Graphene thin-film material reinforced and toughened by using mechanical bonds, and preparation and application of graphene thin-film material

Abstract

The invention provides a graphene thin film material reinforced and toughened by using mechanical bonds as well as preparation and application of the graphene thin film material. The preparation method comprises the following steps: synthesizing a bifunctional mechanical interlocking molecule, dissolving the bifunctional mechanical interlocking molecule in an organic solvent, and soaking a graphene oxide film; according to the types of functional groups carried by the mechanically interlocked molecules, adding a reagent beneficial to the combination of the mechanically interlocked molecules and the graphene oxide into the organic solvent; washing and drying the graphene oxide film material obtained after soaking; soaking with hydriodic acid, and then washing and drying to obtain a mechanical bond reinforced and toughened graphene film material; the mechanical interlocking molecule in the graphene thin film material reinforced and toughened by the mechanical bond is one of rotaxane, isohydrocarbon and daisy chain. According to the method disclosed by the invention, the graphene film material is bridged through mechanical bonds, so that the graphene film material is reinforced and toughened.

Description

Technical Field

[0001] The invention belongs to the field of synthetic chemistry and nanocomposite material preparation, and relates to a method for preparing a graphene film material reinforced and toughened by using mechanical bonds, and specifically, relates to a method for preparing a reinforced and toughened graphene film material by using mechanical interlocking molecules. Background Art

[0002] Graphene has great application prospects in many fields such as supercapacitors, flexible electronic devices, electromagnetic interference shielding materials, and aerospace due to its excellent mechanical strength and conductivity. However, once a macroscopic film is formed, the weak interaction between the sheets (mainly hydrogen bonds) often leads to the loss of excellent performance, which limits the further application and development of graphene materials. Therefore, how to obtain high-performance graphene film materials faces great challenges. The surface of graphene materials usually contains abundant oxygen-containing functional groups, which helps to form covalent bonds / non-covalent bonds between sheets, thereby regulating the interaction between sheets. At present, most studies are on enhancing the strength of graphene film materials by introducing covalent bonds / non-covalent bonds, but the elongation is rarely improved.

[0003] Mechanical bonds are a kind of spatial network entanglement, which mainly exists in mechanically interlocked molecules, which are a class of molecules with special topological structures formed based on host-guest recognition. Compared with traditional covalent bonds / non-covalent bonds, mechanical bonds can achieve controllable intramolecular motion. At the same time, mechanical bonds also have both dynamics and stability. Under the action of force, they can undergo intramolecular motion and dissipate energy, but their structure remains stable. However, there are few reports on the use of mechanical bonds to strengthen and toughen graphene film materials. Summary of the invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a two-dimensional film material strengthened and toughened by mechanical bonds, and a preparation method and application thereof. The graphene film material prepared by bridging graphene material sheets by mechanical bonds has excellent mechanical properties, stretchability, conductivity and multifunctionality, and the preparation method is simple and universal.

[0005] The object of the present invention is achieved through the following solutions:

[0006] The second aspect of the present invention provides a method for preparing a graphene film material reinforced and toughened by mechanical bonds, the method comprising the following steps:

[0007] S1. synthesizing a bifunctional mechanical interlocking molecule; wherein the bifunctional mechanical interlocking molecule comprises two functional groups;

[0008] S2, dissolving the mechanical interlocking molecules obtained in step S1 in an organic solvent, and soaking the graphene oxide film; the functional groups of the mechanical interlocking molecules react with the oxygen-containing functional groups on the surface of the graphene oxide to form mainly covalent bonds;

[0009] S3, washing and drying the graphene oxide film material obtained in step S2;

[0010] S4, soaking the graphene oxide film obtained in step S3 with hydroiodic acid, washing and drying, to obtain a graphene film material with mechanical bond reinforcement and toughening.

[0011] As an embodiment of the present invention, in step S1, the mechanically interlocked molecule is at least one of a rotaxane, a catenane, and a daisy chain.

[0012] As an embodiment of the present invention, in step S1, the two functional groups are the same or different; the functional group is selected from one of a hydroxyl group, a carboxyl group, and an epoxy group.

[0013] As an embodiment of the present invention, in step S2, hydrogen bonds may also be generated, but since their strength is much smaller than that of covalent bonds, they can be ignored.

[0014] As an embodiment of the present invention, in step S2, the covalent bond reaction includes an esterification reaction and / or an epoxy ring-opening reaction. For example, an esterification reaction between a hydroxyl group and a carboxyl group; an epoxy ring-opening reaction between an epoxy group and a carboxyl group. The epoxy ring-opening reaction between an epoxy group and a carboxyl group can occur at a high temperature such as 80-90°C.

[0015] As an embodiment of the present invention, when the functional group carried by the mechanical interlocking molecule is a hydroxyl group, the covalent bond reaction is an esterification reaction, and a reagent that helps the mechanical interlocking molecule and graphene oxide to combine is added to the organic solvent in step S2. The reagent includes at least one of a catalyst and a coupling agent.

[0016] As an embodiment of the present invention, the coupling agent is selected from one of dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The amount of the catalyst added to the organic solvent is 2-4 times the molar equivalent of the added mechanical interlocking molecule. In some embodiments, the amount of the added catalyst is 2.4 times the molar equivalent of the added mechanical interlocking molecule.

[0017] As an embodiment of the present invention, the catalyst is selected from one of 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene. The amount of the catalyst added to the organic solvent is 0.1-0.5 times the molar equivalent of the added mechanical interlocking molecules. In some embodiments, the amount of the added catalyst is 0.2 times the molar equivalent of the added mechanical interlocking molecules.

[0018] As an embodiment of the present invention, the esterification reaction is carried out at 20-40° C. for 1-6 hours. In some embodiments, the esterification reaction is carried out at room temperature for 3 hours.

[0019] As an embodiment of the present invention, when the covalent bond reaction is an epoxy ring-opening reaction, the participation of a catalyst and a coupling agent is not required. For example, when the functional group carried by the mechanical interlocking molecule is an epoxy group. The reaction temperature of the epoxy ring-opening reaction is 80-100°C and the time is 8-24 hours. In some embodiments, the reaction temperature of the epoxy ring-opening reaction is 80°C and the time is 12 hours.

[0020] As an embodiment of the present invention, in step S2, the surface of the graphene oxide film has oxygen-containing functional groups, which include one or more of hydroxyl groups, carboxyl groups, and epoxy groups.

[0021] As an embodiment of the present invention, in step S2, the graphene oxide film is a self-supporting film prepared by vacuum filtration of a graphene oxide aqueous solution.

[0022] As an embodiment of the present invention, in step S2, the organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, chloroform, and dimethyl sulfoxide.

[0023] As an embodiment of the present invention, in step S2, the mechanical interlocking molecules are dissolved in a mixed solution formed by an organic solvent, and the content of the mechanical interlocking molecules is in the range of 3-10 mg / mL.

[0024] As an embodiment of the present invention, in step S2, the thickness of the graphene oxide film is controlled to be 3-10 μm.

[0025] As an embodiment of the present invention, in step S2, the soaking process is carried out at 20-40° C. for 2-12 hours. The esterification reaction is very efficient with the participation of a catalyst, can occur at room temperature, and reacts completely within a few hours. In some embodiments, the soaking process is carried out at room temperature for 3 hours.

[0026] As an embodiment of the present invention, in step S3, the detergent used is ethanol, and the drying treatment conditions are vacuum drying at 40-60° C. for 2-12 hours.

[0027] As an embodiment of the present invention, in step S4, the immersion process is carried out at 20-40° C. for 2-6 hours. The immersion process is the reduction of graphene oxide by hydroiodic acid, removing unreacted oxygen-containing functional groups on the surface of graphene oxide to convert it into graphene. In some embodiments, the immersion process is carried out at room temperature for 3 hours.

[0028] As an embodiment of the present invention, in step S4, the detergent used is ethanol, and the drying treatment conditions are vacuum drying at 40-60° C. for 2-12 hours.

[0029] The second aspect of the present invention provides a graphene film material reinforced and toughened by mechanical bonds, which is prepared by the above-mentioned preparation method.

[0030] The third aspect of the present invention provides an application of a graphene film material reinforced and toughened by mechanical bonds, wherein the application is to apply the graphene film material reinforced and toughened by mechanical bonds to a flexible electronic device, including a flexible electrode.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The method of the present invention bridges the graphene film material through mechanical bonds and utilizes the intramolecular movement of the mechanical bonds to achieve the strengthening and toughening of the graphene film material. On the basis of improving the strength and toughness, the elongation is also significantly improved.

[0033] 2. The method of the present invention bridges the graphene film material through mechanical bonds, has excellent flexibility and stretchability, and can still conduct electricity while maintaining a long stretching rate, which is of great significance to the application development of graphene film materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0035] Figure 1 is the structural formula of the relevant mechanically interlocked molecules listed in the embodiments of the present invention;

[0036] Figure 2 is a macroscopic photograph of the graphene film material prepared in Example 1 of the present invention;

[0037] Figure 3 is a scanning electron microscope morphology photograph of the graphene film material prepared in Example 1 of the present invention;

[0038] Figure 4 is the tensile stress-strain curve of the graphene film material prepared in Example 1 of the present invention;

[0039] Figure 5 Schematic diagram of the anti-fatigue bending of the graphene film material prepared in Example 1 of the present invention and a comparison diagram of the tensile mechanical properties before and after bending;

[0040] Figure 6 This is a picture of the graphene film material prepared in Example 1 of the present invention being used as a flexible electrode to drive a light-emitting diode;

[0041] Figure 7 This is a picture of the graphene film material prepared in Example 1 of the present invention being used as a flexible electrode to drive a mechanical joint;

[0042] Figure 8 This is a picture of the graphene film material prepared in Example 1 of the present invention being used as a flexible electrode to drive a mechanical joint to grasp a small ball;

[0043] Fig. 9 is the tensile stress-strain curve of the graphene film material prepared in Example 2 of the present invention;

[0044] Fig.10 is a photograph of the graphene film material prepared in Example 3 of the present invention being folded into a windmill;

[0045] Fig.11 is the tensile stress-strain curve of the graphene film material prepared in Example 4 of the present invention;

[0046] Fig.12 This is the synthetic route of the hydroxyl-containing [2] rotaxane in Example 1 of the present invention;

[0047] Fig.13 is the H NMR spectrum of the hydroxyl-containing [2] rotaxane in Example 1 of the present invention;

[0048] Fig.14 is a high-resolution mass spectrum of the hydroxyl-containing [2] rotaxane in Example 1 of the present invention;

[0049] Fig.15 This is the synthetic route of the epoxy group-containing [2] rotaxane in Example 2 of the present invention;

[0050] Fig.16 is the H NMR spectrum of the epoxy group-containing [2] rotaxane in Example 2 of the present invention;

[0051] Fig.17 is a high-resolution mass spectrum of the epoxy group-containing [2] rotaxane in Example 2 of the present invention;

[0052] Fig.18This is the synthetic route of the hydroxyl-containing daisy chain monomer in Example 4 of the present invention;

[0053] Fig.19 is the H NMR spectrum of the daisy chain monomer containing hydroxyl group in Example 4 of the present invention;

[0054] Fig. 20 This is a high-resolution mass spectrum of the hydroxyl-containing daisy chain monomer in Example 4 of the present invention. DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0056] The present invention is further described in detail below with reference to specific embodiments.

[0057] The performance characteristics of the graphene film material reinforced and toughened by mechanical bonds prepared by the present invention are as follows:

[0058] The microscopic morphology of the graphene film was obtained by field emission scanning electron microscopy (test voltage was 10 kV).

[0059] The stress-strain curve of the graphene film was obtained by a mechanical stretching machine (stretching rate was 0.2 mm / min).

[0060] Example 1

[0061] This embodiment provides a method for preparing a graphene film material that is reinforced and toughened using mechanical bonds. Specifically, the method comprises the following steps:

[0062] Step 1: Design and synthesize hydroxyl-containing [2]rotaxanes, such as Figure 1 a, and the synthesis steps are shown in Fig.12 (According to the amount of reactants given in the synthesis route, the final product can be obtained by increasing or decreasing the amount in equal proportion). Fig.13 , 1 H NMR (CDCl 3,298K,400MHz)δ(ppm):7.67(s,1H),7.62(dd,J=8.5,1.9Hz,1H),7.46(d,J=1.9Hz,1H),6.98(s,2 H),6.86(d,J=8.6Hz,1H),6.61(s,3H),5.16(s,2H),4.36(t,J=7.2Hz,4H),4.26(t,J=6.7Hz,2H),4 .22-4.12 (m, 4H), 3.96-3.86 (m, 4H), 3.66-3.37 (m, 26H), 3.18-3.10 (m, 2H), 2.28 (s, 6H), 2.17 (d, J = 3.5 Hz, 6H), 1.90 (t, J = 6.9 Hz, 2H), 1.80-1.71 (m, 4H), 1.55-1.52 (m, 4H), 1.92-1.20 (m, 40H). Mass spectrum see Fig.14 , HRMS: m / z calcd for C 71 H 117 N 4 O 14 ,1249.8561[M-PF 6 ] + ; found 1249.8556[M-PF 6 ] + .

[0063] Step 2: Dissolve the [2]rotaxane obtained in step 1 in tetrahydrofuran at a concentration of 5 mg / mL, take 5 mL and soak the graphene oxide film in a 25°C environment for 3 hours.

[0064] Step 3: 10 mg of 4-dimethylaminopyridine and 10 mg of dicyclohexylcarbodiimide were added simultaneously to the tetrahydrofuran in which the graphene oxide film was soaked in step 2, and the mixture was kept at 25° C. for 3 hours.

[0065] Step 4: The graphene oxide film obtained in step 3 was washed with anhydrous ethanol to remove unreacted [2]rotaxane, 4-dimethylaminopyridine and dicyclohexylcarbodiimide, and then the washed graphene oxide film was placed in a vacuum oven at 45° C. and dried for 4 hours.

[0066] Step 5: Soak the graphene oxide film obtained in step 4 with hydroiodic acid, wash it with anhydrous ethanol to remove the hydroiodic acid after 3 hours, and then place the washed graphene film in a vacuum oven at 45° C. to dry for 4 hours.

[0067] Step 6: Set up a comparative experiment, replace the hydroxyl-containing [2]rotaxane with heptaethylene glycol, keep other conditions unchanged, and obtain a heptaethylene glycol-bridged graphene film; without adding [2]rotaxane and heptaethylene glycol, a pure graphene film is obtained.

[0068] The performance of the three graphene films prepared in Example 1 was characterized and compared. For the convenience of description, RBG represents the graphene film bridged by [2]rotaxane, HBG represents the graphene film bridged by heptaethylene glycol, and rGO represents the pure graphene film; (1) The RBG film can be bent without damage, such as Figure 2 As shown, the film is flexible. (2) The cross-section of the RBG film is stacked layer by layer, and the nitrogen element is evenly dispersed, as shown in Figure 3 As shown in Figure 2, it shows that [2] the rotaxane is uniformly dispersed in the graphene film. (3) The mechanical properties of the RBG film are better than those of the HBG and rGO films, as shown in Figure 2. Figure 4 As shown in the figure, it is shown that the presence of [2] rotaxane improves the performance of graphene film, which further proves that mechanical bonds can be used to prepare enhanced and toughened graphene film materials. (4) After 100 times of repeated bending of 180°, the mechanical properties of RBG film can still be maintained at a high level, as shown in the figure. Figure 5 As shown, it shows that the RBG film has good anti-fatigue bending performance.

[0069] The RBG film prepared in Example 1 was subjected to application experiments. Figure 6 As shown in the figure, when the film is stretched to 20% elongation, the brightness of the LED remains basically unchanged, but when the elongation reaches 23%, the film breaks and the LED goes out; when the film is attached to the finger and bent, the brightness of the LED is not affected, indicating that the RBG film has excellent stretchability and flexibility; in addition, the RBG film can drive the movement of mechanical joints as a flexible electrode and can grab small balls, such as Figure 7 and Figure 8 In summary, the obtained mechanical bond-bridged graphene film material has excellent mechanical properties and fatigue resistance, as well as excellent flexibility and stretchability, and can be used as a flexible electrode, with a broad application space.

[0070] Example 2

[0071] This embodiment provides a method for preparing a graphene film material that is reinforced and toughened using mechanical bonds. Specifically, the method comprises the following steps:

[0072] Step 1: Design and synthesize a [2]rotaxane containing an epoxy group, such as Figure 1 b, and the synthesis steps are shown in Fig.15 (According to the amount of reactants given in the synthesis route, the final product can be obtained by increasing or decreasing the amount in equal proportion). Fig.16 , 1 HNMR (CDCl 3,298K,400MHz)δ(ppm):7.64(d,J=7.5Hz,1H),7.48(s,1H),7.46(d,J=1.9Hz,1H),7.01( m,4H),6.87(d,J=8.4Hz,1H),6.69(s,1H),4.36(t,J=6.2Hz,2H),4.27(m,2H),4.15(m,4 H), 3.90 (m, 4H), 3.67-3.40 (m, 22H), 3.13 (s, 2H), 2.91 (m, 2H), 2.75 (m, 2H), 2.47 (m, 2H), 2.28 (m, 2H), 2.20 (m, 6H), 1.79-1.71 (m, 4H), 1.56-1.49 (m, 8H), 1.36-1.19 (m, 32H). Mass spectrum see Fig.17 , HRMS: m / z calcd for C 69 H 111 N 2 O 15 ,1207.7979[M-PF 6 ] + ; found1207.7960[M-PF 6 ] + .

[0073] Step 2: Dissolve the [2]rotaxane obtained in step 1 in N,N-dimethylformamide at a concentration of 5 mg / mL, take 5 mL to soak the graphene oxide film, and soak it in an environment of 80°C for 12 hours.

[0074] Step 3: The graphene oxide film obtained in step 2 was washed with anhydrous ethanol to remove unreacted [2]rotaxane, and then the washed graphene oxide film was placed in a vacuum oven at 45° C. and dried for 4 hours.

[0075] Step 4: Soak the graphene oxide film obtained in step 3 with hydroiodic acid, wash it with anhydrous ethanol to remove the hydroiodic acid after 3 hours, and then place the washed graphene film in a vacuum oven at 45° C. to dry for 4 hours.

[0076] The tensile stress-strain curve of the graphene film prepared in Example 2 is shown in Fig. 9 As shown, it proves that it has good mechanical tensile properties.

[0077] Example 3

[0078] This embodiment provides a method for preparing a graphene film material that is reinforced and toughened using mechanical bonds. Specifically, the method comprises the following steps:

[0079] Step 1: Design and synthesize hydroxyl-containing catenane, such as Figure 1c, the synthesis method and corresponding spectrum are detailed in J.Am.Chem.Soc.2023,145(16),9011-9020.

[0080] Step 2: Dissolve the catenane obtained in step 1 in chloroform at a concentration of 5 mg / mL, take 5 mL to soak the graphene oxide film, and soak it in a 25°C environment for 3 hours.

[0081] Step 3: 10 mg of 4-dimethylaminopyridine and 10 mg of dicyclohexylcarbodiimide were added simultaneously to the chloroform in which the graphene oxide film was soaked in step 2, and the mixture was kept at 25° C. for 3 hours.

[0082] Step 4: Wash the graphene oxide film obtained in step 3 with anhydrous ethanol to remove unreacted catenane, 4-dimethylaminopyridine and dicyclohexylcarbodiimide, and then place the washed graphene oxide film in a vacuum oven at 45° C. to dry for 4 hours.

[0083] Step 5: Soak the graphene oxide film obtained in step 4 with hydroiodic acid, wash it with anhydrous ethanol to remove the hydroiodic acid after 3 hours, and then place the washed graphene film in a vacuum oven at 45° C. to dry for 4 hours.

[0084] Fig.10 A photograph showing the graphene film prepared in Example 3 being bent into a windmill is shown, proving that the graphene film has excellent flexibility.

[0085] Example 4

[0086] This embodiment provides a method for preparing a graphene film material that is reinforced and toughened using mechanical bonds. Specifically, the method comprises the following steps:

[0087] Step 1: Design and synthesize a hydroxyl-containing daisy chain, such as Figure 1 d, and the synthesis steps are shown in Fig.18 (According to the amount of reactants given in the synthesis route, the final product can be obtained by increasing or decreasing the amount in equal proportion). Fig.19 , 1 HNMR ((CD 3 ) 2S=O, 298K, 400MHz) δ (ppm): 7.57 (dd, J=8.5, 1.9Hz, 1H), 7.46 (d, J=1.9Hz, 1H), 7.37 (d, J=8.4Hz, 2H), 7.09 (d, J=8. 6Hz,1H),6.97(d,J=8.5Hz,2H),4.23(t,J=6.5Hz,2H),4.17(t,J=3.8Hz,2H),4.13(t,J=4.0Hz,2H),4.01(s,2H),3 .96 (t, J = 6.4 Hz, 2H), 3.80-3.77 (m, 4H), 3.64-3.61 (m, 4H), 3.58-3.55 (m, 4H), 3.84-3.48 (m, 12H), 3.37 (t, J = 6.4 Hz, 2H), 2.81 (t, J = 7.7 Hz, 2H), 1.73-1.66 (m, 4H), 1.56 (t, J = 5.9 Hz, 2H), 1.41-1.37 (m, 6H), 1.33-1.23 (m, 20H). Mass spectrum see Fig. 20 , HRMS: m / z calcd for C 48 H 80 NO 12 ,862.5675[M-PF 6 ] + ; found 862.5672[M-PF 6 ] + .

[0088] Step 2: Dissolve the daisy chain obtained in step 1 in N,N-dimethylacetamide at a concentration of 5 mg / mL, take 5 mL to soak the graphene oxide film, and soak it in a 25°C environment for 3 hours.

[0089] Step 3: 10 mg of 4-dimethylaminopyridine and 10 mg of dicyclohexylcarbodiimide were added simultaneously to the dimethyl sulfoxide in which the graphene oxide film was soaked in step 2, and the mixture was kept at 25° C. for 3 hours.

[0090] Step 4: Wash the graphene oxide film obtained in step 3 with anhydrous ethanol to remove unreacted daisy chains, 4-dimethylaminopyridine and dicyclohexylcarbodiimide, and then place the washed graphene oxide film in a vacuum oven at 45° C. to dry for 4 hours.

[0091] Step 5: Soak the graphene oxide film obtained in step 4 with hydroiodic acid, wash it with anhydrous ethanol to remove the hydroiodic acid after 3 hours, and then place the washed graphene film in a vacuum oven at 45° C. to dry for 4 hours.

[0092] The tensile stress-strain curve of the graphene film prepared in Example 4 is as follows: Fig.11 As shown, it proves that it has good mechanical tensile properties.

[0093] The method of the present invention utilizes mechanical bonds to strengthen and toughen graphene films, effectively introduces mechanical interlocking molecules into the film through organic solvent immersion and reaction between functional groups, and then obtains graphene film materials bridged by mechanical bonds through reduction with hydroiodic acid. The most prominent feature of mechanical bonds is intramolecular motion, that is, under the action of external forces, non-dissociated intramolecular motion can occur between interlocking components, giving the mechanical interlocking molecules dynamics and stability. The present invention utilizes the unique intramolecular motion of mechanical bonds to prepare a stretchable and flexible graphene film, whose elongation can reach more than 20%, which is beneficial to the application of graphene films in the field of flexible electronics. Among them, the required mechanical interlocking molecules can be designed as needed, so this method has universal applicability.

[0094] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for preparing a graphene film material reinforced and toughened by mechanical bonds, characterized in that: The method comprises the following steps: S1. synthesizing a bifunctional mechanical interlocking molecule; wherein the bifunctional mechanical interlocking molecule comprises two functional groups; S2, dissolving the mechanical interlocking molecules obtained in step S1 in an organic solvent, and soaking the graphene oxide film; the functional groups of the mechanical interlocking molecules react with the oxygen-containing functional groups on the surface of the graphene oxide to form mainly covalent bonds; S3, washing and drying the graphene oxide film material obtained in step S2; S4, soaking the graphene oxide film obtained in step S3 with hydroiodic acid, washing and drying, to obtain a graphene film material with mechanical bond reinforcement and toughening.

2. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 1, characterized in that: In step S1, the mechanically interlocked molecule is at least one of a rotaxane, a catenane, and a daisy chain.

3. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 1, characterized in that: In step S1, the two functional groups are the same or different; the functional group is selected from one of a hydroxyl group, a carboxyl group, and an epoxy group.

4. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 1, characterized in that: The reaction of the covalent bond includes an esterification reaction and / or an epoxy ring-opening reaction.

5. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 1, characterized in that: When the functional group carried by the mechanical interlocking molecule is a hydroxyl group, the covalent bond reaction is an esterification reaction, and a reagent that helps the mechanical interlocking molecule and graphene oxide to combine is added to the organic solvent in step S2.

6. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 5, characterized in that: The reagent includes at least one of a catalyst and a coupling agent; the coupling agent is selected from one of dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and the catalyst is selected from one of 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

7. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 1, characterized in that: In step S2, the surface of the graphene oxide film has oxygen-containing functional groups; the oxygen-containing functional groups include one or more of hydroxyl groups, carboxyl groups, and epoxy groups.

8. The method for preparing a graphene film material reinforced and toughened by mechanical bonds according to claim 1, characterized in that: In step S2, the organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, chloroform, and dimethyl sulfoxide.

9. A graphene film material with mechanical bond reinforcement and toughening obtained by the method as described in any one of claims 1 to 8.

10. Use of a mechanically bond-reinforced and toughened graphene film material obtained by the method according to any one of claims 1 to 8 in the preparation of flexible electronic devices.

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