A super-flexible graphene glass and its preparation method

Abstract

The present invention relates to a super-flexible graphene glass and a preparation method thereof, and relates to the technical field of composite materials. The super-flexible graphene glass comprises, by mass parts, 75-85 parts of chopped glass fibers, 15-25 parts of a flexible polymer, 0.5-1 part of graphene quantum dots having C=C bonds, and 3-5 parts of a toughening agent. The super-flexible graphene glass of the present invention can effectively prevent the problem of interfacial delamination of the graphene glass material, prevent the crack propagation on the graphene glass, and improve the tensile modulus and flexural elastic modulus, so that the graphene glass has higher flexibility while having high strength.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly to a super-flexible graphene glass, a preparation method thereof and an application thereof. Background Art

[0002] As a new type of composite material, graphene glass not only retains the good light transmittance of glass itself, but also endows glass with excellent properties of graphene such as ultra-high electrical conductivity, thermal conductivity and surface hydrophobicity, greatly expanding the application space of glass and triggering a revolutionary transformation of the glass industry from large-volume low-value-added applications to energy-saving high-value-added applications. At present, it has been widely studied in the fields of batteries, self-cleaning glass, anti-fog glass, industrial protection, aerospace materials, reinforcing materials, etc. Due to the high strength, high electrical conductivity and high specific surface area of graphene, modifying polymer materials with it is expected to obtain high-performance polymer-based composite materials, making the composite materials have high electrical conductivity, high strength, high thermal stability and certain flame retardancy, further expanding the application scope of polymer materials. With the increasing application of graphene glass in flexible electronic devices, transparent conductive films and other fields, it is required that the graphene glass material has both high strength and ultra-high flexibility.

[0003] The Chinese patent application with the publication number of CN114671629A discloses a method for preparing graphene glass fibers, which includes pre-combining graphite with glass fibers, forming a thermoplastic body with a polymer, and then feeding it into an eccentric internal mixer. The rotor of the eccentric internal mixer is an eccentric rotor, which continuously changes the material space during rotation, thereby generating tensile rheology. During the tensile rheology process, graphite is stretched and peeled into graphene, and at the same time, the glass fibers are stretched and combed into a directional distribution.

[0004] This method solves the problem in the prior art that the excellent mechanical properties of graphene are applied to the research of composite materials. For example, when adding graphene to polymer composite materials, due to the difficulty of dispersing graphene, directly adding graphene to the polymer makes it difficult to exert its performance and causes waste of graphene at the same time. The addition of polymer in graphene glass can preferably retain the strengthening function of graphene glass, but the graphene glass added with polymer has insufficient flexibility, and its strengthening performance will also be greatly attenuated in high-temperature and high-humidity environments. At the same time, the strengthening of materials added with graphene often leads to an increase in the brittleness of the materials. The greater the brittleness, the worse the flexibility. If you want to increase the toughness of the materials, the strength needs to be sacrificed.

[0005] The Chinese patent application with the publication number CN105802019A discloses a graphene / glass fiber reinforced polypropylene composite material and its preparation method. The graphene / glass fiber reinforced polypropylene composite material includes the following components in parts by weight: 60 - 90 parts by mass of polypropylene, 5 - 20 parts by mass of epoxy resin, 0.01 - 5 parts by mass of graphene, 5 - 20 parts by mass of glass fiber, 0.1 - 1 part by mass of silane coupling agent, 5 - 10 parts by mass of ethanol, 0.05 - 2 parts by mass of antioxidant, and 0.5 - 3 parts by mass of compatibilizing toughening agent.

[0006] The thermal stability, strength, and toughness of the above-prepared graphene / glass fiber reinforced polypropylene composite material are significantly improved, and the phenomenon of floating fibers is effectively eliminated, thus expanding the practical application of polypropylene composite materials. However, when the graphene glass material is applied to flexible electronic devices, especially to the curved screen of mobile phones, the problem of interfacial delamination between the toughening agent and the graphene and glass matrix is likely to occur. The delamination of the toughening agent generates voids, which can trigger microcracks and shear bands in the surrounding matrix to dissipate energy. The rapid expansion of microcracks and shear bands easily causes the material to undergo brittle fracture.

[0007] In summary, although adding a toughening agent can improve the poor flexibility of graphene glass to a certain extent, the phenomenon of toughening agent delamination occurs in graphene glass, resulting in the generation of microcracks in graphene glass, and then the crack propagation leads to brittle fracture. Summary of the Invention

[0008] To solve the above problems, the present invention provides a super-flexible graphene glass and its preparation method, which can effectively prevent the problem of interfacial delamination of graphene glass materials, prevent the crack propagation on graphene glass, improve the tensile modulus and flexural elastic modulus, so that graphene glass has higher flexibility while having high strength.

[0009] In the first aspect, a super-flexible graphene glass provided by the present invention, the super-flexible graphene glass includes 75 - 85 parts by mass of chopped glass fibers, 15 - 25 parts by mass of flexible polymer, 0.5 - 1 part by mass of graphene quantum dots with C=C bonds, and 3 - 5 parts by mass of toughening agent.

[0010] In the above technical solution, the flexible polymer can effectively reduce the brittleness of graphene glass materials. The polar groups in the flexible polymer bind to the surface groups of chopped glass fibers through hydrogen bonds, reducing interfacial stress concentration. At the same time, the graphene is adsorbed through π-π stacking, enhancing the interfacial bonding strength between graphene and chopped glass fibers, and improving the overall mechanical strength and durability of the material.

[0011] The C=C bonds on the surface of graphene quantum dots with C=C bonds are covalently bonded to the Si-OH covalent bonds in the chopped glass fibers, reducing interfacial delamination. The graphene quantum dots with C=C bonds and the chopped glass fibers can deform synchronously when bent, avoiding plastic failure caused by interfacial slip, reducing the ultimate bending radius of the graphene glass, improving the overall flexibility of the material, and reducing the generation of cracks. At the same time, due to the small size of the graphene quantum dots with C=C bonds, they can be evenly dispersed in the flexible polymer, avoiding the problem of agglomeration and reducing local stress concentration. The graphene quantum dots with C=C bonds form hydrogen bonds or covalent bonds with the flexible polymer through surface functional groups (such as hydroxyl groups and carboxyl groups), effectively transferring and dispersing external stress and inhibiting crack propagation.

[0012] The toughening agent forms chemical bonds or hydrogen bonds with graphene and chopped glass fibers through active groups (such as hydroxyl groups and carboxyl groups), reducing the defects of interfacial bonding force. At the same time, it spans across microcracks, effectively preventing crack propagation, absorbing a large amount of energy, increasing the fracture energy, and improving the tensile modulus and flexural elastic modulus of the material. At the same time, the toughening agent and graphene act synergistically to improve the stability of the material in a wide temperature range (-50°C to 200°C).

[0013] Optionally, the toughening agent includes a modified ionic gel electrolyte and cellulose nanofibers, and the mass ratio of the modified ionic gel electrolyte to the cellulose nanofibers is 3-5:1.

[0014] By adopting the above technical solution, the reversible supramolecular bonds (such as ionic coordination and hydrogen bonds) in the modified ionic gel electrolyte can be broken and reformed when stressed, dissipating energy. The cellulose nanofibers are embedded in the chopped glass fibers through hydrogen bonds or van der Waals forces to form a rigid support framework, inhibiting crack propagation, enhancing the interfacial bonding force, and improving the fracture resistance. The two act synergistically to jointly improve the fatigue resistance and flexibility of the graphene glass.

[0015] Optionally, the modified ionic gel electrolyte includes a hydrophilic polymer, an EMIMTFSI ionic liquid, a crosslinking agent, and water, and the mass ratio of the hydrophilic polymer:EMIMTFSI ionic liquid:crosslinking agent:water is 1:4-6:0.3-0.5:12-18.

[0016] By adopting the above technical solution, the hydrophilic polymer contains a large number of hydroxyl groups, has high water solubility, good film-forming property, and excellent biocompatibility. Under the action of a cross-linking agent, it cross-links with the ionic liquid to avoid excessive aggregation of ions. At the same time, by utilizing the extremely low surface tension of the ionic liquid, it penetrates to the graphene-glass interface, fills the microcracks and voids. The polymer chains in the modified ionic gel electrolyte are combined with the C=C bonds of the graphene quantum dots through grafting reactions to construct a covalent-non-covalent double network structure, reducing the risk of fracture caused by stress concentration. At the same time, the synergistic effect of the graphene quantum dots with C=C bonds and the modified ionic gel electrolyte can achieve high transparency of the graphene glass material.

[0017] Optionally, by mass parts, the graphene glass comprises 0.5-1 part of an interfacial modifier.

[0018] By adopting the above technical solution, the addition of the interfacial modifier can effectively improve the interfacial bonding strength between the toughening agent and the chopped glass fibers, enable the toughening agent to form a dispersed phase in the chopped glass fibers, and at the same time can also enhance the binding force between the graphene quantum dots with C=C bonds and the flexible polymer, which is beneficial to improving the stability of the graphene glass.

[0019] In a second aspect, a preparation method of a super-flexible graphene glass provided by the present invention adopts the following technical solution:

[0020] Premixing of the flexible polymer and the graphene quantum dots with C=C bonds: Add the flexible polymer to the toughening agent and stir, then add the graphene quantum dots with C=C bonds, and perform ultrasonic treatment for 30-60 min under the condition of 20-30 kHz to ensure uniform dispersion and form a mixed solution;

[0021] Integrating the chopped glass fibers: Add the chopped glass fibers and the interfacial modifier to the mixed solution, and mechanically stir until there is no agglomeration to form a mixture;

[0022] Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and then heat and cure at 70-90 °C for 2-3 h to obtain the super-flexible graphene glass.

[0023] Optionally, the preparation method of the graphene quantum dots with C=C bonds comprises the following steps:

[0024] Preparation of carboxylated graphene quantum dots: Put graphene oxide into the H 2 SO 4 / HNO 3 solution and perform ultrasonic peeling at 40 kHz for 2-4 h to obtain carboxylated graphene quantum dots;

[0025] Covalent grafting on the surface of graphene quantum dots: Carboxylated graphene quantum dots and glycidyl methacrylate are reacted at 50 - 70 °C for 10 - 12 h, and graphene quantum dots with C=C bonds are obtained after purification.

[0026] By adopting the above technical solution, C=C bonds are introduced on the surface of graphene. The C=C bonds on the surface of graphene quantum dots are covalently bonded to Si-OH in the chopped glass fibers, reducing interfacial delamination. At the same time, the graphene quantum dots with C=C bonds and the chopped glass fibers can deform synchronously during bending, avoiding plastic failure caused by interfacial slip, reducing the ultimate bending radius of the graphene glass, and improving the overall flexibility of the material.

[0027] Optionally, the preparation method of the toughening agent includes the following steps:

[0028] Preparation of modified ionic gel electrolyte: A hydrophilic polymer is dissolved in a mixed solvent of deionized water and EMIMTFSI ionic liquid, and a cross-linking agent is added and stirred at 70 - 90 °C until completely dissolved to obtain a modified ionic gel electrolyte solution;

[0029] Cellulose nanofiber / ionic gel composite: Cellulose nanofibers are dispersed in the modified ionic gel electrolyte solution, magnetically stirred for 2 - 3 h, and then ultrasonically treated for 30 - 40 min under the condition of 20 - 30 kHz to ensure uniform dispersion, and cross-linked at room temperature for 24 h to obtain a toughening agent.

[0030] By adopting the above technical solution, cellulose nanofibers form a rigid structure in the glass fibers, and hinder crack propagation through crack deflection and fiber bridging mechanisms, improving fracture toughness. The polar groups (such as amide groups) in the modified ionic gel electrolyte are combined with -Si-OH on the glass surface through hydrogen bonds or covalent bonds, reducing interfacial stress concentration. Under the action of external force, the modified ionic gel electrolyte first dissipates energy through the fracture of dynamic bonds, and then the rigid network structure of cellulose nanofibers further resists damage through fiber pull-out and fracture, realizing staged toughening.

[0031] In the third aspect, the present invention provides an application of a super-flexible graphene glass or a super-flexible graphene glass prepared by a preparation method of a super-flexible graphene glass in flexible display screens, wearable devices, curved touch panels, and sensors.

[0032] In summary, the present invention includes at least one of the following beneficial technical effects:

[0033] By adding a flexible polymer, the brittleness of the graphene glass material can be effectively reduced, and the interfacial bonding between graphene and chopped glass fibers can be enhanced.

[0034] By adding graphene quantum dots with C=C bonds, they can be evenly dispersed in polydimethylsiloxane, avoiding agglomeration problems and reducing local stress concentration. Graphene quantum dots form hydrogen bonds or covalent bonds with flexible polymers through surface functional groups (such as hydroxyl groups and carboxyl groups), effectively transmitting and dispersing external stress and inhibiting crack propagation. The C=C bonds on the surface of graphene quantum dots are covalently bonded to the Si-OH in the chopped glass fibers, reducing interfacial delamination. At the same time, the graphene quantum dots with C=C bonds and the chopped glass fibers can deform synchronously when bent, avoiding plastic failure caused by interfacial slip, reducing the ultimate bending radius of the graphene glass, and improving the overall flexibility of the material.

[0035] 3. By adding a toughening agent, chemical bonds or hydrogen bonds are formed with graphene and chopped glass fibers through active groups (such as hydroxyl groups and carboxyl groups), reducing the defects of interfacial bonding force. At the same time, it spans across microcracks, effectively preventing crack propagation, absorbing a large amount of energy, increasing the fracture energy, and improving the tensile modulus and flexural elastic modulus of the material. At the same time, the toughening agent and graphene act synergistically to improve the stability of the material in a wide temperature range (-50°C to 200°C). Detailed implementation manners

[0036] The present invention will be further described in detail below with reference to the embodiments.

[0037] The materials used in the following embodiments can all be obtained through market purchase.

[0038] Embodiment 1: This embodiment discloses a super-flexible graphene glass and its preparation method.

[0039] A super-flexible graphene glass includes 75 parts by mass of chopped glass fibers, 25 parts of flexible polymer, 0.5 part of graphene quantum dots with C=C bonds, and 5 parts of toughening agent. The toughening agent is silicone powder, and the flexible polymer is selected as transparent polyimide. In other embodiments, the flexible polymer can also be selected as polydimethylsiloxane or polyurethane.

[0040] The preparation method of the super-flexible graphene glass includes the following steps:

[0041] S1. Preparation of a mixed solution of transparent polyimide and graphene quantum dots with C=C bonds:

[0042] S11. Preparation of graphene quantum dots with C=C bonds: Put graphene oxide into the H 2 SO 4 / HNO 3 solution and ultrasonically exfoliate it for 3 h at 40 kHz to obtain carboxylated graphene quantum dots. Then react the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtain graphene quantum dots with C=C bonds after purification;

[0043] S12. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Add silicone powder to polydimethylsiloxane and stir, then add graphene quantum dots with C=C bonds, and ultrasonically treat for 40 min under the condition of 25 kHz to ensure uniform dispersion and form a mixed solution.

[0044] S2. Incorporating chopped glass fibers: Add chopped glass fibers to the mixed solution and mechanically stir until there is no agglomeration to form a mixture.

[0045] S3. Curing and molding: Pour the mixture into a mold, vacuum degas, and then heat and cure at 80 °C for 3 h to obtain super-flexible graphene glass #1.

[0046] Example 2: This example discloses a super-flexible graphene glass and its preparation method.

[0047] A super-flexible graphene glass includes 85 parts by mass of chopped glass fibers, 15 parts of polyurethane, 1 part of graphene quantum dots with C=C bonds, and 3 parts of silicone powder.

[0048] The preparation method of this super-flexible graphene glass is the same as that of Example 1.

[0049] Example 3: This example discloses a super-flexible graphene glass and its preparation method.

[0050] A super-flexible graphene glass includes 80 parts by mass of chopped glass fibers, 20 parts of polydimethylsiloxane, 0.8 part of graphene quantum dots with C=C bonds, and 4 parts of silicone powder.

[0051] The preparation method of this super-flexible graphene glass is the same as that of Example 1.

[0052] Example 4: This example discloses a super-flexible graphene glass and its preparation method.

[0053] A super-flexible graphene glass includes 80 parts by mass of chopped glass fibers, 20 parts of polydimethylsiloxane, 0.8 part of graphene quantum dots with C=C bonds, and 4 parts of toughening agent. The toughening agent includes a modified ionic gel electrolyte and cellulose nanofibers, and the mass ratio of the modified ionic gel electrolyte to cellulose nanofibers is 3:1. The modified ionic gel electrolyte includes a hydrophilic polymer, EMIMTFSI ionic liquid, cross-linking agent, and water. The hydrophilic polymer is polyvinyl alcohol. In other examples, the hydrophilic polymer can also be selected as polyacrylamide, etc. The cross-linking agent is borax. In other examples, the cross-linking agent can also be selected as glutaraldehyde. The mass ratio of polyvinyl alcohol:EMIMTFSI ionic liquid:borax:water is 1:4:0.3:12.

[0054] The preparation method of the ultra-flexible graphene glass is as follows:

[0055] S1. Preparation of a mixture of polydimethylsiloxane and graphene quantum dots with C=C bonds:

[0056] S11. Preparation of graphene quantum dots with C=C bonds: Put graphene oxide into H 2 SO 4 / HNO 3 solution and ultrasonically exfoliate it for 3 h at an environment of 40 kHz to obtain carboxylated graphene quantum dots. Then react the carboxylated graphene quantum dots with glycidyl methacrylate at 60 °C for 12 h, and obtain graphene quantum dots with C=C bonds after purification;

[0057] S12. Preparation of toughening agent: Dissolve polyvinyl alcohol in a mixed solvent of deionized water and EMIMTFSI ionic liquid, add borax and stir at 80 °C until completely dissolved to obtain a modified ionic gel electrolyte solution. Then disperse cellulose nanofibers in the modified ionic gel electrolyte solution, stir magnetically for 2 h, and then ultrasonically treat it for 35 min under the condition of 25 kHz to ensure uniform dispersion. Let it stand at room temperature for crosslinking for 24 h to obtain a toughening agent;

[0058] S13. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Add polydimethylsiloxane to the toughening agent and stir, then add graphene quantum dots with C=C bonds, and ultrasonically treat it for 40 min under the condition of 25 kHz to ensure uniform dispersion to form a mixture.

[0059] S2. Incorporate chopped glass fibers: Add chopped glass fibers to the mixture and mechanically stir until there is no agglomeration to form a mixture.

[0060] S3. Curing and molding: Pour the mixture into a mold, remove air bubbles under vacuum, and heat and cure it at 80 °C for 3 h to obtain ultra-flexible graphene glass #4.

[0061] Example 5: This example discloses an ultra-flexible graphene glass and its preparation method.

[0062] An ultra-flexible graphene glass comprises 80 parts by mass of chopped glass fibers, 20 parts by mass of polydimethylsiloxane, 0.8 parts by mass of graphene quantum dots having C=C bonds, and 4 parts by mass of a toughener, wherein the toughener comprises a modified ion gel electrolyte and cellulose nanofibers, wherein the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 5:1, and the modified ion gel electrolyte comprises polyacrylamide, EMIMTFSI ionic liquid, glutaraldehyde, and water, wherein the mass ratio of the polyacrylamide:EMIMTFSI ionic liquid:glutaraldehyde:water is 1:6:0.5:18.

[0063] The preparation method of the ultra-flexible graphene glass is the same as that of Example 4.

[0064] Example 6: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0065] An ultra-flexible graphene glass comprises 80 parts by mass of chopped glass fibers, 20 parts by mass of polydimethylsiloxane, 0.8 parts by mass of graphene quantum dots having a C=C bond, and 4 parts by mass of a toughening agent, wherein the toughening agent comprises a modified ion gel electrolyte and cellulose nanofibers, wherein the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 4:1, and the modified ion gel electrolyte comprises polyvinyl alcohol, EMIMTFSI ionic liquid, borax, and water, wherein the mass ratio of the polyvinyl alcohol:EMIMTFSI ionic liquid:borax:water is 1:5:0.4:15.

[0066] The preparation method of the ultra-flexible graphene glass is the same as that of Example 4.

[0067] Example 7: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0068] An ultra-flexible graphene glass comprises 80 parts by mass of chopped glass fibers, 20 parts of polydimethylsiloxane, 0.8 parts of graphene quantum dots having C=C bonds, 4 parts of a toughening agent, and 0.6 parts of an interface modifier, wherein the toughening agent comprises a modified ion gel electrolyte and cellulose nanofibers, wherein the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 4:1, and the modified ion gel electrolyte comprises polyvinyl alcohol, EMIMTFSI ionic liquid, borax, and water, wherein the mass ratio of the polyvinyl alcohol:EMIMTFSI ionic liquid:borax:water is 1:5:0.4:15, and the interface modifier is 3-aminopropyltriethoxysilane. In other embodiments, other silane coupling agents such as vinyltri(β-methoxyethoxy)silane and vinyltrimethoxysilane may also be selected.

[0069] The preparation method of the ultra-flexible graphene glass is as follows:

[0070] S1. Preparation of a mixture of polydimethylsiloxane and graphene quantum dots with C=C bonds:

[0071] S11. Preparation of graphene quantum dots with C=C bonds: Put graphene oxide into the H 2 SO 4 / HNO 3 solution and ultrasonically exfoliate it for 3 h at 40 kHz to obtain carboxylated graphene quantum dots. Then react the carboxylated graphene quantum dots with glycidyl methacrylate at 60 °C for 12 h, and obtain graphene quantum dots with C=C bonds after purification;

[0072] S12. Preparation of toughener: Dissolve polyvinyl alcohol in a mixed solvent of deionized water and EMIMTFSI ionic liquid, add borax and stir at 80 °C until completely dissolved to obtain a modified ionic gel electrolyte solution. Then disperse cellulose nanofibers in the modified ionic gel electrolyte solution, stir magnetically for 2 h, and then ultrasonically treat it for 35 min under the condition of 25 kHz to ensure uniform dispersion. Let it stand at room temperature for crosslinking for 24 h to obtain a toughener;

[0073] S13. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Add polydimethylsiloxane to the above toughener and stir, then add graphene quantum dots with C=C bonds, and ultrasonically treat it for 40 min under the condition of 25 kHz to ensure uniform dispersion and form a mixture.

[0074] S2. Incorporation of short glass fibers: Add short glass fibers and KH-550 silane coupling agent to the mixture and mechanically stir until there is no agglomeration to form a mixture.

[0075] S3. Curing and molding: Pour the mixture into a mold, remove air bubbles under vacuum, and heat and cure it at 80 °C for 3 h to obtain super-flexible graphene glass #7.

[0076] Comparative Example 1: This comparative example provides a comparative super-flexible graphene glass, which is the same as Example 7, except that high-silica glass fibers are selected instead of short glass fibers.

[0077] Comparative Example 2: This comparative example provides a comparative super-flexible graphene glass, which is the same as Example 7, except that the rigid polymer polyimide is selected instead of the flexible polymer polydimethylsiloxane.

[0078] Comparative Example 3: This comparative example provides a comparative super-flexible graphene glass, which has the same components as the super-flexible graphene glass in Example 7, except that graphene oxide is selected instead of graphene quantum dots with C=C bonds.

[0079] The preparation method of the comparative super-flexible graphene glass includes the following steps:

[0080] S1. Preparation of the mixture of polydimethylsiloxane and graphene quantum dots with C=C bonds:

[0081] S11. Preparation of the toughening agent: Dissolve polyvinyl alcohol in a mixed solvent of deionized water and EMIMTFSI ionic liquid, add borax, and stir at 80 °C until completely dissolved to obtain a modified ionic gel electrolyte solution. Then disperse cellulose nanofibers in the modified ionic gel electrolyte solution, stir magnetically for 2 h, and then perform ultrasonic treatment at 25 kHz for 35 min to ensure uniform dispersion. Let it stand at room temperature for crosslinking for 24 h to obtain the toughening agent;

[0082] S12. Premixing of polydimethylsiloxane and graphene oxide: Add polydimethylsiloxane to the above-mentioned toughening agent and stir, then add graphene oxide, and perform ultrasonic treatment at 25 kHz for 40 min to ensure uniform dispersion to form a mixture.

[0083] S2. Incorporation of chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent to the mixture, and mechanically stir until there is no agglomeration to form a mixture.

[0084] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and then heat and cure at 80 °C for 3 h to obtain super-flexible graphene glass D3.

[0085] Comparative Example 4: This comparative example provides a comparative super-flexible graphene glass, which has the same components as the super-flexible graphene glass in Example 7, except that: only the modified ionic gel electrolyte is selected as the toughening agent.

[0086] The preparation method of the comparative super-flexible graphene glass includes the following steps:

[0087] S1. Preparation of the mixture of polydimethylsiloxane and graphene quantum dots with C=C bonds:

[0088] S11. Preparation of graphene quantum dots with C=C bonds: Put graphene oxide into H 2 SO 4 / HNO 3 solution, and perform ultrasonic exfoliation at 40 kHz for 3 h to obtain carboxylated graphene quantum dots. Then react the carboxylated graphene quantum dots with glycidyl methacrylate at 60 °C for 12 h, and obtain graphene quantum dots with C=C bonds after purification;

[0089] S12. Preparation of the toughening agent: Dissolve polyvinyl alcohol in a mixed solvent of deionized water and EMIMTFSI ionic liquid, add borax, and stir at 80 °C until completely dissolved to obtain the toughening agent;

[0090] S13. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Add polydimethylsiloxane to the above toughening agent and stir, then add graphene quantum dots with C=C bonds, and ultrasonically treat for 40 min under the condition of 25 kHz to ensure uniform dispersion and form a mixed solution.

[0091] S2. Incorporating chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent to the mixed solution, and mechanically stir until there is no agglomeration to form a mixture.

[0092] S3. Curing and molding: Pour the mixture into a mold, remove air bubbles under vacuum, and heat and cure at 80 °C for 3 h to obtain super-flexible graphene glass D4.

[0093] Comparative Example 5: This comparative example provides a comparative super-flexible graphene glass, which has the same components as the super-flexible graphene glass in Example 7, except that: the toughening agent only selects cellulose nanofibers.

[0094] The preparation method of the comparative super-flexible graphene glass includes the following steps:

[0095] S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots with C=C bonds:

[0096] S11. Preparation of graphene quantum dots with C=C bonds: Put graphene oxide into H 2 SO 4 / HNO 3 solution and ultrasonically exfoliate for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then react the carboxylated graphene quantum dots with glycidyl methacrylate at 60 °C for 12 h, and obtain graphene quantum dots with C=C bonds after purification;

[0097] S12. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Add cellulose nanofibers to polydimethylsiloxane and stir, then add graphene quantum dots with C=C bonds, and ultrasonically treat for 40 min under the condition of 25 kHz to ensure uniform dispersion and form a mixed solution.

[0098] S2. Incorporating chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent to the mixed solution, and mechanically stir until there is no agglomeration to form a mixture.

[0099] S3. Curing and molding: Pour the mixture into a mold, remove air bubbles under vacuum, and heat and cure at 80 °C for 3 h to obtain super-flexible graphene glass D5.

[0100] Comparative Example 6: This comparative example provides a comparative super-flexible graphene glass, which is the same as Example 7, except that carbon nanotubes are selected instead of cellulose nanofibers.

[0101] Comparative Example 7: This comparative example provides a comparative super-flexible graphene glass, which has the same components as the super-flexible graphene glass in Example 7, except that an ionic gel electrolyte is selected instead of the modified ionic gel electrolyte.

[0102] The preparation method of the comparative super-flexible graphene glass includes the following steps:

[0103] S1. Preparation of a mixture of polydimethylsiloxane and graphene quantum dots with C=C bonds:

[0104] S11. Preparation of graphene quantum dots with C=C bonds: Put graphene oxide into H 2 SO 4 / HNO 3 solution and ultrasonically exfoliate it for 3 h at 40 kHz to obtain carboxylated graphene quantum dots. Then react the carboxylated graphene quantum dots with glycidyl methacrylate at 60 °C for 12 h, and obtain graphene quantum dots with C=C bonds after purification;

[0105] S12. Preparation of toughening agent: Dissolve polyvinyl alcohol in EMIMTFSI ionic liquid, stir until homogeneous to obtain an ionic gel electrolyte solution. Then disperse cellulose nanofibers in the ionic gel electrolyte solution, magnetically stir for 2 h, and then ultrasonically treat it for 35 min under the condition of 25 kHz to ensure uniform dispersion. Let it stand at room temperature for crosslinking for 24 h to obtain a toughening agent;

[0106] S13. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Add polydimethylsiloxane to the above toughening agent and stir, then add graphene quantum dots with C=C bonds, and ultrasonically treat it for 40 min under the condition of 25 kHz to ensure uniform dispersion to form a mixture.

[0107] S2. Incorporating chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent to the mixture, and mechanically stir until there is no agglomeration to form a mixture.

[0108] S3. Curing and molding: Pour the mixture into a mold, remove air bubbles under vacuum, and heat and cure it at 80 °C for 3 h to obtain super-flexible graphene glass D7.

[0109] Perform performance tests on the super-flexible graphene glasses #1-7 of Examples 1-4 of the present invention and the super-flexible graphene glasses D1-D7 of Comparative Examples 1-7, including crack propagation rate, tensile strength, shear strength, flexural strength, minimum bending radius, fracture strain, and critical load. Among them, the tensile strength is tested in accordance with the national standard GB / T 1040.2-2006; the shear strength is tested in accordance with the national standard GB / T 16825-2008; the flexural strength is tested in accordance with the national standard GB / T 9341-2000; the crack propagation rate is tested using the K-value method; the calculation of the fracture strain is usually based on the deformation amount of the material in the tensile test, and the calculation formula is δ = ΔL / L × 100%, where ΔL is the deformation amount and L is the original length. The performance test results obtained are shown in Table 1.

[0110] Table 1

[0111]

[0112] By comparing the data of Examples 1-3 with that of Example 4, it can be seen that different toughening agents are added in Examples 1-3 and Example 4. Example 4 adds the toughening agent of the present application. Through reasonable proportioning with other components in the super-flexible graphene glass, the super-flexible graphene glass prepared by adding the toughening agent of the present application exhibits relatively excellent flexibility and strength.

[0113] From the data of Examples 4-6, especially Example 6, it can be seen that through more reasonable proportioning of the components in the toughening agent of the present application, the super-flexible graphene glasses in the examples perform excellently in all aspects.

[0114] Comparing Examples 4-6 with Example 7, Example 7 adds an interfacial modifier. After adding the interfacial modifier to the graphene glass, the crack propagation rate, tensile strength, shear strength, flexural strength, minimum bending radius, fracture strain, and critical load of the graphene glass are all greatly improved. This is because the addition of the interfacial modifier can effectively improve the interfacial bonding strength between the toughening agent and the chopped glass fibers, making the toughening agent form a dispersed phase in the chopped glass fibers. At the same time, it can also enhance the binding force between the graphene quantum dots with C=C bonds and the flexible polymer, which is beneficial to improving the stability of the graphene glass.

[0115] Compared with Comparative Examples 1-3, in Comparative Example 1, high-silica glass fiber was selected to replace the chopped glass fiber of the present application; in Comparative Example 2, rigid polymer polyimide was selected to replace the flexible polymer polydimethylsiloxane of the present application; in Comparative Example 3, graphene oxide was selected to replace the graphene quantum dots with C=C bonds of the present application. The flexibility and strength of the graphene glass in Comparative Examples 1-3 were much lower than those of the graphene glass prepared in Example 7. This is because the flexible polymer can effectively reduce the brittleness of the graphene glass material. The polar groups in the flexible polymer combine with the surface groups of the chopped glass fiber through hydrogen bonds, reducing the interfacial stress concentration. At the same time, the graphene is adsorbed through π-π stacking, enhancing the interfacial bonding strength between the graphene and the chopped glass fiber, and improving the overall mechanical strength and durability of the material. The C=C bonds on the surface of the graphene quantum dots with C=C bonds are covalently bonded to the Si-OH in the chopped glass fiber, reducing interfacial delamination. The graphene quantum dots with C=C bonds and the chopped glass fiber can deform synchronously during bending, avoiding plastic failure caused by interfacial slip, reducing the ultimate bending radius of the graphene glass, improving the overall flexibility of the material, and reducing the generation of cracks. At the same time, due to the small size of the graphene quantum dots with C=C bonds, they can be uniformly dispersed in the flexible polymer, avoiding agglomeration problems and reducing local stress concentration. The graphene quantum dots with C=C bonds form hydrogen bonds or covalent bonds with the flexible polymer through surface functional groups (such as hydroxyl groups, carboxyl groups), effectively transmitting and dispersing external stress, and inhibiting crack propagation. The toughening agent forms chemical bonds or hydrogen bonds with graphene and chopped glass fiber through active groups (such as hydroxyl groups, carboxyl groups), reducing the defects of the interfacial bonding force. At the same time, it spans across microcracks, effectively preventing crack propagation, absorbing a large amount of energy, increasing the fracture energy, and improving the tensile modulus and flexural modulus of the material. At the same time, the toughening agent and graphene act synergistically to improve the stability of the material in a wide temperature range (-50°C to 200°C).

[0116] Compared with Comparative Examples 5-8, in Comparative Example 5, a modified ionic gel electrolyte was selected to replace the toughening agent of the present application; in Comparative Example 6, cellulose nanofibers were selected to replace the toughening agent of the present application; in Comparative Example 7, carbon nanotubes were selected to replace the cellulose nanofibers; in Comparative Example 8, an ionic gel electrolyte was selected to replace the modified ionic gel electrolyte. The flexibility and strength of the graphene glass in Comparative Examples 5-8 were much lower than those of the graphene glass prepared in Example 7. This is because the reversible supramolecular bonds (such as ionic coordination and hydrogen bonds) in the modified ionic gel electrolyte in the toughening agent of the present application can break and reform when stressed, dissipating energy. The cellulose nanofibers are embedded in the chopped glass fibers through hydrogen bonds or van der Waals forces to form a rigid support framework, inhibiting crack propagation, enhancing the interfacial bonding force, and improving the fracture resistance. Under external force, the modified ionic gel electrolyte first dissipates energy through the breakage of dynamic bonds, and then the rigid network of cellulose nanofibers further resists damage through fiber pull-out and fracture, achieving staged toughening. The two work together to improve the fatigue resistance and flexibility of the graphene glass.

[0117] It can be seen from this that the materials after replacement in the toughening agent cannot play a role in the toughening agent, but will instead reduce the effect of the toughening agent. Therefore, each component cannot be randomly replaced by other materials.

[0118] The above are all preferred embodiments of the present invention, and the protection scope of the present invention is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. An ultra-flexible graphene glass, characterized in that: The ultra-flexible graphene glass comprises 75-85 parts by mass of chopped glass fibers, 15-25 parts by mass of flexible polymers, 0.5-1 parts by mass of graphene quantum dots having C=C bonds, and 3-5 parts by mass of toughening agents; The toughening agent includes a modified ion gel electrolyte and cellulose nanofibers, the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 3-5:1, the modified ion gel electrolyte includes a hydrophilic polymer, EMIMTFSI ionic liquid, a crosslinking agent, and water, and the mass ratio of the hydrophilic polymer: EMIMTFSI ionic liquid: crosslinking agent: water is 1:4-6:0.3-0.5:12-18.

2. The ultra-flexible graphene glass according to claim 1, characterized in that: The graphene glass further comprises 0.5-1 part of an interface modifier by mass.

3. A method for preparing the ultra-flexible graphene glass using any one of claims 1 to 2, characterized in that: The following steps are involved: Premixing the flexible polymer with the graphene quantum dots having C=C bonds: adding the flexible polymer to the toughening agent and stirring, then adding the graphene quantum dots having C=C bonds, and ultrasonically treating for 30-60 minutes at 20-30kHz to ensure uniform dispersion to form a mixed solution; Integrating the chopped glass fibers: adding the chopped glass fibers and the interfacial modifier into the mixed solution, and mechanically stirring until there is no agglomeration, to form a mixture; ‌Curing and molding‌: Pour the mixture into a mold, perform vacuum degassing, and heat and cure it at 70-90°C for 2-3 hours to obtain the ultra-flexible graphene glass.

4. The method for preparing ultra-flexible graphene glass according to claim 3, characterized in that: The method for preparing graphene quantum dots having C=C bonds comprises the following steps: Preparation of carboxylated graphene quantum dots: Graphene oxide was placed in a H2SO4 / HNO3 solution and subjected to ultrasonic exfoliation at 40kHz for 2-4h to obtain carboxylated graphene quantum dots; Covalent grafting of graphene quantum dots on the surface: reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 50-70° C. for 10-12 hours, and obtaining the graphene quantum dots with C=C bonds after purification.

5. The method for preparing ultra-flexible graphene glass according to claim 3, characterized in that: The preparation method of the toughening agent comprises the following steps: Preparation of the modified ion gel electrolyte: dissolving the hydrophilic polymer in a mixed solvent of deionized water and the EMIMTFSI ionic liquid, adding the crosslinking agent and stirring at 70-90° C. until completely dissolved, to obtain the modified ion gel electrolyte solution; The cellulose nanofiber / ion gel composite: the cellulose nanofiber is dispersed in the modified ion gel electrolyte solution, magnetically stirred for 2-3 hours, and then ultrasonically treated for 30-40 minutes at 20-30kHz to ensure uniform dispersion, and cross-linked at room temperature for 24 hours to obtain the toughening agent.

6. Application of ultra-flexible graphene glass in flexible display screens, wearable devices, curved touch panels, and sensors, characterized in that: Ultra-flexible graphene glass prepared using the ultra-flexible graphene glass as described in any one of claims 1-2, or the method for preparing ultra-flexible graphene glass as described in any one of claims 3-5.

Images