Graphene composite material and preparation method thereof

Abstract

The application provides a graphene composite material and a preparation method thereof, and relates to the technical field of nanocomposites. The preparation method comprises the following steps: S1, graphene foam is grown on a three-dimensional porous metal template by using a chemical vapor deposition method to obtain a three-dimensional porous metal template containing the graphene foam; and S2, after the template product obtained in the step S1 is soaked by using an EPEK-C solution, acid etching is performed, and then the graphene composite material is prepared by soaking in tetrahydrofuran. According to the above preparation method, the three-dimensional graphene foam is pretreated and structurally controlled by selecting a specific structure of EPEK-C, and finally the three-dimensional graphene foam / polymer composite material with strong interface bonding, complete structure and excellent comprehensive performance is successfully prepared.

Description

Technical Field

[0001] This invention relates to the field of nanocomposite materials technology, and in particular to a graphene composite material and its preparation method. Background Technology

[0002] Three-dimensional graphene foam is a three-dimensional porous network structure composed of interconnected graphene sheets. It not only inherits the excellent properties of graphene, but also has the characteristics of low density and high porosity due to its interconnected porosity. It provides an ideal framework for stress transmission, electron transport and functional loads, and shows great potential in the fields of energy, sensing and composite materials.

[0003] Currently, the main methods for preparing graphene foam include chemical vapor deposition (CVD), hydrothermal self-assembly, and template-guided methods. Among these, CVD using nickel foam as a template can produce three-dimensional graphene networks with complete structure, excellent conductivity, and highly interconnected pores, making it a commonly used method for obtaining high-quality graphene foam. However, this method requires removing the nickel template by acid etching after CVD growth to obtain self-supporting graphene foam.

[0004] However, using such self-supporting graphene foams as reinforcing skeletons in polymer-based composites still faces two major technical bottlenecks: First, the pure graphene foam obtained after etching away the template has extremely thin graphene walls, resulting in limited overall structural mechanical strength. During subsequent composite material preparation, processing, or use, it is highly susceptible to collapse or damage under external forces, leading to structural failure and performance degradation. Second, the large specific surface area and hydrophobic surface of graphene foam make it difficult for high-viscosity polymer resins (especially high-performance engineering plastics) to fully and uniformly wet the entire three-dimensional network. Incomplete wetting leads to weakened interfacial bonding and pore defects, severely restricting the improvement of the composite material's overall performance. Therefore, how to simultaneously improve the wettability and interfacial bonding between the graphene foam and the polymer matrix without damaging the three-dimensional interconnected network, thereby enhancing the thermal conductivity of chlorinated polyaryletherketone resin, has become a critical technical problem urgently needing to be solved in this field.

[0005] In view of this, it is necessary to design an improved graphene composite material and its preparation method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a graphene composite material and its preparation method.

[0007] To achieve the above-mentioned objectives, in a first aspect, the present invention provides a graphene composite material, wherein the graphene composite material is a foam having a three-dimensional porous network structure, comprising a graphene skeleton and a chlorinated polyaryletherketone resin covering the graphene skeleton, wherein the chlorinated polyaryletherketone resin is distributed on the surface and in the pore structure of the graphene skeleton.

[0008] Secondly, the present invention provides a method for preparing graphene composite materials, comprising the following steps:

[0009] S1. Graphene foam is grown on a pretreated three-dimensional porous metal template by chemical vapor deposition to obtain a three-dimensional porous metal template containing graphene foam. During the chemical vapor deposition process of growing graphene foam, H2 is introduced into the reactor at a flow rate of 8-12 sccm and a vacuum degree of 3-5 Pa. When heating begins, the temperature inside the reactor is raised to 1000-1200℃ and held for 20-30 min. Then, CH4 is introduced at a flow rate of 20-30 sccm and the pressure inside the reactor is 77-79 Pa.

[0010] S2. The three-dimensional porous metal template containing graphene foam obtained in step S1 is immersed in a chlorinated polyaryletherketone resin solution, vacuumed to remove bubbles and then dried to obtain a three-dimensional porous metal template wrapped with chlorinated polyaryletherketone resin. The three-dimensional porous metal template is then removed by acid etching to obtain the graphene composite material.

[0011] Preferably, in step S2, the chlorinated polyaryletherketone resin solution is prepared by dissolving chlorinated polyaryletherketone resin in tetrahydrofuran, and its mass fraction is 5-10%.

[0012] Preferably, in step S1, the three-dimensional porous metal template is a nickel foam template, and its pretreatment is carried out according to the following steps: the nickel foam template is placed in an acetic acid solution, sonicated for 20-30 minutes, and ultrasonically cleaned with anhydrous ethanol. After washing, it is dried to obtain the pretreated nickel foam template.

[0013] Preferably, the acetic acid solution has a mass fraction of 45-55%.

[0014] Preferably, in step S2, the acid etching product needs to be soaked in tetrahydrofuran for 5-10 minutes after acid etching.

[0015] Preferably, the chlorinated polyaryletherketone resin has a mass fraction of 5%.

[0016] Preferably, in step S2, the soaking time is 60-120 minutes.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention pretreats and structurally regulates three-dimensional graphene foam using a soluble polyarylether ketone resin (EPEK-C) with a specific structure, ultimately successfully preparing a three-dimensional graphene foam / polymer composite material with strong interfacial bonding, complete structure, and excellent comprehensive performance. The EPEK-C resin has benzene ring end groups and does not contain fluorine atoms. Compared to conventional soluble polyarylether ketones with fluorine end groups, it avoids the problem of excessively low surface energy caused by the strong electron-withdrawing effect of fluorine atoms. Especially at relatively low molecular weight conditions, the fluorine-free end group design ensures that the resin has high surface energy, allowing it to better wet the graphene surface and laying the physical foundation for subsequent formation of a strong interfacial bond. This molecular-level design solves the key problems of poor wettability and weak interfacial adhesion between graphene and polymer resins in existing technologies.

[0019] 2. The method for preparing graphene composite materials provided by this invention involves immersing a three-dimensional porous metal template containing graphene foam in an EPEK-C solution, followed by acid etching to remove the template. Because EPEK-C resin possesses excellent toughness and acid resistance, it can act as a protective layer in the acid etching environment, effectively buffering the direct impact and potential corrosion damage of the acid solution on the fragile graphene thin layer, preventing the graphene network from collapsing or breaking during template removal, and significantly improving the structural integrity of the composite material. Secondly, the EPEK-C layer constructs a gradient transition layer between the graphene and the subsequently filled target polymer matrix. Compared to the inert graphene surface, EPEK-C has better thermodynamic compatibility and chemical similarity with most high-performance engineering plastic resins. This greatly improves the wetting and spreading of the three-dimensional network structure by the target polymer resin, ensuring that the resin can fully fill the pores, thereby achieving a strong interfacial bond between the graphene framework and the matrix.

[0020] 3. The preparation method provided by the present invention avoids the blockage of the graphene main body pores by the dense secondary network formed by excessive EPEK-C residue after acid etching by soaking the product in a specific solvent (tetrahydrofuran). This step achieves precise control of the final microstructure of the composite material. Attached Figure Description

[0021] Figure 1 The molecular formula of EPEK-C used in the preparation of graphene composite materials in this invention;

[0022] Figure 2 These are SEM images of Ni-GF obtained in Example 1 of this invention at different magnifications;

[0023] Figure 3 This is a SEM image of the pure graphene foam prepared in Comparative Example 1 of this invention.

[0024] Figure 4The graphene composite material prepared in Example 1 of this invention is shown in SEM images at different magnifications.

[0025] Figure 5 The Raman spectra of the graphene composite material and Ni-GF prepared in Example 1 of this invention are shown below.

[0026] Figure 6 This is a SEM image of the graphene composite material prepared in Comparative Example 2 of the present invention.

[0027] Figure 7 The elemental distribution diagram of Ni-GF obtained in Example 1 is shown.

[0028] Figure 8 This is an elemental distribution diagram of the graphene composite material prepared in Example 1. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0031] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] On one hand, the present invention provides a graphene composite material, which is a foam with a three-dimensional porous network structure, including a graphene skeleton and a chlorinated polyaryletherketone resin covering the graphene skeleton, wherein the chlorinated polyaryletherketone resin is distributed on the surface and in the pore structure of the graphene skeleton.

[0033] On the other hand, the present invention also provides a method for preparing the above-mentioned graphene composite material, comprising the following steps:

[0034] S1. Graphene foam is grown on a pretreated three-dimensional porous metal template by chemical vapor deposition to obtain a three-dimensional porous metal template containing graphene foam. During the chemical vapor deposition process of growing graphene foam, H2 is introduced into the reactor at a flow rate of 8-12 sccm and a vacuum degree of 3-5 Pa. When heating begins, the temperature inside the reactor is raised to 1000-1200℃ and held for 20-30 min. Then CH4 is introduced at a flow rate of 20-30 sccm.

[0035] S2. The three-dimensional porous metal template containing graphene foam obtained in step S1 is immersed in EPEK-C (chlorinated polyarylether ketone resin) solution for 60-120 min, vacuumed to remove bubbles and then dried to obtain a three-dimensional porous metal template encapsulated in EPEK-C. The three-dimensional porous metal template is then removed by acid etching to obtain the graphene composite material.

[0036] The preparation mechanism of the above method is as follows: First, graphene is catalytically grown on the surface of a three-dimensional porous metal template by template-guided chemical vapor deposition to replicate its network structure and construct a three-dimensional graphene framework. Next, the framework is pretreated with an EPEK-C resin solution. This resin, with its high surface energy, achieves good wetting of the graphene surface and forms a firmly bonded resin layer on the graphene surface. Finally, the metal template is removed by acid etching. During this process, the pre-formed EPEK-C layer can effectively buffer the acid impact and protect the integrity of the graphene network. After the template is removed, the excess EPEK-C is removed by soaking in a specific solvent (such as tetrahydrofuran) to prevent it from clogging the network channels, thus finally forming a dual continuous composite material with the target polymer as the continuous phase and the three-dimensional graphene network as the reinforcing phase, and with a strong and complete interface between the two phases.

[0037] In some embodiments, in step S1, the three-dimensional porous metal template can be a porous template such as a nickel foam template. When the nickel foam template is used as the template, its pretreatment is carried out according to the following steps: the nickel foam template is placed in a 45-55% acetic acid solution, sonicated for 20-30 minutes, and ultrasonically cleaned 3 times with anhydrous ethanol for 10-15 minutes each time. After washing, it is dried to obtain the pretreated nickel foam template.

[0038] In some embodiments, in step S2, the EPEK-C solution is prepared by dissolving chlorinated polyaryletherketone resin in tetrahydrofuran, with a mass fraction of 5-10%, preferably 5%. It should be noted that the chlorinated polyaryletherketone resin is prepared using phenolphthalein and 4,4'-difluorobenzophenone as raw materials and an alkali metal carbonate as a catalyst. Its specific preparation method is a commonly used method in the art, and therefore will not be described in detail here.

[0039] In particular, in some embodiments, after acid etching, the acid etching product is soaked in tetrahydrofuran for 5-10 minutes to dissolve and remove some of the EPEK-C.

[0040] The graphene composite material and its preparation method provided by the present invention will be further described below with reference to specific embodiments:

[0041] Example 1

[0042] This embodiment provides a method for preparing graphene composite materials, including the following steps:

[0043] S1. Place the nickel foam template in a 55% acetic acid solution and ultrasonically clean it for 30 min. Then, ultrasonically clean it three times with anhydrous ethanol for 10 min each time. Dry it to obtain a pretreated nickel foam template. Place the pretreated nickel foam template in a tube furnace and evacuate it. When the vacuum degree inside the tube reaches 3 Pa, introduce H2 gas until the tube reaches the standard atmospheric pressure. Then, evacuate it again to a vacuum degree of 3 Pa. Repeat this process three times. After completion, continuously introduce H2 at a flow rate of 8 sccm. Raise the temperature inside the tube to 1000°C and stabilize it for 30 min. Then, start introducing CH4 at a flow rate of 30 sccm. Control the furnace pressure at 79 Pa. After growing for 1 h, stop heating and introducing CH4 gas. Introduce Ar gas at a flow rate of 500 sccm. After cooling, obtain a graphene foam with a nickel framework, denoted as Ni-GF.

[0044] S2. The Ni-GF obtained in step S1 is immersed in an EPEK-C solution for 60 min, vacuumed to remove bubbles, and then dried at 60℃ for 30 min to obtain EPEK-C-encapsulated Ni-GF. This is then immersed in a 3 mol / L HCl solution at 80℃ to etch the nickel foam template until no bubbles are generated on the material surface. The material is then rinsed three times with deionized water and dried at 60℃ to obtain the GF / EPEK-C material. The GF / EPEK-C material is then immersed in tetrahydrofuran (purity ≥99.9%) at room temperature (25℃) for 5 min to remove some of the EPEK-C. Finally, it is rinsed with deionized water at 95℃ and vacuum dried to obtain the graphene composite material. The EPEK-C solution is obtained by dissolving EPEK-C in tetrahydrofuran (purity ≥99.9%). The molecular formula of EPEK-C is as follows: Figure 1 As shown. It should be noted that, unless otherwise specified, the reagents and raw materials used in the embodiments of the present invention can be obtained through commercial purchase.

[0045] The SEM images of Ni-GF before and after etching (i.e., the Ni-GF obtained in step S1) at different magnifications in this embodiment are as follows: Figure 2 As shown, Figure 2 Figure (a1) in the image corresponds to a 500 μm SEM image before etching (Ni-GF). Figure 2 Figure (a2) in the image corresponds to the SEM image at 100 μm before etching. Comparing the two images, it is clear that after etching, some irregular microstructures appear in the originally regular network structure. The SEM images of the graphene composite material obtained after etching at different magnifications are shown below. Figure 4 As shown, Figure 4 Figure (a1) shows a 500 μm SEM image of the etched graphene composite material. Figure 4Figure (a2) shows the SEM image at 100 μm after etching. The bright spots in the image are the EPEK-C resin residue after washing. This is because when the SEM electron beam acts on the non-conductive EPEK-C, a charge accumulation effect is formed, which leads to signal enhancement in this part, thus forming bright spots. This result shows that EPEK-C fully and uniformly wets the entire three-dimensional network of the graphene framework.

[0046] The elemental distribution diagrams of Ni-GF and the graphene composite material formed after etching are shown below. Figure 7 , Figure 8 As shown, the results indicate that the Ni-GF before etching contains Ni and C elements, while the graphene composite material after etching contains only C elements. However, the distribution morphology of C elements in the two is highly consistent, indicating that the graphene composite material replicates the network structure of the nickel foam template very well.

[0047] Raman spectra of graphene composite material (after treatment) and Ni-GF (before treatment) are shown below. Figure 5 As shown, the results indicate that the presence or absence of Ni-GF and the nickel template has a significant impact on the structural integrity of graphene composites: the spectrum of nickel-containing graphene foam (Ni-GF) shows only a sharp G peak, indicating that its graphene has high crystallinity and very few defects; while the graphene composite after removing the nickel template shows both D and G peaks, and its ID / IG intensity ratio is 0.5992. This confirms that the process of acid etching to remove the nickel template, while forming a self-supporting graphene network, also introduces or exposes more structural defects.

[0048] Example 2

[0049] This embodiment provides a method for preparing graphene composite materials, including the following steps:

[0050] S1. The nickel foam template was placed in a 45% acetic acid solution and cleaned with an ultrasonic cleaner for 20 minutes. Then, it was ultrasonically cleaned three times with anhydrous ethanol for 15 minutes each time. After drying, the pretreated nickel foam template was obtained. The pretreated nickel foam template was placed in a tube furnace and evacuated. When the vacuum degree inside the tube reached 3 Pa, H2 gas was introduced until the tube reached the standard atmospheric pressure. Then, the vacuum degree was evacuated again to 3 Pa. This process was repeated three times. After completion, H2 was continuously introduced at a flow rate of 8 sccm. The temperature inside the tube was raised to 1000°C and stabilized for 30 minutes. Then, CH4 was introduced at a flow rate of 30 sccm. The pressure inside the furnace was controlled at 79 Pa. After growing for 1 hour, heating and CH4 gas introduction were stopped. Ar gas was introduced at a flow rate of 500 sccm. After cooling, graphene foam with a nickel framework was obtained, denoted as Ni-GF.

[0051] S2. The Ni-GF obtained in step S1 is immersed in an EPEK-C solution for 120 min, vacuumed to remove bubbles, and then dried at 60℃ for 30 min to obtain EPEK-C-encapsulated Ni-GF. This is then immersed in a 3 mol / L HCl solution at 80℃ to etch a foamed nickel template until no bubbles are generated on the material surface. The material is then rinsed three times with deionized water and dried at 60℃ to obtain the GF / EPEK-C material. At room temperature, the GF / EPEK-C material is immersed in tetrahydrofuran (purity ≥99.9%) for 10 min to remove some of the EPEK-C. Finally, it is rinsed with deionized water at 95℃ and vacuum dried to obtain the graphene composite material. The EPEK-C solution is obtained by dissolving EPEK-C in tetrahydrofuran (purity ≥99.9%).

[0052] Comparative Example 1

[0053] The only difference between this comparative example and Example 1 is that the step of immersing Ni-GF in EPEK-C solution in step S2 is omitted. That is, Ni-GF is directly acid-etched to obtain pure graphene foam. The remaining experimental steps are the same as in Example 1 and will not be repeated here.

[0054] The SEM image of the pure graphene foam prepared in this comparative example is shown below. Figure 3 As shown, it is similar to Figure 2 The structures are not significantly different. Figure 4 Compared with pure graphene foam, the composite material clearly shows that EPEK-C resin is uniformly distributed in the network structure of the composite material.

[0055] Comparative Example 2

[0056] This comparative example provides a method for preparing a graphene composite material, including the following steps:

[0057] S1. The nickel foam template is placed in a 55% acetic acid solution and cleaned with an ultrasonic cleaner for 30 minutes. Then, it is ultrasonically cleaned three times with anhydrous ethanol for 10 minutes each time. After drying, the pretreated nickel foam template is obtained. The pretreated nickel foam template is placed in a tube furnace and evacuated. When the vacuum degree inside the tube reaches 3 Pa, H2 gas is introduced until the tube reaches the standard atmospheric pressure. Then, the vacuum degree is evacuated again to 3 Pa. This process is repeated three times. After completion, H2 is continuously introduced at a flow rate of 8 sccm. The temperature inside the tube is raised to 1000°C and stabilized for 30 minutes. Then, CH4 is introduced at a flow rate of 30 sccm. The furnace pressure is controlled at 79 Pa. After growth for 1 hour, heating and CH4 gas introduction are stopped. Ar gas is introduced at a flow rate of 500 sccm. After cooling, graphene foam with a nickel framework is obtained, denoted as Ni-GF.

[0058] S2. The Ni-GF obtained in step S1 is immersed in a 3 mol / L HCl solution at 80°C to etch the nickel foam template until no bubbles are generated on the material surface. After rinsing with deionized water three times and drying at 60°C, the resulting product is immersed in EPEK-C solution for 60 min and then removed, dried and cured to obtain the graphene composite material.

[0059] The SEM image of the composite material prepared in this comparative example is shown below. Figure 6 As shown in the figure, obvious cracks can be seen on the surface of the composite material as circled in red. This is because in the preparation method of first acid etching and then adding EPEK-C, the acidic solution directly impacts the graphene thin layer during the etching process of the template, causing the graphene thin layer to crack and affecting the structural integrity of the composite material. This result further illustrates the unique advantages of the technical solution of adding EPEK-C first and then acid etching in this invention.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A graphene composite material, characterized in that, The graphene composite material is a foam with a three-dimensional porous network structure, including a graphene skeleton and a chlorinated polyaryletherketone resin covering the graphene skeleton. The chlorinated polyaryletherketone resin is distributed on the surface and in the pore structure of the graphene skeleton.

2. A method for preparing the graphene composite material according to claim 1, characterized in that, Includes the following steps: S1. Graphene foam is grown on a pretreated three-dimensional porous metal template by chemical vapor deposition to obtain a three-dimensional porous metal template containing graphene foam. During the chemical vapor deposition process of growing graphene foam, H2 is introduced into the reactor at a flow rate of 8-12 sccm and a vacuum degree of 3-5 Pa. When heating begins, the temperature inside the reactor is raised to 1000-1200℃ and held for 20-30 min. Then, CH4 is introduced at a flow rate of 20-30 sccm and the pressure inside the reactor is 77-79 Pa. S2. The three-dimensional porous metal template containing graphene foam obtained in step S1 is immersed in a chlorinated polyaryletherketone resin solution, vacuumed to remove bubbles and then dried to obtain a three-dimensional porous metal template wrapped with chlorinated polyaryletherketone resin. The three-dimensional porous metal template is then removed by acid etching to obtain the graphene composite material.

3. The preparation method according to claim 2, characterized in that, In step S2, the chlorinated polyaryletherketone resin solution is prepared by dissolving chlorinated polyaryletherketone resin in tetrahydrofuran, and its mass fraction is 5-10%.

4. The preparation method according to claim 2, characterized in that, In step S1, the three-dimensional porous metal template is a nickel foam template, and its pretreatment is carried out as follows: the nickel foam template is placed in an acetic acid solution, sonicated for 20-30 minutes, and ultrasonically cleaned with anhydrous ethanol. After washing, it is dried to obtain the pretreated nickel foam template.

5. The preparation method according to claim 4, characterized in that, The acetic acid solution has a mass fraction of 45-55%.

6. The preparation method according to claim 2, characterized in that, In step S2, after acid etching, the acid etching product needs to be soaked in tetrahydrofuran for 5-10 minutes.

7. The preparation method according to claim 3, characterized in that, The chlorinated polyaryletherketone resin has a mass fraction of 5%.

8. The preparation method according to claim 3, characterized in that, In step S2, the soaking time is 60-120 minutes.

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