Curvature gradient superstructure evaporation casting induced lightweight high-strength structural material

Abstract

The present application relates to a kind of curvature gradient superstructure evaporative casting induced light high-strength structural materials, specifically, a kind of graphene-based superstructure material is disclosed, the graphene-based layer of the material is internally by graphene sheet layer in curvature gradient way interlock, tightly arranged composition.This material is light and high-strength.

Description

Technical Field

[0001] This invention relates to the field of materials, and more specifically, to a curvature gradient superstructure evaporation casting-induced ultra-strong structural material. Background Technology

[0002] The materials industry is the foundation of the national economy. With the rise of my country's national strength and status, the development of fields such as national defense, marine development, aerospace, artificial intelligence, intelligent portable devices, advanced rail transportation, and life sciences urgently requires new and specialized core materials. With the development of aerospace and micro / portable electronic devices, the preparation of lightweight, high-strength functional materials and high-performance energy storage materials / devices has demonstrated significant strategic importance. The era of comprehensive breakthroughs in core technologies for high-end new materials has arrived, making the development of lightweight, high-strength new functional materials and the exploration of their applications in the energy and environmental fields of great strategic significance.

[0003] However, in existing structural materials, it is often difficult to achieve both lightweight and high strength simultaneously. High-strength materials, such as stainless steel, copper, and titanium alloys, are usually accompanied by high density, which limits their application in specialized fields such as aerospace. In addition, high-strength materials are generally difficult to precision machine, resulting in structural components with simple configurations that are not suitable for precision applications. Summary of the Invention

[0004] The inventors discovered that in existing structural materials, lightweight and high strength are often mutually exclusive. To address this, they invented a novel graphene-based superstructure material: a curvature gradient superstructure evaporation casting-induced ultra-strong structural material. This material is spontaneously formed by evaporation casting of curvature gradient graphene-based superstructures at room temperature. The resulting structural material is 1% the size of its original size before evaporation casting. Its interior consists of densely folded graphene sheets arranged in a curvature gradient pattern. The interlocking of the graphene sheets enhances the mechanical properties of the structure. By introducing mortise and tenon joints, high-strength structural components can also be fabricated. The prepared structure is lightweight and high-strength, and the material self-forms at room temperature. The fabrication method is simple, safe, and environmentally friendly. Introducing other special materials during the fabrication process can further enhance the material's functionality, demonstrating significant application potential.

[0005] In a first aspect, the present invention proposes a graphene-based superstructure material. According to embodiments of the present invention, the graphene-based interior of the material is composed of graphene sheets arranged in a curvature gradient manner. The interior of the material is composed of densely wrinkled graphene sheets arranged in a curvature gradient manner, with the graphene sheets interlocking to enhance the mechanical properties of the structure. The resulting structure is lightweight and high-strength, and the material self-forms at room temperature. The preparation method is simple, safe, and environmentally friendly.

[0006] According to embodiments of the present invention, the above-mentioned graphene-based superstructure material may further include at least one of the following additional technical features:

[0007] According to an embodiment of the present invention, the graphene base layer of the material is composed of graphene sheets interlocked and tightly arranged in a curvature gradient manner.

[0008] According to an embodiment of the present invention, the graphene base layer is formed by spontaneous shrinkage of a curvature gradient graphene-based superstructure through evaporation casting at room temperature.

[0009] According to an embodiment of the present invention, the thickness of the graphene sheets is 90-110 nm. According to an embodiment of the present invention, excessively thick or thin sheets will affect the strength and formability of the material. If the sheets are too thin, it is difficult to form effective interlocking between the sheets, resulting in poor mechanical properties and reduced controllability of the shrinkage deformation process, leading to an uncontrollable structure. If the sheets are too thick, the prepared structural material will be too large, making it difficult to controllably prepare microstructures, and the degree of shrinkage deformation will be reduced, making it difficult to prepare complex structures.

[0010] According to an embodiment of the present invention, the thickness of the graphene sheet is 100 nm. Under this thickness condition, the material exhibits better strength and formability according to an embodiment of the present invention.

[0011] According to an embodiment of the present invention, the bulk density of the graphene-based superstructure material is 1.3-1.5 g / cm³. -3 According to embodiments of the present invention, if the density is too low, the mechanical properties of the lightweight, high-strength structural material deteriorate, making it difficult to achieve "high strength"; if the density is too high, the material becomes too dense, making it difficult to achieve "lightweight".

[0012] According to an embodiment of the present invention, the bulk density of the graphene-based superstructure material is 1.4 g / cm³. -3 According to embodiments of the present invention, the material at this bulk density better meets the requirements of "high strength" and "lightweight".

[0013] According to an embodiment of the present invention, the graphene in the graphene base layer is alkaline graphene oxide.

[0014] According to an embodiment of the present invention, the alkaline graphene oxide is obtained by treating graphene oxide with an alkaline solution.

[0015] According to an embodiment of the present invention, the alkaline solution is selected from ammonia water, potassium hydroxide or sodium hydroxide solution.

[0016] According to an embodiment of the present invention, the solubility of the alkaline solution is 0.1-0.2 mol / L. -1 .

[0017] According to an embodiment of the present invention, the concentration of the graphene oxide dispersion is 2-5 mg / mL. -1 .

[0018] According to an embodiment of the present invention, the volume ratio of the alkaline solution to the graphene oxide dispersion is 1:60-1:30.

[0019] According to embodiments of the present invention, the alkaline graphene oxide further comprises dopant materials. The inventors have discovered that adding dopant materials can improve the performance of the material. For example, by adding conductive and thermally conductive materials such as CNTs, BN, or Mxene, the electrical and thermal conductivity of the graphene structure can be increased, allowing it to be better applied in cutting-edge fields such as chips and integrated circuits. Furthermore, these one-dimensional and two-dimensional materials can cross-link with graphene sheets, enhancing the mechanical properties of the material. Adding magnetic materials allows the graphene-based structure to be further controlled using magnetic fields, which serve as passive control sources and can be applied to fields such as material transport, signal monitoring, and drug release in microchannels. Adding pseudocapacitive materials allows lightweight, high-strength graphene to possess pseudocapacitive energy storage properties while being used as structural components, further enabling its application in the field of micro-energy storage. According to embodiments of the present invention, the dopant materials are selected from materials that can be dispersed or dissolved in aqueous solutions.

[0020] According to an embodiment of the present invention, the doping material is selected from conductive and thermally conductive materials, magnetic materials, or pseudocapacitive materials.

[0021] According to an embodiment of the present invention, the conductive and thermally conductive material is selected from CNT, BN, or Mxene.

[0022] According to an embodiment of the present invention, the magnetic material is selected from Fe3O4 or Co2O3.

[0023] According to an embodiment of the present invention, the pseudocapacitive material is selected from MnO2 or RuO2.

[0024] According to an embodiment of the present invention, the mass ratio of the doped material to graphene oxide is 1:10-1:5.

[0025] In another aspect, the present invention also provides a method for preparing graphene-based superstructure materials. According to an embodiment of the present invention, the method includes:

[0026] (1) Alkaliize the graphene oxide to obtain an alkaline graphene oxide mixed dispersion.

[0027] (2) The alkaline graphene oxide mixed dispersion is subjected to heating and cooling treatment to obtain graphene-based hydrogel.

[0028] (3) The graphene-based hydrogel is cut by laser to obtain a graphene-based hydrogel sheet, wherein the graphene-based hydrogel sheet contains graphene sheets arranged with a curvature gradient.

[0029] (4) The graphene-based hydrogel sheet is placed on a superhydrophobic substrate at room temperature to obtain a graphene-based superstructure material.

[0030] According to the method of the present invention, in step (3), graphene-based hydrogels are cut with a laser to obtain graphene-based hydrogel sheets with different simple geometric configurations. The internal structure consists of graphene sheets arranged with curvature gradients and composite components doped therein. By changing the position, size, and thickness of the laser cutting, graphene-based hydrogel sheets with curvature gradients can be obtained. In step (4), the graphene-based hydrogel sheets with curvature gradients are placed on a superhydrophobic substrate. At room temperature, they spontaneously dehydrate and deform under the induction of curvature gradient, resulting in a lightweight and high-strength graphene-based superstructure material with a complex configuration. According to the method of the present invention, the material is formed by the spontaneous shrinkage of the graphene-based superstructure with curvature gradients through evaporation casting at room temperature. The internal structure consists of densely wrinkled graphene sheets arranged with curvature gradients. The graphene sheets interlock with each other, enhancing the mechanical properties of the structure. The prepared structure is lightweight and high-strength, and the material is self-forming at room temperature. The preparation method is simple, safe, and environmentally friendly.

[0031] According to embodiments of the present invention, the method may further include at least one of the following additional technical features:

[0032] According to an embodiment of the present invention, the method includes placing the graphene-based hydrogel sheet described in step (3) flat on a PTFE substrate and laser-cutting it to obtain the graphene-based hydrogel sheet. The graphene-based hydrogel sheet has a tenon-and-mortise interlocking structure, wherein the interlocking structure comprises two parts, a and b. Part a is a superstructure with a significant curvature gradient, and part b is a superstructure with a less significant curvature gradient. According to the method of the present invention, during the evaporation casting process, the curvature gradient induces part a to shrink and bend, and parts a and b are tightly interlocked to form a high-strength assembly. According to the method of the present invention, by introducing a tenon-and-mortise structure, a high-strength structural component can be prepared. According to the method of the present invention, the curvature gradient of part a is more significant than that of part b, and significant bending deformation occurs during the shrinkage process. According to an embodiment of the present invention, the alkalization treatment is carried out by adding a graphene oxide dispersion to a hydrothermal reactor, adding an alkaline solution, and thoroughly stirring and mixing.

[0033] According to an embodiment of the present invention, the alkaline solution is selected from ammonia water, potassium hydroxide or sodium hydroxide solution.

[0034] According to an embodiment of the present invention, the solubility of the alkaline solution is 0.1-0.2 mol / L.-1 According to embodiments of the present invention, this concentration is a suitable concentration for achieving the oriented alignment of graphene oxide and further preparing concentric graphene hydrogels. If the concentration is too low, the graphene oxide dispersion will be in a disordered state, making it difficult to prepare an ordered structure; if the concentration is too high, excessive alkali will produce a salting-out effect, causing the graphene oxide sheets to aggregate, making it difficult to effectively prepare concentric graphene hydrogel superstructures.

[0035] According to an embodiment of the present invention, the concentration of the graphene oxide dispersion is 2-5 mg / mL. -1 According to embodiments of the present invention, this concentration is a suitable concentration for preparing concentric graphene hydrogels. If the concentration is too low, the graphene oxide sheets cannot form effective cross-links during the hydrothermal process, making it difficult to form a hydrogel, and even more difficult to form a concentric graphene hydrogel superstructure. If the concentration is too high, the excessive pressure during the hydrothermal process will cause excessive internal pressure in the prepared graphene hydrogel, leading to implosion and structural collapse.

[0036] According to an embodiment of the present invention, the volume ratio of the alkaline solution to the graphene oxide dispersion is 1:60-1:30. This volume ratio is a suitable concentration for achieving the oriented alignment of graphene oxide and further preparing concentric graphene hydrogels. If the amount of alkali added is too low, the graphene oxide dispersion will be in a disordered state, making it difficult to prepare an ordered structure; if the amount of alkali added is too high, the excess alkali will produce a salting-out effect, causing the graphene oxide sheets to aggregate, making it difficult to effectively prepare concentric graphene hydrogel superstructures.

[0037] According to an embodiment of the present invention, step (1) further includes doping materials. According to an embodiment of the present invention, the introduction of doping materials during the preparation process can further enhance the material's functionality and has great application potential. The inventors have discovered that adding doping materials can improve the material's performance. For example, by adding conductive and thermally conductive materials such as CNT, BN, or Mxene, the electrical and thermal conductivity of graphene structural materials can be increased, allowing them to be better applied in cutting-edge fields such as chips and integrated circuits. Furthermore, these one-dimensional and two-dimensional materials can cross-link with graphene sheets, enhancing the material's mechanical properties. Adding magnetic materials allows graphene-based structural materials to be further controlled using magnetic fields. Magnetic fields are passive control sources and can be applied to fields such as material transport, signal monitoring, and drug release in microchannels. Adding pseudocapacitive materials allows lightweight, high-strength graphene to possess pseudocapacitive energy storage properties while being used as structural components, further enabling its application in the field of micro-energy storage.

[0038] According to an embodiment of the present invention, the alkalization treatment is carried out by adding graphene oxide dispersion to a hydrothermal reactor, adding an alkaline solution and doping materials, and thoroughly stirring and mixing.

[0039] According to an embodiment of the present invention, the doping material is selected from materials that can be dispersed or dissolved in aqueous solutions.

[0040] According to an embodiment of the present invention, the doping material is selected from conductive and thermally conductive materials, magnetic materials, or pseudocapacitive materials.

[0041] According to an embodiment of the present invention, the conductive and thermally conductive material is selected from CNT, BN, or Mxene.

[0042] According to an embodiment of the present invention, the magnetic material is selected from Fe3O4 or Co2O3.

[0043] According to an embodiment of the present invention, the pseudocapacitive material is selected from MnO2 or RuO2.

[0044] According to an embodiment of the present invention, the mass ratio of the dopant material to graphene oxide is less than or equal to 1:5. According to an embodiment of the present invention, if the amount of dopant material added is too high, it will affect the orderly arrangement of the graphene oxide sheets during the hydrothermal process, making it difficult to prepare curvature gradient graphene superstructures.

[0045] According to an embodiment of the present invention, the heat treatment is carried out by pouring the alkaline graphene oxide mixed dispersion into a hydrothermal reactor, and then placing it in an oven for a hydrothermal reaction of 6-12 hours. According to an embodiment of the present invention, this time is a suitable time for preparing concentric graphene superstructures. If the time is too short, the degree of hydrogel reduction will decrease, thereby affecting the subsequent curvature gradient induced evaporation casting process; 12 hours is sufficient for complete reaction, while too long a time will result in energy waste.

[0046] According to an embodiment of the present invention, the inner liner of the hydrothermal reactor is cylindrical.

[0047] According to an embodiment of the present invention, after the alkaline graphene oxide mixed dispersion is poured into the hydrothermal reactor, it is further mixed and stirred in the inner liner of the hydrothermal reactor.

[0048] According to an embodiment of the present invention, the temperature of the hydrothermal reaction is 160℃-200℃. According to an embodiment of the present invention, this temperature is suitable for preparing concentric graphene superstructures. If the temperature is too low, the degree of hydrogel reduction decreases, thus affecting the subsequent curvature gradient-induced evaporation casting process; if the temperature is too high, the internal pressure of the hydrothermal reactor during the hydrothermal process is too high, and violent turbulence is generated inside the graphene oxide dispersion, disrupting its effective arrangement and making it difficult to form concentric graphene hydrogel superstructures.

[0049] According to an embodiment of the present invention, the temperature of the cooling process is room temperature.

[0050] According to an embodiment of the present invention, the graphene-based hydrogel is a cylindrical concentrically oriented graphene-based hydrogel.

[0051] According to an embodiment of the present invention, the graphene-based hydrogel sheet has a geometric configuration.

[0052] According to an embodiment of the present invention, the geometric configuration is a simple configuration.

[0053] According to an embodiment of the present invention, the geometric configuration is a cuboid, a cross shape, or a dumbbell shape.

[0054] According to an embodiment of the present invention, the thickness of the graphene-based hydrogel sheet is 1-5 mm. According to an embodiment of the present invention, this thickness is within the range for achieving controllable shrinkage and deformation of the curvature gradient graphene hydrogel. When the thickness is too low, the shrinkage process of the graphene hydrogel sheet is greatly affected by the substrate and the environment, resulting in poor controllability; when the thickness is too high, the graphene hydrogel sheet becomes rigid, and the degree of bending and other deformations is affected, making it difficult to prepare complex graphene structural materials.

[0055] According to an embodiment of the present invention, the superhydrophobic substrate is selected from a smooth polytetrafluoroethylene plate, a glass plate treated with hydrophobicity, or a plastic plate.

[0056] In another aspect, the present invention also provides a method for preparing graphene-based superstructure materials. According to an embodiment of the present invention, the method includes:

[0057] (1) The graphene oxide and doped materials are subjected to alkalization treatment to obtain an alkaline graphene oxide mixed dispersion. The alkalization treatment is carried out by adding the graphene oxide dispersion to a hydrothermal reactor, adding an alkaline solution and the doped materials, and stirring thoroughly. The alkaline solution is selected from ammonia water, potassium hydroxide or sodium hydroxide solution, and the solubility of the alkaline solution is 0.1-0.2 mol / L. -1 The concentration of the graphene oxide dispersion is 2-5 mg / mL. -1 The volume ratio of the alkaline solution to the graphene oxide dispersion is 1:60-1:30. The dopant material is selected from materials that can be dispersed or dissolved in aqueous solutions. The dopant material is selected from conductive and thermally conductive materials, magnetic materials, or pseudocapacitive materials. The conductive and thermally conductive material is selected from CNT, BN, or Mxene. The magnetic material is selected from Fe3O4 or Co2O3. The pseudocapacitive material is selected from MnO2 or RuO2. The mass ratio of the dopant material to the graphene oxide is 1:10-1:5.

[0058] (2) The alkaline graphene oxide mixed dispersion is subjected to heating and cooling treatment to obtain graphene-based hydrogel. The heating treatment is carried out by pouring the alkaline graphene oxide mixed dispersion into a hydrothermal reactor and then placing it in an oven for a hydrothermal reaction of 6-12 hours. The temperature of the hydrothermal reaction is 160℃-200℃. The temperature of the cooling treatment is room temperature.

[0059] (3) A graphene-based hydrogel sheet is laid flat on a PTFE substrate and laser-cut to obtain a graphene-based hydrogel sheet. The graphene-based hydrogel sheet has a tenon-and-mortise interlocking structure, wherein the interlocking structure includes two parts, a and b. Part a is a superstructure with obvious curvature gradient, and part b is a superstructure with indistinct curvature gradient. The graphene-based hydrogel sheet has a geometric configuration, which is a cuboid, a cross shape, or a dumbbell shape. The thickness of the graphene-based hydrogel sheet is 1-5 mm.

[0060] (4) At room temperature, the graphene-based hydrogel sheet is placed on a superhydrophobic substrate and then allowed to dry naturally. The hydrogel spontaneously shrinks. The superhydrophobic substrate is selected from smooth polytetrafluoroethylene plates, hydrophobically treated glass plates, or plastic plates to obtain graphene-based superstructure materials. According to the method of the present invention, in step (3), the graphene-based hydrogel is laser-cut to obtain graphene-based hydrogel sheets with different simple geometric configurations. The internal structure consists of graphene sheets arranged with curvature gradients and composite components doped therein. By changing the position, size, and thickness of the laser cutting, curvature gradient graphene-based hydrogel sheets can be obtained. In step (4), the curvature gradient graphene-based hydrogel sheet is placed on a superhydrophobic substrate. At room temperature, it spontaneously dehydrates and deforms while shrinking under the induction of curvature gradient, thus obtaining a lightweight and high-strength graphene-based superstructure material with a complex configuration. According to the method of the present invention, the material is formed by spontaneous shrinkage of a curvature gradient graphene-based superstructure through evaporation casting at room temperature. Its interior is composed of dense, wrinkled graphene sheets arranged in a curvature gradient manner, with the graphene sheets interlocking to enhance the mechanical properties of the structure. The prepared structure is lightweight and high-strength, and the material is self-forming at room temperature. The preparation method is simple, safe, and environmentally friendly. The introduction of doping materials during the preparation process can further enhance the material's functionality and has great application prospects.

[0061] The method according to embodiments of the present invention may further include one of the following technical features:

[0062] According to an embodiment of the present invention, the graphene-based superstructure material is composed of graphene sheets arranged in a curvature gradient manner, wherein the thickness of the graphene sheets is 90-110 nm. According to an embodiment of the present invention, excessively thick or thin thickness will affect the strength and formability of the material. If too thin, it is difficult for the sheets to form effective interlocking, resulting in poor mechanical properties and reduced controllability of the shrinkage deformation process, leading to an uncontrollable structure. If too thick, the prepared structural material will be too large, making it difficult to controllably prepare microstructures, and the degree of shrinkage deformation will be reduced, making it difficult to prepare complex structures.

[0063] According to an embodiment of the present invention, the graphene-based superstructure material is composed of graphene sheets arranged in a curvature gradient manner, and the thickness of the graphene sheets is 100 nm. According to an embodiment of the present invention, under this thickness condition, the material exhibits better strength and formability.

[0064] According to an embodiment of the present invention, the bulk density of the graphene-based superstructure material is 1.3-1.5 g / cm³. -3 According to embodiments of the present invention, if the density is too low, the mechanical properties of the lightweight, high-strength structural material deteriorate, making it difficult to achieve "high strength"; if the density is too high, the material becomes too dense, making it difficult to achieve "lightweight".

[0065] According to an embodiment of the present invention, the bulk density of the graphene-based superstructure material is 1.4 g / cm³. -3 According to embodiments of the present invention, the material at this bulk density better meets the requirements of "high strength" and "lightweight".

[0066] According to an embodiment of the present invention, the size of the prepared structural material is 1% of the size before spontaneous dehydration at room temperature in step (3), which is on the millimeter-micrometer scale.

[0067] According to embodiments of the present invention, the present invention also proposes a curvature gradient superstructure evaporation casting-induced lightweight high-strength structural material (i.e., the graphene-based superstructure material described in the present invention). The material matrix is ​​composed of dense, wrinkled graphene sheets arranged in a curvature gradient manner. The thickness of the micro-sheets is about 100 nm. The sheets interlock with each other, which enhances the mechanical properties of the structure. At the same time, the graphene has a low density, and the prepared structure is lightweight and high-strength.

[0068] According to embodiments of the present invention, the present invention also proposes a curvature gradient superstructure evaporation casting-induced lightweight high-strength structural material, the method steps of which are as follows:

[0069] (1) Dissolve 2-5 mg / mL -1 The graphene oxide dispersion was added to a hydrothermal reactor, along with an appropriate amount of alkaline solution and other dopants, and then thoroughly stirred and mixed.

[0070] (2) Pour the alkaline graphene oxide mixed dispersion from step 1 into a hydrothermal reactor, then place it in an oven and perform a hydrothermal reaction for 6-12 hours. Cool to room temperature to obtain a cylindrical concentric circle oriented graphene-based hydrogel.

[0071] (3) By using laser cutting of hydrogel, graphene-based hydrogel sheets with different simple geometric configurations are obtained. The internal structure consists of graphene sheets arranged with curvature gradient and composite components doped therein. By changing the position, size and thickness of laser cutting, curvature gradient graphene-based superstructures can be obtained in a controllable manner.

[0072] (4) The curvature gradient graphene-based superstructure was placed on a superhydrophobic substrate. Under room temperature conditions, it spontaneously dehydrated and deformed while shrinking under the induction of curvature gradient, resulting in a lightweight and high-strength graphene-based superstructure with a complex configuration.

[0073] The alkaline solution is ammonia, potassium hydroxide, or sodium hydroxide solution, with the concentration of potassium hydroxide or sodium hydroxide solution being 0.1-0.2 mol / L. -1 The volume ratio of alkaline solution to graphene oxide dispersion is 1:60-1:30; the doping materials are conductive and thermally conductive materials such as CNT, BN, and MXene, magnetic materials such as Fe3O4 and Co2O3, and pseudocapacitive materials such as MnO2 and RuO2, and the mass ratio of doping materials to graphene oxide is 1:10-1:5.

[0074] Furthermore, the hydrothermal reaction temperature is 160℃-200℃;

[0075] Furthermore, the geometric configuration is a simple configuration such as cuboid, cross, dumbbell, etc., and the thickness of the graphene-based hydrogel is 1-5mm;

[0076] Furthermore, the superhydrophobic substrate can be a smooth polytetrafluoroethylene sheet, a hydrophobically treated glass sheet, a plastic sheet, etc.

[0077] In another aspect, the present invention also proposes a graphene-based superstructure material. According to an embodiment of the present invention, the material is prepared by the method described above.

[0078] According to embodiments of the present invention, the present invention has at least one of the following technical effects:

[0079] (1) The material described in this invention is obtained by the spontaneous evaporation casting process of hydrogel (i.e., the room temperature condition in step 4 of the preparation method). Due to the influence of capillary force, the evaporation casting process will cause the graphene sheets to shrink and wrinkle, and the size will be greatly reduced. The macroscopic size is about 1 / 100 of that before evaporation casting. Moreover, the evaporation casting process can prepare three-dimensional complex structures that are difficult to obtain directly by laser, which is a very good method for preparing micro-complex structural parts.

[0080] (2) The material described in this invention contains dense and oriented graphene sheets with intersecting layers that are tightly bonded yet have some porosity, making the prepared material lightweight and strong with excellent mechanical properties. The millimeter-scale cubic structure can withstand ton-level pressure.

[0081] (3) The material described in this invention is self-forming at room temperature, with extremely low energy consumption, and is green, safe and environmentally friendly. Attached Figure Description

[0082] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0083] Figure 1 This is a schematic diagram of the microstructure of the concentric graphene hydrogel prepared in Example 1.

[0084] Figure 2 This is a schematic diagram of laser cutting the concentric graphene hydrogel prepared in Example 1 in different directions.

[0085] Figure 3 Example 1 shows the mortise and tenon joint structure design and its microstructure.

[0086] Figure 4 The image shows a scanning electron microscope (SEM) image of the curvature gradient graphene superstructure prepared in Example 1.

[0087] Figure 5 The image shows the microstructure of the lightweight, high-strength graphene prepared in Example 1 using a scanning electron microscope (SEM).

[0088] Figure 6 Electron image of the cross-shaped curvature gradient graphene superstructure prepared in Example 1;

[0089] Figure 7 A schematic diagram of the microstructure of the cross-shaped curvature gradient graphene superstructure prepared in Example 1;

[0090] Figure 8 An electron image of the cross-shaped curvature gradient graphene superstructure prepared in Example 1 after evaporation casting;

[0091] Figure 9 Mechanical properties of the cubic lightweight high-strength graphene structural component prepared in Example 1 are demonstrated.

[0092] Figure 10 Electronic photographs of the mortise and tenon joint structure prepared in Example 1 and its tensile test electronic photographs. Detailed Implementation

[0093] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0094] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are available from publicly available commercial sources.

[0095] In the following embodiments:

[0096] The graphene oxide dispersion was prepared as follows: In a 0°C cold trap, 1300 mL of concentrated sulfuric acid (98 wt%) was placed in a 5000 mL beaker (clean and anhydrous). While stirring, 50 g of pre-frozen graphite powder was added. After stirring for 2 hours, 150 g of potassium permanganate was slowly added, ensuring the temperature rise did not exceed 5°C. The beaker was then placed in a 55°C water bath and stirred for 8-10 hours to obtain a viscous slurry. The slurry was slowly poured into an excess of ice water while stirring, maintaining a temperature rise of no more than 5°C during the water addition. After cooling to room temperature, 300 mL of hydrogen peroxide (30 wt%) was added. The dispersion changed from dark brown to golden yellow. The solution was then stirred for 20 minutes to ensure thorough mixing and reaction, followed by settling. Discard the supernatant, add 4000 mL of deionized water to the lower sediment, stir for 20 minutes, let it settle, discard the supernatant, add another 4000 mL of deionized water to the lower sediment, stir, let it settle, and discard the supernatant. Repeat this process once a day for 7 days. Place the sediment obtained in the last step in a dialysis bag for dialysis, changing the water daily until the solution pH = 7. Then, dialyze the sediment at 10000 rpm. -1 Centrifuge at 30 min for 30 min to remove lower impurities and upper supernatant, yielding 10 mg / mL. -1 ~20mg / mL -1 The graphene oxide dispersion was calibrated and set aside for later use.

[0097] Example 1

[0098] (1) Prepare a concentration of 3.5 mg / mL -1 Graphene oxide dispersion;

[0099] (2) Mix 60 mL of graphene oxide dispersion with 1 mL of ammonia water, pour into a 100 mL reaction vessel, and stir magnetically for 30 minutes;

[0100] (3) The hydrothermal reactor was placed in an oven and subjected to hydrothermal reaction at 180°C for 6 hours. Then it was allowed to cool naturally to room temperature to obtain a cylindrical concentric graphene hydrogel. Figure 1 ).

[0101] (4) Laser cutting of graphene hydrogel yields hydrogel sheets with a thickness of 2 mm. Different microstructures can be obtained by different cutting directions, such as transverse, longitudinal, and oblique cuts. Among them, the curvature center of the graphene sheets in the transversely cut hydrogel points inward, the curvature center of the graphene sheets in the longitudinally cut hydrogel points outward, and the curvature center of the graphene sheets in the obliquely cut hydrogel also points outward, and in two different directions, up and down. Figure 2 ).

[0102] (5) The obtained hydrogel sheet is placed flat on the PTFE substrate, and a geometric pattern is laser-engraved. Then it is dried naturally. During the water evaporation process, the hydrogel spontaneously shrinks and undergoes shape changes under the induction of curvature gradient, finally obtaining a complex configuration of lightweight and high-strength structural component.

[0103] (6) The transverse hydrogel sheet obtained in step 4 is placed flat on a PTFE substrate, and a tenon-and-mortise interlocking structure is prepared by laser cutting. The structural design and microstructure are as follows: Figure 3 As shown, the interlocking structure comprises two parts, a and b, with part a being a distinct curvature gradient superstructure. During the evaporation casting process, the curvature gradient induces shrinkage and bending deformation in part a, causing parts a and b to interlock tightly and form a high-strength assembly.

[0104] from Figure 4 The SEM images show that the curvature gradient graphene hydrogel prepared in this embodiment has a curvature gradient structure in the horizontal direction and a parallel orientation structure in the vertical direction, with a pore size of approximately 10 μm to 30 μm. Figure 5 The SEM images show that after the evaporation casting process, the microstructure of the graphene superstructure still maintains its orientation structure, with a sheet thickness of about 100 nm and the interlayer spacing almost disappears. Figure 6 The image is a cross-shaped photograph obtained from a cross-section of a hydrogel sheet, and its microstructure is as follows. Figure 7 As shown, it exhibits a clear curvature gradient asymmetric structure, and its macroscopic morphology changes significantly after evaporation casting. Figure 8 ).

[0105] The lightweight, high-strength graphene prepared in this embodiment was polished into a 3mm × 3mm × 3mm cubic structure, and then placed between two 2mm thick stainless steel plates. When a 1.2-ton car drove over it, the graphene superstructure did not suffer any damage, while the stainless steel plates developed obvious dents. Figure 9 ).

[0106] The mechanical strength of the mortise and tenon structure obtained in test step 6 was tested. The millimeter-level assembled structure can withstand the tensile force of a 1.28kg laptop computer. Figure 10 Electronic photographs of mortise and tenon structural components and electronic photographs of tensile tests.

[0107] Example 2

[0108] (1) Prepare a concentration of 3 mg / mL -1 Graphene oxide dispersion;

[0109] (2) Mix 60 mL of graphene oxide dispersion with 1 mL of ammonia water and 0.1 g of Fe3O4, pour the mixture into a 100 mL reaction vessel, and stir magnetically for 30 minutes;

[0110] (3) Place the hydrothermal reactor in an oven and perform a hydrothermal reaction at 160°C for 6 hours. Then allow it to cool naturally to room temperature to obtain a cylindrical concentric graphene-based hydrogel.

[0111] (4) Laser cutting of graphene hydrogel yields hydrogel sheets with a thickness of 2 mm. The specific cutting method is the same as in Example 1.

[0112] (5) The obtained hydrogel sheets are laid flat on a smooth PTFE substrate, and geometric patterns are laser-engraved. Then, they are dried naturally. During the water evaporation process, the hydrogel spontaneously shrinks and undergoes shape changes under the induction of curvature gradient, finally obtaining a complex configuration of lightweight and high-strength graphene magnetic structure.

[0113] (6) The design and preparation of the mortise and tenon joint structure are the same as in Example 1.

[0114] The curvature gradient graphene hydrogel prepared in this embodiment exhibits a curvature gradient structure in the horizontal direction and a parallel orientation structure in the vertical direction, with a pore size of approximately 10 μm to 30 μm, in which Fe3O4 nanoparticles are dispersed. After the evaporation and casting process, the microstructure of the graphene superstructure retains its orientation structure, with a sheet thickness of approximately 150 nm and almost no interlayer spacing. The macroscopic morphology of the cross-shaped transversely cut hydrogel sheets changes significantly after evaporation and casting.

[0115] The compression and tensile tests in this embodiment are the same as in Embodiment 1. After being run over by a 1.2-ton car, the graphene superstructure did not suffer any damage; the millimeter-scale composite structural component can withstand the tensile force of a 1.28kg laptop.

[0116] Comparative Example 1

[0117] (1) Prepare a concentration of 3.5 mg / mL -1 Graphene oxide dispersion;

[0118] (2) Pour 60 mL of graphene oxide dispersion into a 100 mL reaction vessel and stir magnetically for 30 minutes;

[0119] (3) Place the hydrothermal reactor in an oven and perform a hydrothermal reaction at 180°C for 6 hours. Then allow it to cool naturally to room temperature to obtain a cylindrical graphene hydrogel.

[0120] (4) Use a laser to cut the graphene hydrogel from different directions, such as cross-cutting, longitudinal cutting, and oblique cutting, to obtain a hydrogel sheet with a thickness of 2 mm.

[0121] (5) The obtained hydrogel sheet is placed flat on the PTFE substrate, geometric patterns are laser-engraved, and then it is naturally dried.

[0122] (6) The hydrogel sheet obtained in step 4 is placed flat on a PTFE substrate, and a tenon-and-mortise interlocking structure is prepared by laser cutting. The interlocking structure consists of two parts, a and b. During the evaporation of water, the volume of parts a and b decreases and shrinks into a whole to form an assembly.

[0123] The graphene hydrogel prepared in this embodiment has a disordered structure with a pore size of approximately 5 μm to 20 μm. After the evaporation and casting process, the graphene microstructure exhibits a disordered, multi-folded structure, and the pores disappear. Step 5 yields a geometrically shaped hydrogel. During water evaporation, the hydrogel spontaneously shrinks, reducing its size, but its shape does not change significantly.

[0124] The compression and tensile tests in this embodiment are the same as in Embodiment 1. After being run over by a 1.2-ton car, the graphene structure was completely destroyed and became fragmented; the millimeter-scale composite structure broke when it lifted a 1.28kg laptop.

[0125] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0126] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing graphene-based superstructure materials, characterized in that, include: (1) Alkaliize the graphene oxide to obtain an alkaline graphene oxide mixed dispersion; (2) The alkaline graphene oxide mixed dispersion is subjected to heating and cooling treatment to obtain a graphene-based hydrogel with sheet orientation. (3) The graphene-based hydrogel is cut by laser to obtain a graphene-based hydrogel sheet, wherein the graphene-based hydrogel sheet contains graphene sheets arranged with a curvature gradient. (4) The graphene-based hydrogel sheet is placed on a superhydrophobic substrate at room temperature to obtain a graphene-based superstructure material.

2. The method according to claim 1, characterized in that, The process involves placing the graphene-based hydrogel described in step (3) flat on a PTFE substrate and preparing a graphene-based hydrogel sheet by laser cutting. The graphene-based hydrogel sheet has a tenon-and-mortise interlocking structure, wherein the interlocking structure includes two parts, a and b. Part a is a distinct curvature gradient superstructure, and part b is a non-distinct curvature gradient superstructure.

3. The method according to claim 1 or 2, characterized in that, The alkalization treatment is carried out by adding the graphene oxide dispersion to a hydrothermal reactor, adding an alkaline solution, and stirring thoroughly.

4. The method according to claim 3, characterized in that, The alkaline solution is selected from ammonia water, potassium hydroxide or sodium hydroxide solution.

5. The method according to claim 3, characterized in that, The concentration of the alkaline solution is 0.1-0.2 mol / L.

6. The method according to claim 3, characterized in that, The concentration of the graphene oxide dispersion is 2-5 mg / mL.

7. The method according to claim 3, characterized in that, The volume ratio of the alkaline solution to the graphene oxide dispersion is 1:60-1:

30.

8. The method according to claim 1, characterized in that, Step (1) further includes doping materials.

9. The method according to claim 8, characterized in that, The alkalization treatment is carried out by adding graphene oxide dispersion to a hydrothermal reactor, adding alkaline solution and dopant materials, and stirring thoroughly.

10. The method according to claim 9, characterized in that, The mass ratio of the doped material to graphene oxide is 1:10-1:

5.

11. The method according to claim 8, characterized in that, The doping material is selected from materials that can be dispersed or dissolved in aqueous solutions.

12. The method according to claim 8, characterized in that, The doping material is selected from conductive and thermally conductive materials, magnetic materials, or pseudocapacitive materials.

13. The method according to claim 12, characterized in that, The conductive and thermally conductive materials are selected from CNT, BN, or MXene.

14. The method according to claim 12, characterized in that, The magnetic material is selected from Fe3O4 or Co2O3.

15. The method according to claim 12, characterized in that, The pseudocapacitive material is selected from MnO2 or RuO2.

16. The method according to claim 1, characterized in that, The heat treatment is carried out by pouring the alkaline graphene oxide mixture into a hydrothermal reactor, then placing it in an oven for a hydrothermal reaction for 6-12 hours.

17. The method according to claim 16, characterized in that, The inner liner of the hydrothermal reactor is cylindrical.

18. The method according to claim 16, characterized in that, After the alkaline graphene oxide mixture was poured into the hydrothermal reactor, it was further mixed and stirred inside the reactor.

19. The method according to claim 16, characterized in that, The temperature of the hydrothermal reaction is 160 ℃-200 ℃.

20. The method according to claim 1, characterized in that, The cooling process is performed at room temperature.

21. The method according to claim 1, characterized in that, The graphene-based hydrogel is a cylindrical concentrically oriented graphene-based hydrogel.

22. The method according to claim 1, characterized in that, The graphene-based hydrogel sheet has a geometric configuration.

23. The method according to claim 22, characterized in that, The geometric configuration is a cuboid, a cross shape, or a dumbbell shape.

24. The method according to claim 1, characterized in that, The thickness of the graphene-based hydrogel sheet is 1-5 mm.

25. The method according to claim 1, characterized in that, Step (4) further includes placing the graphene-based hydrogel sheet on a superhydrophobic substrate at room temperature, laser-engraving geometric patterns, and then allowing it to dry naturally. The hydrogel spontaneously shrinks and deforms to obtain a graphene-based superstructure material.

26. The method according to claim 1, characterized in that, The graphene-based superstructure material is composed of graphene sheets arranged in a curvature gradient manner, and the thickness of the graphene sheets is 90-110 nm.

27. The method according to claim 26, characterized in that, The thickness of the graphene sheet is 100 nm.

28. The method according to claim 1, characterized in that, The bulk density of the graphene-based superstructure material is 1.3-1.5 g / cm³. 3 .

29. The method according to claim 28, characterized in that, The bulk density of the graphene-based superstructure material is 1.4 g / cm³. 3 .

30. A method for preparing graphene-based superstructure materials, characterized in that, include: (1) Alkali treatment is performed on graphene oxide and doped materials to obtain an alkaline graphene oxide mixed dispersion. The alkali treatment is carried out by adding the graphene oxide dispersion to a hydrothermal reactor, adding an alkaline solution and doped materials, and stirring thoroughly. The alkaline solution is selected from ammonia water, potassium hydroxide or sodium hydroxide solution, the concentration of the alkaline solution is 0.1-0.2 mol / L, the concentration of the graphene oxide dispersion is 2-5 mg / mL, the volume ratio of the alkaline solution to the graphene oxide dispersion is 1:60-1:30, the doped materials are selected from materials that can be dispersed or dissolved in aqueous solutions, the doped materials are selected from conductive and thermally conductive materials, magnetic materials or pseudocapacitive materials, the conductive and thermally conductive materials are selected from CNT, BN or MXene, the magnetic materials are selected from Fe3O4 or Co2O3, the pseudocapacitive materials are selected from MnO2 or RuO2, and the mass ratio of the doped materials to graphene oxide is 1:10-1:

5. (2) The alkaline graphene oxide mixed dispersion is subjected to heating and cooling treatment to obtain graphene-based hydrogel. The heating treatment is carried out by pouring the alkaline graphene oxide mixed dispersion into a hydrothermal reactor and then placing it in an oven for a hydrothermal reaction for 6-12 hours. The temperature of the hydrothermal reaction is 160 ℃-200 ℃. The temperature of the cooling treatment is room temperature. (3) Graphene-based hydrogel is laid flat on a PTFE substrate and laser-cut to prepare a graphene-based hydrogel sheet. The graphene-based hydrogel sheet has a tenon-and-mortise interlocking structure, wherein the interlocking structure includes two parts, a and b. Part a is a superstructure with obvious curvature gradient, and part b is a superstructure with indistinct curvature gradient. The graphene-based hydrogel sheet has a geometric configuration, which is a cuboid, a cross, or a dumbbell shape. The thickness of the graphene-based hydrogel sheet is 1-5 mm. (4) Under room temperature conditions, the graphene-based hydrogel sheet is placed on a superhydrophobic substrate and then allowed to dry naturally. The hydrogel shrinks spontaneously. The superhydrophobic substrate is selected from a smooth polytetrafluoroethylene plate, a glass plate or a plastic plate that has been hydrophobically treated, so as to obtain a graphene-based superstructure material.

31. A graphene-based superstructure material, characterized in that, The material is prepared by the method described in any one of claims 1-29 or the method described in claim 30.

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