Modified graphene oxide based on wet chemical modification and preparation method thereof

Abstract

The application belongs to the technical field of functional materials, and particularly relates to modified graphene oxide based on wet chemical modification and a preparation method thereof. The preparation method of the modified graphene oxide based on wet chemical modification comprises the following steps: S1: performing a thiol-ene click reaction on graphene oxide to obtain mesoporous-containing graphene oxide; and S2: performing alkyne group modification on the mesoporous-containing graphene oxide to obtain alkyne group-modified graphene oxide, and then performing an azide-alkyne click reaction on the alkyne group-modified graphene oxide and azide-POSS to obtain modified graphene oxide based on wet chemical modification. The modified graphene oxide with a specific spatial structure is prepared, the specific surface area of the material can be effectively increased, and the stability under a high-temperature environment can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional materials, and particularly relates to a modified graphene oxide based on wet chemical modification and a preparation method thereof. BACKGROUND

[0002] Graphene is a two-dimensional nanomaterial with a honeycomb-like six-membered ring planar network structure. The special structural characteristics endow graphene with excellent mechanical strength, chemical stability, high specific surface area, electrical conductivity and thermal conductivity. Therefore, graphene has broad application prospects in the fields of energy, materials, health and environment. Graphene oxide is a nano material with a unique quasi-two-dimensional layered structure composed of hexagonal carbon nets and sp 2 , sp 3 hybrid carbon by introducing covalent C-O bonds in graphene. It contains a large number of oxygen-containing groups such as carboxyl and hydroxyl groups. These functional groups make graphene oxide have good reactivity and hydrophilicity, and provide a large number of active sites for connecting other molecular structures and functional groups, and are easy to functionalize and have high controllability. Proper surface functionalization of graphene oxide can prevent them from aggregating during reduction. This method of functional modification of graphene oxide not only maintains the excellent properties of graphene, but also introduces new surface functional groups and endows new surface properties.

[0003] Chinese patent (publication number CN108707236B) discloses a preparation method for synthesizing graphene oxide grafted fluorine-containing polymer by click chemistry, which comprises the following steps: (1) preparing graphene oxide by improved Hummer's method; (2) alkynylating graphene oxide; (3) azidizing fluorine-containing polymer; (4) synthesizing graphene oxide grafted fluorine-containing polymer by click chemistry. The application can significantly improve the grafting rate, the preparation process is simple, and is suitable for industrial production. The material prepared by the application has the characteristics of high tensile strength, good thermal stability and high mechanical strength. However, the modified graphene oxide prepared by the existing technology has problems such as insufficient specific surface area and thermal stability, and cannot be controlled in space structure, which affects its further application.

[0004] Therefore, how to design the active groups in graphene oxide, treat different groups of graphene oxide through different click chemistry reactions, and prepare modified graphene oxide with specific spatial structure to effectively improve the specific surface area and obtain good thermal stability has become a direction to be studied. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a modified graphene oxide based on wet chemical modification and a preparation method thereof; the present application selects graphene oxide rich in carboxyl groups as raw material, utilizes double bond and thiol-ene click reaction to perform thiol-ene click reaction, performs alkyne group on the graphene oxide by carboxyl group, and then performs azide-alkyne click reaction with azidized POSS to prepare modified graphene oxide with specific spatial structure, which can effectively increase the specific surface area of the material and improve the stability under high temperature environment.

[0006] The technical scheme of the present application is as follows:

[0007] In the first aspect of the present application, a preparation method of modified graphene oxide based on wet chemical modification is provided, comprising the following steps:

[0008] S1: performing thiol-ene click reaction on graphene oxide to obtain mesoporous graphene oxide;

[0009] S2: performing alkyne group on the mesoporous graphene oxide to obtain alkyne graphene oxide, and then performing azide-alkyne click reaction with azidized POSS to obtain modified graphene oxide based on wet chemical modification.

[0010] As a preferred technical scheme of the present application, the step of thiol-ene click reaction comprises: dispersing 1-3 parts of graphene oxide in 400-500 parts of N,N-dimethylformamide to form a dispersion liquid, adding 0.04-0.08 parts of azobisisobutyronitrile and 2-6 parts of mercapto mesoporous silica under the protection of nitrogen atmosphere, and performing heating reaction to obtain mesoporous graphene oxide.

[0011] As a preferred scheme, the weight fraction of graphene oxide in the present application can be 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, etc.

[0012] As a preferred scheme, the weight fraction of azobisisobutyronitrile in the present application can be 0.04 parts, 0.05 parts, 0.06 parts, 0.07 parts or 0.08 parts, etc.

[0013] As a preferred scheme, the weight fraction of mercapto mesoporous silica in the present application can be 2 parts, 3 parts, 4 parts, 5 parts or 6 parts, etc.

[0014] As a preferred technical scheme of the present application, the conditions of the heating reaction comprise: reacting at 70-80 DEG C for 10-12 h, cooling to room temperature, filtering, washing with water, and freeze-drying.

[0015] As a preferred technical scheme of the present application, the preparation method of the mercapto mesoporous silica comprises: mixing 200-250 parts of anhydrous ethanol and 200-250 parts of deionized water by weight, sequentially adding 6-10 parts of tetraethyl orthosilicate, 3-5 parts of 3-mercaptopropyl trimethoxysilane, 0.6-0.8 parts of ammonia water and 0.2-0.6 parts of cetyl trimethyl ammonium bromide, stirring for 8-10 hours, centrifuging, washing with water, drying, and obtaining the mercapto mesoporous silica.

[0016] As a preferred scheme, the weight fraction of the tetraethyl orthosilicate in the present application can be 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc.

[0017] As a preferred scheme, the weight fraction of the 3-mercaptopropyl trimethoxysilane in the present application can be 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts, etc.

[0018] As a preferred scheme, the weight fraction of the ammonia water in the present application can be 0.6 parts, 0.65 parts, 0.7 parts, 0.75 parts or 0.8 parts, etc.

[0019] As a preferred scheme, the weight fraction of the cetyl trimethyl ammonium bromide in the present application can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts or 0.6 parts, etc.

[0020] As a preferred technical scheme of the present application, the graphene oxide is carboxylated graphene oxide, the flake diameter is 0.5-5 μm, and the thickness is 0.8-1.2 nm.

[0021] Firstly, the present application uses tetraethyl orthosilicate and 3-mercaptopropyl trimethoxysilane as double silicon sources, uses cetyl trimethyl ammonium bromide as a template agent, and uses ammonia water as a catalyst, to prepare mercapto mesoporous silica with high specific surface area through co-hydrolysis / condensation of mercapto silane and tetraethyl orthosilicate; meanwhile, due to the existence of a large number of double bonds in graphene oxide, these double bonds can be used as functional reaction active sites, and can directly react with mercapto groups to realize functional modification of graphene oxide through thiol-ene click reaction, so that mercapto mesoporous silica is combined on graphene oxide through click reaction under the initiation of azobisisobutyronitrile, and graphene oxide containing mesopores is obtained.

[0022] As a preferred technical scheme of the present application, the preparation method of the azido POSS comprises: adding 8-10 parts of chloropropyl POSS and 2.4-2.8 parts of sodium azide into a mixed solution of 180-200 parts of tetrahydrofuran and 500-520 parts of N,N-dimethylformamide for azidation treatment, to obtain azido POSS.

[0023] As a preferred scheme, the weight fraction of the chloropropyl POSS in the application can be 8 parts, 8.5 parts, 9 parts, 9.5 parts or 10 parts, etc.

[0024] As a preferred scheme, the weight fraction of the sodium azide in the application can be 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts or 2.8 parts, etc.

[0025] As a preferred scheme, the azide treatment conditions include: placed in a nitrogen atmosphere, reacted at 60-70℃ for 20-24h, cooled to room temperature, then added 480-500 parts of dichloromethane and stirred for 10-12min, then added 900-1000 parts of deionized water and stirred for 30-40min, settled and separated, separated the dichloromethane layer, washed with water, dried, rotary evaporated, and separated by column chromatography.

[0026] As a preferred scheme, the step of alkynylating includes: adding 1-3 parts of the mesoporous graphene oxide to 400-500 parts of N,N-dimethylformamide by weight and ultrasonic dispersion, then adding 1.2-1.8 parts of propargyl alcohol and stirring uniformly, then adding 8-10 parts of N,N'-dicyclohexyl carbodiimide and 3-5 parts of 4-dimethylamino pyridine, and reacting at 24-26℃ for 20-24h, centrifuging, washing with N,N-dimethylformamide, and vacuum drying to obtain alkynylated graphene oxide.

[0027] As a preferred scheme, the azide-alkyne click reaction conditions include: adding 1-3 parts of alkynylated graphene oxide and 6-10 parts of azide POSS to 80-100 parts of N,N-dimethylformamide by weight, adding 1.6-1.8 parts of cuprous bromide and 2.4-2.8 parts of pentamethyl diethylene triamine in turn under a nitrogen atmosphere and stirring and mixing, and reacting at 24-28℃ for 40-48h, centrifuging, vacuum drying, and obtaining modified graphene oxide based on wet chemical modification.

[0028] The application uses chloropropyl POSS as raw material, converts it into azide POSS by reaction with sodium azide; the edges of the mesoporous graphene oxide contain carboxyl groups, and the esterification of propargyl alcohol with graphene oxide is used to realize the alkylation of graphene oxide; finally, azide POSS and alkynylated graphene oxide are connected by azide-alkyne click reaction to graft POSS to the edges of graphene oxide material, and modified graphene oxide based on wet chemical modification is obtained.

[0029] In the second aspect of the application, a modified graphene oxide based on wet chemical modification is provided, which is prepared by the method of the first aspect.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] (1) The present application uses carboxylated graphene oxide as raw material, first combines mesoporous silica and double bond through thiol-ene click reaction, then performs graphene alkyne grafting with the aid of carboxyl and azido-alkyne click reaction with azido POSS, since the carboxyl groups of carboxylated graphene oxide are mainly concentrated on the edges of the material and the double bonds are distributed on the surface of the material, mesoporous silica and POSS can be respectively grafted on different positions of graphene oxide through different click chemistry reactions, thereby obtaining modified graphene oxide with specific spatial structure, and the introduced mesoporous silica and POSS synergistically improve the specific surface area of the material and increase the thermal stability.

[0032] (2) The present application introduces thiol mesoporous silica into graphene oxide through thiol-ene click reaction, on the one hand, the thiol mesoporous silica has a regular pore structure, which can significantly increase the total pore volume of the composite material, and on the other hand, the mesoporous structure of the silica and the interlayer pores of the graphene oxide form hierarchical pores, which comprehensively improve the specific surface area of the material; in addition, the skeleton structure of the mesoporous silica blocks heat transfer, reduces the surface area of the oxygen-containing groups of graphene oxide exposed to a high-temperature environment, and delays the thermal degradation process, thereby improving the thermal stability of the material.

[0033] (3) The present application grafts POSS to the edges of graphene oxide material through azido-alkyne click reaction, the rigid cage structure of POSS introduces micropores / mesopores on the surface of graphene oxide, thereby improving the total pore volume and effectively increasing the specific surface area; in addition, the bond energy of the Si-O bond introduced by POSS is much higher than that of the C-C bond, which can maintain the skeleton structure of the material at high temperature, and the Si-O-Si skeleton can improve the thermal stability of graphene oxide. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description, and obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0035] Figure 1 It is a schematic diagram of thiol-ene click reaction of the present application embodiment 1.

[0036] Figure 2 It is a schematic diagram of alkyne grafting reaction of the present application embodiment 1.

[0037] Figure 3 It is a schematic diagram of azido-alkyne click reaction of the present application embodiment 1. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present application, the present application is illustrated by the following examples. It should be understood by those skilled in the art that the examples are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0039] Some components in the examples and comparative examples are from the following sources:

[0040] Commercially available graphene oxide, product number G476611, purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd.;

[0041] Commercially available carboxylated graphene oxide, product number XF004, purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd.;

[0042] N,N-dimethylformamide, CAS number 68-12-2, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0043] Azobisisobutyronitrile, CAS number 78-67-1, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0044] Tetraethyl silicate, CAS number 78-10-4, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0045] 3-Mercaptopropyltrimethoxysilane, CAS number 4420-74-0, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0046] Ammonia, CAS number 1336-21-6, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0047] Cetyltrimethylammonium bromide, CAS number 57-09-0, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0048] Chloropropyl POSS, product number O140428, purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd.;

[0049] Sodium azide, CAS number 26628-22-8, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0050] Tetrahydrofuran, CAS number 109-99-9, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0051] Dichloromethane, CAS number 75-09-2, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0052] Propargyl alcohol, CAS number 107-19-7, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0053] N,N'-Dicyclohexylcarbodiimide, CAS No. 538-75-0, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0054] 4-Dimethylaminopyridine, CAS No. 1122-58-3, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0055] Cuprous bromide, CAS No. 7787-70-4, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0056] Pentamethyldiethylenetriamine, CAS No. 3030-47-5, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0057] Example 1

[0058] The present embodiment provides a preparation method of modified graphene oxide based on wet chemical modification, comprising the following steps:

[0059] S1: 3 parts of carboxylated graphene oxide (product number XF004, flake diameter 2 μm, thickness 1 nm) were dispersed in 500 parts of N,N-dimethylformamide to form a dispersion liquid, 0.08 parts of azobisisobutyronitrile and 6 parts of mercapto mesoporous silica were added under the protection of nitrogen atmosphere, and the reaction was carried out at 80℃ for 10h, then cooled to room temperature, filtered, washed with water, and freeze-dried to obtain mesoporous-containing graphene oxide;

[0060] S2: 3 parts of the mesoporous-containing graphene oxide were added to 500 parts of N,N-dimethylformamide and ultrasonically dispersed, then 1.8 parts of propargyl alcohol was added and stirred uniformly, then 10 parts of N,N'-dicyclohexylcarbodiimide and 5 parts of 4-dimethylaminopyridine were added, and the reaction was carried out at 26℃ for 20h, then centrifuged, washed with N,N-dimethylformamide, and vacuum dried to obtain alkynylated graphene oxide; 3 parts of the alkynylated graphene oxide and 10 parts of azidated POSS were added to 100 parts of N,N-dimethylformamide, and 1.8 parts of cuprous bromide and 2.8 parts of pentamethyldiethylenetriamine were added in turn under the protection of nitrogen atmosphere, and the temperature was controlled at 4℃, then stirred and mixed, and the reaction was carried out at 28℃ for 40h, then centrifuged and vacuum dried to obtain modified graphene oxide based on wet chemical modification.

[0061] Preparation of the mercapto mesoporous silica: 250 parts of anhydrous ethanol and 250 parts of deionized water were mixed, 10 parts of tetraethyl orthosilicate, 5 parts of 3-mercaptopropyltrimethoxysilane, 0.8 parts of ammonia water and 0.6 parts of cetyltrimethylammonium bromide were added in turn, stirred for 10h, centrifuged, washed with water, and dried to obtain mercapto mesoporous silica.

[0062] Preparation of the azido-POSS: 10 parts of chloropropyl POSS, 2.8 parts of sodium azide were added into a mixture of 200 parts of tetrahydrofuran and 500 parts of N,N-dimethylformamide under nitrogen atmosphere, and the mixture was reacted at 70°C for 20 h. After cooling to room temperature, 500 parts of dichloromethane was added and stirred for 12 min. Then, 1000 parts of deionized water was added and stirred for 40 min. After standing and separating, the dichloromethane layer was washed with water, dried, rotary evaporated, and separated by a chromatographic column to obtain azido-POSS.

[0063] Example 2

[0064] The present example provides a preparation method of modified graphene oxide based on wet chemical modification, comprising the following steps:

[0065] S1: 1 part of carboxylated graphene oxide (product number XF004, flake diameter of 2 μm, thickness of 1 nm) was dispersed in 400 parts of N,N-dimethylformamide to form a dispersion liquid. Under the protection of nitrogen atmosphere, 0.04 parts of azobisisobutyronitrile and 2 parts of mercapto mesoporous silica were added, and the mixture was reacted at 70°C for 12 h. After cooling to room temperature, the mixture was filtered, washed with water, and freeze-dried to obtain mesoporous-containing graphene oxide.

[0066] S2: 1 part of the mesoporous-containing graphene oxide was added into 400 parts of N,N-dimethylformamide and ultrasonically dispersed. Then, 1.2 parts of propargyl alcohol was added and stirred uniformly. Subsequently, 8 parts of N,N'-dicyclohexyl carbodiimide and 3 parts of 4-dimethylamino pyridine were added, and the mixture was reacted at 24°C for 24 h. After centrifugation, the mixture was washed with N,N-dimethylformamide and vacuum dried to obtain alkyne-modified graphene oxide. 1 part of the alkyne-modified graphene oxide and 6 parts of azido-POSS were added into 80 parts of N,N-dimethylformamide, and 1.6 parts of cuprous bromide and 2.4 parts of pentamethyldiethylenetriamine were sequentially added under nitrogen atmosphere while controlling the temperature at 2°C. The mixture was stirred and mixed, and reacted at 24°C for 48 h. After centrifugation, the mixture was vacuum dried to obtain modified graphene oxide based on wet chemical modification.

[0067] Preparation of the mercapto mesoporous silica: 200 parts of anhydrous ethanol and 200 parts of deionized water were mixed, and 6 parts of tetraethyl orthosilicate, 3 parts of 3-mercaptopropyl trimethoxysilane, 0.6 parts of ammonia water, and 0.2 parts of cetyltrimethylammonium bromide were sequentially added and stirred for 8 h. After centrifugation, the mixture was washed with water and dried to obtain mercapto mesoporous silica.

[0068] Preparation of the azido-POSS: 8 parts of chloropropyl POSS, 2.4 parts of sodium azide were added into a mixture of 180 parts of tetrahydrofuran and 520 parts of N,N-dimethylformamide under nitrogen atmosphere, and reacted at 60℃ for 24h. After cooling to room temperature, 480 parts of dichloromethane was added and stirred for 12min. Then 900 parts of deionized water was added and stirred for 40min. After standing and separating, the dichloromethane layer was separated, washed with water, dried, rotary evaporated, and separated by column chromatography to obtain azido-POSS.

[0069] Example 3

[0070] The present embodiment provides a preparation method of modified graphene oxide based on wet chemical modification, comprising the following steps:

[0071] S1: 2 parts of carboxylated graphene oxide (product number XF004, flake diameter of 2μm, thickness of 1nm) was dispersed in 450 parts of N,N-dimethylformamide to form a dispersion liquid. Under the protection of nitrogen atmosphere, 0.06 parts of azobisisobutyronitrile and 4 parts of thiol mesoporous silica were added and reacted at 75℃ for 11h. After cooling to room temperature, filtration, water washing, and freeze-drying, thiol mesoporous graphene oxide was obtained.

[0072] S2: 2 parts of the thiol mesoporous graphene oxide was added into 450 parts of N,N-dimethylformamide and ultrasonically dispersed. Then 1.4 parts of propargyl alcohol was added and stirred uniformly. Then 9 parts of N,N'-dicyclohexyl carbodiimide and 4 parts of 4-dimethylamino pyridine were added and reacted at 25℃ for 22h. After centrifugation, N,N-dimethylformamide washing, and vacuum drying, alkynylated graphene oxide was obtained. 2 parts of the alkynylated graphene oxide and 8 parts of azido-POSS were added into 90 parts of N,N-dimethylformamide. Under nitrogen atmosphere, 1.7 parts of cuprous bromide and 2.6 parts of pentamethyldiethylenetriamine were added in sequence and stirred and mixed. Then the mixture was reacted at 25℃ for 45h. After centrifugation and vacuum drying, modified graphene oxide based on wet chemical modification was obtained.

[0073] Preparation of the thiol mesoporous silica: 220 parts of anhydrous ethanol and 220 parts of deionized water were mixed. Then 8 parts of tetraethyl orthosilicate, 4 parts of 3-mercaptopropyl trimethoxysilane, 0.7 parts of ammonia water, and 0.4 parts of cetyl trimethyl ammonium bromide were added in sequence and stirred for 9h. After centrifugation, water washing, and drying, thiol mesoporous silica was obtained.

[0074] Preparation of azido-POSS: 9 parts of chloropropyl POSS and 2.6 parts of sodium azide were added into a mixture of 190 parts of tetrahydrofuran and 510 parts of N,N-dimethylformamide under a nitrogen atmosphere, and the mixture was reacted at 65°C for 22 hours. After being cooled to room temperature, 490 parts of dichloromethane was added and stirred for 11 minutes. Then, 950 parts of deionized water was added and stirred for 35 minutes. After being allowed to stand and separate into layers, the dichloromethane layer was separated, washed with water, dried, and rotary evaporated. The product was separated by a chromatographic column to obtain azido-POSS.

[0075] Comparative Example 1

[0076] The present comparative example provides a preparation method of modified graphene oxide, comprising the following steps:

[0077] S1: 10 parts of chloropropyl POSS and 2.8 parts of sodium azide were added into a mixture of 200 parts of tetrahydrofuran and 500 parts of N,N-dimethylformamide under a nitrogen atmosphere, and the mixture was reacted at 70°C for 20 hours. After being cooled to room temperature, 500 parts of dichloromethane was added and stirred for 12 minutes. Then, 1000 parts of deionized water was added and stirred for 40 minutes. After being allowed to stand and separate into layers, the dichloromethane layer was separated, washed with water, dried, and rotary evaporated. The product was separated by a chromatographic column to obtain azido-POSS.

[0078] S2: 3 parts of carboxylated graphene oxide (product number XF004, with a sheet diameter of 2 μm and a thickness of 1 nm) was ultrasonically dispersed in 500 parts of N,N-dimethylformamide. Then, 1.8 parts of propargyl alcohol was added and stirred uniformly. Subsequently, 10 parts of N,N'-dicyclohexyl carbodiimide and 5 parts of 4-dimethylamino pyridine were added, and the mixture was reacted at 26°C for 20 hours. After being centrifuged, the product was washed with N,N-dimethylformamide and vacuum dried to obtain alkynylated graphene oxide. Then, 3 parts of the alkynylated graphene oxide and 10 parts of azido-POSS were added into 100 parts of N,N-dimethylformamide. Under a nitrogen atmosphere, 1.8 parts of cuprous bromide and 2.8 parts of pentamethyldiethylenetriamine were sequentially added while the temperature was controlled at 4°C. The mixture was stirred and reacted at 28°C for 40 hours. After being centrifuged, the product was vacuum dried to obtain modified graphene oxide based on wet chemical modification.

[0079] Comparative Example 2

[0080] The present comparative example provides a preparation method of modified graphene oxide, comprising the following steps:

[0081] S1: 250 parts of anhydrous ethanol and 250 parts of deionized water were mixed. Subsequently, 10 parts of tetraethyl orthosilicate, 5 parts of 3-mercaptopropyl trimethoxysilane, 0.8 parts of ammonia water, and 0.6 parts of cetyltrimethylammonium bromide were sequentially added and stirred for 10 hours. After being centrifuged, the product was washed with water and dried to obtain mercapto mesoporous silica.

[0082] S2: 3 parts of carboxylated graphene oxide (product number XF004, flake diameter 2 μm, thickness 1 nm) were dispersed in 500 parts of N,N-dimethylformamide to form a dispersion liquid, 0.08 parts of azobisisobutyronitrile and 6 parts of mercapto mesoporous silica were added under the protection of nitrogen atmosphere, and the mixture was reacted at 80℃ for 10h, cooled to room temperature, filtered, washed with water, and freeze-dried to obtain modified graphene oxide;

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 1 is that graphene oxide (product number G476611) is used instead of carboxylated graphene oxide (product number XF004).

[0085] The performance of graphene oxide was tested, and the test method was as follows:

[0086] (1) Specific surface area test: test according to the requirements of "GB / T 42310-2023 Nanotechnology Determination of Specific Surface Area of Graphene Powder by Argon Adsorption Static Volume Method".

[0087] (2) Thermal stability test: the prepared graphene oxide was tested by thermogravimetric analysis: the mass of the test sample was about 10 mg, the test temperature range was 25℃~300℃, the heating rate was 5℃ / min, the nitrogen atmosphere, the gas flow was about 200 mL / min; the thermal stability was expressed by the weight loss rate at 250℃.

[0088] The performance test data are shown in Table 1.

[0089] Table 1 Performance test results

[0090] Specific surface area (m2 / g) Loss on ignition at 250°C (%) Example 1 452 5.1 Example 2 438 6.3 Example 3 445 5.6 Comparative Example 1 341 20.5 Comparative Example 2 356 19.2 Comparative Example 3 402 9.4 Commercially available carboxylated graphene oxide 195 50.2

[0091] From the above, it can be seen that the carboxyl-rich graphene oxide is selected as the raw material, the thiol-ene click reaction is carried out by using double bond and thiol-ene click reaction, the alkyne group is introduced through carboxyl group, and then the azido-alkyne click reaction is carried out with azido-POSS, so as to prepare modified graphene oxide with specific spatial structure, which can effectively increase the specific surface area of the material and improve the stability in high temperature environment.

[0092] Compared with Example 1, the specific surface area of the modified graphene oxide in Comparative Example 1 is reduced and the thermal stability is poor because the thiol-ene click reaction is not performed on the modified graphene oxide and the effect of the mercapto mesoporous silica is absent; compared with Example 1, the specific surface area of the modified graphene oxide in Comparative Example 2 is reduced and the thermal stability is poor because the azide-alkyne click reaction is not performed on the modified graphene oxide and the effect of the POSS is absent; compared with Example 1, the specific surface area of the modified graphene oxide in Comparative Example 3 is reduced and the thermal stability is poor because the commercially available graphene oxide (item number G476611) is used instead of the carboxylated graphene oxide (item number XF004), and the subsequent modification effect is poor due to the small number of carboxyl groups in the commercially available graphene oxide.

Claims

1. A method for preparing modified graphene oxide based on wet chemical modification, characterized in that, include The following steps: S1: Graphene oxide is subjected to a thiol-ene click reaction to obtain mesoporous graphene oxide. S2: The mesoporous graphene oxide is alkynylated to obtain alkynylated graphene oxide, and then it is reacted with azido-alkynylated POSS to obtain modified graphene oxide based on wet chemical modification. The steps of the thiol-ene click reaction include: dispersing 1-3 parts by weight of graphene oxide in 400-500 parts by weight of N,N-dimethylformamide to form a dispersion; adding 0.04-0.08 parts by weight of azobisisobutyronitrile and 2-6 parts by weight of mercapto-mesoporous silica under a nitrogen atmosphere and heating to obtain mesoporous graphene oxide; The method for preparing the mercapto-based mesoporous silica includes: mixing 200-250 parts by weight of anhydrous ethanol and 200-250 parts by weight of deionized water, then sequentially adding 6-10 parts by weight of tetraethyl silicate, 3-5 parts by weight of 3-mercaptopropyltrimethoxysilane, 0.6-0.8 parts by weight of ammonia and 0.2-0.6 parts by weight of hexadecyltrimethylammonium bromide, stirring for 8-10 hours, centrifuging, washing with water, and drying to obtain mercapto-based mesoporous silica; The graphene oxide is carboxylated graphene oxide with a sheet diameter of 0.5~5μm and a thickness of 0.8~1.2nm.

2. The method for preparing modified graphene oxide based on wet chemical modification according to claim 1, characterized in that, The conditions for the heating reaction include: reacting at 70-80°C for 10-12 hours, cooling to room temperature, filtering, washing with water, and freeze-drying.

3. The method for preparing modified graphene oxide based on wet chemical modification according to claim 1, characterized in that, The preparation method of the azidated POSS includes: adding 8-10 parts by weight of chloropropyl POSS and 2.4-2.8 parts by weight of sodium azide to a mixture of 180-200 parts by weight of tetrahydrofuran and 500-520 parts by weight of N,N-dimethylformamide for azidation treatment to obtain azidated POSS.

4. The method for preparing modified graphene oxide based on wet chemical modification according to claim 3, characterized in that, The conditions for the azidation treatment include: reacting in a nitrogen atmosphere at 60-70°C for 20-24 hours, cooling to room temperature, then adding 480-500 parts of dichloromethane and stirring for 10-12 minutes, then adding 900-1000 parts of deionized water and stirring for 30-40 minutes, allowing the mixture to stand and separate into layers, separating the dichloromethane layer, washing with water, drying, rotary evaporation, and separation by column chromatography.

5. The method for preparing modified graphene oxide based on wet chemical modification according to claim 1, characterized in that, The alkynylation step includes: adding 1-3 parts by weight of the mesoporous graphene oxide to 400-500 parts of N,N-dimethylformamide and dispersing it ultrasonically; then adding 1.2-1.8 parts of propynyl alcohol and stirring until homogeneous; then adding 8-10 parts of N,N'-dicyclohexylcarbodiimide and 3-5 parts of 4-dimethylaminopyridine; reacting at 24-26°C for 20-24 hours; centrifuging; washing with N,N-dimethylformamide; and vacuum drying to obtain alkynylated graphene oxide.

6. The method for preparing modified graphene oxide based on wet chemical modification according to claim 1, characterized in that, The conditions for the azido-alkyne click reaction include: adding 1-3 parts by weight of alkynylated graphene oxide and 6-10 parts by weight of azido-p-POSS to 80-100 parts by weight of N,N-dimethylformamide; adding 1.6-1.8 parts by weight of cuprous bromide and 2.4-2.8 parts by weight of pentamethyldiethylenetriamine sequentially at a temperature of 2-4°C under a nitrogen atmosphere and stirring; reacting at 24-28°C for 40-48 hours; centrifuging; and vacuum drying to obtain modified graphene oxide based on wet chemical modification.

7. A modified graphene oxide based on wet chemical modification, characterized in that... ， Prepared by the method according to any one of claims 1-6.

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