Method for grafting modification of graphene surface

Abstract

The invention discloses a method for grafting and modifying the surface of graphene, and relates to a method for modifying graphene. According to the method, graphene and a polymer containing a polar group are taken as raw materials, aluminum trichloride is taken as a catalyst, Fridel-Crafts reaction is performed in a solvent dimethyl sulfoxide to obtain grafted graphene, then the grafted graphene is compounded with resin to obtain the graphene reinforced composite material, and the material effectively improves the mechanical properties of the composite material. According to the method, an organic chemical synthesis technology and a material processing technology are combined, and a simple and effective way is provided for interface regulation and control of the graphene reinforced resin-based composite material.

Description

Technical Field

[0001] The present invention relates to a method for modifying graphene, in particular to a method for grafting modification of the graphene surface. Background Art

[0002] Graphene is a novel carbon nanomaterial, a quasi-two-dimensional structure composed of sp 2 carbon atoms in a honeycomb lattice, having extremely high thermal conductivity, huge electron migration rate, and outstanding mechanical properties, etc., and is considered an ideal reinforcement for composite materials. Research in recent years has found that graphene can, to a certain extent, improve the thermal and electrical conductivity of resins and also has great potential in improving the mechanical properties of composite materials. The interface is an important guarantee for giving full play to the load transfer function of the reinforcement. Generally speaking, the graphene surface has strong chemical inertness, is not wetted by polar resin precursor solvents, and cannot form an effective bond with non-polar resins, and thus cannot effectively transfer the load. How to chemically modify the graphene surface to form a dense bond with the resin is an indispensable topic for the development of graphene / resin-based composite materials.

[0003] At present, chemical modification of the graphene surface has not received sufficient attention, but there are more studies on interface regulation of carbon nanotubes with the same chemical structure as graphene, mainly including strong oxidation treatment and halogenation, esterification, amidation, and surfactant modification based on this. Strong oxidation treatment improves the bonding between the graphene structure on the carbon nanotube surface and the resin to a certain extent, but causes great damage to the graphene structure and is not conducive to the improvement of the performance of composite materials; while surfactant modification has limited improvement on interface bonding and cannot form strong interface bonding. Therefore, it is very necessary to develop a new surface chemical treatment process for graphene. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for grafting modification of the graphene surface. The present invention uses graphene and polymer as raw materials, aluminum chloride as a catalyst, and DMSO as a solvent, and modifies the graphene by Friedel-Crafts reaction to effectively improve the mechanical properties of resin-based composite materials and obtain graphene-reinforced resin-based composite materials.

[0005] The technical solution of the present invention is as follows: A method for grafting modification of the graphene surface, which is a method for catalytically synthesizing 2,5-dihydrothiophene compounds containing chiral quaternary carbon, and its modification route is shown as follows:

[0006] Wherein: R is a polar group such as a hydroxyl group, a carboxyl group, an amide group, etc.

[0007] The specific steps are as follows: Under nitrogen protection, raw material graphene GO, polymer grafting agent, and catalyst aluminum chloride AlCl 3 were added to dimethyl sulfoxide DMSO, reacted at a certain temperature for a period of time, the reaction system was poured into a methanol / dilute hydrochloric acid mixed system to terminate the reaction, centrifuged and washed multiple times, and the grafted graphene was placed in a vacuum drying oven to dry for later use.

[0008] The specific steps are as follows: Under nitrogen protection, the polymer was dissolved in dry DMSO, heated and stirred for 30 minutes to obtain a homogeneous and transparent solution. Then graphene was added to the solution, and the DMSO solution of aluminum chloride was slowly added dropwise. After reacting at a certain temperature for a period of time, the reaction system was poured into a V 稀盐酸 :V 甲醇 = 1:1 mixed solution for centrifugation and suction filtration washing 4 - 6 times, and the grafted graphene was dried in a vacuum drying oven for later use.

[0009] Furthermore, the feed ratio is the following molar ratio: GO: polymer: AlCl 3 = 1:3.3:1.2.

[0010] Furthermore, the molar concentration of graphene GO is 0.2 mol / L.

[0011] Furthermore, the concentration of 5Å MS is 45 mg / mL.

[0012] Furthermore, DMSO was dried for 72 h using 4Å molecular sieve (pre-dried at 100 °C for 4 h) before use.

[0013] In the present invention, the room temperature is 15 - 30 °C. R on the side chain of product III graphene is provided by R of raw material II, so R of the product is the same as R of raw material II.

[0014] The beneficial effects of the present invention are as follows: 1. The present invention provides a simple and effective method for grafting and modifying graphene through the Fridel-Crafts reaction using graphene, polymer as raw materials, aluminum chloride as a catalyst, and DMSO as a solvent. This method is applicable to various different types of polymers, the raw materials are simple and easily available, the reaction conditions are mild, the operation is simple, and it also has atom economy, meeting the concept of green chemistry. The obtained grafted graphene as a reinforcing agent can effectively improve the mechanical properties of resin-based composites.

[0015] 2. The present invention combines organic synthesis and material processing technologies, providing a new method for the graft modification of graphene, its uniform dispersion in the resin matrix, and the formation of strong interfacial bonding, which is expected to improve the mechanical and electrical properties of graphene / resin-based composites. It has broad application prospects in the fields of aerospace, vehicle transportation, electronics, battery energy, etc., and has great economic and social benefits. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the contact angle of the product of Example 1 of the present invention; Figure 2 It is an infrared spectrum diagram of the product of Example 1 of the present invention; Figure 3 It is a schematic diagram of the thermogravimetric analysis of the product of Example 1 of the present invention. Detailed Embodiments

[0017] The following embodiments will help to understand the present invention, but do not limit the content of the present invention.

[0018] Example 1

[0019] In this embodiment: The grafted polymer is polyvinyl alcohol, and the degree of polymerization M W = 13000 - 23000.

[0020] Steps: Under nitrogen protection, dissolve 2 g of polyvinyl alcohol in 40 mL of dry DMSO, heat and stir at 90 °C for 30 min to obtain a homogeneous and transparent solution. Take 0.16 g of graphene powder, add it to 10 mL of DMSO and sonicate for 30 min, and then add the sonicated solution to the polyvinyl alcohol solution. Dissolve 2 g of aluminum chloride in 20 mL of dry DMSO, and then slowly add it to a three-necked flask. React for 18 h under nitrogen protection. Pour the obtained dispersion system into a methanol / dilute hydrochloric acid mixed system (VCH 3 OH:VHCl = 1:1) to terminate the reaction, centrifuge and wash multiple times, and put the grafted graphene into a vacuum drying oven to dry for standby.

[0021] Dissolve 0.1 g of PVA-GO in 20 mL of freshly distilled acetone, and ultrasonically mix for 2 h at room temperature for later use. Place 10 g of epoxy resin EP-44 in a three-necked flask, add 50 mL of acetone, and mechanically stir for 3 h at room temperature. Then add the graphene suspension to the three-necked flask, heat to 60 °C, and stir for 2 h. Subsequently, add 2 mg of silane coupling agent KH-550 and stir for about 2 h. Remove the acetone to completely fuse PVA-GO, EP-44, and KH-550. Observe the state of the mixture until it becomes viscous, pour it into a mold, let it stand overnight, and remove the bubbles. The next day, cure it in a vacuum drying oven at 80 °C for 1 h, 120 °C for 1.5 h, and 140 °C for 2 h, and take it out after natural cooling to room temperature for later use to obtain the PVA-GO / EP composite material.

[0022] The test data of Product III-1 are as follows: Contact angle: 70.9 ± 0.72 o . Infrared spectrum: λ -1 (cm -1 , KBr) 3306, 2943, 1734, 1254. Thermogravimetric analysis: weight loss rate 43.39%. Compared with the ungrafted GO / EP, the mechanical properties of the composite material PVA-GO / EP have increased the tensile strength and flexural strength by 16.2% and 23% respectively.

[0023] Example 2

[0024] In this example: The grafted substance is polyacrylic acid PPA, and the degree of polymerization M W = 10000 - 15000.

[0025] Steps: Under nitrogen protection, dissolve 3.2 g of polyacrylic acid in 40 mL of dry DMSO, heat and stir at 90 °C for 30 min to obtain a homogeneous and transparent solution. Take 0.16 g of graphene powder, add it to 10 mL of DMSO and ultrasonicate for 30 min, and add the sonicated solution to the polyvinyl alcohol solution. Dissolve 2 g of aluminum chloride in 20 mL of dry DMSO, and then slowly add it to the three-necked flask. React for 18 h under nitrogen protection, pour the obtained dispersion system into a methanol / dilute hydrochloric acid mixed system (VCH 3 OH:VHCl = 1:1) to terminate the reaction, centrifuge and wash multiple times, and place the grafted graphene in a vacuum drying oven to dry for later use.

[0026] Dissolve 0.16 g of PPA-GO in 20 mL of freshly distilled acetone, and ultrasonically mix for 2 h at room temperature for later use. Place 10 g of epoxy resin EP-44 in a three-necked flask, add 50 mL of acetone, and mechanically stir for 3 h at room temperature. Then add the graphene suspension to the three-necked flask, heat to 60 °C, and stir for 2 h. Subsequently, add 2 mg of silane coupling agent KH-550 and stir for about 2 h. Remove the acetone to completely fuse PPA-GO, EP-44, and KH-550. Observe the state of the mixture until it becomes viscous, pour it into a mold, let it stand overnight, and remove the bubbles. The next day, cure it in a vacuum drying oven at 80 °C for 1 h, 120 °C for 1.5 h, and 140 °C for 2 h, and then take it out after natural cooling to room temperature for use, obtaining the PPA-GO / EP composite material.

[0027] The test data of compound III-2 are as follows: Contact angle: 69.2±0.31 o . Infrared spectrum: λ -1 (cm -1 , KBr) 3310, 2925, 1742, 1231. Thermogravimetric analysis: weight loss rate 40.73%. Compared with the ungrafted GO / EP, the mechanical properties of the composite material PPA-GO / EP have increased the tensile strength and flexural strength by 20.6% and 32.4% respectively.

[0028] Example 3

[0029] In this example: The grafted substance is polyacrylamide PMA, and the degree of polymerization M W = 1000 - 3000.

[0030] Steps: Under nitrogen protection, dissolve 3.2 g of polyacrylamide in 40 mL of dry DMSO, heat and stir at 90 °C for 30 min to obtain a homogeneous and transparent solution. Take 0.16 g of graphene powder, add it to 10 mL of DMSO and ultrasonicate for 30 min, and then add the sonicated solution to the polyvinyl alcohol solution. Dissolve 2 g of aluminum chloride in 20 mL of dry DMSO, and then slowly add it to a three-necked flask. React for 18 h under nitrogen protection, pour the obtained dispersion system into a methanol / dilute hydrochloric acid mixed system (VCH 3 OH:VHCl = 1:1) to terminate the reaction, centrifuge and wash multiple times, and put the grafted graphene into a vacuum drying oven to dry for later use.

[0031] Dissolve 0.16 g of PMA-GO in 20 mL of freshly distilled acetone, and ultrasonically mix for 2 h at room temperature for later use. Place 10 g of epoxy resin EP-44 in a three-necked flask, add 50 mL of acetone, and mechanically stir for 3 h at room temperature. Then add the graphene suspension to the three-necked flask, heat up to 60 °C, and stir for 2 h. Subsequently, add 2 mg of silane coupling agent KH-550 and stir for about 2 h. Remove the acetone to completely fuse PMA-GO, EP-44, and KH-550. Observe the state of the mixture until it becomes viscous, pour it into a mold, let it stand overnight, and remove the bubbles. The next day, cure it in a vacuum drying oven at 80 °C for 1 h, 120 °C for 1.5 h, and 140 °C for 2 h, and then take it out after natural cooling to room temperature for use, obtaining the PMA-GO / EP composite material.

[0032] The test data of compound III-3 are as follows: Contact angle: 80.5±0.76 o . Infrared spectrum: λ -1 (cm -1 , KBr) 3326, 2879, 1753, 1268. Thermogravimetric analysis: weight loss rate 33.28%. Compared with the ungrafted GO / EP, the mechanical properties of the composite material PMA-GO / EP have increased the tensile strength and flexural strength by 19.5% and 28.2% respectively.

Claims

1. A method for grafting modification of graphene surface, characterized in that: The method is shown in the following formula: ; Wherein: R is a polar group such as hydroxyl, carboxyl, amide, etc.; The specific steps are: Under nitrogen protection, the raw material graphene GO, polymer graft body, and catalyst aluminum chloride AlCl3 are added to dimethyl sulfoxide DMSO for reaction, and the reaction system is poured into a methanol / dilute hydrochloric acid mixture system to terminate the reaction. The reaction is centrifuged and washed several times, and the grafted graphene is placed in a vacuum drying oven for drying and standby use.

2. A method for grafting modification of graphene surface according to claim 1, characterized in that: The specific steps of the method are: Under nitrogen protection, the polymer was dissolved in dry DMSO, heated and stirred for 30 minutes to obtain a uniform and transparent solution. Then graphene was added to the solution, and then aluminum chloride DMSO solution was slowly added dropwise. After the reaction, the reaction system was poured into V 稀盐酸 :V 甲醇 =1:1 mixed solution, centrifuged, filtered and washed 4 to 6 times, and the grafted graphene was dried in a vacuum drying oven for later use.

3. A method for grafting modification of graphene surface as claimed in claim 1 or 2, characterized in that: The method feed ratio is the following molar ratio: GO: polymer: AlCl3 = 1: 3.3: 1.

2.

4. A method for grafting modification of graphene surface as claimed in claim 1 or 2, characterized in that: The molar concentration of graphene GO in the method is 0.2 mol / L.

5. The synthesis method according to claim 2, characterized in that A method for grafting modification of the graphene surface as described in claim 1 or 2, characterized in that the DMSO in the method is dried for 72 hours with a 4Å molecular sieve (pre-dried at 100°C for 4 hours) before use.

6. A method for grafting modification of graphene surface according to claim 1 or 2, characterized in that: The post-treatment method in the method step is: pour the reaction system into V 稀盐酸 :V 甲醇 =1:1 mixed solution was centrifuged, filtered and washed 4 to 6 times, and then dried in a vacuum drying oven for 72 h to obtain product III.

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