of deionized water. The mixture was sonicated for 20 min to ensure uniform dispersion, resulting in a dispersion. Subsequently, 2.6~2.68 mL (preferably 2.64 mL) of mPEG-Ac and 2.35~2.45 mL (preferably 2.4 mL) of ACMO were added to the dispersion, and the mixture was stirred for about 15 min to dissolve it, resulting in a mixed solution.

[0044] 3) Preparation of hydrogels.

[0045] Transfer the mixture to a three-necked flask equipped with an inlet and outlet gas line, connect it to the nitrogen gas line, and continuously purge with nitrogen for approximately 20–40 minutes to thoroughly remove dissolved oxygen. After deoxygenation, add a magnetic stir bar to the flask, quickly seal the inlet and outlet, and wrap the three-necked flask with an ice bath. Then place it on a magnetic stirrer and stir at 400–600 rpm for 10–30 minutes. Simultaneously, weigh 0.1–0.3 g of potassium persulfate (KPS) powder, dissolve it in 10 mL of deionized water, add a magnetic stir bar, and stir at 400–600 rpm for 10–30 minutes until completely dissolved. After the aforementioned ice bath stirring is complete, quickly add the KPS solution (0.5–1.5 mL) and TEMED (15–25 μL) to the three-necked flask. The mixture was then quickly transferred to a petri dish and placed in an oven to complete the polymerization at a temperature of 50–70 °C for 10–14 h. The resulting hydrogel was named GF-x, where x represents the mass of Fe3O4-NH2 added, expressed in mg.

[0046] In the above steps, apart from the aforementioned core component, the main functions of the remaining components are: Potassium persulfate (KPS) is a thermal initiator. Under heating conditions, it decomposes to generate free radicals, which initiate the polymerization reaction of mPEG-Ac and ACMO monomers.

[0047] N,N,N',N'-Tetramethylethylenediamine (TEMED) is used as a promoter (accelerator) to form a redox initiation system with KPS. It can significantly accelerate the generation of free radicals at relatively low temperatures (such as ice baths), thereby rapidly initiating polymerization.

[0048] Deionized water is the main solvent for the reaction, used to disperse GO and Fe3O4-NH2, and to dissolve the monomers.

[0049] Ethanol is used as a co-solvent in the Fe3O4 amination process to help APTES disperse uniformly and react with the Fe3O4 surface.

[0050] Aminopropyltriethoxysilane (APTES) is a silane coupling agent used for surface amination of Fe3O4 nanoparticles, grafting amino groups (-NH2) onto their surface to obtain Fe3O4-NH2. This is a key step in constructing a hydrogen-bonded network and achieving good dispersion.

[0051] The following are several specific embodiments of the present invention, which do not constitute a limitation on the present invention.

[0052] Example 1 A method for preparing a hydrogel that balances strength and electromagnetic wave absorption: The raw material components, by mass, include: 10 mg Fe3O4-NH2 and 20 mg GO. By volume, they include: 20 mL deionized water, 2.64 mL mPEG-Ac, 2.4 mL ACMO, 1 mL 2 wt% KPS solution, and 20 μL TEMED. Fe3O4-NH2 was obtained by the following method: 100 mg of Fe3O4 was added to a mixture of 5 mL ethanol and 5 mL deionized water, and the mixture was continuously stirred in an oil bath at 50 °C for 30 min. Then, 0.5 mL of APTES was added, and the mixture was stirred at 50 °C for 1 h. After the reaction, the mixture was centrifuged at 8000 r / min for 5 min to separate the solid. Finally, Fe3O4-NH2 was obtained by vacuum drying at 60 °C for 12 h.

[0053] (1) Mix deionized water, Fe3O4-NH2, GO, mPEG-Ac, ACMO, 2 wt% KPS solution and TEMED in a beaker according to the above raw material components volume, and stir evenly with a dropper to ensure that the two monomers are fully dissolved.

[0054] (2) Transfer the mixture to a three-necked flask equipped with an inlet and an outlet pipe, connect the nitrogen gas line, and continuously introduce nitrogen gas for 30 minutes to fully remove dissolved oxygen.

[0055] (3) After deoxygenation, add a magnetic stir bar to the flask, quickly seal the inlet and outlet, and wrap the three-necked flask with an ice bath. Then place it on a magnetic stirrer and stir at 500 r / min for 20 min. At the same time, weigh 0.2 g of KPS powder, dissolve it in 10 mL of deionized water, add a magnetic stir bar, and stir at 500 r / min for 20 min until completely dissolved.

[0056] (4) After the above-mentioned stirring in an ice bath is completed, quickly add 1 mL of KPS solution and 20 μL of LTEMED to the three-necked flask. Then quickly transfer the mixture into a petri dish and place it in an oven at 60 °C for 12 h to complete the polymerization.

[0057] Example 2 A method for preparing a hydrogel that balances strength and electromagnetic wave absorption: The raw material components, by mass, include: 20 mg Fe3O4-NH2 and 20 mg GO. By volume, they include: 20 mL deionized water, 2.64 mL mPEG-Ac, 2.4 mL ACMO, 1 mL 2 wt% KPS solution, and 20 μL TEMED. Fe3O4-NH2 was obtained by the following method: 100 mg of Fe3O4 was added to a mixture of 5 mL ethanol and 5 mL deionized water, and the mixture was continuously stirred in an oil bath at 60 °C for 30 min. Then, 0.5 mL of APTES was added, and the mixture was stirred at 60 °C for 1 h. After the reaction, the mixture was centrifuged at 8000 r / min for 5 min to separate the solid. Finally, Fe3O4-NH2 was obtained by vacuum drying at 60 °C for 12 h.

[0058] (1) Mix deionized water, Fe3O4-NH2, GO, mPEG-Ac, ACMO, 2 wt% KPS solution and TEMED in a beaker according to the above raw material components volume, and stir evenly with a dropper to ensure that the two monomers are fully dissolved.

[0059] (2) Transfer the mixture to a three-necked flask equipped with an inlet and an outlet pipe, connect the nitrogen gas line, and continuously introduce nitrogen gas for 30 minutes to fully remove dissolved oxygen.

[0060] (3) After deoxygenation, add a magnetic stir bar to the flask, quickly seal the inlet and outlet, and wrap the three-necked flask with an ice bath. Then place it on a magnetic stirrer and stir at 500 r / min for 20 min. At the same time, weigh 0.2 g of KPS powder, dissolve it in 10 mL of deionized water, add a magnetic stir bar, and stir at 500 r / min for 20 min until completely dissolved.

[0061] (4) After the above-mentioned stirring in an ice bath is completed, quickly add 1 mL of KPS solution and 20 μL of LTEMED to the three-necked flask. Then quickly transfer the mixture into a petri dish and place it in an oven at 60 °C for 12 h to complete the polymerization.

[0062] Example 3 A method for preparing a hydrogel that balances strength and electromagnetic wave absorption: The raw material components, by mass, include: 30 mg Fe3O4-NH2 and 20 mg GO. By volume, they include: 20 mL deionized water, 2.64 mL mPEG-Ac, 2.4 mL ACMO, 1 mL 2 wt% KPS solution, and 20 μL TEMED. Fe3O4-NH2 was obtained by the following method: 100 mg of Fe3O4 was added to a mixture of 5 mL ethanol and 5 mL deionized water, and the mixture was continuously stirred in an oil bath at 70 °C for 30 min. Then, 0.5 mL of APTES was added, and the mixture was stirred at 70 °C for 1 h. After the reaction, the mixture was centrifuged at 8000 r / min for 5 min to separate the solid. Finally, Fe3O4-NH2 was obtained by vacuum drying at 60 °C for 12 h.

[0063] (1) Mix deionized water, Fe3O4-NH2, GO, mPEG-Ac, ACMO, 2 wt% KPS solution and TEMED in a beaker according to the above raw material components volume, and stir evenly with a dropper to ensure that the two monomers are fully dissolved.

[0064] (2) Transfer the mixture to a three-necked flask equipped with an inlet and an outlet pipe, connect the nitrogen gas line, and continuously introduce nitrogen gas for 30 minutes to fully remove dissolved oxygen.

[0065] (3) After deoxygenation, add a magnetic stir bar to the flask, quickly seal the inlet and outlet, and wrap the three-necked flask with an ice bath. Then place it on a magnetic stirrer and stir at 500 r / min for 20 min. At the same time, weigh 0.2 g of KPS powder, dissolve it in 10 mL of deionized water, add a magnetic stir bar, and stir at 500 r / min for 20 min until completely dissolved.

[0066] (4) After the above-mentioned stirring in an ice bath is completed, quickly add 1 mL of KPS solution and 20 μL of LTEMED to the three-necked flask. Then quickly transfer the mixture into a petri dish and place it in an oven at 60 °C for 12 h to complete the polymerization.

[0067] Example 4 A method for preparing a hydrogel that balances strength and electromagnetic wave absorption: The raw material components, by mass, include: 40 mg Fe3O4-NH2 and 20 mg GO. By volume, they include: 20 mL deionized water, 2.64 mL mPEG-Ac, 2.4 mL ACMO, 1 mL 2 wt% KPS solution, and 20 μL TEMED. Fe3O4-NH2 was obtained by the following method: 100 mg of Fe3O4 was added to a mixture of 5 mL ethanol and 5 mL deionized water, and the mixture was continuously stirred in an oil bath at 60 °C for 30 min. Then, 0.5 mL of APTES was added, and the mixture was stirred at 60 °C for 1 h. After the reaction, the mixture was centrifuged at 8000 r / min for 5 min to separate the solid. Finally, Fe3O4-NH2 was obtained by vacuum drying at 60 °C for 12 h.

[0068] (1) Mix deionized water, Fe3O4-NH2, GO, mPEG-Ac, ACMO, 2 wt% KPS solution and TEMED in a beaker according to the above raw material components volume, and stir evenly with a dropper to ensure that the two monomers are fully dissolved.

[0069] (2) Transfer the mixture to a three-necked flask equipped with an inlet and an outlet pipe, connect the nitrogen gas line, and continuously introduce nitrogen gas for 30 minutes to fully remove dissolved oxygen.

[0070] (3) After deoxygenation, add a magnetic stir bar to the flask, quickly seal the inlet and outlet, and wrap the three-necked flask with an ice bath. Then place it on a magnetic stirrer and stir at 500 r / min for 20 min. At the same time, weigh 0.2 g of KPS powder, dissolve it in 10 mL of deionized water, add a magnetic stir bar, and stir at 500 r / min for 20 min until completely dissolved.

[0071] (4) After the above-mentioned stirring in an ice bath is completed, quickly add 1 mL of KPS solution and 20 μL of LTEMED to the three-necked flask. Then quickly transfer the mixture into a petri dish and place it in an oven at 60 °C for 12 h to complete the polymerization.

[0072] Comparative Example 1 It is almost identical to Example 1, except that the amount of Fe3O4-NH2 and GO added is 0.

[0073] After testing the electromagnetic parameters of the hydrogel samples prepared according to the examples using a vector network analyzer, the GF-30 hydrogel, with a thickness of 2.07 mm, achieved an absorption bandwidth of 6.4 GHz and a minimum reflection loss as low as -57.0 dB, which is significantly better than the control sample without the addition of Fe3O4-NH2 and GO.

[0074] In further embodiments of the present invention, experiments were conducted using a combination of "2.5 mL of mPEG-Ac, 2.6 mL of ACMO, 1 mL of 1 wt% KPS solution and 15 μL of TEMED" and "3 mL of mPEG-Ac, 3 mL of ACMO, 1 mL of 3 wt% KPS solution and 25 μL of TEMED". The reaction conditions in step 6 were designed to be 50 °C or 70 °C, and the polymerization reaction time fluctuated between 16 and 20 h. The results were similar to those in Examples 1-4 above, indicating that the main factors affecting performance in the present invention are the addition of Fe3O4-NH2 and GO.

[0075] Figure 1 Photographs of the obtained GF and pure hydrogels are shown. All hydrogels are stretchable and macroscopically uniform. Unlike the transparency of the pure hydrogel, these four GF hydrogels appear black.

[0076] from Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6It is evident that both pure hydrogels and GF hydrogels possess internal wrinkled structures, which facilitate multiple reflections and scattering of incident electromagnetic waves. Furthermore, as... Figure 6 As shown, Fe3O4 nanoparticles also aggregate in the GF-40 hydrogel, and this aggregation affects the magnetic coupling effect of the hydrogel.

[0077] from Figure 7 As can be seen, except for GF-10, the mechanical properties of GF hydrogels are significantly improved. Specifically, the tensile strength and fracture strain of GF-10 hydrogel are comparable to those of pure hydrogel, at 0.16-0.17 MPa and 453-459%, respectively. With increasing Fe3O4-NH2 content, both the tensile strength and fracture strain of GF hydrogels show an increasing trend. Notably, GF-30 reaches 0.43 MPa and 1019%, respectively, representing increases of 153% and 122% compared to GF-10. However, with further increases in Fe3O4-NH2 content, the performance of GF-40 hydrogel is weaker than that of GF-30, with a tensile strength of 0.33 MPa and a fracture strain of 821%. Nevertheless, these values ​​are still much higher than those of pure hydrogels, indicating that the introduction of Fe3O4-NH2 and GO significantly enhances the mechanical strength of the hydrogel.

[0078] from Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 The two-dimensional RL curves show that, in contrast, the pure hydrogel exhibits a minimum reflection loss of -16.4 dB and a maximum EAB of 5.3 GHz at a thickness of 2.06 mm. In stark contrast, the incorporation of amination-modified Fe3O4 particles significantly enhances the microwave absorption performance of the hydrogel. Specifically, GF-10 achieves a minimum reflection loss of -54.6 dB and a maximum EAB of 5.4 GHz at a thickness of 1.98 mm. Similarly, GF-20 achieves a minimum reflection loss of -55.9 dB and a maximum EAB of 5.8 GHz at a thickness of 2.68 mm. GF-30 stands out with the most significant microwave absorption characteristics, achieving a minimum reflection loss of -57.0 dB and a maximum EAB of 6.4 GHz at a thickness of 2.06 mm. However, with a continuous increase in Fe3O4-NH2 content, the performance of GF-40 deviates from this upward trend. Conversely, at a thickness of 1.65 mm, the minimum reflection loss is -22.4 dB, and the EAB frequency is relatively narrow, at only 2.6 GHz. This indicates that while an appropriate amount of Fe3O4-NH2 particles can significantly enhance the microwave absorption of the hydrogel, excessive addition may lead to performance degradation.

[0079] In summary, this invention successfully prepared a GO / Fe3O4 composite hydrogel and systematically investigated the effects of Fe3O4-NH2 content on its structure, mechanical properties, and microwave absorption performance. The GF-30 hydrogel containing 20 mg GO and 30 mg Fe3O4-NH2 exhibited excellent overall performance due to its uniform dispersion and the stable three-dimensional hydrogen bond network formed between the aminated Fe3O4, GO, and polymer matrix. This interconnected structure not only significantly improved tensile strength, fracture strain, and toughness but also promoted impedance matching and synergistic loss mechanisms, including dielectric loss, magnetic loss, and interfacial polarization. Therefore, this hydrogel achieved strong broadband microwave absorption at a thickness of 2.06 mm, RL min The value is -57.0 dB, and the EAB is 6.4 GHz.

Claims

1. A hydrogel that balances strength and electromagnetic wave absorption, characterized in that, The hydrogel is an interpenetrating network structure composed of polymer chains / GO / Fe3O4-NH2, wherein the polymer chains form a continuous network structure, GO sheets are dispersed therein as a rigid framework, and Fe3O4-NH2 consists of amination Fe3O4 nanoparticles uniformly loaded on the GO surface or between polymer chains. Amino groups form hydrogen bonds with oxygen-containing functional groups on the polymer chains and GO sheets, connecting the oxygen-containing groups of GO, Fe3O4-NH2 and the polymer matrix.

2. The hydrogel according to claim 1, which balances strength and electromagnetic wave absorption, is characterized in that... The polymer chain is formed by cross-linking polyethylene glycol methyl ether acrylate-480 and acryloylmorpholine.

3. The hydrogel according to claim 1, which balances strength and electromagnetic wave absorption, is characterized in that... By weight, the ratio of GO to Fe3O4-NH2 is 20:(10~40).

4. The hydrogel according to claim 1, which balances strength and electromagnetic wave absorption, is characterized in that... The ratio of GO to Fe3O4-NH2 by weight is 20:30, the thickness of the hydrogel is 2.07 mm, and the minimum reflection loss RL is... min The maximum effective absorption bandwidth is -57.0 dB, EAB. max It is 6.4 GHz.

5. The method for preparing the hydrogel that balances strength and electromagnetic wave absorption as described in claim 1, characterized in that, Includes the following steps: S1. Amination of Fe3O4 yields Fe3O4-NH2; S2. Add the Fe3O4-NH2 and GO to deionized water and disperse them by ultrasonication to obtain a dispersion. S3. Add polyethylene glycol methyl ether acrylate-480 and acrylamide to the dispersion and dissolve them to obtain a mixture; S4. Remove dissolved oxygen from the mixture, seal the container, and stir under ice bath conditions; S5. Add the thermal initiator and accelerator to the stirred mixture, and seal the container again to obtain the hydrogel after the polymerization reaction is completed.

6. The method for preparing a hydrogel that balances strength and electromagnetic wave absorption according to claim 5, characterized in that, The method for implementing the S1,Fe3O4 amination treatment is as follows: Fe3O4 was added to a mixture of ethanol and deionized water and heated to react; then a silane coupling agent was added and heated to react again; the solid was then separated and dried to obtain Fe3O4-NH2.

7. The method for preparing a hydrogel that balances strength and electromagnetic wave absorption according to claim 6, characterized in that, The first heating reaction was carried out under the following conditions: oil bath at 50~70℃, with continuous stirring for 30 min; the second heating reaction was carried out under the following conditions: oil bath at 50~70℃, with continuous stirring for 60 min; the drying was carried out under the following conditions: vacuum drying at 60℃ for 12 h.

8. The method for preparing a hydrogel that balances strength and electromagnetic wave absorption according to claim 5, characterized in that, In step S2, 10-40 mg of Fe3O4-NH2 and 20 mg of GO are added to deionized water and ultrasonically dispersed. In step S3, 2.6-2.68 mL of polyethylene glycol methyl ether acrylate-480 and 2.35-2.45 mL of acryloylmorpholine are added to the dispersion. In step S5, 0.1-0.3 g of thermal initiator and 15-25 μL of accelerator are added to the stirred mixture.

9. The method for preparing a hydrogel that balances strength and electromagnetic wave absorption according to claim 8, characterized in that, The thermal initiator is potassium persulfate, and the accelerator is N,N,N',N'-tetramethylethylenediamine.

10. The method for preparing a hydrogel that balances strength and electromagnetic wave absorption according to claim 5, characterized in that, The stirring conditions for step S4 are: stirring at a speed of 400-600 r / min for 10-30 min. The polymerization reaction for step S5 is completed in an oven under the conditions of 50-70 ℃ for 10-14 h.

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