A graphene-bacterial cellulose-MXene hybrid aerogel and its preparation, epoxy resin-based composite material and its preparation

Abstract

The present invention belongs to the technical fields of polymer composite materials and solid lubricating materials, and provides a graphene-bacterial cellulose-MXene hybrid aerogel and its preparation, as well as an epoxy resin-based composite material and its preparation. The graphene-bacterial cellulose-MXene hybrid aerogel of the present invention has a three-dimensional porous network structure constructed from graphene, bacterial cellulose, and MXene thin nanosheets. The present invention introduces bacterial cellulose and MXene thin nanosheets into the graphene aerogel to construct the graphene-bacterial cellulose-MXene hybrid aerogel. The introduction of bacterial cellulose and MXene thin nanosheets can, on the one hand, achieve a synergistic enhancement of the tribological properties of the epoxy resin composite material, and on the other hand, improve the strength and structural continuity of the graphene aerogel.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials and solid lubricating materials, and in particular to a graphene-bacterial cellulose-MXene hybrid aerogel and its preparation, and an epoxy resin-based composite material and its preparation. Background Art

[0002] Epoxy resins are widely used in the automotive, marine, and aerospace industries due to their low cost, easy processing, and excellent mechanical properties. However, their inherent brittleness, weak heat resistance, and poor wear resistance severely limit their application in mechanical moving parts. A common modification method is to introduce filler reinforcements into the resin matrix to improve its friction and wear properties. However, the dispersion of filler reinforcements within the resin matrix and the interfacial bonding between the filler and the resin matrix often limit the full potential of the filler's reinforcing properties.

[0003] Graphene aerogels have seen rapid development in recent years. Within graphene aerogels, nanosheets interact to form a three-dimensional porous network structure, enabling the construction of continuous heat conduction pathways within the epoxy resin matrix while preventing the aggregation of graphene nanosheets within the resin matrix. However, single graphene aerogels have structural defects that make it difficult to form continuous heat conduction pathways within the resin matrix, hindering the timely removal of frictional heat from the friction interface. Furthermore, single graphene aerogels have limited effect on improving the performance of friction transfer films on resin composites. Therefore, the tribological properties of single graphene aerogel-reinforced resin composites need to be further improved. Summary of the Invention

[0004] In view of this, the present invention aims to provide a graphene-bacterial cellulose-MXene hybrid aerogel and its preparation, as well as an epoxy resin-based composite material and its preparation. The graphene-bacterial cellulose-MXene hybrid aerogel provided by the present invention, when used to reinforce an epoxy resin matrix, improves the tribological properties of the epoxy resin-based composite material.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a graphene-bacterial cellulose-MXene hybrid aerogel. The graphene-bacterial cellulose-MXene hybrid aerogel has a three-dimensional porous network structure constructed by graphene, bacterial cellulose and MXene thin layer nanosheets.

[0007] The present invention provides a method for preparing the graphene-bacterial cellulose-MXene hybrid aerogel described in the above technical solution, comprising the following steps:

[0008] mixing and dispersing graphene oxide, bacterial cellulose, MXene thin layer nanosheets, a reducing agent, and a cross-linking agent to obtain a mixed system;

[0009] The mixed system is sequentially subjected to a hydrothermal reduction reaction and freeze-dried to obtain the graphene-bacterial cellulose-MXene hybrid aerogel.

[0010] Preferably, the mass ratio of the graphene oxide, bacterial cellulose and MXene thin layer nanosheets is 1:0.25:(0.5-2); the concentration of graphene oxide in the mixed system is 1-4 mg / mL.

[0011] Preferably, the reducing agent comprises isoascorbic acid and the cross-linking agent comprises cysteine.

[0012] Preferably, the mass ratio of the reducing agent to the cross-linking agent is (1-2):(1-2); the mass ratio of the reducing agent to graphene oxide is (1.5-2):1.

[0013] Preferably, the temperature of the hydrothermal reduction reaction is 80-100° C., and the time is 4-6 hours.

[0014] Preferably, after the hydrothermal reduction reaction and before the freeze-drying, the hybrid hydrogel obtained by the hydrothermal reduction reaction is placed in deionized water for replacement and impurity removal.

[0015] The present invention also provides an epoxy resin-based composite material, comprising a graphene-bacterial cellulose-MXene hybrid aerogel and an epoxy resin cured material infused into the graphene-bacterial cellulose-MXene hybrid aerogel;

[0016] The graphene-bacterial cellulose-MXene hybrid aerogel is the graphene-bacterial cellulose-MXene hybrid aerogel described in the above technical solution or the graphene-bacterial cellulose-MXene hybrid aerogel obtained by the preparation method described in the above technical solution.

[0017] The present invention also provides a method for preparing the epoxy resin-based composite material described in the above technical solution, comprising the following steps:

[0018] Mixing epoxy resin and curing agent for pre-curing to obtain pre-cured liquid;

[0019] The graphene-bacterial cellulose-MXene hybrid aerogel is impregnated in the pre-curing liquid, and vacuum impregnation and curing are performed in sequence to obtain the epoxy resin-based composite material.

[0020] Preferably, the mass ratio of the epoxy resin to the curing agent is 3:(0.5-2), and the curing agent includes triethylenetetramine;

[0021] The pre-curing temperature is 20-30°C and the time is 5-10 minutes;

[0022] The vacuum degree of the vacuum impregnation is 0.06-0.08 MPa, the temperature is 40-60° C., and the time is 0.4-0.8 h;

[0023] The curing comprises sequentially performing room temperature curing and heating curing;

[0024] The room temperature curing time is 4 to 8 hours;

[0025] The temperature of the heating curing is 80-120° C., and the time is 6-10 hours.

[0026] The present invention provides a graphene-bacterial cellulose-MXene hybrid aerogel having a three-dimensional porous network structure constructed from graphene, bacterial cellulose, and MXene thin nanosheets. The present invention introduces bacterial cellulose and MXene thin nanosheets into the graphene aerogel to construct the graphene-bacterial cellulose-MXene hybrid aerogel. The introduction of bacterial cellulose and MXene thin nanosheets synergistically enhances the tribological properties of epoxy resin composites while also improving the strength and structural continuity of the graphene aerogel.

[0027] The present invention also provides a method for preparing the graphene-bacterial cellulose-MXene hybrid aerogel described in the above technical solution, comprising the following steps: mixing and dispersing graphene oxide, bacterial cellulose, MXene thin nanosheets, a reducing agent, and a crosslinking agent to obtain a mixed system; and sequentially subjecting the mixed system to a hydrothermal reduction reaction and freeze-drying to obtain the graphene-bacterial cellulose-MXene hybrid aerogel. The reducing agent is added to the present invention, which, on the one hand, promotes the reduction and assembly of graphene oxide and, on the other hand, effectively inhibits the oxidation of the MXene thin nanosheets during the reaction. The crosslinking agent effectively connects the MXene thin nanosheets and graphene nanosheets, thereby crosslinking them. Furthermore, the bacterial cellulose assembles with the MXene thin nanosheets and graphene nanosheets through π-π stacking and hydrogen bonding, further supplementing the strength and structural integrity of the hybrid aerogel, ultimately forming a graphene-bacterial cellulose-MXene hybrid aerogel.

[0028] The present invention provides an epoxy resin-based composite material comprising a graphene-bacterial cellulose-MXene hybrid aerogel and an epoxy resin cured material infused within the graphene-bacterial cellulose-MXene hybrid aerogel; the graphene-bacterial cellulose-MXene hybrid aerogel is the graphene-bacterial cellulose-MXene hybrid aerogel described in the above technical solution or the graphene-bacterial cellulose-MXene hybrid aerogel obtained by the preparation method described in the above technical solution. During the friction process of the epoxy resin-based composite material of the present invention, the graphene-bacterial cellulose-MXene hybrid aerogel constructs a three-dimensional heat conduction network within the epoxy resin matrix, which can promptly and effectively transfer the frictional heat generated during the friction process, thereby preventing the epoxy resin matrix from softening, degrading, and deteriorating its wear resistance due to frictional heat accumulation. In addition, during the friction process of the epoxy resin-based composite material, the graphene, bacterial cellulose, and MXene thin nanosheets are slowly and gradually released to the friction interface, participating in the formation of a friction transfer film, constructing a high-quality friction transfer film, and further improving the tribological performance of the epoxy resin-based composite material. The epoxy resin-based composite material provided by the present invention has excellent tribological properties.

[0029] The present invention also provides a method for preparing the epoxy resin-based composite material described in the above technical solution, comprising the following steps: mixing an epoxy resin and a curing agent, precuring to obtain a precuring liquid; impregnating a graphene-bacterial cellulose-MXene hybrid aerogel in the precuring liquid, and sequentially performing vacuum impregnation and curing to obtain the epoxy resin-based composite material. The present invention utilizes vacuum impregnation to infuse the precuring liquid into the graphene-bacterial cellulose-MXene hybrid aerogel. The cured epoxy resin fills the three-dimensional porous structure of the graphene-bacterial cellulose-MXene hybrid aerogel, while the graphene-bacterial cellulose-MXene hybrid aerogel acts as a skeleton network within the epoxy resin matrix, forming a bicontinuous structure. The advantages of this bicontinuous structure are: on the one hand, it solves the dispersion problem of graphene, bacterial cellulose, and MXene thin nanosheets within the resin matrix; on the other hand, the bicontinuous structure can promptly and effectively remove the frictional heat generated during the friction process, suppressing the accumulation of frictional heat at the friction interface. In addition, graphene, bacterial cellulose, and MXene thin nanosheets are slowly and gradually released to the friction interface during the friction process of epoxy resin-based composites, participating in the generation process of friction transfer film, constructing high-quality friction transfer film, and further improving the tribological properties of epoxy resin-based composites. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Graphs showing the wear rate and friction coefficient of the epoxy resin-based composite materials obtained in Example 1 and Comparative Example 1;

[0031] Figure 2These are scanning electron microscope images of the graphene-bacterial cellulose-MXene hybrid aerogels obtained in Examples 1 to 3;

[0032] Figure 3 The cross-sectional photographs of the epoxy resin-based composite materials obtained in Example 1 and Comparative Example 1;

[0033] Figure 4 Graph showing thermal conductivity of the epoxy resin-based composite materials obtained in Example 1 and Comparative Example 1;

[0034] Figure 5 These are scanning electron microscope photos of the worn surfaces of the epoxy resin-based composite materials obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0035] The present invention provides a graphene-bacterial cellulose-MXene hybrid aerogel. The graphene-bacterial cellulose-MXene hybrid aerogel has a three-dimensional porous network structure constructed by graphene, bacterial cellulose and MXene thin layer nanosheets.

[0036] In the present invention, the graphene-bacterial cellulose-MXene hybrid aerogel preferably further includes a reducing agent and a cross-linking agent.

[0037] In the present invention, in the graphene-bacterial cellulose-MXene hybrid aerogel, the mass ratio of graphene oxide, bacterial cellulose and MXene thin layer nanosheets is preferably 1:0.25:(0.5-2), and more preferably 1:0.25:(1.0-1.5).

[0038] In the present invention, the mass ratio of the reducing agent to the cross-linking agent is preferably (1-2): (1-2), more preferably 1: 1. In the present invention, the mass ratio of the reducing agent to the graphene oxide is preferably (1.5-2): 1.

[0039] The present invention also provides a method for preparing the graphene-bacterial cellulose-MXene hybrid aerogel described in the above technical solution, comprising the following steps:

[0040] mixing and dispersing graphene oxide, bacterial cellulose, MXene thin layer nanosheets, a reducing agent, and a cross-linking agent to obtain a mixed system;

[0041] The mixed system is sequentially subjected to a hydrothermal reduction reaction and freeze-dried to obtain the graphene-bacterial cellulose-MXene hybrid aerogel.

[0042] In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0043] The present invention mixes and disperses graphene oxide, bacterial cellulose, MXene thin-layer nanosheets, a reducing agent and a cross-linking agent to obtain a mixed system.

[0044] In the present invention, the number of layers of the MXene thin nanosheets is preferably ≤5.

[0045] In the present invention, the reducing agent preferably includes isoascorbic acid. In the present invention, the reducing agent can reduce graphene oxide on the one hand, and inhibit the oxidation of MXene thin nanosheets on the other hand.

[0046] In the present invention, the crosslinking agent preferably includes cysteine. In the present invention, the amino and thiol groups in the crosslinking agent cysteine can effectively connect the MXene thin layer nanosheets and graphene nanosheets, playing a crosslinking role.

[0047] In the present invention, the mass ratio of graphene oxide, bacterial cellulose, and MXene thin nanosheets is preferably 1:0.25:(0.5-2), more preferably 1:0.25:(1.0-1.5). In the present invention, the concentration of graphene oxide in the mixed system is preferably 1-4 mg / mL, more preferably 1.5-3.5 mg / mL, and even more preferably 2-3 mg / mL.

[0048] In the present invention, the mass ratio of the reducing agent to the cross-linking agent is preferably (1-2): (1-2), more preferably 1: 1. In the present invention, the mass ratio of the reducing agent to the graphene oxide is preferably (1.5-2): 1.

[0049] In the present invention, the mixing and dispersing of the graphene oxide, bacterial cellulose, MXene thin nanosheets, a reducing agent and a cross-linking agent preferably includes: ultrasonically dispersing the graphene oxide, bacterial cellulose and MXene thin nanosheets in water to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion; and stirring and mixing the graphene oxide / bacterial cellulose / MXene mixed dispersion, the reducing agent and the cross-linking agent. In the present invention, the ultrasonic dispersion is preferably carried out under nitrogen protection. In the present invention, ultrasonic dispersion under nitrogen protection can prevent the MXene thin nanosheets from being oxidized. In the present invention, the stirring and mixing time is preferably 0.5 to 1 hour. In the present invention, the stirring and mixing temperature is preferably room temperature, that is, neither additional heating nor additional cooling is required.

[0050] After obtaining the mixed system, the present invention sequentially performs a hydrothermal reduction reaction and freeze-drying on the mixed system to obtain the graphene-bacterial cellulose-MXene hybrid aerogel.

[0051] In the present invention, the temperature of the hydrothermal reduction reaction is preferably 80-100°C, more preferably 85-95°C, and more preferably 90°C; the time is preferably 4-6h, and more preferably 5h. In the present invention, the hydrothermal reduction reaction is preferably carried out in a closed container. In the present invention, during the hydrothermal reduction reaction, cysteine and isoascorbic acid both play a certain reducing role, promoting the reduction and self-assembly of graphene oxide nanosheets. Under the synergistic effect of external heating, the graphene nanosheets assemble into a three-dimensional porous structure, while MXene thin layer nanosheets and bacterial cellulose are interspersed between the graphene nanosheets, constructing more conductive channels and reinforcing the structure of the aerogel.

[0052] After the hydrothermal reduction reaction and before the freeze-drying, the present invention preferably further comprises placing the hybrid hydrogel obtained by the hydrothermal reduction reaction in deionized water for displacement removal. In the present invention, the number of displacement removals is preferably 3 to 4 times, and the time for each displacement removal is preferably 2 hours. In the present invention, the displacement removal can remove impurities in the hydrogel (impurities refer to excess reaction raw materials that do not participate in the construction of the hybrid hydrogel structure, mainly including cysteine and isoascorbic acid).

[0053] In the present invention, the freeze-drying preferably includes sequential freezing and freeze-drying. In the present invention, the freezing is preferably performed in a refrigerator or liquid nitrogen; the freezing time in the refrigerator is preferably 5 to 24 hours; the freezing time in liquid nitrogen is preferably 5 to 10 minutes. In the present invention, the freeze-drying time is preferably ≥ 12 hours, more preferably 12 hours. In the present invention, the freeze-drying is preferably performed in a freeze dryer.

[0054] The present invention also provides an epoxy resin-based composite material, comprising a graphene-bacterial cellulose-MXene hybrid aerogel and an epoxy resin cured material infused into the graphene-bacterial cellulose-MXene hybrid aerogel;

[0055] The graphene-bacterial cellulose-MXene hybrid aerogel is the graphene-bacterial cellulose-MXene hybrid aerogel described in the above technical solution or the graphene-bacterial cellulose-MXene hybrid aerogel obtained by the preparation method described in the above technical solution.

[0056] In the present invention, the mass percentage of the graphene-bacterial cellulose-MXene hybrid aerogel in the epoxy resin-based composite material is preferably 1 to 2%.

[0057] The present invention also provides a method for preparing the epoxy resin-based composite material described in the above technical solution, comprising the following steps:

[0058] Mixing epoxy resin and curing agent for pre-curing to obtain pre-cured liquid;

[0059] The graphene-bacterial cellulose-MXene hybrid aerogel is impregnated in the pre-curing liquid, and vacuum impregnation and curing are performed in sequence to obtain the epoxy resin-based composite material.

[0060] The present invention mixes epoxy resin and curing agent, performs pre-curing, and obtains pre-cured liquid.

[0061] In the present invention, the epoxy resin preferably includes epoxy resin E-51.

[0062] In the present invention, the curing agent preferably includes triethylenetetramine.

[0063] In the present invention, the mass ratio of the epoxy resin to the curing agent is preferably 3:(0.5-2), more preferably 3:(1-1.5).

[0064] In the present invention, the pre-curing temperature is preferably 20-30°C, more preferably 25°C, and the time is preferably 5-10 minutes, more preferably 6-9 minutes, and even more preferably 7-8 minutes. In the present invention, the pre-curing can achieve an appropriate degree of crosslinking and viscosity of the epoxy resin, allowing the graphene-bacterial cellulose-MXene hybrid aerogel to be fully impregnated with the epoxy resin.

[0065] After obtaining the pre-curing liquid, the present invention immerses the graphene-bacterial cellulose-MXene hybrid aerogel in the pre-curing liquid, and sequentially performs vacuum impregnation and curing to obtain the epoxy resin-based composite material.

[0066] In the present invention, the temperature of the vacuum impregnation is preferably 40 to 60°C, more preferably 50°C; the vacuum degree is preferably 0.06 to 0.08 MPa, more preferably 0.07 MPa; the time is preferably 0.4 to 0.8 h, more preferably 0.5 to 0.7 h, and more preferably 0.6 h. In the present invention, the vacuum impregnation preferably includes: immersing the graphene-bacterial cellulose-MXene hybrid aerogel in the pre-curing liquid, and then placing the resulting system in a vacuum environment. Through the vacuum impregnation, the pores inside the graphene-bacterial cellulose-MXene hybrid aerogel are completely infused with epoxy resin.

[0067] After the vacuum impregnation, the present invention preferably further comprises taking out the obtained graphene-bacterial cellulose-MXene hybrid aerogel impregnated with the pre-curing liquid for subsequent curing.

[0068] In the present invention, the curing preferably includes sequentially performing room temperature curing and heating curing.

[0069] In the present invention, the room temperature curing temperature is preferably room temperature, i.e., no additional cooling or heating is required; the curing time is preferably 4 to 8 hours, more preferably 5 to 7 hours. In the present invention, the room temperature curing can prevent the formation of pores in the epoxy resin-based composite material due to rapid curing.

[0070] In the present invention, the temperature of the heating and curing is preferably 80-120°C, more preferably 90-110°C, and more preferably 100°C; the time is preferably 6-10 hours, and more preferably 7-9 hours. In the present invention, the heating and curing allows the epoxy resin material to be completely cured internally to reach a certain strength.

[0071] In the present invention, the curing is set to perform room temperature curing and heating curing in sequence, that is, segmented curing, which is conducive to sufficient cross-linking reaction between the graphene-bacterial cellulose-MXene hybrid aerogel and the epoxy resin and inside the resin, while preventing the generation of pores inside the epoxy resin material; during the curing process, the functional groups on the surface of the graphene-bacterial cellulose-MXene hybrid aerogel can participate in the curing reaction of the epoxy resin during the curing process of the epoxy resin, which can promote the curing reaction of the epoxy resin on the one hand, and improve the interface bonding performance between the hybrid aerogel and the resin matrix on the other hand.

[0072] The graphene-bacterial cellulose-MXene hybrid aerogel and its preparation, the epoxy resin-based composite material and its preparation provided by the present invention are described in detail below with reference to the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0073] Example 1

[0074] The preparation process of graphene-bacterial cellulose-MXene hybrid aerogel is as follows:

[0075] 60 mg of graphene oxide, 15 mg of bacterial cellulose, and 60 mg of MXene thin nanosheets (≤ 5 layers) were mixed and dispersed in 20 mL of deionized water and ultrasonically dispersed under nitrogen protection to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion. 120 mg of isoascorbic acid and 120 mg of cysteine were added to the resulting graphene oxide / bacterial cellulose / MXene mixed dispersion and stirred for 0.5 h to obtain a mixed system. The mixed system was placed in a sealed glass bottle and placed in a 100°C oven for hydrothermal reaction for 5 h. The resulting hybrid hydrogel was then washed in deionized water three times for 2 h each time to remove impurities in the hybrid hydrogel, obtaining a graphene-bacterial cellulose-MXene hybrid hydrogel. The glass bottle containing the graphene-bacterial cellulose-MXene hybrid hydrogel was then placed in liquid nitrogen and frozen for 5 min. It was then placed in a freeze dryer and freeze-dried for 12 h to obtain a graphene-bacterial cellulose-MXene hybrid aerogel.

[0076] The preparation process of epoxy resin-based composite materials is as follows:

[0077] Epoxy resin (E-51) and triethylenetetramine were mixed in a mass ratio of 3:1 and pre-cured at 25°C for 10 minutes to obtain a pre-cured liquid. The prepared graphene-bacterial cellulose-MXene hybrid aerogel was then immersed in the pre-cured liquid and maintained at 50°C for 0.5 hours under vacuum conditions (vacuum degree of 0.06-0.08 MPa) to allow the pre-cured liquid to completely permeate the internal pores of the hybrid aerogel. The hybrid aerogel impregnated with the pre-cured liquid was kept at room temperature for 4 hours and then transferred to a 100°C oven for curing reaction for 6 hours to obtain a graphene-bacterial cellulose-MXene hybrid aerogel-reinforced epoxy resin-based composite material, wherein the mass percentage of the graphene-bacterial cellulose-MXene hybrid aerogel was 1.3%.

[0078] Example 2

[0079] The preparation process of graphene-bacterial cellulose-MXene hybrid aerogel is as follows:

[0080] 60 mg of graphene oxide, 15 mg of bacterial cellulose, and 30 mg of MXene thin nanosheets (number of layers ≤ 5) were mixed and dispersed in 20 mL of deionized water and ultrasonically dispersed uniformly under nitrogen atmosphere to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion. 120 mg of isoascorbic acid and 120 mg of cysteine were added to the above graphene oxide / bacterial cellulose / MXene mixed dispersion and stirred for 0.5 h to obtain a mixed system. The above mixed system was placed in a sealed glass bottle and placed in a 100°C oven for hydrothermal reaction for 5 h. The resulting hybrid hydrogel was then washed in deionized water three times for 2 h each time to remove impurities in the hybrid hydrogel, obtaining a graphene-bacterial cellulose-MXene hybrid hydrogel. The glass bottle containing the graphene-bacterial cellulose-MXene hybrid hydrogel was then placed in liquid nitrogen, frozen for 5 min, and then placed in a freeze dryer for freeze drying for 12 h to obtain a graphene-bacterial cellulose-MXene hybrid aerogel.

[0081] The preparation process of epoxy resin-based composite materials is as follows:

[0082] Epoxy resin (E-51) and triethylenetetramine were mixed in a mass ratio of 3:1 and pre-cured at 25°C for 10 minutes to obtain a pre-cured reaction solution. The graphene-bacterial cellulose-MXene hybrid aerogel prepared above was then immersed in the pre-cured reaction solution and maintained at 50°C under vacuum conditions (vacuum degree of 0.06-0.08 MPa) for 0.5 hours to allow the pre-cured liquid to completely permeate the internal pores of the hybrid aerogel. The resulting hybrid aerogel impregnated with the pre-cured liquid was kept at room temperature for 4 hours and then transferred to a 100°C oven for curing reaction for 6 hours to obtain a graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite material, wherein the mass percentage of the graphene-bacterial cellulose-MXene hybrid aerogel was 1.2%.

[0083] Example 3

[0084] The preparation process of graphene-bacterial cellulose-MXene hybrid aerogel is as follows:

[0085] 60 mg of graphene oxide, 15 mg of bacterial cellulose, and 120 mg of MXene thin nanosheets (number of layers ≤ 5) were mixed and dispersed in 20 mL of deionized water and ultrasonically dispersed under nitrogen protection to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion. 120 mg of isoascorbic acid and 120 mg of cysteine were added to the obtained graphene oxide / bacterial cellulose / MXene mixed dispersion and stirred for 0.5 h to obtain a mixed system. The above mixed system was placed in a sealed glass bottle and placed in a 100°C oven for hydrothermal reaction for 5 h. The resulting hybrid hydrogel was then washed in deionized water three times for 2 h each time to remove impurities in the hybrid hydrogel, obtaining a graphene-bacterial cellulose-MXene hybrid hydrogel. The glass bottle containing the graphene-bacterial cellulose-MXene hybrid hydrogel was then placed in liquid nitrogen and frozen for 5 min. It was then placed in a freeze dryer and freeze-dried for 12 h to obtain a graphene-bacterial cellulose-MXene hybrid aerogel.

[0086] The preparation process of epoxy resin-based composite materials is as follows:

[0087] Epoxy resin (E-51) and triethylenetetramine were mixed in a mass ratio of 3:1 and pre-cured at 25°C for 10 minutes to obtain a pre-cured liquid. Then, the graphene-bacterial cellulose-MXene hybrid aerogel prepared above was immersed in the pre-cured liquid and maintained under vacuum conditions (vacuum degree of 0.06-0.08MPa) for 0.5 hours to allow the resin to completely infuse the internal pores of the aerogel. The resulting epoxy composite material was kept at room temperature for 4 hours and then transferred to a 100°C oven for curing reaction for 6 hours to obtain a graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite material, wherein the mass percentage of graphene-bacterial cellulose-MXene hybrid aerogel was 1.5%.

[0088] Example 4

[0089] The preparation process of graphene-bacterial cellulose-MXene hybrid aerogel is as follows:

[0090] 60 mg of graphene oxide, 15 mg of bacterial cellulose, and 60 mg of MXene thin nanosheets (≤ 5 layers) were mixed and dispersed in 20 mL of deionized water and ultrasonically dispersed under nitrogen protection to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion. 90 mg of isoascorbic acid and 90 mg of cysteine were added to the above graphene oxide / bacterial cellulose / MXene mixed dispersion and stirred for 0.5 h to obtain a pre-reaction solution. The above pre-reaction solution was placed in a sealed glass bottle and placed in a 100°C oven for hydrothermal reaction for 5 h. The resulting hybrid hydrogel was then washed in deionized water three times for 2 h each time to remove impurities in the hybrid hydrogel, obtaining a graphene-bacterial cellulose-MXene hybrid hydrogel. The glass bottle containing the graphene-bacterial cellulose-MXene hybrid hydrogel was then placed in liquid nitrogen and frozen for 5 min. It was then placed in a freeze dryer and freeze-dried for 12 h to obtain a graphene-bacterial cellulose-MXene hybrid aerogel.

[0091] The preparation process of epoxy resin-based composite materials is as follows:

[0092] Epoxy resin (E-51) and triethylenetetramine were mixed in a mass ratio of 3:1 and pre-cured at 25°C for 10 minutes to obtain a pre-cured liquid. The graphene-bacterial cellulose-MXene hybrid aerogel prepared above was then immersed in the pre-cured liquid and maintained at 50°C under vacuum conditions (vacuum degree of 0.06-0.08MPa) for 0.5 hours to allow the pre-cured liquid to completely infuse the internal pores of the hybrid aerogel. The resulting epoxy composite material was kept at room temperature for 6 hours and then transferred to a 100°C oven for curing reaction for 8 hours to obtain a graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite material, wherein the mass percentage of graphene-bacterial cellulose-MXene hybrid aerogel was 1.1%.

[0093] Comparative Example 1

[0094] The difference from Example 1 is that the preparation process of the graphene-bacterial cellulose-MXene hybrid aerogel and the mixing process of the graphene-bacterial cellulose-MXene hybrid aerogel and the epoxy resin solution are omitted, and an epoxy resin material not filled with graphene-bacterial cellulose-MXene hybrid aerogel is prepared.

[0095] Comparative Example 2

[0096] The difference from Example 1 is that graphene-bacterial cellulose-MXene hybrid aerogel is not added, and graphene aerogel is added alone; wherein, the preparation method of graphene aerogel is:

[0097] 60 mg of graphene oxide was dispersed in 20 mL of deionized water and ultrasonically dispersed to obtain a graphene oxide dispersion. 90 mg of isoascorbic acid and 90 mg of cysteine were added to the graphene oxide dispersion and stirred for 0.5 h to obtain a mixed system. The mixed system was placed in a sealed glass bottle and placed in a 100°C oven for a hydrothermal reaction for 5 h. The resulting hydrogel was then washed in deionized water three times for 2 h each time to remove impurities, resulting in a graphene hydrogel. The glass bottle containing the graphene hydrogel was then placed in liquid nitrogen and frozen for 5 min. It was then freeze-dried in a freeze dryer for 12 h to obtain a graphene aerogel.

[0098] Comparative Example 3

[0099] The difference from Example 1 is that bacterial cellulose is omitted and graphene-MXene hybrid aerogel is added. The preparation method of graphene-MXene hybrid aerogel is the same as that of Example 1 for preparing graphene-bacterial cellulose-MXene hybrid aerogel, except that bacterial cellulose is not added.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that the MXene thin layer nanosheets (number of layers ≤ 5 layers) are omitted, and graphene-bacterial cellulose hybrid aerogel is added. The preparation method of the graphene-bacterial cellulose hybrid aerogel is the same as that of Example 1 for preparing the graphene-bacterial cellulose-MXene hybrid aerogel, except that the MXene thin layer nanosheets (number of layers ≤ 5 layers) are not added.

[0102] Performance testing and characterization

[0103] The friction and wear properties of the graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite materials prepared in Examples 1 to 4 and the epoxy resin composite materials obtained in Comparative Examples 1 to 4 were tested respectively. The test method is as follows:

[0104] The test conditions were: a pressure of 10 N, a sliding friction linear velocity of 0.063 m / s (200 r / min), a duration of 60 minutes, and room temperature. A ball-on-disc tribometer was used, with GCr15 steel (6 mm in diameter) serving as the friction partner. The friction coefficient was automatically output after data collection was processed by a connected computer. The wear volume ΔV of the epoxy composite was measured using a three-dimensional profilometer, and the specific wear rate of the epoxy composite was calculated using the formula K = ΔV / P·L, where K is the specific wear rate, ΔV is the wear volume, P is the applied load, and L is the sliding distance. The test results are shown in Table 1.

[0105] Table 1 Friction data of epoxy resin based composite materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4

[0106]

[0107] As shown in Table 1, the specific wear rate and friction coefficient of the graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite material prepared in Example 1 are 1.56×10 -5 mm 3 (N·m) -1 and 0.22, which are respectively reduced by 96% and 37% compared with Comparative Example 1, achieving a significant improvement in the wear resistance and lubrication properties of the epoxy resin material.

[0108] Figure 1 The graphs are the wear rate and friction coefficient of the epoxy resin-based composite materials obtained in Comparative Example 1 and Example 1. Figure 1 In the figure, (a) is the wear rate diagram, and (b) is the friction coefficient diagram; Figure 1 It can be seen that after the epoxy resin is reinforced with graphene-bacterial cellulose-MXene hybrid aerogel, the friction coefficient and wear amount are greatly reduced.

[0109] The internal porous structure of the graphene-bacterial cellulose-MXene hybrid aerogels obtained in Examples 1 to 3 was characterized by scanning electron microscopy. Figure 2 , Figure 2 In the figure, (a) to (c) correspond to the scanning electron micrographs of the graphene-bacterial cellulose-MXene hybrid aerogels obtained in Examples 1 to 3, respectively, and (d) to (f) are the local magnified scanning electron micrographs of (a) to (c). Figure 2 It can be seen that within the graphene-bacterial cellulose-MXene hybrid aerogel, graphene, bacterial cellulose, and MXene thin nanosheets simultaneously participate in constructing the aerogel skeleton structure, reducing the internal defects of the aerogel and constructing a typical continuous three-dimensional cross-linked network structure. However, as the MXene concentration increases further, the cross-linking density of the aerogel network increases further, which is not conducive to the effective infusion of the subsequent resin ( Figure 2 (c)).

[0110] Figure 3 The cross-sectional views of the epoxy resin-based composite materials obtained in Example 1 and Comparative Example 1 are shown, wherein (a) to (c) are cross-sectional views of the epoxy resin-based composite materials obtained in Comparative Example 1, and (d) to (f) are cross-sectional views of the epoxy resin-based composite materials obtained in Example 1. Figure 3 It can be seen that compared with the typical brittle fracture characteristics of pure epoxy resin, the graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite material exhibits obvious toughness fracture characteristics, which effectively improves the impact toughness and fracture strength of the epoxy resin-based composite material.

[0111] Figure 4The thermal conductivity diagram of the epoxy resin-based composite material obtained in Example 1 and Comparative Example 1 is shown in FIG. Figure 4 It can be seen that compared with pure epoxy resin, the thermal conductivity of graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin-based composite material is increased by 153%, further confirming that graphene-bacterial cellulose-MXene hybrid aerogel constructs an effective heat conduction channel inside the resin matrix.

[0112] Figure 5 The scanning electron microscope photos of the worn surfaces of the epoxy resin-based composite materials obtained in Example 1 and Comparative Example 1 are shown. Figure 5 In the figure, (a) and (b) are scanning electron microscope photos of the wear surface of the epoxy resin-based composite material obtained in Comparative Example 1, and (c) and (d) are scanning electron microscope photos of the wear surface of the epoxy resin-based composite material obtained in Example 1. Figure 5 It can be seen that compared with pure epoxy resin, the wear scar width and depth of the graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin composite material are greatly reduced, further confirming that the wear resistance of the graphene-bacterial cellulose-MXene hybrid aerogel reinforced epoxy resin composite material is greatly enhanced.

[0113] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A graphene-bacterial cellulose-MXene hybrid aerogel, characterized in that: The graphene-bacterial cellulose-MXene hybrid aerogel has a three-dimensional porous network structure constructed by graphene, bacterial cellulose and MXene thin layer nanosheets; The preparation method of the graphene-bacterial cellulose-MXene hybrid aerogel comprises the following steps: mixing and dispersing graphene oxide, bacterial cellulose, MXene thin layer nanosheets, a reducing agent, and a cross-linking agent to obtain a mixed system; The mixed system is subjected to a hydrothermal reduction reaction and freeze-dried in sequence to obtain the graphene-bacterial cellulose-MXene hybrid aerogel; The mass ratio of the graphene oxide, bacterial cellulose and MXene thin layer nanosheets is 1:0.25:(0.5-2); The reducing agent comprises isoascorbic acid, and the cross-linking agent comprises cysteine; The mass ratio of the reducing agent to the cross-linking agent is (1-2): (1-2); the mass ratio of the reducing agent to graphene oxide is (1.5-2): 1; The temperature of the hydrothermal reduction reaction is 80-100°C and the time is 4-6 hours; The mixing and dispersing of the graphene oxide, bacterial cellulose, MXene thin-layer nanosheets, a reducing agent and a cross-linking agent includes: ultrasonically dispersing the graphene oxide, bacterial cellulose and MXene thin-layer nanosheets in water to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion; and stirring and mixing the graphene oxide / bacterial cellulose / MXene mixed dispersion, the reducing agent and the cross-linking agent.

2. The method for preparing the graphene-bacterial cellulose-MXene hybrid aerogel according to claim 1, characterized in that: The following steps are involved: mixing and dispersing graphene oxide, bacterial cellulose, MXene thin layer nanosheets, a reducing agent, and a cross-linking agent to obtain a mixed system; The mixed system is subjected to a hydrothermal reduction reaction and freeze-dried in sequence to obtain the graphene-bacterial cellulose-MXene hybrid aerogel; The mass ratio of the graphene oxide, bacterial cellulose and MXene thin layer nanosheets is 1:0.25:(0.5-2); The reducing agent comprises isoascorbic acid, and the cross-linking agent comprises cysteine; The mass ratio of the reducing agent to the cross-linking agent is (1-2): (1-2); the mass ratio of the reducing agent to graphene oxide is (1.5-2): 1; The temperature of the hydrothermal reduction reaction is 80-100°C and the time is 4-6 hours; The mixing and dispersing of the graphene oxide, bacterial cellulose, MXene thin-layer nanosheets, a reducing agent and a cross-linking agent includes: ultrasonically dispersing the graphene oxide, bacterial cellulose and MXene thin-layer nanosheets in water to obtain a graphene oxide / bacterial cellulose / MXene mixed dispersion; and stirring and mixing the graphene oxide / bacterial cellulose / MXene mixed dispersion, the reducing agent and the cross-linking agent.

3. The preparation method according to claim 2, characterized in that The concentration of graphene oxide in the mixed system is 1-4 mg / mL.

4. The preparation method according to claim 2, characterized in that After the hydrothermal reduction reaction and before the freeze-drying, the method further comprises placing the hybrid hydrogel obtained by the hydrothermal reduction reaction in deionized water for replacement and impurity removal.

5. An epoxy resin-based composite material, characterized in that: It includes a graphene-bacterial cellulose-MXene hybrid aerogel and an epoxy resin cured material infused into the graphene-bacterial cellulose-MXene hybrid aerogel; The graphene-bacterial cellulose-MXene hybrid aerogel is the graphene-bacterial cellulose-MXene hybrid aerogel according to claim 1 or the graphene-bacterial cellulose-MXene hybrid aerogel obtained by the preparation method according to any one of claims 2 to 4.

6. The method for preparing the epoxy resin-based composite material according to claim 5, characterized in that: The following steps are involved: Mixing epoxy resin and curing agent for pre-curing to obtain pre-cured liquid; The graphene-bacterial cellulose-MXene hybrid aerogel is impregnated in the pre-curing liquid, and vacuum impregnation and curing are performed in sequence to obtain the epoxy resin-based composite material.

7. The preparation method according to claim 6, characterized in that The mass ratio of the epoxy resin to the curing agent is 3:(0.5-2); the curing agent includes triethylenetetramine; The pre-curing temperature is 20-30°C and the time is 5-10 minutes; The vacuum degree of the vacuum impregnation is 0.06-0.08 MPa, the temperature is 40-60° C., and the time is 0.4-0.8 h; The curing comprises sequentially performing room temperature curing and heating curing; The room temperature curing time is 4 to 8 hours; The temperature of the heating curing is 80-120° C., and the time is 6-10 hours.

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