Super-flexible graphene glass and preparation method thereof

Abstract

The invention relates to super-flexible graphene glass and a preparation method thereof, and relates to the technical field of composite materials. The super-flexible graphene glass comprises the following components in parts by mass: 75-85 parts of chopped glass fibers, 15-25 parts of a flexible polymer, 0.5-1 part of graphene quantum dots with C = C bonds and 3-5 parts of a toughening agent. According to the super-flexible graphene glass, the problem of interface delamination of a graphene glass material can be effectively prevented, crack propagation on the graphene glass is prevented, and the tensile modulus and the bending elastic modulus are improved, 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 in particular to ultra-flexible graphene glass, a preparation method and application thereof. Background Art

[0002] As a new type of composite material, graphene glass not only maintains the advantages of good light transmittance of glass itself, but also gives glass excellent properties such as ultra-high electrical conductivity, thermal conductivity and surface hydrophobicity of graphene, which greatly expands the application space of glass and triggers a revolutionary transformation of the glass industry from large-scale low-value-added applications to economical 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, and reinforced materials. Since graphene has high strength, high electrical conductivity, and high specific surface area, it is expected to obtain high-performance polymer-based composite materials by modifying polymer materials with it, so that the composite materials have high electrical conductivity, high strength, high thermal stability and certain flame retardancy, further expanding the application range of polymer materials. With the increasing application of graphene glass in flexible electronic devices, transparent conductive films and other fields, graphene glass materials are required to have both high strength and ultra-high flexibility.

[0003] The Chinese invention patent application with publication number CN114671629A discloses a method for preparing graphene glass fiber, including pre-compounding graphite and glass fiber, forming a thermoplastic body with a high molecular 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 extensional rheology. During the extensional rheology process, the graphite is stretched and peeled into graphene, and the glass fiber is stretched and combed into a directional distribution.

[0004] This method solves the problem of applying the excellent mechanical properties of graphene to the research of composite materials in the prior art, such as adding graphene to polymer composite materials. Since graphene is difficult to disperse, adding graphene directly to polymers makes it difficult to exert its performance and causes waste of graphene. The addition of polymers to graphene glass can better retain the strengthening function of graphene glass, but the flexibility of graphene glass with added polymers is insufficient, and the strengthening performance in high temperature and high humidity environments will also be greatly attenuated. At the same time, the reinforcement of materials with added graphene often leads to increased brittleness of the materials. The greater the brittleness, the worse the flexibility. If you want to increase the toughness of the material, you need to sacrifice strength.

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

[0006] The thermal stability, strength and toughness of the graphene / glass fiber reinforced polypropylene composite prepared above are significantly improved, and the floating fiber phenomenon is effectively eliminated, thereby expanding the practical application of polypropylene composite materials. However, when graphene glass materials are applied to flexible electronic devices, especially when applied to curved screens of mobile phones, the toughening agent and the graphene and glass matrix are prone to interface delamination. The delamination of the toughening agent produces voids, which will cause microcracks and shear bands in the surrounding matrix to dissipate energy. The rapid expansion of microcracks and shear bands can easily cause brittle fracture of the material.

[0007] In summary, although the addition of toughening agents can improve the poor flexibility of graphene glass to a certain extent, the graphene glass will experience delamination of the toughening agent, resulting in microcracks in the graphene glass, and then the cracks propagate and cause brittle fracture. Summary of the invention

[0008] In order to solve the above problems, the present invention provides an ultra-flexible graphene glass and a preparation method thereof, which can effectively prevent the problem of interface delamination of graphene glass materials, prevent the expansion of cracks on the graphene glass, and improve the tensile modulus and bending elastic modulus, so that the graphene glass has higher flexibility while having high strength.

[0009] In a first aspect, the present invention provides an ultra-flexible graphene glass, which comprises, by mass, 75-85 parts of chopped glass fibers, 15-25 parts of flexible polymers, 0.5-1 parts of graphene quantum dots having C=C bonds, and 3-5 parts of toughening agents.

[0010] In the above technical scheme, 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 to reduce the interfacial stress concentration. At the same time, the graphene is adsorbed through π-π stacking to enhance the interface bonding strength between the graphene and the chopped glass fiber, thereby 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 with Si-OH in the chopped glass fibers to reduce interface delamination. The graphene quantum dots with C=C bonds and the chopped glass fibers can deform synchronously when bent to avoid plastic failure caused by interface slip, reduce the ultimate bending radius of graphene glass, improve the overall flexibility of the material, and reduce 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 to avoid agglomeration problems and reduce 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 and carboxyl groups), effectively transfer and disperse external stress, and inhibit crack propagation.

[0012] The toughening agent forms chemical bonds or hydrogen bonds with graphene and chopped glass fibers through active groups (such as hydroxyl and carboxyl groups), reducing the defects of interfacial bonding force. At the same time, it spans over microcracks, effectively preventing crack propagation, absorbing a large amount of energy, increasing fracture energy, and improving the tensile modulus and bending elastic modulus of the material. At the same time, the toughening agent and graphene work synergistically to improve the stability of the material in a wide temperature range (-50°C to 200°C). Optionally, the toughening agent comprises a modified ion gel electrolyte and cellulose nanofibers, and the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 3-5:1.

[0013] By adopting the above technical scheme, the reversible supramolecular bonds (such as ion coordination and hydrogen bonds) in the modified ion gel electrolyte can be broken and reformed when subjected to stress, 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, inhibit crack propagation, enhance interfacial bonding strength, and improve fracture resistance. The two work together to improve the fatigue resistance and flexibility of graphene glass.

[0014] Optionally, the modified ion gel electrolyte comprises a hydrophilic polymer, an EMIMTFSI ionic liquid, a cross-linking agent, and water, and the mass ratio of the hydrophilic polymer: EMIMTFSI ionic liquid: cross-linking agent: water is 1:4-6:0.3-0.5:12-18.

[0015] By adopting the above technical solution, the hydrophilic polymer contains a large number of hydroxyl groups, has the characteristics of high water solubility, good film-forming property and excellent biocompatibility. It is cross-linked with the ionic liquid under the action of the cross-linking agent to avoid excessive aggregation of ions. At the same time, the extremely low surface tension of the ionic liquid is used to penetrate into the graphene-glass interface to fill microcracks and gaps. The polymer chains in the modified ion gel electrolyte are combined with the C=C bonds of the graphene quantum dots through a grafting reaction 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 ion gel electrolyte can achieve the high transparency of the graphene glass material.‌ Optionally, the graphene glass includes 0.5-1 parts of interface modifier by mass.

[0016] By adopting the above technical scheme, the addition of the interface modifier can effectively improve the interface bonding strength between the toughening agent and the chopped glass fibers, so that the toughening agent forms a dispersed phase in the chopped glass fibers. At the same time, it can also enhance the bonding 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.

[0017] In a second aspect, the present invention provides a method for preparing ultra-flexible graphene glass, which adopts the following technical solution: Premixing the flexible polymer with the graphene quantum dots having a C=C bond: adding the flexible polymer to the toughening agent and stirring, then adding the graphene quantum dots having a C=C bond, and ultrasonically treating for 30-60 minutes at 20-30 kHz to ensure uniform dispersion to form a mixed solution; Integration of chopped glass fibers: adding chopped glass fibers and interfacial modifiers into the mixed solution, mechanically stirring until there is no agglomeration, to form a mixture; ‌Curing and molding‌: Pour the mixture into a mold, vacuum degassing it, and then heat and cure it at 70-90°C for 2-3 hours to obtain ultra-flexible graphene glass.

[0018] Optionally, 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 ultrasonically exfoliated at 40 kHz for 2-4 h to obtain carboxylated graphene quantum dots. Covalent grafting of graphene quantum dots on the surface: Carboxylated graphene quantum dots are reacted with glycidyl methacrylate at 50-70° C. for 10-12 h, and graphene quantum dots with C=C bonds are obtained after purification.

[0019] By adopting the above technical solution, C=C bonds are introduced on the graphene surface. The C=C bonds on the surface of graphene quantum dots are covalently bonded with Si-OH in the chopped glass fibers to reduce interface 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 interface slip, reducing the maximum bending radius of the graphene glass, and improving the overall flexibility of the material.

[0020] Optionally, the preparation method of the toughening agent comprises the following steps: Preparation of modified ion gel electrolyte: Dissolve the hydrophilic polymer in a mixed solvent of deionized water and EMIMTFSI ionic liquid, add a cross-linking agent and stir at 70-90°C until completely dissolved to obtain a modified ion gel electrolyte solution; Cellulose nanofiber / ion gel composite: The cellulose nanofibers were dispersed in the modified ion gel electrolyte solution, magnetically stirred for 2-3 hours, and then ultrasonically treated at 20-30 kHz for 30-40 min to ensure uniform dispersion. The solution was allowed to crosslink at room temperature for 24 hours to obtain a toughening agent.

[0021] By adopting the above technical solution, cellulose nanofibers form a rigid structure in glass fibers, hinder crack propagation through crack deflection and fiber bridging mechanisms, improve fracture toughness, and the polar groups (such as amide groups) in the modified ion gel electrolyte are bonded to -Si-OH on the glass surface through hydrogen bonds or covalent bonds to reduce interfacial stress concentration. Under the action of external force, the modified ion gel electrolyte first dissipates energy through dynamic bond breakage, and then the rigid network structure of cellulose nanofibers further resists damage through fiber pullout and breakage, achieving staged toughening.

[0022] In a third aspect, the present invention provides an ultra-flexible graphene glass or an ultra-flexible graphene glass preparation method, and the ultra-flexible graphene glass obtained is used in flexible display screens, wearable devices, curved touch panels, and sensors.

[0023] In summary, the present invention includes at least one of the following beneficial technical effects: By adding flexible polymers, the brittleness of graphene glass materials can be effectively reduced and the interface bonding between graphene and chopped glass fibers can be enhanced.

[0024] 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 and carboxyl groups), effectively transmitting and dispersing external stress and inhibiting crack propagation. The C=C bonds on the surface of graphene quantum dots covalently bond with Si-OH in chopped glass fibers to reduce interface delamination. At the same time, graphene quantum dots with C=C bonds and chopped glass fibers can deform synchronously when bent, avoiding plastic failure caused by interface slip, reducing the limit bending radius of graphene glass, and improving the overall flexibility of the material.

[0025] 3. By adding toughening agents, active groups (such as hydroxyl and carboxyl groups) form chemical bonds or hydrogen bonds with graphene and chopped glass fibers, reducing the defects of interfacial bonding force. At the same time, they span the microcracks, effectively preventing crack expansion, absorbing a large amount of energy, increasing fracture energy, and improving the tensile modulus and bending elastic modulus of the material. At the same time, the toughening agent and graphene work synergistically to improve the stability of the material in a wide temperature range (-50°C to 200°C). DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the embodiments.

[0027] The materials used in the following examples can all be purchased from the market.

[0028] Example 1: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0029] An ultra-flexible graphene glass comprises 75 parts by mass of chopped glass fibers, 25 parts by mass of a flexible polymer, 0.5 parts by mass of graphene quantum dots having a C=C bond, and 5 parts by mass of a toughening agent, wherein the toughening agent is silicone powder, and the flexible polymer is transparent polyimide. In other embodiments, the flexible polymer may also be polydimethylsiloxane or polyurethane.

[0030] The preparation method of ultra-flexible graphene glass comprises the following steps: S1. Preparation of a mixed solution of transparent polyimide and graphene quantum dots having a C=C bond: S11. Preparation of graphene quantum dots with C=C bonds: placing graphene oxide in a H2SO4 / HNO3 solution and ultrasonically exfoliating for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtaining graphene quantum dots with C=C bonds after purification; 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 perform ultrasonic treatment at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0031] S2. Integration of chopped glass fibers: Add chopped glass fibers into the mixed liquid and mechanically stir until there are no agglomerates to form a mixture.

[0032] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and heat and cure at 80°C for 3 hours to obtain ultra-flexible graphene glass #1.

[0033] Example 2: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0034] The invention discloses an ultra-flexible graphene glass comprising 85 parts of chopped glass fibers, 15 parts of polyurethane, 1 part of graphene quantum dots with C=C bonds and 3 parts of silicone powder by weight.

[0035] The preparation method of the ultra-flexible graphene glass is the same as that in Example 1.

[0036] Example 3: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0037] The ultra-flexible graphene glass comprises 80 parts of chopped glass fibers, 20 parts of polydimethylsiloxane, 0.8 parts of graphene quantum dots with C=C bonds, and 4 parts of silicone powder by mass.

[0038] The preparation method of the ultra-flexible graphene glass is the same as that in Example 1.

[0039] Example 4: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0040] A super-flexible graphene glass comprises 80 parts of chopped glass fibers, 20 parts of polydimethylsiloxane, 0.8 parts of graphene quantum dots with C=C bonds, and 4 parts of toughening agents by mass. The toughening agent comprises a modified ion gel electrolyte and cellulose nanofibers, and the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 3:1. The modified ion gel electrolyte comprises a hydrophilic polymer, an EMIMTFSI ionic liquid, a crosslinking agent, and water. The hydrophilic polymer is polyvinyl alcohol. In other embodiments, the hydrophilic polymer can also be polyacrylamide. The crosslinking agent is borax. In other embodiments, the crosslinking agent can also be glutaraldehyde. The mass ratio of polyvinyl alcohol: EMIMTFSI ionic liquid: borax: water is 1:4:0.3:12.

[0041] The preparation method of ultra-flexible graphene glass is as follows: S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots having a C=C bond: S11. Preparation of graphene quantum dots with C=C bonds: placing graphene oxide in a H2SO4 / HNO3 solution and ultrasonically exfoliating for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtaining graphene quantum dots with C=C bonds after purification; S12, preparation of toughening agent: polyvinyl alcohol was dissolved in a mixed solvent of deionized water and EMIMTFSI ionic liquid, borax was added and stirred at 80°C until completely dissolved to obtain a modified ion gel electrolyte solution, cellulose nanofibers were dispersed in the modified ion gel electrolyte solution, magnetically stirred for 2 hours, and then ultrasonically treated at 25kHz for 35 minutes to ensure uniform dispersion, and cross-linked at room temperature for 24 hours to obtain a toughening agent; S13, premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: polydimethylsiloxane was added to the toughening agent and stirred, and then graphene quantum dots with C=C bonds were added, and ultrasonic treatment was performed at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0042] S2. Integration of chopped glass fibers: Add chopped glass fibers into the mixed liquid and mechanically stir until there are no agglomerates to form a mixture.

[0043] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and heat and cure at 80°C for 3 hours to obtain ultra-flexible graphene glass #4.

[0044] Example 5: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0045] 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.

[0046] The preparation method of the ultra-flexible graphene glass is the same as that of Example 4.

[0047] Example 6: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0048] 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.

[0049] The preparation method of the ultra-flexible graphene glass is the same as that of Example 4.

[0050] Example 7: This example discloses an ultra-flexible graphene glass and a preparation method thereof.

[0051] 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.

[0052] The preparation method of the ultra-flexible graphene glass is as follows: S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots having a C=C bond: S11. Preparation of graphene quantum dots with C=C bonds: placing graphene oxide in a H2SO4 / HNO3 solution and ultrasonically exfoliating for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtaining graphene quantum dots with C=C bonds after purification; S12, preparation of toughening agent: polyvinyl alcohol was dissolved in a mixed solvent of deionized water and EMIMTFSI ionic liquid, borax was added and stirred at 80°C until completely dissolved to obtain a modified ion gel electrolyte solution, cellulose nanofibers were dispersed in the modified ion gel electrolyte solution, magnetically stirred for 2 h, and then ultrasonically treated at 25 kHz for 35 min to ensure uniform dispersion, and cross-linked at room temperature for 24 h to obtain a toughening agent; S13, premixing polydimethylsiloxane and graphene quantum dots with C=C bonds: add polydimethylsiloxane to the above-mentioned toughening agent and stir, then add graphene quantum dots with C=C bonds, and perform ultrasonic treatment at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0053] S2. Integration of chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent into the mixed solution and mechanically stir until there is no agglomeration to form a mixture.

[0054] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and heat and cure it at 80°C for 3 hours to obtain ultra-flexible graphene glass #7.

[0055] Comparative Example 1: This comparative example provides a comparative ultra-flexible graphene glass, which is the same as Example 7, except that high-silica glass fiber is used instead of short-cut glass fiber.

[0056] Comparative Example 2: This comparative example provides a comparative ultra-flexible graphene glass, which is the same as Example 7, except that a rigid polymer polyimide is used instead of a flexible polymer polydimethylsiloxane.

[0057] Comparative Example 3: This comparative example provides a comparative ultra-flexible graphene glass, which has the same components as the ultra-flexible graphene glass of Example 7, except that graphene oxide is used instead of graphene quantum dots with C=C bonds.

[0058] The preparation method of the ultra-flexible graphene glass comprises the following steps: S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots having a C=C bond: S11. Preparation of toughening agent: polyvinyl alcohol was dissolved in a mixed solvent of deionized water and EMIMTFSI ionic liquid, borax was added and stirred at 80°C until completely dissolved to obtain a modified ion gel electrolyte solution, cellulose nanofibers were dispersed in the modified ion gel electrolyte solution, magnetically stirred for 2 h, and then ultrasonically treated at 25 kHz for 35 min to ensure uniform dispersion, and cross-linked at room temperature for 24 h to obtain a toughening agent; S12, premixing of polydimethylsiloxane and graphene oxide: polydimethylsiloxane was added to the toughening agent and stirred, and then graphene oxide was added, and ultrasonic treatment was performed at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0059] S2. Integration of chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent into the mixed solution and mechanically stir until there is no agglomeration to form a mixture.

[0060] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and heat and cure it at 80°C for 3 hours to obtain ultra-flexible graphene glass D3.

[0061] Comparative Example 4: This comparative example provides a comparative ultra-flexible graphene glass, which has the same components as the ultra-flexible graphene glass of Example 7, except that: the toughening agent only uses modified ion gel electrolyte.

[0062] The preparation method of the ultra-flexible graphene glass comprises the following steps: S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots having a C=C bond: S11. Preparation of graphene quantum dots with C=C bonds: placing graphene oxide in a H2SO4 / HNO3 solution and ultrasonically exfoliating for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtaining graphene quantum dots with C=C bonds after purification; S12, preparation of a toughening agent: dissolving polyvinyl alcohol in a mixed solvent of deionized water and EMIMTFSI ionic liquid, adding borax and stirring at 80° C. until completely dissolved, to obtain a toughening agent; S13, premixing polydimethylsiloxane and graphene quantum dots with C=C bonds: add polydimethylsiloxane to the above-mentioned toughening agent and stir, then add graphene quantum dots with C=C bonds, and perform ultrasonic treatment at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0063] S2. Integration of chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent into the mixed solution and mechanically stir until there is no agglomeration to form a mixture.

[0064] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and heat and cure it at 80°C for 3 hours to obtain ultra-flexible graphene glass D4.

[0065] Comparative Example 5: This comparative example provides a comparative ultra-flexible graphene glass, which has the same components as the ultra-flexible graphene glass of Example 7, except that: only cellulose nanofibers are used as the toughening agent.

[0066] The preparation method of the ultra-flexible graphene glass comprises the following steps: S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots having a C=C bond: S11. Preparation of graphene quantum dots with C=C bonds: placing graphene oxide in a H2SO4 / HNO3 solution and ultrasonically exfoliating for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtaining graphene quantum dots with C=C bonds after purification; S12. Premixing of polydimethylsiloxane and graphene quantum dots with C=C bonds: Cellulose nanofibers were added to polydimethylsiloxane and stirred, and then graphene quantum dots with C=C bonds were added. Ultrasonic treatment was performed at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0067] S2. Integration of chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent into the mixed solution and mechanically stir until there is no agglomeration to form a mixture.

[0068] S3. Curing and molding: Pour the mixture into a mold, perform vacuum degassing, and heat and cure it at 80°C for 3 hours to obtain ultra-flexible graphene glass D5.

[0069] Comparative Example 6: This comparative example provides a comparative ultra-flexible graphene glass, which is the same as Example 7, except that carbon nanotubes are used instead of cellulose nanofibers.

[0070] Comparative Example 7: This comparative example provides a comparative ultra-flexible graphene glass, which has the same components as the ultra-flexible graphene glass of Example 7, except that an ion gel electrolyte is used instead of a modified ion gel electrolyte.

[0071] The preparation method of the ultra-flexible graphene glass comprises the following steps: S1. Preparation of a mixed solution of polydimethylsiloxane and graphene quantum dots having a C=C bond: S11. Preparation of graphene quantum dots with C=C bonds: placing graphene oxide in a H2SO4 / HNO3 solution and ultrasonically exfoliating for 3 h at 40 kHz to obtain carboxylated graphene quantum dots, then reacting the carboxylated graphene quantum dots with glycidyl methacrylate at 60°C for 12 h, and obtaining graphene quantum dots with C=C bonds after purification; S12, preparation of toughening agent: polyvinyl alcohol was dissolved in EMIMTFSI ionic liquid, stirred until homogeneous, to obtain ion gel electrolyte solution, and cellulose nanofibers were dispersed in the ion gel electrolyte solution, magnetically stirred for 2 h, and then ultrasonically treated at 25 kHz for 35 min to ensure uniform dispersion, and allowed to stand at room temperature for cross-linking for 24 h to obtain toughening agent; S13, premixing polydimethylsiloxane and graphene quantum dots with C=C bonds: add polydimethylsiloxane to the above-mentioned toughening agent and stir, then add graphene quantum dots with C=C bonds, and perform ultrasonic treatment at 25 kHz for 40 minutes to ensure uniform dispersion to form a mixed solution.

[0072] S2. Integration of chopped glass fibers: Add chopped glass fibers and KH-550 silane coupling agent into the mixed solution and mechanically stir until there is no agglomeration to form a mixture.

[0073] S3. Curing and molding: Pour the mixture into a mold, degas in vacuum, and heat and cure at 80°C for 3 hours to obtain ultra-flexible graphene glass D7.

[0074] The ultra-flexible graphene glasses #1-7 of Examples 1-4 of the present invention and the ultra-flexible graphene glasses D1-D7 of Comparative Examples 1-7 were subjected to performance tests, including crack growth rate, tensile strength, shear strength, bending strength, minimum bending radius, fracture strain, and critical load, wherein the tensile strength was tested in accordance with the national standard GB / T1040.2-2006; the shear strength was tested in accordance with the national standard GB / T 16825-2008; the bending strength was tested in accordance with the national standard GB / T9341-2000; the crack growth rate was tested using the K value method; the calculation of fracture strain is usually based on the deformation of the material in the tensile test, and the calculation formula is δ=ΔL / L×100%, wherein ΔL is the deformation, and L is the original length. The obtained performance test results are shown in Table 1.

[0075] Table 1

[0076] By comparing the data of Examples 1-3 with Example 4, it can be seen that the toughening agents added in Examples 1-3 are different from those in Example 4. Example 4 adds the toughening agent of the present application, and through reasonable proportioning with other components in the ultra-flexible graphene glass, the ultra-flexible graphene glass prepared by adding the toughening agent of the present application exhibits relatively excellent flexibility and strength.

[0077] It can be seen from the data of Examples 4-6, especially Example 6, that by making a more reasonable ratio of the components in the toughening agent of the present application, the ultra-flexible graphene glass in the examples has excellent performance in all aspects.

[0078] Compared with Example 7, Example 7 adds an interface modifier. After the interface modifier is added to the graphene glass, the crack growth rate, tensile strength, shear strength, bending strength, minimum bending radius, fracture strain, and critical load of the graphene glass are greatly improved. This is because the addition of the interface modifier can effectively improve the interface bonding strength between the toughening agent and the chopped glass fiber, so that the toughening agent forms a dispersed phase in the chopped glass fiber. At the same time, it can also enhance the bonding 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.

[0079] Compared with Comparative Examples 1-3, Example 7 uses high-silica glass fiber to replace the chopped glass fiber of the present application, Comparative Example 2 uses rigid polymer polyimide to replace the flexible polymer polydimethylsiloxane of the present application, and Comparative Example 3 uses graphene oxide 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 are 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, and the polar groups in the flexible polymer are combined with the surface groups of the chopped glass fiber through hydrogen bonds to reduce interfacial stress concentration. At the same time, graphene is adsorbed through π-π stacking to enhance the interface bonding strength between graphene and the chopped glass fiber, thereby improving the overall mechanical strength and durability of the material. The C=C bonds on the surface of graphene quantum dots with C=C bonds are covalently bonded with Si-OH in the chopped glass fibers to reduce interface delamination. The graphene quantum dots with C=C bonds and the chopped glass fibers can deform synchronously when bent to avoid plastic failure caused by interface slip, reduce the ultimate bending radius of graphene glass, improve the overall flexibility of the material, and reduce 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 to avoid agglomeration problems and reduce 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 and carboxyl groups), effectively transfer and disperse external stress, and inhibit crack propagation. The toughening agent forms chemical bonds or hydrogen bonds with graphene and chopped glass fibers through active groups (such as hydroxyl 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 fracture energy, and improving the tensile modulus and bending elastic modulus of the material. At the same time, the toughening agent works synergistically with graphene to improve the stability of the material in a wide temperature range (-50°C to 200°C).

[0080] Compared with Comparative Examples 5-8, Example 7 uses a modified ion gel electrolyte to replace the toughening agent of the present application, Comparative Example 6 uses cellulose nanofibers to replace the toughening agent of the present application, Comparative Example 7 uses carbon nanotubes to replace cellulose nanofibers, and Comparative Example 8 uses an ion gel electrolyte to replace a modified ion gel electrolyte. The flexibility and strength of the graphene glass in Comparative Examples 5-8 are much lower than those of the graphene glass obtained in Example 7. This is because the reversible supramolecular bonds (such as ion coordination and hydrogen bonds) in the modified ion gel electrolyte in the toughening agent of the present application can be broken and re-formed when subjected to force, dissipating energy, and the cellulose nanofibers are embedded in the chopped glass fibers through hydrogen bonds or van der Waals forces to form a rigid support framework, inhibit crack propagation, enhance interfacial bonding, and improve fracture resistance. Under the action of external force, the modified ion gel electrolyte first dissipates energy through dynamic bond fracture, and then the rigid network of cellulose nanofibers further resists damage through fiber pull-out and fracture, achieving "staged toughening", and the two work together to improve the fatigue resistance and flexibility of graphene glass.

[0081] From this we can see that the replaced materials in the toughening agent cannot play a role in the toughening agent, but will reduce the effect of the toughening agent. Therefore, each component cannot be replaced by other materials at will.

[0082] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in 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 of chopped glass fibers, 15-25 parts of flexible polymers, 0.5-1 parts of graphene quantum dots with C=C bonds, and 3-5 parts of toughening agents by mass.

2. The ultra-flexible graphene glass according to claim 1, characterized in that: The toughening agent comprises a modified ion gel electrolyte and cellulose nanofibers, and the mass ratio of the modified ion gel electrolyte to the cellulose nanofibers is 3-5:

1.

3. The ultra-flexible graphene glass according to claim 2, characterized in that: The modified ion gel electrolyte comprises a hydrophilic polymer, an EMIMTFSI ionic liquid, a cross-linking agent, and water. The mass ratio of the hydrophilic polymer: the EMIMTFSI ionic liquid: the cross-linking agent: the water is 1:4-6:0.3-0.5:12-18.

4. The ultra-flexible graphene glass according to any one of claims 1 to 3, characterized in that: The graphene glass further comprises 0.5-1 part of an interface modifier by mass.

5. A method for preparing the ultra-flexible graphene glass using any one of claims 1 to 4, 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 20-30 kHz 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.

6. The method for preparing ultra-flexible graphene glass according to claim 5, 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 ultrasonically exfoliated at 40 kHz for 2-4 h 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.

7. The method for preparing ultra-flexible graphene glass according to claim 5, 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, then ultrasonically treated for 30-40 minutes at 20-30 kHz to ensure uniform dispersion, and cross-linked at room temperature for 24 hours to obtain the toughening agent.

8. 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 1-4, or the method for preparing ultra-flexible graphene glass as described in any one of claims 5-7.

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