A self-repairing graphene composite material and preparation method thereof

Abstract

The present invention discloses a self-healing graphene composite material and a preparation method thereof. A graphene derivative is added to an aqueous organic solution and stirred, followed by adding a borate solution and continued stirring to prepare the self-healing graphene composite material. The organic matter is one or more organic substances containing hydroxyl groups. The graphene composite material prepared using the preparation method of the present invention is cross-linked through ester bonds formed by esterification between carboxyl groups on the edges of graphene oxide and hydroxyl groups of the organic matter, borate ester bonds formed between the borate and the organic matter, and hydrogen bonding between the borate ester bonds. The graphene composite material exhibits a certain self-healing function in a gel state, and can therefore be used as a self-healing graphene composite material.

Description

Technical Field

[0001] The present invention belongs to the field of high-performance functional composite materials and relates to a self-repairing graphene composite material and a preparation method thereof. Background Art

[0002] Graphene is an emerging two-dimensional carbon material. Its carbon atoms are arranged in a sp2 hybridized orbital, similar to a single layer of graphite. Carbon atoms have four valence electrons, three of which form sp2 bonds. This means each carbon atom contributes an unbonded electron in a pz orbital. The pz orbitals of neighboring atoms, oriented perpendicular to the plane, can form pi bonds, with these newly formed pi bonds being partially filled. Graphene oxide and partially reduced graphene oxide are materials formed by oxidizing graphene (a single carbon sheet). In graphene oxide, carbon atoms on the graphene surface are replaced by oxygen atoms, forming functional groups such as hydroxyl (-OH), carboxyl (-COOH), and epoxy (-O-). The chemical structure of graphene oxide is relatively complex, and its surface contains a large number of functional groups. The presence of these functional groups makes graphene oxide have good hydrophilicity, biocompatibility and solubility, which also makes graphene oxide an important material for the application of graphene in biomedicine, energy storage and other fields. The related graphene composite materials also have broad research prospects. Graphene composite materials can be compounded with other materials according to their purpose and usage scenarios to make them have specific and better properties. They can be used in energy storage, conductivity, thermal conductivity, sensing and other fields as needed. However, the currently prepared graphene composite materials cannot repair themselves after being stretched and broken, resulting in a decrease in their conductivity and other properties, thereby affecting the use of the entire device and failing to meet the needs of certain current industrial production.

[0003] Patent CN111154207A discloses a method for preparing a high-tensile-stress self-repairing composite. The material is made from graphene oxide and polyvinyl alcohol using a freeze-thaw cycle followed by drying. The composite utilizes the rich oxygen-containing groups of graphene oxide to increase the composite's hydrogen bonding sites, forming a dynamically reversible hydrogen bond network that imparts self-repairing properties while also enhancing the composite's mechanical properties. However, the self-repairing composite prepared in this patent takes too long to self-repair and requires heating conditions for self-repair. Its self-repairing efficiency is low and cannot meet modern requirements for self-repairing materials. Summary of the Invention

[0004] The present invention aims to provide a self-healing graphene composite material and its preparation method. This approach primarily involves designing and preparing the material, incorporating specific chemicals and nanomaterials to create a self-healing mechanism within the material. When the material is damaged, these chemicals and nanomaterials automatically initiate the repair mechanism, reconnecting and repairing the material. This repair process is quick and requires no heating.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing self-repairing graphene fibers comprises adding a graphene derivative to an aqueous solution of an organic substance and stirring and mixing the mixture, then adding a borate solution and continuing to stir the mixture to prepare a self-repairing graphene composite material; the organic substance is one or more of alcohols, celluloses, carboxylic acids, and starches containing hydroxyl groups.

[0007] Furthermore, the above-mentioned method for preparing a self-repairing graphene fiber includes the following steps:

[0008] (1) Preparation of organic solution:

[0009] First, the organic powder is added to deionized water, subjected to ultrasonic dispersion treatment, and then stirred on a magnetic stirrer with a magnetic stirrer to fully dissolve it; then, the mixture is allowed to cool sufficiently at room temperature to obtain an organic solution;

[0010] (2) Preparation of self-healing graphene composite materials:

[0011] The graphene derivative is added to an organic solution and dispersed evenly by ultrasonic treatment. A magnetic stirrer is then added and stirred on a magnetic stirrer so that the graphene derivative is fully dispersed into a viscous state in the organic solution. Finally, a borate solution is added dropwise and stirred to obtain a self-healing graphene composite material.

[0012] Furthermore, the organic matter in step (1) is one or more of polyvinyl alcohol, polyethylene glycol, hydroxypropyl methylcellulose, and polypropylene alcohol.

[0013] Furthermore, the mass percentage concentration of the organic solution in step (1) is 0.5 to 30%.

[0014] Furthermore, the ultrasonic dispersion time in step (1) is 0.5 to 3 hours, and the ultrasonic dispersion power is 50W to 600W.

[0015] Furthermore, during the magnetic stirring in step (1), the temperature is controlled between 20 and 100° C., and the stirring time is controlled between 0.5 and 4 h.

[0016] Furthermore, the graphene derivative in step (2) is selected from one or more of graphene oxide, reduced graphene oxide, single-layer graphene, multilayer graphene, and graphene doped with other elements, and the mass of the graphene derivative added is 0.1% to 50% of the mass of the organic matrix.

[0017] Furthermore, in step (2), after adding the graphene derivative to the organic solution, the temperature is controlled to be between 15° C. and 45° C., and the stirring time is controlled to be between 2 and 8 hours. The ultrasonic dispersion time is 0.5 to 3 hours, and the ultrasonic dispersion power is 50W to 600W.

[0018] Furthermore, the borate in step (2) is one or more of borax, sodium borate, lithium borate, potassium borate, calcium borate, magnesium borate, sodium metaborate, lithium metaborate, potassium metaborate, calcium metaborate, and magnesium metaborate; the mass percentage concentration of the borate solution is 0.1 to 10%, and the volume of the added borate solution accounts for 0.5% to 5% of the volume of the organic solution.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) Since the carboxyl groups on the edge of graphene oxide react with the hydroxyl groups on the organic matter to form ester bonds, the organic matter and graphene oxide are connected through covalent bonds. The ester bonds can exist for a considerable period of time at room temperature, thereby enhancing the durability of the material's self-healing properties.

[0021] (2) The added borate and organic matter can react to form a polymer material with a cross-linked network structure. In water, the reaction between borate and organic matter will form a borate ester bond. A borate ester bond is a chemical bond between a borate ion and a hydroxyl group. During the reaction, the borate ion in the borate reacts with the hydroxyl group (-OH) in the organic matter to form a borate ester bond, while releasing water molecules (H2O). The formation of the borate ester bond causes cross-linking between the organic molecules, forming a 3D network structure, which gives the material good physical and chemical properties, such as elasticity, viscosity and water absorption.

[0022] (3) At the same time, in the borate ester bond, one of the three oxygen atoms in the borate ester bond forms a hydrogen bond with the hydrogen atom in the other hydroxyl group. This hydrogen bonding force can enhance the stability of the borate ester bond, restrict the rotation and vibration of the ester group, and increase the polarity of the borate ester bond.

[0023] (4) The present invention utilizes the above reaction to prepare a self-healing graphene composite material. The method is low in cost and easy to prepare and process. The prepared material has high repair efficiency and speed and can quickly restore its original performance after being damaged. At the same time, it has good plasticity and durability, can adapt to complex stress and environmental changes, and does not require additional special conditions such as heat and pressure. It can self-repair at room temperature, is convenient for practical application, has good engineering application prospects, and can be widely used in construction, aerospace, automobile, electronics and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 To test the self-repairing performance of the self-repairing graphene composite material prepared in Example 1 of the present invention;

[0025] Figure 2 This is a SEM image of the self-healing graphene composite material prepared in Example 1 of the present invention;

[0026] Figure 3 This is a SEM image of the self-healing graphene composite material prepared in Example 2 of the present invention;

[0027] Figure 4 This is a SEM image of the self-healing graphene composite material prepared in Example 3 of the present invention;

[0028] Figure 5 This is a Raman spectrum of the self-healing graphene composite material prepared in Example 1 of the present invention;

[0029] Figure 6 This is a Raman spectrum of the self-healing graphene composite material prepared in Example 2 of the present invention;

[0030] Figure 7 This is a Raman spectrum of the self-healing graphene composite material prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] The present invention addresses the shortcomings of existing graphene composite materials. First, organic powder is dissolved in deionized water to obtain an organic solution. Then, a graphene derivative is added to the organic solution and mixed evenly. Borate is then added, and the mixture is stirred at room temperature to obtain a self-healing graphene material. The graphene composite material prepared using the above preparation method is cross-linked through ester bonds formed by esterification reaction between carboxyl groups on the edges of graphene oxide and hydroxyl groups of the organic material, borate ester bonds formed between the borate and the organic material, and hydrogen bonding between the borate ester bonds. In the gel state, the graphene composite material has a certain self-healing function and can therefore be used as a self-healing graphene composite material.

[0033] Example 1

[0034] (1) Preparation of organic solution:

[0035] First, 10 g of polyvinyl alcohol powder was weighed and added to 90 ml of deionized water. After ultrasonic dispersion at 80 W for 0.5 h, a magnetic stirrer was added and stirred on a magnetic stirrer at 95°C for 1 h to fully dissolve the powder. The powder was then allowed to cool at room temperature to obtain a polyvinyl alcohol solution.

[0036] (2) Preparation of self-healing graphene composite materials:

[0037] 1 g of graphene oxide was weighed and added to 90 ml of polyvinyl alcohol solution. The mixture was evenly dispersed by ultrasonic treatment at an ultrasonic power of 80 W for 0.5 h. Then a magnetic stirrer was added and stirred on a magnetic stirrer for 6 h at a stirring temperature of 30°C, so that the graphene oxide was fully dispersed into a viscous state in the polyvinyl alcohol solution. Finally, 450 μl of sodium metaborate solution with a mass percentage concentration of 0.3% was added dropwise, and the mixture was stirred to obtain a self-healing graphene composite material.

[0038] Performance testing:

[0039] The self-repairing performance of the material was tested by using an XS (08) SD-200 type electronic single yarn strength tester to test the composite material prepared by the present invention. The tensile rate was 20 mm / min, the gauge was 10 mm, and the pre-tension was 1 cN. The breaking strength and elongation at break of the composite fiber were tested. The tensile strength of the material was first measured to be 184 MPa and the elongation at break was 91.27%. Figure 1 As shown, it can be seen that after the material is cut, it can be placed at room temperature for 20 to 30 seconds, and the fracture can successfully self-repair, and no obvious fracture occurs after stretching, showing the excellent self-repair performance of the material. At the same time, the tensile strength of the material after one self-repair is measured to be 138Mpa, and the elongation at break is 71.13%. Figure 2 It can be seen that the graphene surface morphology and structure of the material after short-term self-repair remain good; Figure 5It can be seen that the Raman characteristic peak of the material after a short period of self-repair is consistent with the Raman characteristic peak of graphene, indicating that the self-repair process of the material will not affect the structure of the graphene inside it.

[0040] Example 2

[0041] (1) Preparation of organic solution:

[0042] First, 5 g of polyethylene glycol powder was weighed and added to 95 ml of deionized water. After ultrasonic dispersion at 80 W for 1 hour, a magnetic stirrer was added and stirred on a magnetic stirrer for 1 hour at 30°C to fully dissolve the mixture. The mixture was then allowed to cool at room temperature to obtain a polyethylene glycol solution.

[0043] (2) Preparation of self-healing graphene composite materials:

[0044] 0.5 g of graphene oxide was weighed and added to a polyethylene glycol solution, and the mixture was evenly dispersed by ultrasonic treatment at an ultrasonic power of 80 W for 0.5 h. Then, a magnetic stirrer was added and stirred on a magnetic stirrer for 5 h at a stirring temperature of 25°C, so that the graphene oxide was fully dispersed into a viscous state in the polyethylene glycol solution. Finally, 400 μl of a lithium metaborate solution with a mass percentage concentration of 0.4% was added dropwise, and the mixture was stirred to obtain a self-healing graphene composite material.

[0045] Performance testing:

[0046] The self-repairing performance of the material was tested by using an XS (08) SD-200 type electronic single yarn strength tester to test the composite material prepared by the present invention. The tensile rate was 20 mm / min, the gauge was 10 mm, the pre-tension was 1 cN, and the breaking strength and breaking elongation of the composite fiber were tested. First, the tensile strength of the material was measured to be 140 MPa, and the breaking elongation was 69.82%. Then it was cut and placed at room temperature for 30 to 60 seconds. The fracture was able to successfully self-repair, and no obvious breakage occurred after stretching. After repeated 5 times, it was placed for 20 to 80 seconds and was still able to self-repair. At the same time, the tensile strength of the material after repeated self-repair was measured to be 104 MPa, and the breaking elongation was 56.39%. This shows the excellent self-repairing performance of the material. Figure 3 This is the SEM image of the surface morphology of the material after multiple cutting and repair. Figure 6 The Raman spectrum of the material after multiple cutting and repair shows that the graphene surface morphology structure of the material after short-term self-repair is well maintained, and the Raman characteristic peak of the material after short-term self-repair is consistent with the Raman characteristic peak of graphene, indicating that the self-repair process of the material will not affect the structure of its internal graphene, and the self-repair performance of the material is very durable.

[0047] Example 3

[0048] (1) Preparation of organic solution:

[0049] First, 3 g of polyvinyl alcohol powder was weighed and added to 97 ml of deionized water. After ultrasonic dispersion at 180 W for 1 hour, a magnetic stirrer was added and stirred on a magnetic stirrer for 0.8 hour at 95°C to fully dissolve the powder. The powder was then allowed to cool at room temperature to obtain a polyvinyl alcohol solution.

[0050] (2) Preparation of self-healing graphene composite materials:

[0051] 0.3 g of partially reduced graphene oxide was weighed and added to a polyvinyl alcohol solution. The mixture was evenly dispersed by ultrasonic treatment at an ultrasonic power of 80 W for 0.5 h. Then a magnetic stirrer was added and stirred on a magnetic stirrer for 6 h at a stirring temperature of 30°C, so that the graphene oxide was fully dispersed into a viscous state in the polyvinyl alcohol solution. Finally, 500 μl of a calcium metaborate solution with a mass percentage concentration of 0.35% was added dropwise, and the self-healing graphene composite material was obtained after stirring.

[0052] Performance testing:

[0053] The self-repairing performance of the material was tested. The composite material prepared by the present invention was tested using an XS (08) SD-200 electronic single yarn strength tester. The tensile rate was 20 mm / min, the gauge was 10 mm, and the pre-tension was 1 cN. The breaking strength and breaking elongation of the composite fiber were tested. First, the tensile strength of the material was measured to be 89.82 MPa, and the breaking elongation was 56.39%. Then it was cut and placed at room temperature for 30 to 60 seconds. The fracture was able to successfully self-repair, and no obvious breakage occurred after stretching. After repeated 5 times, it was placed for 40 to 80 seconds and was still able to self-repair. At the same time, the tensile strength of the material after repeated self-repair was measured to be 55.41 MPa, and the breaking elongation was 40.32%. This shows the excellent self-repairing performance of the material. Figure 4 This is the SEM image of the surface morphology of the material after multiple cutting and repair. Figure 7 The Raman spectrum of the material after multiple cutting and repair shows that the graphene surface morphology structure of the material after short-term self-repair is well maintained, and the Raman characteristic peak of the material after short-term self-repair is consistent with the Raman characteristic peak of graphene, indicating that the self-repair process of the material will not affect the structure of its internal graphene, and the self-repair performance of the material is very durable.

[0054] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0055] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a self-repairing graphene composite material, characterized in that: The following steps are involved: (1) Preparation of organic solution: First, 10 g of polyvinyl alcohol powder was weighed and added to 90 ml of deionized water. After ultrasonic dispersion at 80 W for 0.5 h, a magnetic stirrer was added and stirred on a magnetic stirrer at 95°C for 1 h to fully dissolve the powder. The powder was then allowed to cool at room temperature to obtain a polyvinyl alcohol solution. (2) Preparation of self-healing graphene composite materials: 1 g of graphene oxide was weighed and added to 90 ml of polyvinyl alcohol solution. The mixture was evenly dispersed by ultrasonic treatment at an ultrasonic power of 80 W for 0.5 h. Then a magnetic stirrer was added and stirred on a magnetic stirrer for 6 h at a stirring temperature of 30°C, so that the graphene oxide was fully dispersed into a viscous state in the polyvinyl alcohol solution. Finally, 450 μl of sodium metaborate solution with a mass percentage concentration of 0.3% was added dropwise, and the mixture was stirred to obtain a self-healing graphene composite material.

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