Preparation method of MOFs modified foam metal / functional resin composite material for neutron / gamma ray shielding and material

Abstract

The invention provides a preparation method of an MOFs modified foam metal / functional resin composite for neutron / gamma ray shielding, and belongs to the technical field of radiation shielding materials. The preparation method comprises the following steps: growing a Gd-MOFs (gadolinium-based organic metal framework) nanosheet with oriented morphology on the surface of foam metal in situ by utilizing a solvothermal method, and then carrying out vacuum impregnation on BN and WO3 functionalized epoxy resin into a porous structure of MOFs modified foam metal; the neutron / gamma ray shielding composite material with a microscopic interface mechanical interlocking structure and a macroscopic interpenetrating phase structure is prepared through step-by-step thermocuring; the preparation method provided by the invention is simple and low in cost, can significantly improve the comprehensive performance of the mixed radiation field shielding material, and has important application value in the field of nuclear radiation protection.

Description

Technical Field

[0001] The invention relates to the technical field of radiation shielding materials, in particular to a preparation method and material of a MOFs-modified foam metal / functionalized resin composite material for neutron / gamma ray shielding. Background Art

[0002] High-performance radiation shielding materials are crucial to the safe use and high-quality development of nuclear energy, and are an important guarantee for the healthy work of practitioners and the normal operation of equipment. Neutrons and gamma rays are two typical objects of external irradiation protection in the nuclear field. Due to their different ways of interacting with matter, there are differences in the radiation shielding mechanism. Neutrons are extremely penetrating due to their electrical neutrality. They need to be slowed down by light elements in the shielding body, and then absorbed and shielded by elements with a large neutron absorption cross-section; while gamma-ray shielding requires the use of high atomic number elements. Therefore, in order to achieve neutron / gamma-ray mixed radiation field shielding, it is necessary to introduce both light elements and heavy elements into the material at the same time.

[0003] Polymer-based composite materials have the advantages of light weight and strong designability. By introducing different types of radiation shielding functional fillers into the polymer matrix, neutron / gamma-ray mixed radiation field shielding materials can be prepared. In order to improve the radiation shielding effectiveness of the material, the amount of filler needs to be increased, but when the amount of filler is too high, the mechanical properties of the material will be significantly reduced. To solve this problem, researchers have constructed an interpenetrating phase structure by combining polymer-based radiation shielding materials with silanized modified porous skeleton materials (foam ceramics, foam metals, etc.) to improve the mechanical properties of the composite shielding materials. However, due to the small interaction cross-section between most porous skeleton materials and radiation, the comprehensive shielding effectiveness of the interpenetrating phase composite materials is somewhat lost. At the same time, silanization treatment, as a general modification method, lacks specificity in regulating the interface effect of heterogeneous materials and optimizing stress transfer, resulting in the mechanical properties of the material still needing to be improved. Therefore, in the research and development of materials for neutron / gamma-ray mixed radiation field shielding, how to synergistically enhance the radiation shielding effectiveness and mechanical properties of polymer-based composite materials is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] In view of the above technical difficulties, the purpose of the present invention is to provide a MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding and a preparation method thereof. The material is based on the principle of heterogeneous nucleation (no need to add substances that promote nucleation), and uses a solvent thermal reaction to in-situ grow Gd-MOFs (gadolinium-based organic metal framework) nanosheets with oriented morphology on the porous skeleton of the foam metal, and the MOFs modified foam metal is composited with BN / WO3 functionalized resin to obtain a composite material for neutron / gamma ray shielding. At the same time, through the coupling regulation of components and structures, the radiation shielding effectiveness and mechanical properties of the composite material are synergistically enhanced. The metal node of Gd-MOFs is the Gd element with a large neutron absorption cross section, which can significantly improve the radiation shielding effectiveness of the material; the organic node of Gd-MOFs has rich functional groups, which can enhance the chemical interaction between the porous skeleton and the functionalized resin, thereby improving the mechanical properties of the material; the in-situ grown oriented morphology Gd-MOFs nanosheets construct a mechanical interlocking structure between the foam metal and the functionalized resin, further strengthening the mechanical properties of the composite material.

[0005] Specifically, the above invention object is achieved through the following technical solutions:

[0006] First, the present application provides a method for preparing a MOFs-modified foam metal / functionalized resin composite material for neutron / gamma-ray shielding, and the specific steps are as follows:

[0007] 1) using hydrochloric acid, deionized water and anhydrous ethanol to alternately ultrasonically clean the foam metal (such as foam nickel, foam copper, foam iron nickel, etc.) to completely remove the surface oxide layer, then vacuum drying at 60-80° C. to constant weight, and then placing it in the lining of the reactor (preferably a corrosion-resistant polytetrafluoroethylene lining) at a certain placement angle for standby use;

[0008] 2) Add gadolinium chloride hexahydrate (GdCl3·6H2O) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) to N,N-dimethylformamide (DMF) in sequence, stir magnetically for 10 to 15 minutes, transfer the mixed solution (MOF precursor solution) to a reactor in which a foam metal has been placed, seal the reactor, and perform a solvothermal reaction at 120 to 150°C to allow MOFs (metal organic frameworks) to grow in situ on the surface of the foam metal; after the reactor is cooled to room temperature, take out the reacted foam metal, wash it with ethanol until no product falls off, and then vacuum dry it at 60 to 80°C to constant weight to obtain a MOFs-modified foam metal for standby use;

[0009] 3) mixing boron nitride (BN) as a neutron shielding filler, tungsten trioxide (WO3) as a gamma-ray shielding filler, an epoxy resin matrix, and an epoxy resin curing agent according to a mass ratio, and dispersing them evenly using a planetary stirrer to obtain a precursor solution with neutron / gamma-ray shielding function;

[0010] 4) Place the MOFs-modified metal foam into a mold, and use a vacuum impregnation process to infuse the precursor solution with neutron / γ-ray shielding function into its pores; after the curing is completed, wait until the sample cools naturally to room temperature, and demold to obtain a MOFs-modified metal foam / functionalized resin composite material for neutron / γ-ray shielding. The above vacuum impregnation process can reduce the generation of bubbles after the resin is cured and form an interlocking structure between the resin and the MOFs on the surface of the metal foam.

[0011] The above-mentioned “vacuum impregnation process” is a conventional technology in the art, as disclosed in the document “Wang L, Ma Z, Qiu H, et al. Significantly enhanced electromagnetic interference shielding performances of epoxy nanocomposites with long-range aligned lamellar structures[J]. Nano-Micro Letters, 2022, 14(1): 224.”

[0012] Preferably, in the above step 1), the ultrasonic power is 400-500W, the concentration of hydrochloric acid is 0.1-0.5mol / L; the placement angle (the angle between the foam metal and the inner lining surface of the reactor) ranges from 45° to 90°, so that the Gd-MOFs nanosheets grow uniformly in situ on the metal porous skeleton.

[0013] Preferably, in the above step 2), the molar ratio of gadolinium chloride hexahydrate (GdCl3·6H2O), 1,2,4,5-benzenetetracarboxylic dianhydride and N,N-dimethylformamide is (4-6):(3-7):100, and the solvent thermal reaction time is 2-6 hours.

[0014] Preferably, in the above step 3), the rotation speed of the planetary agitator is 3000-5000 rpm, and the mixing time is 30-60 s; the mass ratio of neutron shielding filler boron nitride (BN), gamma-ray shielding filler tungsten trioxide (WO3), epoxy resin matrix, and epoxy resin curing agent is (1-1.2): (9-10.5): (8-9): (2-2.5). Boron nitride is beneficial to improving the neutron shielding performance of the material; tungsten trioxide is beneficial to improving the gamma-ray shielding performance of the material, and fillers in this ratio can be better dispersed in the resin.

[0015] Preferably, in the above step 4), the vacuum degree of the vacuum impregnation process is -10 to -30 kPa, and the holding time is 30 to 50 min; in order to protect the morphology of MOFs during the curing process,

[0016] Preferably, in the above step 4), "curing" refers to a step-by-step curing procedure, that is, pre-curing at room temperature (25°C) for 1 to 1.5 hours, then placing in an oven, heating from room temperature to 30 to 35°C, keeping warm for 1 to 1.5 hours, and then heating to 45 to 50°C, keeping warm for 2 hours, with a heating rate of 3°C / min. The step-by-step curing procedure is used to prevent the internal stress generated by too fast curing from destroying the MOFs nanosheet structure.

[0017] Secondly, the present application provides a MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding prepared by the above method.

[0018] Compared with the prior art, the preparation method provided in this application has the following beneficial effects:

[0019] (1) The present application adopts an in-situ growth method and regulates the placement angle parameters, uses a foam metal porous skeleton as a nucleation substrate, and makes Gd-MOFs nanosheets in-situ modify the porous skeleton, and the Gd-MOFs nanosheets grow into an oriented morphology, which greatly enhances the interface compatibility, thereby improving the mechanical properties of the composite material;

[0020] (2) The Gd element with a large neutron absorption cross section is effectively introduced into the MOFs nanosheets, which not only improves the mechanical properties of the material, but also improves the neutron shielding function, thus achieving a synergistic enhancement of the radiation shielding effectiveness and mechanical properties of the composite material;

[0021] (3) The raw materials for preparing composite shielding materials are easy to obtain, the preparation method is simple, the cost is low, and it is suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use are briefly introduced below. Figure 1 Schematic diagram of the preparation route of MOFs-modified foam metal / functionalized resin composites for neutron / γ-ray shielding.

[0023] Figure 2 This is a SEM image of the microscopic morphology of the interface of the composite material prepared in Example 1.

[0024] Figure 3 This is a schematic diagram of the foam metal placement structure of Example 3;

[0025] Among them, 1-MOF precursor solution, 2-nickel foam, 3-connection point, 4-Teflon lining, 5-angle control rod, and θ is the placement angle.

[0026] Figure 4 This is a SEM image of the microscopic morphology of the interface of the composite material prepared in Comparative Example 1.

[0027] Figure 5This is a SEM image of the microscopic morphology of the interface of the composite material prepared in Comparative Example 2.

[0028] Figure 6 This is a SEM image of the microscopic morphology of the interface of the composite material prepared in Comparative Example 3.

[0029] Figure 7 This is a SEM image of the microscopic morphology of the interface of the composite material prepared in Comparative Example 5. DETAILED DESCRIPTION

[0030] Example 1

[0031] In this embodiment, the preparation route of the MOFs modified foam metal / functionalized resin composite material for neutron / γ-ray shielding is as follows: Figure 1 As shown, the specific steps are as follows:

[0032] 1) Use 0.3 mol / L hydrochloric acid, deionized water and anhydrous ethanol to alternately ultrasonically clean nickel foam (50 mm×50 mm×5 mm, 20 ppi, Shanghai Yinghuixiong Electronic Materials Co., Ltd.) at 400 W ultrasonic power to completely remove its surface oxide layer (showing bright metallic luster), vacuum dry it at 70°C to constant weight, and then place the nickel foam in the liner of a 300 mL reactor (Shanghai Xiniu Laber Instrument Co., Ltd., liner specification 71*138 mm, material is polytetrafluoroethylene) at a placement angle (θ) of 90°.

[0033] 2) Gadolinium chloride hexahydrate (GdCl3·6H2O) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) were added to N,N-dimethylformamide (DMF) in a molar ratio of 4:3:100. After magnetic stirring for 10 minutes, 150 mL of the mixed solution (MOF precursor solution) was transferred to a reactor in which nickel foam had been placed. The reactor was sealed and subjected to solvent thermal reaction at 120°C for 6 hours to allow MOFs to grow in situ on the surface of nickel foam. After the reactor was cooled to room temperature, the nickel foam after the reaction was taken out and washed with ethanol until no product fell off. Then, it was vacuum dried at 70°C to constant weight to obtain Gd-MOFs modified nickel foam for later use.

[0034] 3) 1 g of neutron shielding filler boron nitride (BN), 9 g of γ-ray shielding filler tungsten trioxide (WO3), 8 g of epoxy resin matrix (E51 brand), and 2 g of epoxy resin curing agent (T31 brand) were mixed, and mixed for 60 seconds at a speed of 4200 rpm using a planetary stirrer to make them evenly dispersed to obtain a precursor solution with neutron / γ-ray shielding function;

[0035] 4) The Gd-MOFs modified nickel foam obtained in step 2) is placed in a mold (50mm×50mm×5mm), and the precursor solution with neutron / γ-ray shielding function is infused into its pores by a vacuum impregnation process (maintained at -30kPa vacuum for 30 minutes) until the Gd-MOFs modified nickel foam is immersed in the precursor, and a step-by-step curing procedure is adopted: pre-curing at room temperature (25°C) and standing for 1 hour, then placed in an oven, heated from room temperature to 30°C, kept warm for 1 hour, then heated to 45°C, kept warm for 2 hours, and the heating rate is 3°C / min. After the curing is completed, wait until the sample cools down naturally to room temperature, and after demolding, a MOFs modified metal foam / functionalized resin composite material for neutron / γ-ray shielding (50mm×50mm×5mm) is obtained. Its SEM picture is as follows Figure 2 shown.

[0036] Example 2

[0037] Except that the placement angle of the foam metal in step 1) is 75° and the solvent thermal reaction time in step 2) is 2 h, other steps and conditions are the same as those in Example 1.

[0038] Example 3

[0039] The preparation steps of the MOFs modified foam metal / functionalized resin composite material in this embodiment are as follows:

[0040] 1) Use 0.1 mol / L hydrochloric acid, deionized water and anhydrous ethanol to alternately ultrasonically clean aluminum foam (50 mm × 50 mm × 5 mm, 15 ppi) at 450 W ultrasonic power to completely remove the surface oxide layer (showing bright metallic luster), vacuum dry it at 70 ° C to constant weight, and then place it in a 300 mL reactor liner at a placement angle of 45°. Figure 3 shown.

[0041] 2) Gadolinium chloride hexahydrate (GdCl3·6H2O) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) were added to N,N-dimethylformamide (DMF) in a molar ratio of 6:7:100. After magnetic stirring for 15 minutes, 150 mL of the mixed solution (MOF precursor solution) was transferred to a reactor where aluminum foam had been placed. The reactor was sealed and subjected to solvent thermal reaction at 150°C for 4 hours to allow MOFs to grow in situ on the surface of aluminum foam. After the reactor was cooled to room temperature, the aluminum foam after the reaction was taken out and washed with ethanol until no product fell off. It was then vacuum dried at 80°C to constant weight to obtain Gd-MOFs modified aluminum foam.

[0042] like Figure 3In the internal structure of the reactor shown, the angle control rod 5 is made of aluminum alloy, the upper end of which is connected to the Teflon liner 4 of the reactor by epoxy resin glue, and the lower end is spot welded to form a connection point 3 with the nickel foam 2 to control the placement angle θ formed by the nickel foam 2 and the bottom surface of the Teflon liner 4 of the reactor, and to allow the foam metal to be fully immersed in the MOF precursor solution. In this embodiment, θ = 45°.

[0043] In a specific implementation, the placement angle may be adjusted by other methods. As long as the placement angle can be controlled within the range of 45°-90°, the foam metal can grow uniformly.

[0044] 3) Boron nitride (BN) as a neutron shielding filler, tungsten trioxide (WO3) as a gamma-ray shielding filler, an epoxy resin matrix (E51 brand), and an epoxy resin curing agent (T31 brand) were mixed in a mass ratio (the amounts were 1.2 g, 10.5 g, 9 g, and 2.5 g, respectively), and mixed for 30 seconds at a speed of 5000 rpm using a planetary stirrer to make them evenly dispersed to obtain a precursor solution with neutron / gamma-ray shielding function;

[0045] 4) Place the Gd-MOFs modified aluminum foam into a mold (50mm×50mm×5mm), and use a vacuum impregnation process (maintained at -10kPa vacuum for 50min) to infuse the precursor solution with neutron / γ-ray shielding function into its pores until the Gd-MOFs modified aluminum foam is immersed in the precursor, and then use a step-by-step curing procedure: pre-curing at room temperature (25°C) and standing for 1.5h, then put it in an oven, heat it from room temperature to 35°C, keep it warm for 1.5h, then heat it to 50°C, keep it warm for 2h, and the heating rate is 3°C / min. After the curing is completed, wait until the sample cools down to room temperature naturally, and demold it to obtain a MOFs modified metal foam / functionalized resin composite material for neutron / γ-ray shielding (50mm×50mm×5mm).

[0046] Example 4

[0047] The preparation steps of the MOFs modified foam metal / functionalized resin composite material in this embodiment are as follows:

[0048] 1) Using 0.5 mol / L hydrochloric acid, deionized water and anhydrous ethanol, alternately ultrasonically cleaned the nickel-iron foam (50 mm×50 mm×5 mm, 25 ppi) at 500 W ultrasonic power, completely removed the surface oxide layer (showing bright metallic luster), vacuum dried at 80° C. to constant weight, and then placed in the liner of a 300 mL reactor at an angle of 85° (same as Example 1);

[0049] 2) Gadolinium chloride hexahydrate (GdCl3·6H2O) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) were added to N,N-dimethylformamide (DMF) in a molar ratio of 5:5:100. After magnetic stirring for 15 minutes, 150 mL of the mixed solution was transferred to a reactor in which foamed iron-nickel was placed. The reactor was sealed and subjected to solvent thermal reaction at 150°C for 6 hours to allow MOFs to grow in situ on the surface of the foamed iron-nickel. After the reactor was cooled to room temperature, the foamed iron-nickel after the reaction was taken out and washed with ethanol until no product fell off. It was then vacuum dried at 80°C to constant weight to obtain Gd-MOFs modified foamed iron-nickel.

[0050] 3) Boron nitride (BN) as a neutron shielding filler, tungsten trioxide (WO3) as a gamma-ray shielding filler, an epoxy resin matrix (E51 brand), and an epoxy resin curing agent (T31 brand) were mixed in a mass ratio (the amounts were 1.1 g, 10 g, 8 g, and 2.5 g, respectively), and a planetary stirrer was used to mix them at a speed of 4500 rpm for 45 seconds to make them evenly dispersed, thereby obtaining a precursor solution with neutron / gamma-ray shielding function;

[0051] 4) Place the Gd-MOFs modified nickel-iron foam into a mold (50mm×50mm×5mm), and use a vacuum impregnation process (maintained at -20kPa vacuum for 40min) to infuse the precursor solution with neutron / γ-ray shielding function into its pores until the Gd-MOFs modified nickel-iron foam is immersed in the precursor, and then use a step-by-step curing procedure: pre-curing at room temperature (25°C) and standing for 1.2h, then put it in an oven, heat it from room temperature to 35°C, keep it warm for 1.2h, then heat it to 50°C, keep it warm for 2h, and the heating rate is 3°C / min. After the curing is completed, wait until the sample cools down naturally to room temperature, and demold it to obtain a MOFs modified metal foam / functionalized resin composite material (50mm×50mm×5mm) for neutron / γ-ray shielding.

[0052] Comparative Example 1

[0053] Except that the curing procedure in step 4) is to keep at 50° C. for 2 h, the other steps and conditions are the same as those in Example 1.

[0054] Comparative Example 2

[0055] Except that the placement angle in step 1) is 0°, the other steps and conditions are the same as those in Example 1.

[0056] Comparative Example 3

[0057] Except that the placement angle in step 1) is 30°, the other steps and conditions are the same as those in Example 1.

[0058] Comparative Example 4

[0059] The functionalized resin composite material prepared in this embodiment does not introduce a foamed metal porous skeleton, and the specific preparation steps are as follows:

[0060] 1) Boron nitride (BN) as a neutron shielding filler, tungsten trioxide (WO3) as a γ-ray shielding filler, an epoxy resin matrix (E51 brand), and an epoxy resin curing agent (T31 brand) were mixed according to a mass ratio (the amounts were 1 g, 9 g, 8 g, and 2 g, respectively), and a planetary stirrer was used to mix for 60 seconds at a speed of 4500 rpm to make them evenly dispersed to obtain a precursor solution with neutron / γ-ray shielding function;

[0061] 2) Pour the precursor solution obtained in 1) into a mold (50 mm × 50 mm × 5 mm), heat it at 50°C for 2 h, wait until the sample naturally cools to room temperature, and demold to obtain a functionalized resin composite material for neutron / γ-ray shielding (50 mm × 50 mm × 5 mm).

[0062] Comparative Example 5

[0063] The foam metal / functionalized resin composite material prepared in this embodiment does not use MOFs to modify the foam metal, and the specific steps are as follows:

[0064] 1) Using 0.3 mol / L hydrochloric acid, deionized water and anhydrous ethanol, alternately ultrasonically clean nickel foam (50 mm×50 mm×5 mm, 20 ppi) at 400 W ultrasonic power to completely remove the surface oxide layer (showing bright metallic luster), and then vacuum dry at 70° C. to constant weight for later use;

[0065] 2) 1g of neutron shielding filler boron nitride (BN), 9g of γ-ray shielding filler tungsten trioxide (WO3), 8g of epoxy resin matrix (E51 brand), and 2g of epoxy resin curing agent (T31 brand) were mixed (the amounts were 1g, 9g, 8g, and 2g, respectively), and a planetary stirrer was used to mix at a speed of 4200rpm to make them evenly dispersed to obtain a precursor solution with neutron / γ-ray shielding function;

[0066] 3) The pure nickel foam obtained in 1) after removing the oxide layer is placed in a mold (50 mm × 50 mm × 5 mm), and the precursor solution with neutron / γ-ray shielding function is infused into its pores by a vacuum impregnation process (maintained at a vacuum degree of -30 kPa for 30 min) until the nickel foam is immersed in the precursor, and then heated at 50°C for 2 h. After the sample is naturally cooled to room temperature, it is demolded to obtain a foam metal / functionalized resin composite material for neutron / γ-ray shielding (50 mm × 50 mm × 5 mm).

[0067] The radiation shielding performance and mechanical properties of the composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were tested. The thermal neutron shielding performance of the materials was tested using an Am-Be neutron source (moderated) and a He-3 detector, the gamma ray shielding performance was tested using a Co-60 source (1.17 MeV, 1.33 MeV), a Cs-137 source (0.662 MeV) and a HPGe detector, and the compression performance was tested according to the standard GB / T 5072-2008. The test results are shown in Table 1 below.

[0068] Table 1 Comparison of radiation shielding properties and mechanical properties of the composite materials obtained in the examples and comparative examples

[0069]

[0070]

[0071] As can be seen from Table 1, Examples 1, 2, and 3 use different solvent thermal reaction times to load different masses of Gd-MOF nanosheets on the metal porous skeleton. It can be seen that with the increase of Gd-MOF nanosheets, the mechanical properties and thermal neutron shielding properties are significantly increased. Examples 4 and 5 show that the functionalization method is highly applicable and Gd-MOF can be grown on a variety of metal skeletons.

[0072] Figure 4-Figure 7 The SEM images of the composite materials prepared in Comparative Examples 1-4 are shown respectively. It can be seen that the reason why the mechanical properties of Comparative Example 1 are reduced compared with Example 1 is that the resin is cured too quickly, which damages the morphology of Gd-MOF ( Figure 4 ), destroying the mechanical interlocking structure. Compared with Example 1, the mechanical properties and shielding properties of Comparative Examples 2 and 3 are both reduced. This is because the placement angle of Comparative Examples 2 and 3 is too small, making the in-situ growth of Gd-MOF on nickel foam not uniform ( Figure 5 , Figure 6 ), which affects the comprehensive performance of the composite material.

[0073] Comparing Comparative Example 4 with Comparative Example 5, it can be seen that the interpenetrating composite material has great advantages in mechanical properties, but since the skeleton occupies a certain volume, the shielding performance is reduced.

[0074] Comparative Example 5 Compared with Example 1, it can be seen that the mechanical interlocking structure formed by Gd-MOF nanosheets and resin ( Figure 7 ), which significantly enhanced the mechanical properties, and the introduced Gd element also greatly improved the shielding performance.

Claims

1. A method for preparing a MOFs-modified foam metal / functionalized resin composite material for neutron / gamma-ray shielding, characterized in that: The specific steps are as follows: 1) Clean and dry the foam metal and place it in a reactor for later use; 2) After gadolinium chloride hexahydrate, 1,2,4,5-benzenetetracarboxylic dianhydride and N,N-dimethylformamide are mixed evenly, the mixture is added to a reactor for reaction; after the reaction is completed, the reactants are dried to a constant weight to obtain MOFs modified foam metal for later use; 3) Evenly mix boron nitride, tungsten trioxide, epoxy resin matrix and epoxy resin curing agent to obtain a precursor solution for later use; 4) placing the MOFs-modified metal foam into a mold, injecting a precursor solution for vacuum impregnation, and demolding after curing to obtain the MOFs-modified metal foam / functionalized resin composite material for neutron / γ-ray shielding.

2. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: Step 1) The foam metal includes at least one of foam nickel, foam copper, and foam iron nickel.

3. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: Step 1) The placement means that the angle between the foam metal and the inner lining surface of the reactor is 45° to 90°.

4. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: Step 1) The cleaning refers to ultrasonic cleaning using hydrochloric acid, deionized water and anhydrous ethanol alternately.

5. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: In step 2), the molar ratio of gadolinium chloride hexahydrate, 1,2,4,5-benzenetetracarboxylic dianhydride and N,N-dimethylformamide added is (4-6):(3-7):100, and the reaction time is 2-6 h.

6. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: In step 3), the mass ratio of the added boron nitride, tungsten trioxide, epoxy resin matrix, and epoxy resin curing agent is (1-1.2):(9-10.5):(8-9):(2-2.5).

7. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: In step 3), the mixing refers to dispersion by a planetary agitator, the rotation speed of the planetary agitator is 3000-5000 rpm, and the mixing time is 30-60 s.

8. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: In step 4), the vacuum impregnation refers to a vacuum degree of -10 to -30 kPa and an impregnation time of 30 to 50 min.

9. The method for preparing the MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding according to claim 1, characterized in that: In step 4), the curing refers to: pre-curing at room temperature for 1 to 1.5 hours; then heating to 30 to 35°C at a heating rate of 3°C / min and keeping warm for 1 to 1.5 hours; finally heating to 45 to 50°C at a heating rate of 3°C / min and keeping warm for 2 hours.

10. A MOFs modified foam metal / functionalized resin composite material for neutron / gamma ray shielding prepared according to any one of claims 1 to 9.

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