Graphene puncture composite material and preparation method thereof

Abstract

The invention discloses a graphene puncture composite material and a preparation method thereof.The composite material is of a three-dimensional porous structure and comprises foam metal, graphene, polyvinyl alcohol and polydopamine, and the graphene, the polyvinyl alcohol and the polydopamine are evenly dispersed in the foam metal and on the surface of the foam metal. The preparation method comprises the following steps: (1) pretreating foam metal; (2) adding the reduced graphene oxide into deionized water to obtain a premix; (3) adding tris (hydroxymethyl) aminomethane and dopamine hydrochloride into the premix to obtain a first mixed solution; (4) adding polyvinyl alcohol into deionized water to obtain a second mixed solution; and (5) the first mixed solution is poured into the second mixed solution, the pretreated foam metal is placed in the second mixed solution to be soaked, then the foam metal is taken out and shaped in a mold, and the composite material is obtained after drying. The composite material provided by the invention can achieve the effects of excellent graphene dispersibility and strong energy absorption.

Description

Technical Field

[0001] This invention relates to functional materials, and in particular to a graphene puncture composite material and its preparation method. Background Technology

[0002] Energy-absorbing materials are a class of specialized engineering materials that dissipate energy generated by external impacts or vibrations safely and efficiently through various mechanisms such as controllable deformation and internal friction, effectively protecting personnel, equipment, or critical structures from damage. With the increasing demands for lightweighting and safety performance in industries such as automotive and aerospace, the need for high-performance energy-absorbing materials is becoming increasingly urgent. Among numerous energy-absorbing materials, foamed metals have attracted considerable attention due to their unique porous structure. It is a special lightweight material with a metal or alloy matrix and a large number of pores, with a porosity exceeding 90%. This unique structure gives foamed metals the characteristics of both structural and functional materials. It not only possesses advantages such as lightweight, high specific strength, and good damping performance, but also absorbs a large amount of energy through the gradual collapse of pores when subjected to impact, exhibiting excellent impact resistance. Therefore, developing new composite materials with foamed metal as the matrix has significant theoretical value and broad application prospects for promoting technological progress in the fields of cushioning and protection.

[0003] These materials, with their unique porous structure and excellent energy absorption capacity, have shown application potential in fields such as aerospace cushioning components and collision protection for new energy vehicles. However, conventional foam metal matrix composites have two major technical bottlenecks: first, the limited plastic deformation capacity of the matrix leads to a sharp drop in energy absorption efficiency under pressure; second, the weak interfacial bonding between traditional filler materials and the metal skeleton easily leads to stress concentration and interfacial failure.

[0004] Existing improvement schemes mostly employ nano-carbon materials for reinforcement. Graphene, due to its high specific surface area and excellent mechanical properties, is often used in composite materials to significantly improve their mechanical properties. However, in practical applications, the lack of effective chemical bonding between graphene and the metal framework leads to insufficient interfacial compatibility, poor dispersion performance, and easy agglomeration when directly filled. Graphene and foamed metal materials cannot form a good bond, often resulting in graphene sheet slippage and interfacial debonding. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a graphene puncture composite material with excellent graphene dispersibility and strong energy absorption; another purpose of this invention is to provide a method for preparing the above-mentioned composite material.

[0006] Technical solution: The graphene puncture composite material of the present invention has a three-dimensional porous structure, including foam metal, graphene, polyvinyl alcohol, and polydopamine. The foam metal is a supporting skeleton, and graphene, polyvinyl alcohol, and polydopamine are uniformly dispersed inside and on the surface of the foam metal.

[0007] The method for preparing the composite material of the present invention includes the following steps: (1) Pretreatment of foamed metal; (2) Add the reduced graphene oxide to deionized water and disperse it evenly to obtain a premix; (3) Tris(hydroxymethyl)aminomethane and dopamine hydrochloride are added to the premix to obtain the first mixture; (4) Add polyvinyl alcohol to deionized water and stir magnetically at 85-95℃ to obtain a second mixture; (5) Pour the first mixture into the second mixture, stir evenly, immerse the pretreated foam metal in it, take it out and shape it in a mold, and dry it to obtain the composite material.

[0008] The foamed metal is one of foamed nickel, foamed copper, or foamed lead.

[0009] The amount of dopamine hydrochloride added is 0.01-0.9 wt% of all raw materials.

[0010] The mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride in step (3) is 1.8-2.2:1; in step (3), after adding tris(hydroxymethyl)aminomethane and dopamine hydrochloride to the premix, magnetic stirring is used to disperse them evenly, and then hydrochloric acid is added dropwise to adjust the pH to 8.3-8.6, and then the mixture is allowed to react for 22-26 hours under magnetic stirring; the magnetic stirring speed in step (3) is 450-550 rpm.

[0011] The magnetic stirring speed in step (4) is 450-550 rpm, and the stirring time is 1.8-2.2 h.

[0012] The stirring speed mentioned in step (5) is 450-550 rpm and the stirring time is 1.8-2.2 h.

[0013] The pretreatment method described in step (1) is to immerse the sample in hydrochloric acid solution for cleaning and then rinse it with water until it becomes neutral.

[0014] Invention principle: This invention innovatively proposes a biphasic polymer synergistic modification strategy, which modifies graphene materials by using polydopamine (PDA) and polyvinyl alcohol (PVA). The hydroxyl active sites of PVA and the catechol functional groups of PDA are introduced to construct a multi-bonded network. The two modified materials work together to better disperse the graphene material and enhance its viscosity.

[0015] PVA, as an environmentally friendly polymer material, possesses excellent film-forming and adhesive properties. Its molecules have hydrogen bonds, enabling it to form a cross-linked network under certain conditions. Dopamine (DA) can form a uniform PDA film on the material surface through self-polymerization, thereby improving the interfacial bonding performance of the material. PDA is a major component of the adhesive proteins secreted by shellfish and other organisms, exhibiting extremely strong adhesiveness and stable fixation on various matrices. Furthermore, it possesses phenolic hydroxyl and amino groups, allowing it to undergo cross-linking reactions with reduced graphene oxide. Therefore, combining PVA and PDA to modify graphene and incorporating it into foamed metals holds promise for significantly enhancing the high-energy absorption performance of composite materials.

[0016] This invention not only achieves the directional assembly of graphene sheets, but also forms a gradient transition layer at the metal-polymer interface. This innovative structure enables the composite material to maintain good mechanical properties under load, resulting in a significant improvement in energy absorption performance compared to traditional filled systems.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) In the composite material prepared by this method, the graphene has good dispersion in the foam metal; (2) The composite material prepared by this method can withstand higher loads when plastic deformation occurs, thus having superior energy absorption potential, strong energy absorption, and specific energy absorption up to 2.61 J / g; (3) The composite material has high mechanical strength and yield strength up to 2.13 MPa. Attached Figure Description

[0018] Figure 1 The microstructure of the composite material prepared in Example 1 before and after compression is shown, where ab is before compression and cd is after compression. Figure 2 A comparison of the stress-strain curves of the composite materials obtained from each experiment; Figure 3 Macroscopic images of different materials before and after compression. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the embodiments.

[0020] The foam metal material used in this invention has a porosity of 96%-98% (30 pores per square mile) and was purchased from Kunshan Guangjiayuan New Materials Co., Ltd.

[0021] The reduced graphene oxide used in this invention was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0022] The PVA, dopamine hydrochloride, and tris(hydroxymethyl)aminomethane (Tris) used in this invention were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0023] Example 1

[0024] The composite material of the present invention has a three-dimensional porous structure, comprising foam metal, graphene, polyvinyl alcohol, and polydopamine, wherein graphene, polyvinyl alcohol, and polydopamine are uniformly dispersed inside and on the surface of the foam metal.

[0025] The method for preparing the composite material of the present invention includes the following steps: (1) Pretreatment of nickel foam: Take a piece of nickel foam with a size of φ20mm×20mm, immerse it in 2mol / L hydrochloric acid solution and ultrasonically clean it for 20 minutes to remove surface oxides. Then rinse it repeatedly with deionized water until neutral, and dry it in an 80℃ oven for 12 hours.

[0026] (2) Weigh 3g of reduced graphene oxide and add it to 295.2g of deionized water. Disperse at 500rpm for 2h, sonicate for 30min, and then disperse at 500rpm for 30min to obtain a premix. Since reduced graphene oxide is a hydrophobic substance, an ultrasonic instrument is used for dispersion to ensure that it is evenly dispersed in water.

[0027] (3) Weigh 1.2g Tris and 0.6g dopamine hydrochloride and add them to the premix. Stir magnetically at 500rpm for 10min at room temperature to disperse it evenly. Add 1-3mol / L dilute hydrochloric acid solution to adjust the pH to 8.5. Then stir magnetically at 500rpm for 24h to obtain the first mixture. In this process, the reaction time is very important. Dopamine hydrochloride forms polydopamine under sufficient stirring, so that graphene can better adhere to the surface and interior of the nickel foam and dissolve more completely.

[0028] (4) Weigh 60g of PVA and add it to 240g of deionized water. Under the conditions of a DF-101S thermostatic magnetic stirrer, adjust the temperature to 90℃ and stir magnetically at 500rpm for 2 hours to disperse it in the water, thus obtaining a second mixture. In this process, the use of magnetic stirring can make the PVA disperse more evenly in the water and dissolve more completely. The magnetic stirring process can promote sufficient contact between PVA molecules and aqueous solution, accelerate the swelling and dissolution process of PVA, and make it quickly dispersed and dissolved to form a transparent and uniform PVA aqueous solution. At the same time, continuous stirring can effectively prevent the dissolved PVA molecules from re-aggregating or gelling, thereby ensuring that the obtained PVA aqueous solution has good stability.

[0029] (5) Pour the first mixture into the second mixture and stir at 500 rpm for 2 hours using a magnetic stirrer to obtain a modified graphene suspension. Stirring with a magnetic stirrer can promote rapid and uniform mixing of the solution, effectively prevent the agglomeration and sedimentation of reduced graphene oxide, and ensure that the prepared suspension has good stability. Immerse the pretreated nickel foam completely in the modified graphene suspension, remove it after 30 minutes to ensure that the suspension fully fills its three-dimensional pores; then remove the nickel foam, place it in a mold for shaping, and then vacuum dry it at 80℃ for 24 hours to obtain the modified graphene puncture composite material. In this embodiment, the mass of PDA is 0.1% of all raw materials, and the mass of PVA is 10% of all raw materials.

[0030] Example 2

[0031] The similarities between this embodiment and Example 1 will not be repeated here. The differences are as follows: the amount of deionized water added in step (2) is 296.82g; the amounts of Tris and dopamine hydrochloride added in step (3) are 0.12g and 0.06g, respectively. In this example, the mass of PDA is 0.01% of the total raw materials, and the mass of PVA is 10% of the total raw materials.

[0032] Example 3

[0033] The similarities between this embodiment and Example 1 will not be repeated here. The differences are as follows: the amount of deionized water added in step (2) is 280.2g; the amounts of Tris and dopamine hydrochloride added in step (3) are 10.8g and 5.4g, respectively. In this example, the mass of PDA is 0.9% of the total raw materials, and the mass of PVA is 10% of the total raw materials.

[0034] Comparative Example 1 The method for preparing the composite material described in this comparative example includes the following steps: (1) Pretreatment of nickel foam: Take a piece of nickel foam with a size of φ20mm×20mm, immerse it in 2mol / L hydrochloric acid solution and ultrasonically clean it for 20 minutes to remove surface oxides. Then rinse it repeatedly with deionized water until neutral, and dry it in an 80℃ oven for 12 hours.

[0035] (2) Weigh 3g of reduced graphene oxide and add it to 295.2g of deionized water. Stir manually until homogeneous to obtain a premix.

[0036] (3) Weigh 1.2g Tris and 0.6g dopamine hydrochloride and add them to the premix. Stir manually until uniform, and add 1-3mol / L dilute hydrochloric acid solution to adjust the pH to 8.5 to obtain the first mixture.

[0037] (4) Weigh 60g of PVA and add it to 240g of deionized water. Under the DF-101S heat-collecting constant temperature magnetic stirrer, adjust the temperature to 90℃ and stir manually until uniform.

[0038] (5) Pour the first mixture into the second mixture and stir manually until homogeneous to obtain a modified graphene suspension. Immerse the pretreated nickel foam completely in the modified graphene suspension for 30 minutes, then remove it to ensure the suspension fully fills its three-dimensional pores. After that, remove the nickel foam, place it in a mold for shaping, and then vacuum dry it at 80°C for 24 hours to obtain the modified graphene puncture composite material. In this example, the mass of PDA is 0.1% of all raw materials, and the mass of PVA is 10% of all raw materials.

[0039] Comparative Example 2 The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the amounts of PVA and deionized water added in step (4) are 30g and 270g, respectively. In this example, the mass of PDA is 0.1% of all raw materials, and the mass of PVA is 5% of all raw materials.

[0040] Comparative Example 3 The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the amount of deionized water added in step (2) is 297g; step (3) is omitted. In this example, the mass of PDA is 0, and the mass of PVA is 10% of all raw materials.

[0041] Comparative Example 4 The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the amounts of PVA and deionized water added in step (4) are 45g and 255g, respectively. In this example, the mass of PDA is 0.1wt% of all raw materials, and the mass of PVA is 7.5% of all raw materials.

[0042] The performance of the composite materials obtained in each experiment was tested according to ISO 13314:2011 standard, and the results are shown in Table 1. Among them, yield strength is the compressive stress when the plastic compressive strain of the specimen reaches 1.0%; energy absorption is the regional integral of the compressive stress-strain curve from 0 to 50% strain; specific energy absorption is the energy absorption per unit mass of the composite material.

[0043] Table 1 Performance test results of each sample sample Yield strength (MPa) <![CDATA[Energy absorption (MJ / m 3 )]]> Specific energy absorption (J / g) Example 1 2.13 1.16 2.61 Example 2 1.72 0.97 2.42 Example 3 1.47 0.99 2.34 Comparative Example 1 1.34 0.90 2.40 Comparative Example 2 0.44 0.41 1.27 Comparative Example 3 0.61 0.64 1.69 Comparative Example 4 0.60 0.59 1.73 As shown in Table 1, the composite material obtained using this method exhibits good energy absorption, with the highest energy absorption reaching 1.16 MJ / m². 3 Compared with composites obtained using other processes (Comparative Example 1), this value is improved by 28.9%. When the mass of PVA accounts for 10% of the total mass of all raw materials, the composite material has the best overall performance. When the mass of PVA accounts for less than 10% of the total mass of all raw materials, the polymer network structure formed by it is relatively sparse, and the bonding and fixing effect on reduced graphene oxide and the supporting effect on the pores of foam metal are significantly reduced, resulting in a significant decrease in the energy absorption capacity of the composite material. When the mass of PVA accounts for more than 10% of the total mass of all raw materials, the viscosity of the system is too high, resulting in some particles not being completely dissolved or flocculent matter being generated, affecting the uniformity and density of the composite material. Therefore, PVA with a mass concentration higher than 10% is not suitable for the preparation of composite materials. When the mass of PDA accounts for 0.01-0.9% of the total mass of all raw materials (Examples 1-3), the resulting composite materials exhibit excellent properties. However, if polydopamine is not added to the composite material (Comparative Example 3), its performance is significantly reduced. This is because the hydrogen bonds and π-π interactions between polydopamine and reduced graphene oxide enhance the hydrophilicity of the graphene composite material, thereby improving its dispersibility and uniformity. When preparing composite materials using other processes described in Comparative Example 1, manual stirring is used, resulting in insufficient uniform dispersion and dissolution, making it impossible to obtain the composite material described in this invention. Because reduced graphene oxide has strong hydrophobicity, thorough stirring and ultrasonic treatment are necessary during its dispersion preparation and polydopamine modification to ensure the uniformity of the dispersion and the adequacy of the modification.

[0044] Figure 1 The microstructure of the composite material obtained in Example 1 before and after compression is shown. Figure 1 a shows the overall morphology of the material before compression, with a clear three-dimensional porous framework structure and a continuous network between the frameworks, indicating that the material has high porosity. Figure 1 b. Further focusing on the local details of the filler, it can be seen that the modified graphene is stacked in a sheet-like manner, forming loose aggregates with a rough surface and a large number of micro-nano-scale pores. Figure 1c shows the morphology of the filler material in the composite material after compression, and it can be seen that some of the filler material has undergone shear failure (marked by yellow dashed lines); Figure 1 Figure d shows the morphology of the foam metal skeleton in the composite material after compression. It can be seen that its failure mode is quite different from that of the filler material in Figure 1c, and the skeleton exhibits tensile failure.

[0045] Figure 2 Typical stress-strain curves of composite materials prepared in different experiments under uniaxial compression are shown. These curves clearly reveal three typical mechanical response stages common to porous materials: the elastic stage, the plateau stage, and the densification stage. First, all curves exhibit an initial linear elastic stage, where stress increases approximately linearly with strain, reflecting the elastic bending deformation of the material's microstructure. By comparing the slopes of the elastic stage, it can be found that the curve of Example 1 has the highest yield strength in this stage. Subsequently, the curves enter a broad plateau stage, characterized by relatively stable stress when strain increases significantly, forming a long stress plateau. This is a key manifestation of the energy absorption capacity of porous materials, the mechanism of which is the gradual buckling and crushing of the internal pore structure of the material. It can be clearly observed from the figures that the plateau stress level and energy absorption of the composite materials obtained in each example are higher than those in the comparative examples, which means that they can withstand higher loads when plastic deformation occurs, thus possessing superior energy absorption potential. When the strain continues to increase to a certain range (approximately 0.5-0.6), all curves enter the densification stage. During this stage, the stress increases sharply with strain, indicating that the pores inside the material have been largely compacted, the solid materials are in contact with each other, and their ability to resist deformation is significantly enhanced. Among them, the curve of Example 1 rises the steepest in this stage, indicating that its densification process is more rapid and thorough.

[0046] Figure 3The macroscopic structural response of the materials under uniaxial compression experiments is clearly demonstrated. The morphology after compression reveals completely different failure mechanisms for the two types of materials: structural buckling is dominant. As shown in the red markings in Examples 1-3, the regular porous structure underwent large-scale, non-uniform buckling and collapse, with deformation concentrated in local weak areas, leading to the crushing of the skeleton, exhibiting typical failure characteristics of porous materials. After crushing, the rearrangement and densification of composite particles and the metal skeleton dominate the energy absorption of the crushing process. In Comparative Examples 1-4, the material underwent uniform overall densification. Notably, obvious particle spalling can be observed at the edges of the compressed samples (such as the area marked by the red dashed line). This indicates that under compressive load, energy is mainly absorbed through the slippage and rearrangement between composite particles and the breakage of the bonding points between particles. This "simultaneous crushing and densification" mode is a typical mechanical response of particle-bonded porous materials, but due to the different compositions of the materials, the particle spalling phenomena are different. The significant differences in particle spalling directly reflect the gradient changes in the mechanical parameters of composite materials with different parameters, which provides intuitive structural evidence for explaining the differences in their macroscopic stress-strain curves (such as the level of plateau stress and energy absorption).

Claims

1. A graphene-based puncture composite material, characterized in that, The composite material is a three-dimensional porous filled structure, including foam metal, graphene, polyvinyl alcohol, and polydopamine. The foam metal is a supporting skeleton, and graphene, polyvinyl alcohol, and polydopamine are uniformly dispersed inside and on the surface of the foam metal.

2. A method for preparing the composite material according to claim 1, characterized in that, Includes the following steps: (1) Pretreatment of foamed metal; (2) Add the reduced graphene oxide to deionized water and disperse it evenly to obtain a premix; (3) Tris(hydroxymethyl)aminomethane and dopamine hydrochloride are added to the premix to obtain the first mixture; (4) Add polyvinyl alcohol to deionized water and stir magnetically at 85-95℃ to obtain a second mixture; (5) Pour the first mixture into the second mixture, stir evenly, immerse the pretreated foam metal in it, take it out and shape it in a mold, and dry it to obtain the composite material.

3. The preparation method according to claim 2, characterized in that, The foamed metal is one of foamed nickel, foamed copper, or foamed aluminum.

4. The preparation method according to claim 2, characterized in that, The amount of dopamine hydrochloride added is 0.01-0.9 wt% of all raw materials.

5. The preparation method according to claim 2, characterized in that, The mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride in step (3) is 1.8-2.2:

1.

6. The preparation method according to claim 2, characterized in that, In step (3), after adding tris(hydroxymethyl)aminomethane and dopamine hydrochloride to the premix, magnetic stirring is used to disperse them evenly. Then, hydrochloric acid is added dropwise to adjust the pH to 8.3-8.6, and the mixture is then stirred under magnetic stirring for 22-26 hours.

7. The preparation method according to claim 6, characterized in that, The magnetic stirring speed mentioned in step (3) is 450-550 rpm.

8. The preparation method according to claim 2, characterized in that, The magnetic stirring speed in step (4) is 450-550 rpm, and the stirring time is 1.8-2.2 h.

9. The preparation method according to claim 2, characterized in that, The stirring speed mentioned in step (5) is 450-550 rpm and the stirring time is 1.8-2.2 h.

10. The preparation method according to claim 2, characterized in that, The pretreatment method described in step (1) is to immerse the sample in hydrochloric acid solution for cleaning and then rinse it with water until it becomes neutral.

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