Graphene hybrid and preparation method and application thereof

Abstract

The invention relates to the technical field of wear-resistant materials, in particular to a graphene hybrid and a preparation method and application thereof.The graphene hybrid is at least prepared from a dopamine solution, nanometer siliceous powder and expanded graphite powder; wherein the nano siliceous powder comprises at least one of nano silicon dioxide or nano silicon carbide, the graphene and the nano siliceous powder are organically combined to prepare the graphene hybrid, the graphene hybrid is endowed with excellent conductivity and wear resistance, and the wear-resistant and conductive application requirements of the material are met.

Description

Technical Field

[0001] The present invention relates to the technical field of wear-resistant materials, and specifically to a graphene hybrid and its preparation method and application. Background Art

[0002] Material wear is a serious problem, which not only seriously affects the appearance, reduces the durability and comfort of materials, but also causes huge economic losses and waste of resources. Graphene, due to its unique two-dimensional layered structure, high specific surface area, low friction coefficient, and excellent mechanical properties, can significantly improve the mechanical properties and wear resistance of polymers, and has become an ideal candidate for improving the wear resistance of materials. However, how to prepare graphene greenly and efficiently on a large scale is still an urgent problem to be solved at present. So far, various methods have been proposed to prepare graphene, including liquid exfoliation, chemical oxidation / reduction, epitaxial growth, chemical vapor deposition (CVD), and electrochemical exfoliation. However, these methods have disadvantages such as high energy consumption, complex operation, use of hazardous chemicals, environmental harm, and low efficiency. The microjet process uses the cavitation effect and high shear force generated by high pressure to exfoliate graphite, which is a method for efficiently preparing graphene on a large scale. However, the inherently large specific surface area of graphene and the π-π conjugation between graphene tend to cause it to agglomerate, thus deteriorating the efficacy of graphene. Chinese Patent Application (Publication No. CN108264038A) discloses a method for simply and batch preparing large-size carbon nanotube / graphene hybrids. Using a liquid carbon-containing precursor as a carbon source, it is injected into the CVD reaction chamber by means of injection, and the CNT / G hybrid is prepared by the form of secondary injection, reducing the preparation cost and simplifying the preparation process. However, the product cannot meet the wear-resistant application requirements of materials. Summary of the Invention

[0003] To solve the above problems, the present invention provides a graphene hybrid and its preparation method and application. By organically combining graphene with nano-siliceous powder, the graphene hybrid is given excellent conductivity and wear resistance, meeting the wear-resistant and conductive application requirements of materials.

[0004] On the one hand, the present invention provides a graphene hybrid, and its preparation raw materials at least include: dopamine solution, nano-siliceous powder, expanded graphite powder; wherein the nano-siliceous powder includes at least one of nano-silica or nano-silicon carbide.

[0005] In one embodiment, the concentration of the dopamine solution is 1.5 - 3 g / L.

[0006] In one embodiment, the preparation method of the dopamine solution is: stirring and dissolving dopamine hydrochloride in a Tris-HCl buffer solution.

[0007] In one embodiment, the pH of the Tris-HCl buffer solution is 7.5 - 9.5.

[0008] In one embodiment, the particle size of the nano-siliceous powder is ≤ 60 nm.

[0009] In one embodiment, the particle size of the nano-siliceous powder is 20 - 40 nm.

[0010] In one embodiment, the particle size of the expanded graphite powder is 800 - 1800 mesh.

[0011] In one embodiment, the particle size of the expanded graphite powder is 1000 mesh.

[0012] In one embodiment, the mass ratio of dopamine hydrochloride, nano-siliceous powder and expanded graphite powder is 2:(0.1 - 1):5.

[0013] In one embodiment, the mass ratio of dopamine hydrochloride, nano-siliceous powder and expanded graphite powder is 2:(0.1 - 0.3):5.

[0014] In one embodiment, the mass ratio of dopamine hydrochloride, nano-siliceous powder and expanded graphite powder is 2:0.2:5.

[0015] On the other hand, the present invention provides a method for preparing a graphene hybrid, which at least includes the following steps:

[0016] Disperse the nano-siliceous powder into the dopamine solution to obtain a dopamine-nano-siliceous powder dispersion; the dopamine-nano-siliceous powder dispersion is passed through a microfluidic homogenizer at least once to obtain a dopamine-nano-siliceous powder aqueous dispersion; adjust the pH of the dopamine-nano-siliceous powder aqueous dispersion to 8.5 - 9.5, and stir and react at 15 - 35 °C for 18 - 24 h to obtain a poly-dopamine modified nano-siliceous powder aqueous dispersion; add expanded graphite powder to the poly-dopamine modified nano-siliceous powder aqueous dispersion, and perform microfluidic circulation treatment for 15 - 50 times to obtain a graphene hybrid (poly-dopamine modified nano-siliceous powder-graphene aqueous dispersion).

[0017] In one embodiment, the pressure of the microfluidic homogenizer is 4000 - 6000 psi (Pounds per square inch, psi for short).

[0018] In one embodiment, the pressure of the microfluidic homogenizer is 5000 psi.

[0019] In one embodiment, the number of times of microfluidic circulation treatment is 30 - 50 times.

[0020] In one embodiment, the pressure of the micro-jet circulation treatment is 15,000 - 30,000 psi.

[0021] In one embodiment, the pressure of the micro-jet circulation treatment is 20,000 psi.

[0022] The present invention prepares polydopamine-functionalized silica (polydopamine-modified nano-silica powder aqueous dispersion) by in-situ polymerization, which is used as an effective exfoliating agent for the exfoliation of graphene. Combined with the micro-jet process, a graphene hybrid is successfully prepared, overcoming the problem of uneven dispersion when graphene or nano-silica powder is directly introduced into the polymer matrix, and greatly reducing the application difficulty. Further, by controlling the micro-jet process parameters, the present invention overcomes the problem of graphene agglomeration, avoids the damage of graphene sheets during the processing, takes into account the high quality and high yield of the graphene hybrid, and is easy to realize large-scale industrial production and popularization and application.

[0023] The third aspect of the present invention provides an application of a graphene hybrid, which is applied to the preparation of wear-resistant polymer materials.

[0024] In one embodiment, the wear-resistant polymer material at least includes a graphene hybrid-polyurethane composite coating and graphene hybrid-modified rubber.

[0025] In one embodiment, the preparation method of the graphene hybrid-polyurethane composite coating at least includes the following steps: mixing the graphene hybrid and aqueous polyurethane in a mass ratio of 1:(2 - 5), and performing vacuum homogenization treatment at 1500 - 2500 r / min for 1.5 - 3 min to obtain a graphene hybrid-polyurethane mixture; scraping the graphene hybrid-polyurethane mixture on the surface of the ultra-fine fiber cloth, and drying it to obtain the graphene hybrid-polyurethane composite coating.

[0026] In one embodiment, the preparation method of the graphene hybrid-polyurethane composite coating includes the following steps: mixing the graphene hybrid and aqueous polyurethane in a mass ratio of 1:3, and performing vacuum homogenization treatment at 2000 r / min for 2 min to obtain a graphene hybrid-polyurethane mixture; using a scraper to scrape the graphene hybrid-polyurethane mixture on the surface of the ultra-fine fiber cloth, and placing it in an oven at 110°C for drying after each scraping, and then performing the scraping of the next layer. After multiple scrapings and drying, the graphene hybrid-polyurethane composite coating is obtained.

[0027] In one embodiment, the viscosity of the aqueous polyurethane at 25°C is 100 - 250 mPa·s.

[0028] In one embodiment, the aqueous polyurethane has a viscosity of 200 mPa·s at 25°C, with the model number AH-1730, and is sourced from Anhui Anda Huatai New Materials Co., Ltd.

[0029] In one embodiment, the scraping thickness of the spreader is 500 - 800 μm (wet film thickness is 500 - 800 μm).

[0030] In one embodiment, the thickness of the graphene hybrid-polyurethane composite coating is 0.8 - 1 mm (dry film thickness).

[0031] Currently, aqueous coatings, especially aqueous polyurethanes (WPU), are widely used in the transportation, manufacturing, and furniture fields. When applied to the protection of leather surface quality, their abrasion resistance and tensile strength need to be further improved. In the present invention, by introducing graphene hybrids into the aqueous polyurethane system and controlling the coating conditions, a wear-resistant coating with excellent properties such as abrasion resistance and tensile strength is obtained, meeting the protection requirements for the surface quality of materials such as leather.

[0032] In one embodiment, the preparation method of the graphene hybrid-modified rubber at least includes the following steps: adding cis-butadiene rubber into an open mill at 60 - 70°C for preliminary plasticization to soften the cis-butadiene rubber; adding graphene hybrids, antioxidant, and toughening agent for mixing to obtain rubber compound; adding sulfur and vulcanization accelerator to the rubber compound and continuing to mix to obtain modified mixed rubber; and vulcanizing and molding the modified mixed rubber to obtain the graphene hybrid-modified rubber.

[0033] In one embodiment, based on the mass of cis-butadiene rubber, the addition amount of the graphene hybrid is 1 - 20%.

[0034] In one embodiment, based on the mass of cis-butadiene rubber, the addition amount of the graphene hybrid is 2 - 5%.

[0035] In one embodiment, the antioxidant is 2,6-di-tert-butyl-p-cresol, the toughening agent is liquid nitrile rubber, and the vulcanization accelerator is a thiuram vulcanization accelerator.

[0036] In one embodiment, the method for preparing the graphene hybrid modified rubber comprises the following steps: adding 50 parts by weight of cis-butadiene rubber into an open mill at 65°C for preliminary plasticizing to soften the cis-butadiene rubber; adding 1.5 parts by weight of the graphene hybrid, 1 part by weight of 2,6-di-tert-butyl-p-cresol, and 5 parts by weight of liquid nitrile rubber for mixing to obtain a rubber compound; adding 1.2 parts by weight of IS-80 insoluble sulfur (Guangzhou Dongxin Chemical Co., Ltd.) and 0.16 parts by weight of tetramethylthiuram disulfide (Guangzhou Dongxin Chemical Co., Ltd.) to the rubber compound, and continuing to mix to obtain a modified mixed rubber; putting the modified mixed rubber into a mold, and curing and molding it in a flat vulcanizer at 160°C (pressure 720 kgf, time 3 min) to obtain the graphene hybrid modified rubber.

[0037] The graphene hybrid provided by the present invention can be directly added to a rubber system to modify the wear resistance of the rubber. It has good dispersibility in the rubber system and does not require additional addition of a dispersion aid. The obtained modified rubber has significantly improved wear resistance and electrical conductivity, better meeting the actual application requirements.

[0038] Beneficial effects

[0039] 1. The present invention provides a graphene hybrid, a preparation method and an application thereof. By organically combining graphene with nano-siliceous powder, the graphene hybrid is given excellent electrical conductivity and wear resistance, meeting the wear-resistant and conductive application requirements of materials.

[0040] 2. The present invention prepares polydopamine-functionalized silica (polydopamine-modified nano-siliceous powder aqueous dispersion) by in-situ polymerization, which is used as an effective exfoliating agent for the exfoliation of graphene. Cooperating with the microfluidic process, the graphene hybrid is successfully prepared, overcoming the problem of uneven dispersion when graphene or nano-siliceous powder is directly introduced into the polymer matrix, and greatly reducing the application difficulty.

[0041] 3. By controlling the microfluidic process parameters, the present invention overcomes the problem of graphene agglomeration, avoids the damage of graphene sheets during the processing, takes into account the high quality and high yield of the graphene hybrid, and is easy to realize large-scale industrial production and popularization and application.

[0042] 4. By introducing the graphene hybrid into the aqueous polyurethane system and controlling the coating conditions, a wear-resistant coating with excellent properties such as wear resistance and tensile strength is obtained, meeting the protection requirements for the surface quality of materials such as leather.

[0043] 5. The graphene hybrid provided by the present invention can be directly added to a rubber system to modify the wear resistance of the rubber. It has good dispersibility in the rubber system and does not require additional addition of a dispersing aid. In addition, since the siliceous nanomaterials are sporadically distributed on the surface of the graphene sheets, they do not hinder the contact between the graphene, thereby avoiding the deterioration of the electrical properties. The finally obtained modified rubber not only has significantly improved wear resistance but also maintains excellent electrical conductivity, and can better meet the actual application requirements. Description of the Drawings

[0044] Figure 1 SEM images of expanded graphite powder (a), nano-silica (b), polydopamine-modified nano-silica (c), and graphene hybrid (d) in Example 1.

[0045] Figure 2 TEM characterization results of the graphene hybrid in Example 1, where (a) is the TEM image, (b) is the elemental surface distribution, and (c) is the EDS energy spectrum analysis chart.

[0046] Figure 3 Rheological test results of the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2 Figure 3 Among them, (a) storage modulus - angular frequency curve graph; (b) loss modulus - angular frequency curve graph; (c) storage modulus - strain curve graph; (d) loss modulus - strain curve graph; (e) shear rate - viscosity curve graph.

[0047] Figure 3 (In (a - e), 1, 2, and 3 respectively represent the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2.

[0048] Figure 4 Surface SEM characterization images of the coatings provided by Application Example 1 (c), Application Comparative Example 1 (b), and Application Comparative Example 2 (a).

[0049] Figure 5 Morphology images of the abrasion resistance tester and the coatings before and after abrasion resistance testing. In the figure, (a) is the taber abrasion resistance tester, (b) is the SiO2@PDA - G / WPU composite coating before abrasion resistance testing, (c) is the SiO2 / EGP / WPU composite coating after abrasion resistance testing, (d) is the WPU coating after abrasion resistance testing, and (e) is the SiO2@PDA - G / WPU composite coating after abrasion resistance testing.

[0050] Figure 6 Mass loss result graph of the samples after the coatings are tested by the Taber abrasion resistance tester. In the figure, 1, 2, and 3 respectively represent the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2.

[0051] Figure 7It is a graph showing the hardness test results of the coatings. In the graph, 1, 2, and 3 respectively represent the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2.

[0052] Figure 8 It is a graph showing the friction coefficient results of the coatings. In the graph, 1, 2, and 3 respectively represent the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2.

[0053] Figure 9 It is the mechanical property test results of WPU coating, SiO2 / EGP / WPU composite coating, and SiO2@PDA-G / WPU composite coating. In the graph, (a) is the tensile stress-strain curve; (b) is the Young's modulus; Figure 9 (In (a-b), 1, 2, and 3 respectively represent the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2. Detailed implementation mode

[0054] Example 1

[0055] One aspect of Example 1 of the present invention provides a graphene hybrid. The preparation raw materials include: dopamine solution, nano-siliceous powder, expanded graphite powder (EGP); wherein the nano-siliceous powder is nano-silica (20 nm, purity 99 wt%), sourced from Jiangsu Xianfeng Nano Materials Technology Co., Ltd.

[0056] The concentration of the dopamine solution is 2 g / L. The preparation method of the dopamine solution is: dissolving 0.2 g of dopamine hydrochloride by stirring in 100 mL of Tris-HCl buffer solution, and the pH of the Tris-HCl buffer solution is 8.5.

[0057] The particle size of the expanded graphite powder is 1000 mesh (fixed carbon 99.5 wt%), sourced from Nanjing Greifa Carbon Materials Co., Ltd.

[0058] The mass ratio of the dopamine hydrochloride, nano-siliceous powder, and expanded graphite powder is 2:0.2:5.

[0059] Example 1 of the present invention provides, on the other hand, a method for preparing a graphene hybrid, comprising the following steps: dispersing nano-silica into a dopamine solution to obtain a dopamine-nano-silica dispersion; adding the dopamine-nano-silica dispersion to the feed inlet of a microfluidic homogenizer, and passing the dispersion through a nozzle and an emulsification chamber under a pressure of 5000 psi, and repeating the treatment once to obtain a dopamine-nano-silica aqueous dispersion; adjusting the pH of the dopamine-nano-silica aqueous dispersion to 8.5, and stirring and reacting at 25 °C for 24 h to obtain a polydopamine-modified nano-silica (SiO2@PDA) aqueous dispersion; adding expanded graphite powder to the polydopamine-modified nano-silica aqueous dispersion, and performing microfluidic circulation treatment 30 times under a pressure of 20000 psi to obtain a graphene hybrid (polydopamine-modified nano-silica-graphene aqueous dispersion, denoted as SiO2@PDA-G).

[0060] Example 2

[0061] Example 2 of the present invention provides a graphene hybrid and a method for preparing the same. The specific implementation manner is the same as that of Example 1, except that the number of microfluidic circulations in the method for preparing the graphene hybrid is replaced by 50 times.

[0062] Example 3

[0063] Example 3 of the present invention provides a graphene hybrid and a method for preparing the same. The specific implementation manner is the same as that of Example 1, except that the nano-siliceous powder is replaced by nano-silicon carbide (40 nm), which is sourced from Aladdin Biochemical Technology Co., Ltd.

[0064] The method for preparing the graphene hybrid comprises the following steps: dispersing nano-silicon carbide into a dopamine solution to obtain a dopamine-nano-silicon carbide dispersion; adding the dopamine-nano-silicon carbide dispersion to the feed inlet of a microfluidic homogenizer, and passing the dispersion through a nozzle and an emulsification chamber under a pressure of 5000 psi, and repeating the treatment once to obtain a dopamine-nano-silicon carbide aqueous dispersion; adjusting the pH of the dopamine-nano-silicon carbide aqueous dispersion to 8.5, and stirring and reacting at 25 °C for 24 h to obtain a polydopamine-modified nano-silicon carbide (SiC@PDA) aqueous dispersion; adding expanded graphite powder to the polydopamine-modified nano-silicon carbide aqueous dispersion, and performing microfluidic circulation treatment 30 times under a pressure of 20000 psi to obtain a graphene hybrid (polydopamine-modified nano-silicon carbide-graphene aqueous dispersion, denoted as SiC@PDA-G)

[0065] Comparative Example 1

[0066] Comparative Example 1 of the present invention provides an aqueous mixture of expanded graphite powder and nano-silica. The preparation method of the aqueous mixture is as follows: 0.5 g of expanded graphite powder and 0.02 g of nano-silica are dispersed in water.

[0067] Application Example 1

[0068] Application Example 1 of the present invention provides a graphene hybrid-polyurethane composite coating. The preparation method of the graphene hybrid-polyurethane composite coating includes the following steps: The graphene hybrid (Example 1) and aqueous polyurethane are mixed at a mass ratio of 1:3, and vacuum homogenization treatment is carried out at 2000 r / min for 2 min to obtain a graphene hybrid-polyurethane mixture; The graphene hybrid-polyurethane mixture is scraped onto the surface of the ultra-fine fabric by a scraper. After each scraping, it is placed in an oven at 110 °C for drying, and then the next layer of scraping is carried out. After scraping 5 times and drying, the graphene hybrid-polyurethane (SiO2@PDA-G / WPU) composite coating is obtained.

[0069] The viscosity of the aqueous polyurethane at 25 °C is 200 mPa·s, the model is AH-1730, and it is sourced from Anhui Anda Huatai New Materials Co., Ltd.

[0070] The scraping thickness of the scraper is 600 μm (wet film thickness is 600 μm).

[0071] The thickness of the graphene hybrid-polyurethane composite coating is 0.83 mm (dry film thickness).

[0072] Application Example 2

[0073] Application Example 2 of the present invention provides a graphene hybrid-polyurethane composite coating. Its specific implementation manner is the same as that of Application Example 1, except that the graphene hybrid (Example 1) is replaced by the graphene hybrid (Example 2).

[0074] Application Example 3

[0075] Application Example 3 of the present invention provides a graphene hybrid-polyurethane composite coating. Its specific implementation manner is the same as that of Application Example 1, except that the graphene hybrid (Example 1) is replaced by the graphene hybrid (Example 3).

[0076] Application Example 4

[0077] Application Example 4 of the present invention provides a graphene hybrid modified rubber, and the preparation method of the graphene hybrid modified rubber includes the following steps: adding 50 parts by weight of cis-butadiene rubber into an open mill at 65 °C for preliminary plasticization to soften the cis-butadiene rubber; adding 1.5 parts by weight of graphene hybrid (Example 1), 1 part by weight of 2,6-di-tert-butyl-p-cresol, and 5 parts by weight of liquid nitrile rubber for mixing to obtain a rubber compound; adding 1.2 parts by weight of IS-80 insoluble sulfur (Guangzhou Dongxin Chemical Co., Ltd.) and 0.16 parts by weight of tetramethylthiuram disulfide (Guangzhou Dongxin Chemical Co., Ltd.) to the rubber compound, and continuing to mix to obtain a modified mixed rubber; putting the modified mixed rubber into a mold, and vulcanizing and molding in a flat vulcanizer at 160 °C (pressure 720 kgf, time 3 min) to obtain the graphene hybrid modified rubber.

[0078] Application Comparative Example 1

[0079] Application Comparative Example 1 of the present invention provides a modified polyurethane composite coating, including the following steps: mixing an aqueous solution of expanded graphite powder and nano-silica (Comparative Example 1) with waterborne polyurethane in a mass ratio of 1:3, and performing vacuum homogenization treatment at 2000 r / min for 2 min to obtain a modified polyurethane mixture; using a spreader to spread the modified polyurethane mixture on the surface of ultra-fine fiber cloth, drying it in an oven at 110 °C after each spreading, and then performing the next layer of spreading. After spreading 5 times and drying, the modified polyurethane composite coating (SiO2-EGP-WPU composite coating) is obtained.

[0080] Application Comparative Example 2

[0081] Application Comparative Example 2 of the present invention provides a polyurethane coating, including the following steps: using a spreader to spread waterborne polyurethane on the surface of ultra-fine fiber cloth, drying it in an oven at 110 °C after each spreading, and then performing the next layer of spreading. After spreading 5 times and drying, the polyurethane coating (WPU coating) is obtained.

[0082] Performance Test

[0083] 1. Perform SEM characterization on the expanded graphite powder, nano-silica, polydopamine-modified nano-silica, and graphene hybrid in the examples. The results are shown in Figure 1 , and analyze Figure 1 It can be seen that EGP has a flaky structure, with relatively thick and regular lamellae. By Figure 1 (b) and Figure 1 (c) comparison, it can be seen that PDA (polydopamine) is coated on the surface of silica through self-polymerization reaction. Comparing Figure 1 (a), the lamellae of SiO2@PDA-G are thinner, and sporadic nanoparticles appear on the surface, indicating that SiO2@PDA adheres to the surface of graphene.

[0084] 2. The graphene hybrid provided in Example 1 was characterized by TEM. The results are shown in Figure 2 , and the analysis Figure 2 shows that the graphene sheets are thin and semi-transparent ( Figure 2 (a)), which is a characteristic of obvious few-layer graphene. Thus, it can be confirmed that micro-jet can effectively exfoliate to obtain few-layer graphene. By careful observation, it can be found that there are a few nanoparticles adhering to the surface of graphene. From Figure 2 (b-c), it can be seen from the elemental mapping and EDS that these nanoparticles contain Si and N elements and are relatively evenly distributed. It can be inferred that these nanoparticles are SiO2@PDA. This is because PDA contains a large number of catechol structural units, and there is a π-π interaction with graphene, so that SiO2@PDA is adsorbed on the surface of graphene to form a hybrid.

[0085] 3. The rheological properties of the SiO2@PDA-G / WPU composite coating provided in Application Example 1, the SiO2 / EGP-WPU composite coating provided in Application Comparative Example 1, and the WPU coating provided in Application Comparative Example 2 were tested. The test results are shown in Figure 3 , and the analysis Figure 3 shows that:

[0086] (1) Figure 3 (a) and 3(b) are the relationships between the storage modulus (G’) and the loss modulus (G”) and the angular frequency in the linear viscoelastic region (strain = 0.1%), respectively. The results show that the G’ of this slurry is higher than G”, and it dominates in the whole region (0.01 - 100 Rad / s), indicating that this slurry has a hydrogel-like behavior, which also proves the network structure formed by the rich interfacial interaction between the WPU molecular chain and the modified graphene.

[0087] (2) Figure 3 (c) and 3(d) are the relationships between the storage modulus and the loss modulus and the strain, respectively. The results show that this printing slurry has a relatively wide (about 10%) linear viscoelastic region, and the entanglement network failure only occurs at high strain (>10%). These behaviors indicate that this slurry has a wide processing window and shear thinning behavior. By comparing the storage modulus of the SiO2 / EGP / WPU slurry, the SiO2@PDA-G / WPU slurry, and WPU with the same filler content, it can be seen that the storage modulus of the WPU slurry and the SiO2 / EGP / WPU slurry is lower, which also indicates that the interfacial interaction formed by the SiO2 / EGP / WPU molecular chain is weaker than that of the SiO2@PDA-G / WPU molecular chain.

[0088] (3) Figure 3(e) is the relationship between the slurry viscosity and the shear rate. The results show that the viscosities of the tested slurries all decrease with the increase of the shear rate. Among them, the SiO2@PDA-G / WPU slurry has the highest viscosity at low shear rates, while the WPU has a low viscosity. This may be due to the strong interfacial interaction between the SiO2@PDA-G and the WPU molecular chains, making it difficult for them to orient, and thus the viscosity decreases slowly.

[0089] 4. Perform SEM characterization on the surfaces of the SiO2@PDA-G / WPU composite coating provided in Application Example 1, the SiO2 / EGP-WPU composite coating provided in Application Comparative Example 1, and the WPU coating provided in Application Comparative Example 2. The results are shown in Figure 4 and analyze Figure 4 to find that:

[0090] From Figure 4 (a), it can be seen that the cross-section of the WPU coating is smooth and flat. While in the SiO2 / EGP-WPU composite coating ( Figure 4 (b)), it can be seen that the cross-section is rough and expanded graphite flakes can be seen. In the SiO2@PDA-G / WPU composite coating ( Figure 4 (c)), a wrinkled structure can be seen, and the fracture cracks show ridge and groove-like stripes, showing non-linear crack propagation, indicating that there is a good interaction between SiO2@PDA-G and WPU. The wrinkled structure can increase the flexibility and stretchability of the composite. When subjected to external forces, the wrinkles can play a role in buffering and dispersing stress, avoiding excessive stress concentration in local areas of the material and resulting in damage.

[0091] 5. Perform wear resistance tests on the SiO2@PDA-G / WPU composite coating provided in Application Example 1, the SiO2 / EGP-WPU composite coating provided in Application Comparative Example 1, and the WPU coating provided in Application Comparative Example 2. The test results are shown in Figures 5 - 8 .

[0092] Figure 5 Shows the abrasion testing machine and the morphology diagrams of the coating before and after the wear resistance test. Figure 6 Shows the mass loss of the samples after the wear resistance test by the Taber abrasion testing machine. From Figure 5 it can be seen that among all the tested samples, the SiO2 / EGP-WPU composite coating shows the worst wear resistance. After 10,000 wear resistance tests, most of the fibers are exposed in the coating (as shown in Figure 5(c)), the average mass loss before and after treatment was (0.3538 ± 0.0027) g. The average mass loss of the WPU coating before and after 10,000 abrasion resistances was (0.3410 ± 0.0030) g, which was not much different from that of the blend coating material. However, the SiO2@PDA-G / WPU composite coating had the lowest relative mass loss before and after 10,000 abrasion tests, with an average mass loss of (0.1789 ± 0.0016) g, and the abrasion resistance was increased to 48% of the original material. From Figure 5 (e), it can also be seen that only a small part of small pits were worn out on the surface of the coating, and fewer ultra-fine fiber cloth fibers were exposed. According to the Shore hardness tester, three hardness tests were carried out on the coatings provided by Application Example 1, Application Comparative Example 1, and Application Comparative Example 2 and their average values were taken. The results showed that the SiO2@PDA-G / WPU composite coating had the best hardness (such as Figure 7 ), which was 48C. The test results further verified that the SiO2@PDA-G / WPU composite coating had excellent abrasion resistance.

[0093] The mechanism of graphene enhancing the abrasion resistance in the composite mainly includes two aspects: one is the unique intrinsic properties of graphene, such as the sheet structure, excellent mechanical properties and low surface friction coefficient; the other is determined by the aggregation state of graphene sheets in the polymer matrix, mainly including the uniformity of spatial dispersion and the interfacial interaction. The improved abrasion resistance of the waterborne polyurethane / graphene composite material comes from the synergistic effect of its intrinsic properties and the optimized aggregation state. The chemically modified graphene surface has a low surface friction coefficient, such as Figure 8 . This makes the composite material have a lower friction coefficient during the wear contact process. Secondly, the unique two-dimensional sheet structure of graphene provides a larger specific surface area. The surface-modified graphene helps the uniform dispersion of graphene in the matrix, avoids agglomeration caused by π-π interaction, and can further optimize its effective specific surface area, strengthen the effective contact surface with the polymer, enhance the destructive stress transfer ability, and achieve the dissipation of wear energy and the inhibition of wear intensity through stress-induced crack tip passivation, deviation, bridging and crack propagation prevention.

[0094] 6. Tensile property tests were carried out on the SiO2@PDA-G / WPU composite coating provided by Application Example 1, the SiO2 / EGP / WPU composite coating provided by Application Comparative Example 1, and the WPU coating provided by Application Comparative Example 2. The test results are shown in Figure 9 . Analyze Figure 9 It can be seen that:

[0095] Filler loading, filler dispersion quality, and the interfacial interaction between the filler and the WPU polymer matrix are parameters that play an important role in the final mechanical properties of the composite material. Figure 9The mechanical properties of the WPU coating, SiO2 / EGP / WPU composite coating, and SiO2@PDA-G / WPU composite coating are shown. It can be seen from the figure that the SiO2 / EGP / WPU composite coating, although SiO2 and EGP are introduced into WPU by blending, also helps to improve the mechanical properties of the coating. The SiO2@PDA-G / WPU composite coating exhibits the highest tensile strength, elongation at break, and elastic modulus. The tensile strength is increased to 83% of the original and the elongation at break is increased to 18% of the original. This is because PDA has high adhesiveness, and there is a strong interaction between PDA and the urethane group and urea group of the hard segment of WPU, improving the interfacial interaction between SiO2@PDA-G and WPU. At the same time, the graphene sheets have a low friction coefficient and good lubrication performance, and a self-lubricating and high-strength continuous transfer film is formed during the wear process, thus improving the wear resistance of WPU. In addition, the combined action of graphene and silica effectively inhibits the propagation of cracks and delays fatigue wear. Comparing the mechanical properties of the SiO2 / EGP / WPU composite coating and the SiO2@PDA-G / WPU composite coating shows that the strengthening effect of surface-modified graphene is better than that of unfunctionalized graphite powder. This may be due to the numerous reactive functional groups on the surface of functionalized graphene, which enhances the interfacial interaction with the polymer matrix and avoids phase separation, resulting in low stress transfer efficiency. In addition, graphene modified with amino groups on the surface has better hydrophilicity and can be well dispersed in the aqueous polyurethane matrix, effectively avoiding agglomeration caused by π-π interaction. In short, the enhanced interfacial interaction and improved dispersion performance synergistically and effectively contribute to stress transfer, thus enhancing the strength and modulus of the polymer matrix.

[0096] 7. (1) The abrasion resistance of the rubber modified with the graphene hybrid provided in Application Example 4 was tested. The test reference standard was GB / T 9867-2008, and the test result was: the DIN abrasion value was 78.6 mm 3 .

[0097] (2) The resistance value of the rubber modified with the graphene hybrid provided in Application Example 4 was tested. The test reference standard was GB / T 20991-2007, and the test result was: 6.42×10 6 Ω.

Claims

1. A graphene hybrid, characterized in that: The raw materials for its preparation at least include: dopamine solution, nano-silicon powder, and expanded graphite powder; wherein the nano-silicon powder includes at least one of nano-silicon dioxide and nano-silicon carbide.

2. The graphene hybrid according to claim 1, characterized in that The particle size of the nano-silicon powder is ≤60nm; the particle size of the expanded graphite powder is 800-1800 meshes.

3. The graphene hybrid according to claim 1, characterized in that: The concentration of the dopamine solution is 1.5-3 g / L. The preparation method of the dopamine solution is: stirring and dissolving dopamine hydrochloride in a Tris-HCl buffer solution.

4. The graphene hybrid according to claim 3, characterized in that: The mass ratio of dopamine hydrochloride, nano-silica powder and expanded graphite powder is 2:(0.1-1):

5.

5. A method for preparing a graphene hybrid according to any one of claims 1 to 4, characterized in that: At least the following steps are included: Nano-silica powder is dispersed in a dopamine solution to obtain a dopamine-nano-silica powder dispersion; the dopamine-nano-silica powder dispersion is passed through a microjet homogenizer at least once to obtain a dopamine-nano-silica powder aqueous dispersion; the pH of the dopamine-nano-silica powder aqueous dispersion is adjusted to 7.5-9.5, and the reaction is stirred at 15-35° C. for 18-24 hours to obtain a polydopamine-modified nano-silica powder aqueous dispersion; expanded graphite powder is added to the polydopamine-modified nano-silica powder aqueous dispersion, and the microjet cycle is treated for 15-50 times to obtain a graphene hybrid.

6. The method for preparing a graphene hybrid according to claim 5, characterized in that: The pressure of the microfluidic circulation treatment is 15000-30000psi.

7. An application of the graphene hybrid according to any one of claims 1 to 4, characterized in that: The invention is applied to the preparation of wear-resistant polymer materials, wherein the wear-resistant polymer materials at least include a graphene hybrid-polyurethane composite coating and a graphene hybrid modified rubber.

8. The use of the graphene hybrid according to claim 7, characterized in that: The preparation method of the graphene hybrid-polyurethane composite coating comprises at least the following steps: mixing the graphene hybrid and the waterborne polyurethane in a mass ratio of 1:(2-5), performing vacuum homogenization treatment at 1500-2500 r / min for 1.5-3 min to obtain the graphene hybrid-polyurethane mixture; and coating the graphene hybrid-polyurethane mixture on the surface of the microfiber cloth by scraping, and drying to obtain the graphene hybrid-polyurethane composite coating.

9. The use of the graphene hybrid according to claim 8, characterized in that: The viscosity of the waterborne polyurethane at 25° C. is 100-250 mPa·s.

10. The use of the graphene hybrid according to claim 7, characterized in that: The preparation method of the graphene hybrid modified rubber comprises at least the following steps: adding butadiene rubber to an open mill at 60-70°C for preliminary plasticization to soften the butadiene rubber; adding graphene hybrid, antioxidant and toughening agent for mixing to obtain rubber compound; adding sulfur and vulcanization accelerator to the rubber compound, and continuing mixing to obtain modified mixed rubber; and vulcanizing and molding the modified mixed rubber to obtain the graphene hybrid modified rubber.

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