In-situ assembly and disassembly of graphene oxide spheres in a solvent environment

Abstract

The secondary assembly process of the prior art graphene oxide material is complex, the controllability of the high-level structure is poor, and the graphene oxide material cannot be reversibly disassembled and re-constructed after assembly. The application provides an in-situ assembly and disassembly method of graphene oxide balls in a solvent environment, which comprises the following steps: soaking a plurality of hydrated graphene oxide balls in water, adding a high-concentration metal ion salt solution to the water, and spontaneously gathering and shrinking the plurality of balls under the cross-linking action of the metal ions to form a firm cross-linking bonding effect at the interface, thereby realizing in-situ assembly in a solvent environment and obtaining a graphene oxide bulk material. When it is necessary to disassemble the bulk, a chelating agent solution is added to the solution, the bulk gradually swells, and the bulk is disassembled into the initial plurality of balls in-situ in the solvent environment. In the process of in-situ assembly and disassembly, the balls are always in a solvent environment, and there is no need for complex operation steps to change the surrounding environment of the units, so that the simplicity, controllability and scale-up of the assembly and disassembly are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to an in-situ assembly and disassembly method for graphene oxide spheres in a solvent environment. Background Technology

[0002] Graphene oxide is a graphene derivative with oxygen-containing functional groups modified on a carbon six-membered ring structure. It has excellent processability, mechanical properties and chemical reactivity, and can be processed into different forms of materials such as spheres, fibers, films and aerogels. One of the effective ways to optimize the mechanical properties and functionality of graphene oxide materials is to reassemble the materials into advanced structures to obtain high-performance graphene oxide materials, which have important applications in water filtration, aerospace engineering, ship corrosion protection and electronic devices. At present, the methods for reassembling graphene oxide materials include solvent swelling-air synergistic contraction, depositing the materials on a solid substrate, spraying water at the bonding interface of the materials and transferring them to a low-humidity environment to allow the materials to self-heal, etc., to obtain macroscopic materials such as fibers, films and bulk materials with advanced structures. However, the above methods face many problems: (1) The processing steps are complicated and require switching the surrounding environment of the graphene oxide materials to air / vacuum / solvent. This non-in-situ assembly increases the preparation cost and is not conducive to the large-scale scaling of advanced structures. (2) The controllability of higher-order structures is poor, making it difficult to regulate the interfacial interactions between graphene oxide materials. Once formed, the higher-order structures are fixed and cannot be reversibly disassembled and reconstructed. The main approach to solving the above problems is to simplify the secondary assembly steps as much as possible and to adjust the interfacial interactions between materials in situ by controlling parameters, so that the materials can be assembled and disassembled in situ in a fixed environment. However, due to the limitations of chemical action design strategies, it is impossible to achieve in-situ assembly and disassembly of graphene oxide materials using simple methods, which seriously restricts the mechanical and functional applications of macroscopic graphene oxide materials. Summary of the Invention

[0003] This invention addresses the problems of complex secondary assembly processes and poor controllability of advanced structures in existing technologies by providing an in-situ assembly and disassembly method for graphene oxide spheres in a solvent environment.

[0004] This invention utilizes the oxygen-containing functional groups of graphene oxide to perform specific structural design of graphene oxide, thereby obtaining stimulus-responsive functional materials. The presence of oxygen-containing functional groups makes graphene oxide highly sensitive to polar solvents; furthermore, they can act as defects to induce wrinkle formation. This invention effectively combines the above-mentioned characteristics of oxygen-containing functional groups with a core-shell structure design. Through the bulging and stretching of hill-like wrinkles, reversible three-dimensional contraction and expansion occur, enabling self-driving under the stimulation of polar solvents, resulting in large actuation deformation, high responsiveness, and long cycle life.

[0005] One of the technical solutions of this invention provides a method for in-situ assembly and disassembly of graphene oxide spheres in a solvent environment, comprising the following steps: A graphene oxide organic solution is dripped into a coagulation bath of an organic solvent through a needle to form graphene oxide gel spheres. After drying the graphene oxide gel spheres, they are immersed in water to obtain hydrated graphene oxide spheres. Multiple hydrated graphene oxide spheres are immersed in water, and a high concentration of metal ion salt solution is slowly added to the water. Under the cross-linking effect of the metal ions, the multiple hydrated graphene oxide spheres spontaneously aggregate and synergistically shrink, forming a strong cross-linking bond at the interface between the spheres, achieving in-situ assembly in a solvent environment to obtain a bulk graphene oxide material. When it is necessary to disassemble the bulk material, a chelating agent solution is slowly added to the solution. The bulk graphene oxide material gradually expands and disassembles in-situ into multiple initial hydrated graphene oxide spheres in the solvent environment.

[0006] The extrusion speed of the graphene oxide organic solution is 0.2 ml / min to 3 ml / min.

[0007] This invention proposes adding a metal ion salt solution to water in which graphene oxide spheres are immersed, causing multiple spheres to spontaneously aggregate and shrink, and cross-linking occurs at the interfaces between the spheres, achieving in-situ assembly. This solves the problem that secondary assembly of graphene oxide materials requires material transfer and alteration of the surrounding environment, resulting in cumbersome processing steps and poor structural controllability. After the addition of a high-concentration metal ion salt solution, the metal ions ionize with the carboxyl groups of the graphene oxide spheres, forming negatively charged carboxylate ions (-COO). — Strong electrostatic interactions form between the spheres, causing cross-linking between the graphene oxide sheets inside the spheres. The spheres then undergo dramatic shrinkage in the solution, with a volume shrinkage rate ≥60%. Simultaneously, the graphene oxide sheets at the interfaces between the spheres also attract each other due to electrostatic interactions, causing the spheres to spontaneously aggregate in the solution and form strong cross-linked adhesion at the interfaces. Multiple spheres assemble in situ into a macroscopic bulk material. This in-situ assembly process is simple, requires no transfer of materials to different environments, and the tightness of the assembly can be controlled by changing the concentration of the metal ion salt solution. The structure is precisely tunable, resulting in the large-scale preparation of macroscopic graphene oxide bulk materials with compressive strengths exceeding 5 MPa.

[0008] Secondly, by adding a chelating agent solution to the in-situ assembled graphene oxide sphere solution, a strong coordination effect is achieved between the chelating agent and metal ions, breaking the cross-linking between the interior and interface of the graphene oxide spheres. This allows the spheres to expand reversibly, while the interfaces de-adhede, enabling the in-situ disassembly and assembly of the graphene oxide bulk material into multiple spheres. This solves the problem of in-situ disassembly of macroscopic graphene oxide materials, which is difficult in existing technologies. Furthermore, the in-situ assembly and disassembly can be repeated ≥3 times, realizing the immediate construction and disassembly recycling of macroscopic materials. The in-situ assembly and disassembly method achieved by this invention is simple. By adjusting the type and concentration of the metal ion salt solution, the assembly speed and the interfacial cross-linking strength between spheres can be precisely controlled. The method does not limit the number of spheres, facilitating large-scale repeated in-situ assembly and disassembly. The prepared macroscopic bulk material is composed of multiple cross-linked graphene oxide spheres, with spherical units of 622 μm to 1530 μm in diameter. The compressive strength of the graphene oxide bulk material is ≥5 MPa, and the density is 1 g / cm³. 3 ~1.5 g / cm 3 It has great application value in wastewater treatment materials containing metal ions, ship anti-corrosion materials, soft machines, spacecraft and other fields.

[0009] The hydrated graphene oxide spheres comprise a core and a shell. The shell encloses the core, which is a network structure formed by overlapping graphene oxide sheets. The shell is formed by overlapping graphene oxide sheets, which have a wrinkled structure.

[0010] In a preferred embodiment of the present invention, the network structure is a porous network structure in which water is dispersed.

[0011] In a preferred embodiment of the present invention, the folded structure is a hilly structure with small contractions or a ridge structure with large contractions.

[0012] Therefore, those skilled in the art should understand that in this invention, the initial state of the wrinkled structure of the shell graphene oxide can be either a hill-like low-wrinkle structure or a ridge-like high-wrinkle structure. Low-wrinkle structures exhibit greater shrinkage under the cross-linking effect of metal ions compared to high-wrinkle structures; however, in this invention, both low-wrinkle and high-wrinkle structures can achieve synergistic shrinkage under the cross-linking effect of metal ions.

[0013] As is common knowledge in this field, the wrinkles in graphene oxide refer to the bending or folding of its two-dimensional sheets caused by factors such as uneven distribution of oxygen-containing functional groups on the surface, stress shrinkage during drying, or interlayer interactions. Smaller wrinkles and a flatter structure are called hill-like low wrinkles; conversely, larger wrinkles and obvious three-dimensional bending or folding in the structure are called ridge-like high wrinkles.

[0014] The metal ion salt solution described in this invention includes one or more of magnesium chloride solution, calcium chloride solution, zinc chloride solution, aluminum chloride solution, and ferric chloride solution. The mass fraction of the metal ion salt solution is ≥10 wt.%, and the mass ratio of the metal ion salt solution to the water in which the hydrated graphene oxide spheres are soaked is 2:8 to 5:5.

[0015] The chelating agent solution described in this invention comprises one or more of the following: disodium ethylenediaminetetraacetate solution, tetrasodium ethylenediaminetetraacetate solution, trisodium aminotriacetate solution, sodium alginate solution, sodium gluconate solution, sodium ethylenediaminetetramethylenephosphonate solution, pentasodium aminotrimethylenephosphonate solution, sodium diethylenetriaminepentamethylenephosphonate solution, sodium tripolyphosphate solution, sodium pyrophosphate solution, and sodium hexametaphosphate solution. The mass fraction of the chelating agent solution is ≥4 wt.%. The mass ratio of the chelating agent solution to the metal ion salt solution is 7:1 to 9:1.

[0016] Furthermore, the organic solvent for the graphene oxide includes one or more of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene glycol, and the coagulation bath includes one or more of ethanol, isopropanol, ethyl acetate, acetic acid, propionic acid, citric acid, acetone, methyl ethyl ketone, and cyclohexanone. The diameter of the hydrated graphene oxide spheres is 900 μm to 2500 μm.

[0017] The volume shrinkage rate of the hydrated graphene oxide spheres is ≥60%. In-situ assembly and disassembly can be repeated ≥3 times.

[0018] The graphene oxide bulk material prepared in this invention is composed of multiple cross-linked hydrated graphene oxide spheres. The diameter of the sphere unit structure is 622 μm to 1530 μm, and the number of spheres is ≥2. The height of the bulk material is ≥622 μm, the length is ≥1 mm, and the density is 1 g / cm³. 3 ~1.5 g / cm 3 Compressive strength ≥ 5 MPa.

[0019] Compared with the prior art, the present invention has the following advantages: 1) By utilizing the cross-linking effect of metal ions on graphene oxide, the synergistic shrinkage and in-situ assembly of multiple graphene oxide spheres can be achieved in a solvent environment. The method is simple and does not require complex processes or variable environmental conditions.

[0020] 2) By using metal ion salt solutions of different types and concentrations, the interfacial cross-linking strength between spheres can be controlled. The higher the valence state and concentration of the metal ions, the greater the interfacial cross-linking strength between spheres, thereby achieving precise control of the in-situ assembled structure and obtaining macroscopic bulk materials of different densities. This solves the problem of precise control of advanced structures during secondary assembly of materials.

[0021] 3) By leveraging the strong coordination of chelating agents with metal ions, the cross-linking effect of metal ions on graphene oxide spheres is broken in situ, enabling in-situ disassembly and assembly of the bulk material and recovery of multiple spheres. Furthermore, this in-situ assembly and disassembly process can be repeated, overcoming the bottleneck of existing technologies that struggle with in-situ disassembly and assembly.

[0022] 4) The prepared in-situ assembled macroscopic bulk materials have excellent mechanical properties and their size can be scaled up, laying the foundation for the engineering application of high-performance graphene oxide materials. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the in-situ assembly and disassembly process of graphene oxide spheres.

[0024] Figure 2 These are polarized light microscope images of the two graphene oxide spheres before, after, and after the first in-situ assembly in Example 1.

[0025] Figure 3 These are polarized light microscope images of the two graphene oxide spheres before, after, and after the 10th in-situ assembly and disassembly of the spheres in Example 1.

[0026] Figure 4 The values ​​represent the volume shrinkage and expansion rates of the graphene oxide spheres in Example 1 in a solvent environment. Detailed Implementation

[0027] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0028] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0029] The embodiments of the present invention will be further described below with reference to several examples.

[0030] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0031] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0032] The cross-linking described in this invention refers to the graphene oxide sheets being bridged by the electrostatic interaction of metal ions.

[0033] The volume shrinkage rate mentioned in this invention refers to the percentage of the volume change of graphene oxide spheres after shrinkage following the addition of a metal ion salt solution, relative to the initial hydrated volume; the expansion rate refers to the percentage of the volume change of graphene oxide spheres after expansion following the addition of a disodium ethylenediaminetetraacetate solution, relative to the expanded hydrated volume.

[0034] like Figure 4 As shown, after adding zinc chloride solution, the volume shrinkage rate of the sphere is 73%. After adding disodium ethylenediaminetetraacetate solution, the volume expansion rate of the sphere during the disassembly and assembly of the bulk material is 73%.

[0035] See Figures 1-4 The in-situ assembly and deassembly method for graphene oxide spheres in a solvent environment according to this invention includes the following steps: Hydrated graphene oxide spheres are prepared using a wet process. Multiple graphene oxide spheres are immersed in water, and a metal ion salt solution with a mass fraction ≥10 wt.% is added to the water. The spheres spontaneously aggregate and shrink in the solvent environment, with a volume shrinkage rate as high as 75%. The spheres then cross-link and assemble in situ into a macroscopic bulk material in the solution environment. A chelating agent solution with a mass fraction ≥4 wt.% is added to the solution, causing the bulk material to gradually expand in volume and deassemble in situ into multiple spheres. During the in-situ assembly and deassembly process, the spheres remain in a solvent environment throughout, eliminating the need for complex operational steps to alter the surrounding environment of the unit, greatly improving the simplicity, controllability, and scalability of the assembly and deassembly.

[0036] Specifically, (1) using a wet organic phase system, an organic solution of graphene oxide is dripped into a coagulation bath of organic solvent through a needle with a diameter of 50 μm to 1000 μm to form graphene oxide gel spheres. After filtering and drying the gel spheres at room temperature, they are soaked in water for more than 10 min to obtain hydrated graphene oxide spheres; (2) Take two or more hydrated graphene oxide spheres and immerse them in water. Slowly add a high concentration of metal ion salt solution to the water from one side of the container. Multiple spheres spontaneously aggregate and shrink together under the cross-linking effect of metal ions. The volume shrinkage rate is ≥60%. The interface between the spheres forms a strong cross-linking bond. In-situ assembly in the solvent environment is achieved within 1 min to obtain a macroscopic graphene oxide bulk material formed by cross-linking multiple spheres. (3) Slowly add chelating agent solution to the above solution. The assembly gradually expands. The assembly in the solvent environment disassembles in situ into the original multiple spheres within 5 minutes. (4) A high concentration of metal ion salt solution is slowly added to the deassembled solution again, and multiple spheres are reassembled in situ for the second time. After adding a chelating agent solution, they are deassembled in situ into multiple spheres again. This process can be repeated to achieve multiple in-situ assembly and deassembly of graphene oxide spheres in a solvent environment.

[0037] Example 1: 1. A 3 mg / g solution of graphene oxide / N,N-dimethylformamide (DMF) was loaded into a syringe. Using a 210 μm diameter needle, the solution was dripped into an acetone coagulation bath at a rate of 0.5 ml / min, with the needle 5 mm above the surface of the bath. After the graphene oxide solution was added, gel spheres formed. The gel spheres were soaked in the coagulation bath for 2 h, then filtered through a sieve and dried at room temperature for 1 day. The dried graphene oxide spheres were then soaked in water for 30 min to obtain hydrated graphene oxide spheres with a diameter of 1470 μm. 2. Two hydrated graphene oxide spheres were immersed in 3 ml of water. 0.75 g of a high-concentration zinc chloride aqueous solution (80 wt.%) was slowly added to the water from one side of the container. Under the cross-linking effect of divalent zinc ions, the two spheres spontaneously aggregated and synergistically contracted, achieving a volume shrinkage rate of up to 73%. Simultaneously, a strong cross-linking bond formed at the interface between the spheres. After 0.8 min of zinc chloride addition, the two spheres assembled in situ into a dumbbell-shaped bulk material in the solution environment. The material had a length of 1865 μm, a width of 947 μm, a height of 947 μm, and a density of 1.4 g / cm³. 3 The compressive strength is 12 MPa. The diameter of the internal spherical units of this material is 947 μm. 3. Slowly add 5.25 g of a 4 wt.% disodium ethylenediaminetetraacetate solution to the solution from step 2. The dumbbell-shaped bulk material gradually expands, with a volume expansion rate of 73%. After 4 minutes of solution addition, the bulk material disassembles and reassembles into two spheres in situ within the solution environment. 4. Add an 80 wt.% zinc chloride aqueous solution to the solution from step 3 again, and the two spheres are reassembled in situ into a dumbbell-shaped bulk material for the second time. Add a 4 wt.% disodium ethylenediaminetetraacetate solution, and the bulk material is again disassembled and reassembled in situ into two spheres. Continue to repeat the addition of zinc chloride aqueous solution and disodium ethylenediaminetetraacetate solution to achieve 10 in-situ assembly and disassembly cycles of the two spheres.

[0038] Comparative Example 1 This comparative example is the same as Example 1, except that a low concentration of zinc chloride aqueous solution is added.

[0039] 1. Take 3 mg / g of graphene oxide / DMF solution and add it dropwise into an acetone coagulation bath through a syringe needle with a diameter of 210 μm. Filter the gel balls, dry them at room temperature, and soak them in water for 30 min to obtain hydrated graphene oxide balls with a diameter of 1470 μm, consistent with step 1 in Example 1. 2. Two hydrated graphene oxide spheres were immersed in 3 ml of water. 0.75 g of a 1 wt.% low-concentration zinc chloride aqueous solution was slowly added to the water from one side of the container. After the addition of the low-concentration zinc chloride solution, the diameter of the two spheres did not change significantly, and the spheres could not be tightly cross-linked and bonded together; they remained two separate spheres and could not be assembled into a bulk material in situ.

[0040] 3. Slowly add 5.25 g of 4 wt.% disodium ethylenediaminetetraacetate solution to the solution in step 2. The diameter of the ball still does not change significantly and remains as two separate balls.

[0041] 4. If sodium chloride aqueous solution and disodium ethylenediaminetetraacetate solution are repeatedly added to the solution in step 3, the diameter of the ball will remain basically unchanged, making it impossible to perform multiple in-situ assembly and disassembly.

[0042] Comparative Example 2 This comparative example is the same as Example 1, except that a 2 wt.% solution of disodium ethylenediaminetetraacetate is added.

[0043] 1. Same as step 1 in Example 1; 2. Two hydrated graphene oxide spheres were immersed in 3 ml of water. 0.75 g of a high-concentration zinc chloride aqueous solution (80 wt.%) was slowly added to the water from one side of the container. Under the cross-linking effect of zinc ions, the two spheres exhibited a volume shrinkage rate of up to 73%, assembling in situ into a dumbbell-shaped bulk material in the solution environment. The material had a length of 1865 μm, a width of 947 μm, a height of 947 μm, and a compressive strength of 12 MPa, consistent with step 2 of Example 1. 3. Slowly add 5.25 g of a 2 wt.% disodium ethylenediaminetetraacetate solution to the solution from step 2. The dumbbell-shaped bulk material expands slightly, with a volume expansion rate of only 34%. After 4 min of solution addition, the bulk material only undergoes slight expansion, increasing in length to 2060 μm and in width and height to 1045 μm, and cannot disassemble and reassemble into two spheres in situ in the solution environment. 4. Adding an 80 wt.% zinc chloride aqueous solution to the solution from step 3 again caused a significant shrinkage in the volume of the bulk material. The shrunken bulk material had a length of 1839 μm and a width and height of 932 μm, slightly smaller than the size of the bulk material after the first assembly. Adding a 2 wt.% disodium ethylenediaminetetraacetate solution did not allow the bulk material to disassemble in situ. The addition of zinc chloride and disodium ethylenediaminetetraacetate solutions of the above-mentioned mass fractions was repeated. On the 10th addition of zinc chloride solution, the length of the bulk material stabilized at 1831 μm, and the width and height stabilized at 927 μm. The addition of disodium ethylenediaminetetraacetate solution still prevented the bulk material from disassembling in situ.

[0044] Example 2: 1. A 5 mg / g solution of graphene oxide / N-methylpyrrolidone (NMP) was loaded into a syringe. Using a 600 μm diameter needle, the solution was dripped into an isopropanol coagulation bath at a rate of 1 ml / min, with the needle tip 6 mm above the surface of the liquid. After the graphene oxide solution was added to the coagulation bath, gel spheres formed. The gel spheres were soaked in the coagulation bath for 5 h, then filtered through a nylon mesh and dried at room temperature for 2 days. The dried graphene oxide spheres were then soaked in water for 60 min to obtain hydrated graphene oxide spheres with a diameter of 1980 μm. 2. Ten hydrated graphene oxide spheres were immersed in 20 ml of water. 13 g of a 10 wt.% aluminum chloride aqueous solution was slowly added to the water from one side of the container. Under the cross-linking effect of trivalent aluminum ions, the ten spheres spontaneously aggregated and synergistically contracted, achieving a volume shrinkage rate of up to 75%. Simultaneously, a strong cross-linking bond formed at the interface between the spheres. After 0.5 min of aluminum chloride addition, the ten spheres assembled in situ into a flat, bulk material in the solution environment. The material had a length of 4980 μm, a width of 3721 μm, a height of 1247 μm, and a density of 1.43 g / cm³. 3 The compressive strength is 14 MPa. The diameter of the internal spherical units of this material is 1247 μm. 3. Slowly add 117 g of a 7 wt.% sodium ethylenediaminetetramethylene phosphate solution to the solution from step 2. The bulk material gradually expands, with a volume expansion rate of 74%. After 3 minutes of solution addition, the bulk material disassembles and assembles into 10 spheres in situ within the solution environment. 4. Add a 10 wt.% aluminum chloride aqueous solution to the solution from step 3 again, and the 10 balls will be assembled into a bulk material in situ for the second time. Add a 7 wt.% sodium ethylenediaminetetramethylene phosphate solution, and the bulk material will be disassembled and reassembled into 10 balls in situ again. Continue to add aluminum chloride aqueous solution and sodium ethylenediaminetetramethylene phosphate solution repeatedly to achieve 5 in-situ assembly and disassembly cycles of the 10 balls.

[0045] Example 3: 1. A 4 mg / g solution of graphene oxide / N,N-dimethylacetamide (DMAc) was loaded into a syringe. Using a 60 μm diameter needle, the solution was dripped into an acetone coagulation bath at a rate of 0.2 ml / min, with the needle 4 mm above the surface of the coagulation bath. After the graphene oxide solution was added to the coagulation bath, gel spheres formed. The gel spheres were soaked in the coagulation bath for 1 h, then filtered through a sieve and dried at room temperature for 12 h. The dried graphene oxide spheres were then soaked in water for 20 min to obtain hydrated graphene oxide spheres with a diameter of 1060 μm. 2. Five hundred hydrated graphene oxide spheres were immersed in 100 ml of water. One hundred and ten thousand grams of a 30 wt.% magnesium chloride aqueous solution were slowly added to the water from one side of the container. Under the cross-linking effect of magnesium ions, the 500 spheres spontaneously aggregated and synergistically contracted, with a volume shrinkage rate as high as 70%. Simultaneously, a strong cross-linking bond formed at the interface between the spheres. After 1 minute of magnesium chloride addition, the 500 spheres assembled in situ into a bulk material in the solution environment. The material had a length of 2 cm, a width of 0.7 cm, a height of 0.14 cm, and a density of 1.37 g / cm³. 3 The compressive strength is 10 MPa. The diameter of the internal spherical units of this material is 710 μm. 3. Slowly add 800 g of a 10 wt.% trisodium triamcinolone solution to the solution from step 2. The bulk material gradually expands, with a volume expansion rate of 70%. After 5 minutes of solution addition, the bulk material disassembles and assembles into 500 spheres in situ within the solution environment. 4. Add a 30 wt.% magnesium chloride aqueous solution to the solution from step 3 again, and the 500 balls will be assembled into a bulk material in situ for the second time. Add a 10 wt.% trisodium nitrilotriacetate solution, and the bulk material will be disassembled and reassembled into 500 balls in situ again. Continue to add magnesium chloride aqueous solution and trisodium nitrilotriacetate solution, achieving three in-situ assembly and disassembly cycles of the 500 balls.

[0046] Example 4: 1. A 3 mg / g graphene oxide / dimethyl sulfoxide (DMSO) solution was loaded into a syringe. Using a 50 μm diameter needle, the solution was dripped into a citric acid coagulation bath at a rate of 0.4 ml / min, with the needle 4 mm above the surface of the solution. After dripping into the coagulation bath, the graphene oxide solution formed gel spheres. The gel spheres were soaked in the coagulation bath for 1 h, then filtered through a nylon mesh and dried at room temperature for 2 days. The dried graphene oxide spheres were then soaked in water for 20 min to obtain hydrated graphene oxide spheres with a diameter of 900 μm. 2. Thirty hydrated graphene oxide spheres were immersed in 40 ml of water. 17 g of a 20 wt.% calcium chloride aqueous solution was slowly added to the water from one side of the container. Under the cross-linking effect of divalent calcium ions, the 30 spheres spontaneously aggregated and synergistically contracted, achieving a volume shrinkage rate of up to 67%. Simultaneously, a strong cross-linking bond formed at the interface between the spheres. After 1 minute of calcium chloride addition, the 30 spheres assembled in situ into a flat, bulk material in the solution environment. The material had a length of 3732 μm, a width of 3110 μm, a height of 622 μm, and a density of 1.2 g / cm³. 3 The compressive strength is 8 MPa. The diameter of the internal spherical units of this material is 622 μm. 3. Slowly add 119 g of a 20 wt.% sodium gluconate solution to the solution from step 2. The bulk material gradually expands, with a volume expansion rate of 67%. After 3 minutes of solution addition, the bulk material disassembles and assembles into 30 spheres in situ within the solution environment. 4. Add a 20 wt.% calcium chloride aqueous solution to the solution from step 3 again, and the 30 balls will be assembled into a bulk material in situ for the second time. Add a 20 wt.% sodium gluconate solution, and the bulk material will be disassembled and reassembled into 30 balls in situ again. Continue to repeat the addition of calcium chloride aqueous solution and sodium gluconate solution to achieve 8 in-situ assembly and disassembly cycles of the 30 balls.

[0047] Example 5: 1. A 3 mg / g graphene oxide / ethylene glycol (EG) solution was loaded into a syringe. Using a 1000 μm diameter needle, the solution was dripped into a cyclohexanone coagulation bath at a rate of 3 ml / min, with the needle tip 7 mm above the surface of the coagulation bath. After the graphene oxide solution was added to the coagulation bath, gel spheres formed. The gel spheres were soaked in the coagulation bath for 5 h, then filtered through a nylon mesh and dried at room temperature for 2 days. The dried graphene oxide spheres were then soaked in water for 60 min to obtain hydrated graphene oxide spheres with a diameter of 2500 μm. 2. Twenty hydrated graphene oxide spheres were immersed in 30 ml of water. 7.5 g of a 30 wt.% ferric chloride aqueous solution was slowly added to the water from one side of the container. Under the cross-linking effect of ferric ions, the 20 spheres spontaneously aggregated and synergistically contracted, achieving a volume shrinkage rate of up to 77%. Simultaneously, a strong cross-linking bond formed at the interface between the spheres. After 0.5 min of ferric chloride addition, the 20 spheres assembled in situ into a flat, bulk material in the solution environment. The material had a length of 7650 μm, a width of 6120 μm, a height of 1530 μm, and a density of 1.5 g / cm³. 3 The compressive strength is 20 MPa. The diameter of the internal spherical units of this material is 1530 μm. 3. Slowly add 67.5 g of sodium tripolyphosphate solution (8 wt.%) to the solution from step 2. The bulk material gradually expands, with a volume expansion rate of 77%. After 5 minutes of solution addition, the bulk material disassembles and reassembles into 20 spheres in situ within the solution environment. 4. Add a 30 wt.% ferric chloride aqueous solution to the solution from step 3 again, and the 20 balls will be assembled into a bulk material in situ for the second time. Add an 8 wt.% sodium tripolyphosphate solution, and the bulk material will be disassembled and reassembled into 20 balls in situ again. Continue to add ferric chloride aqueous solution and sodium tripolyphosphate solution repeatedly to achieve 6 in-situ assembly and disassembly of 20 balls.

[0048] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

[0049] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for in-situ assembly and disassembly of graphene oxide spheres in a solvent environment, characterized in that, The process includes the following steps: A graphene oxide organic solution is dripped into a coagulation bath of an organic solvent using a needle to form graphene oxide gel spheres; after drying the graphene oxide gel spheres, they are immersed in water to obtain hydrated graphene oxide spheres; multiple hydrated graphene oxide spheres are immersed in water, and a high concentration of metal ion salt solution is slowly added to the water. Under the cross-linking effect of the metal ions, the multiple hydrated graphene oxide spheres spontaneously aggregate and synergistically shrink, forming a strong cross-linking bond at the interface between the spheres, achieving in-situ assembly in the solvent environment to obtain a bulk graphene oxide material; when it is necessary to disassemble the bulk material, a chelating agent solution is slowly added to the solution, causing the bulk graphene oxide material to gradually expand and disassemble in-situ into the initial multiple hydrated graphene oxide spheres in the solvent environment; the organic solvent for the graphene oxide includes N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N, One or more of N-dimethylacetamide and ethylene glycol; the coagulation bath includes one or more of ethanol, isopropanol, ethyl acetate, acetic acid, propionic acid, citric acid, acetone, methyl ethyl ketone, and cyclohexanone; the metal ion salt solution includes one or more of magnesium chloride solution, calcium chloride solution, zinc chloride solution, aluminum chloride solution, and ferric chloride solution, the mass fraction of the metal ion salt solution is ≥10 wt.%; the chelating agent solution includes one or more of disodium ethylenediaminetetraacetate solution, tetrasodium ethylenediaminetetraacetate solution, trisodium aminotriacetate solution, sodium alginate solution, sodium gluconate solution, sodium ethylenediaminetetramethylene phosphate solution, pentasodium aminotrimethylenephosphonate solution, sodium diethylenetriaminepentamethylenephosphonate solution, sodium tripolyphosphate solution, sodium pyrophosphate solution, and sodium hexametaphosphate solution.

2. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to claim 1, characterized in that, The hydrated graphene oxide spheres include a core and a shell; the shell encloses the core, the core is formed by overlapping graphene oxide sheets to form a network structure, and the shell is formed by overlapping graphene oxide sheets, the graphene oxide sheets having a wrinkled structure.

3. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to claim 2, characterized in that, The network structure is a porous network structure, in which water is dispersed.

4. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to claim 3, characterized in that, The folded structure is either a hilly structure with small contractions or a ridge structure with large contractions.

5. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to claim 4, characterized in that, The mass ratio of the metal ion salt solution to the water in which the hydrated graphene oxide spheres are soaked is 2:8 to 5:

5.

6. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to any one of claims 1 to 5, characterized in that, The chelating agent solution has a mass fraction ≥ 4 wt.%; the mass ratio of the chelating agent solution to the metal ion salt solution is 7:1 to 9:

1.

7. The in-situ assembly and disassembly method for graphene oxide spheres in a solvent environment according to claim 6, characterized in that, The graphene oxide bulk material has a density of 1 g / cm 3 ~ 1.5 g / cm 3 and a compressive strength of ≥ 5 MPa.

8. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to claim 7, characterized in that, The volume shrinkage rate of the hydrated graphene oxide spheres is ≥60%.

9. The in-situ assembly and disassembly method of graphene oxide spheres in a solvent environment according to claim 8, characterized in that, The in-situ assembly and disassembly are repeated ≥3 times.

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