Preparation method of high-dispersity modified graphene
Modifying graphene nanosheets with nano-silica creates a physical barrier, solving the problem of easy aggregation of graphene nanosheets, improving their dispersibility and stability in solvents, and enhancing the performance of composite materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-03-20
AI Technical Summary
Graphene nanosheets are prone to agglomeration and stacking, resulting in uneven dispersion in solution, which affects their performance and limits their application in various fields.
Graphene nanosheets were modified by modifying nano-silica, and the silica layer formed a physical barrier on the surface of the graphene nanosheets, reducing direct contact between the layers, inhibiting agglomeration, and improving dispersibility and stability.
It effectively improves the dispersibility and stability of graphene nanosheets, inhibits their spontaneous aggregation in solvents, and endows the composite material with catalytic and sensing properties.
Smart Images
Figure CN121698353A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of graphene materials technology, specifically to a method for preparing highly dispersible modified graphene. Background Technology
[0002] Graphene nanosheets are two-dimensional nanomaterials composed of single or several layers (usually less than 10 layers) of stacked graphene, whose atomic structure consists of carbon atoms arranged in sp... 2 The hybridization forms a hexagonal honeycomb lattice, and the layers are bonded by van der Waals forces, resulting in excellent mechanical properties, thermal properties, electrical conductivity, high dielectric loss, and impermeability, among other desirable properties. In recent years, graphene nanosheets have been widely used in optoelectronic materials, conductive materials, corrosion protection, and other fields.
[0003] Graphene possesses a high specific surface area; however, its unique π-π conjugated structure and strong van der Waals forces between its layers make it prone to aggregation and stacking. This significantly reduces the effective specific surface area of graphene nanosheets and prevents them from being uniformly dispersed in solution. Currently, the Hummers method, based on the oxidation of natural graphite, can prepare highly oxidized graphene oxide containing numerous oxygen-containing functional groups such as hydroxyl, carboxyl, and epoxy groups, exhibiting strong hydrophilicity and allowing for uniform dispersion in water. However, graphene nanosheets prepared by other methods (such as electrochemical exfoliation) have a low degree of oxidation, affecting their dispersibility and leading to aggregation and stacking. This, in turn, affects the performance of various properties of graphene nanosheets and limits their applications in various fields. Furthermore, although highly oxidized graphene contains a large number of different oxygen-containing functional groups, the number of hydroxyl groups in these functional groups is far greater than the number of epoxy and carboxyl groups. This may lead to the formation of a large-area hydrogen bond network due to the basal hydroxyl groups, which drives the stacking of layers and causes spontaneous aggregation of graphene oxide. At the same time, due to the presence of a large number of oxygen-containing functional groups, highly oxidized graphene is also prone to violent aggregation in nonpolar solvents due to hydrophobic interactions. Summary of the Invention
[0004] To address the problems existing in the prior art, the present invention aims to provide a method for preparing highly dispersible modified graphene. This method modifies graphene nanosheets by modifying nano-silica, and utilizes the silica layer to form a physical barrier on the surface of the graphene nanosheets, thereby reducing direct contact between layers, inhibiting the aggregation of graphene nanosheets, and improving the dispersibility and stability of graphene nanosheets.
[0005] The objective of this invention is achieved through the following technical solution: A method for preparing highly dispersible modified graphene, comprising: Step 1: Modification of nano-silica: First, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane are added sequentially to an ethanol solution, the pH is adjusted to 3.0-4.0, and the mixture is stirred to obtain a silane solution; then, nano-silica particles are ultrasonically dispersed in anhydrous ethanol, and the silane solution is slowly poured in and stirred to mix; finally, the mixture is centrifuged, filtered, washed, and dried sequentially to obtain modified nano-silica; Step 2: Graphene Nanosheet Modification: First, graphene nanosheets are added to a mixed solvent of toluene and ethanol and ultrasonically dispersed to form a black suspension. Under a nitrogen atmosphere, styryltrimethoxysilane is added, stirred, and mixed. After centrifugation, filtration, washing, and drying, the first-modified graphene is obtained. Then, under a nitrogen atmosphere, γ-glycidyl etheroxypropyltrimethoxysilane and isobutyltrimethoxysilane are added to a DMF solution, followed by the first-modified graphene. The mixture is ultrasonically dispersed, a catalyst is added, and stirred. After centrifugation, filtration, washing, and drying, modified graphene nanosheets are obtained. Step 3: Preparation of composite material: Modified graphene nanosheets are added to DMF solution, stirred and mixed, and ultrasonically dispersed to obtain a suspension; then modified nano-silica is added to the suspension, stirred and mixed, and ultrasonically dispersed; after that, the mixed solution is stirred and reacted in an oil bath, cooled to room temperature, and then filtered, washed and dried to obtain the composite material.
[0006] Based on further optimization of the above scheme, the volume ratio of 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane is 6.5–7.5:1.5–2.5:0.8–1.2, and the volume ratio of 3-aminopropyltrimethoxysilane to ethanol solution is 6.5–7.5:200; the ethanol solution used is an 80% ethanol solution.
[0007] Based on further optimization of the above scheme, the pH value in step one is achieved using a hydrochloric acid solution with a concentration of 1 mol / L.
[0008] Based on further optimization of the above scheme, the mass-to-volume ratio of the nano-silica particles to anhydrous ethanol is 0.8-1.2g:4.5-5.5mL, and the volume ratio of anhydrous ethanol to ethanol solution is 4.5-5.5:200.
[0009] Based on further optimization of the above scheme, the centrifugation steps in both steps one and two are centrifuged at 8000-10000 rpm for 8-10 minutes; the filtration steps are all performed using a ceramic vacuum filter; the washing steps are all performed by repeatedly washing with deionized water and anhydrous ethanol 3-5 times; and the drying steps are all performed by vacuum drying at 60-80℃ for 18-24 hours.
[0010] Based on further optimization of the above scheme, the mass-to-volume ratio of graphene nanosheets, toluene, and ethanol is 18-22 mg: 16-20 mL: 1.5-2.5 mL; the mass-to-volume ratio of graphene nanosheets to styrenetrimethoxysilane is 18-22 mg: 6.5-7.5 mL.
[0011] Based on further optimization of the above scheme, the volume ratio of γ-glycidoxypropyltrimethoxysilane, isobutyltrimethoxysilane to DMF solution is 7.5-8.5:1.5-2.5:145-155; the volume-to-mass ratio of γ-glycidoxypropyltrimethoxysilane to the first modified graphene is 7.5-8.5 mL:98-102 mg.
[0012] Based on further optimization of the above scheme, the catalyst is dibutyltin dilaurate, and the mass ratio of dibutyltin dilaurate to the first modified graphene is 1-2:98-102.
[0013] Based on further optimization of the above scheme, the mass ratio of modified nano-silica to modified graphene nanosheets is 1:2.9-3.1, and the mass-volume ratio of modified graphene nanosheets to DMF solution is 14-16 mg:9-11 mL.
[0014] Based on further optimization of the above scheme, in step three, the oil bath temperature for stirring the mixed solution in the oil bath is 90-110℃, and the stirring time is 5-8h.
[0015] Based on further optimization of the above scheme, the filtration step in step three uses a microporous membrane for filtration; the washing step uses distilled water and anhydrous ethanol to wash repeatedly 3 to 5 times; and the drying step is to perform vacuum drying at 60 to 80°C for 18 to 24 hours.
[0016] The following are the effects of the technical solution of the present invention: This invention first modifies nano-silica using a composite silane coupling system composed of 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane. This not only introduces amino groups (-NH2) into the surface of nano-silica through the condensation reaction between the silanols generated by hydrolysis and the hydroxyl groups on the surface of nano-silica, but also effectively regulates the hydrophobicity of the nano-silica surface, increases steric hindrance, and inhibits the self-aggregation of nano-silica. In addition, it can also compensate for the defect sites of silica, enhance the interfacial anchoring points, and construct an interfacial structure with multiple chemical bonds. Graphene nanosheets were first modified with styryltrimethoxysilane, and then further modified using a composite silane coupling system of γ-glycidyl etheroxypropyltrimethoxysilane and isobutyltrimethoxysilane. The first modification provided active sites for subsequent free radical polymerization, avoiding the problem of insufficient epoxy group loading due to a lack of active sites. The second modification not only introduced epoxy groups (-C2H3O), but also utilized the nucleophilic ring-opening reaction between the epoxy groups and amino groups to "anchor" the modified nano-silica to the surface of the graphene nanosheets through chemical bonds. The silica nanoparticles acted as a physical isolation layer, effectively preventing direct contact between graphene sheets. Combined with steric hindrance and electrostatic repulsion, this significantly improved the dispersion stability of graphene in solvents or matrices. At the same time, it reduced the interaction between graphene sheets and suppressed the stacking of sheets.
[0017] This invention modifies graphene nanosheets with modified silica to form composite materials, effectively improving the dispersibility and stability of graphene nanosheets and inhibiting their spontaneous aggregation in solvents, thereby endowing the composite materials with catalytic, sensing and other properties. Attached Figure Description
[0018] Figure 1 Optical images showing the dispersion test of modified graphene prepared in xylene in the embodiments and comparative examples of this invention.
[0019] Figure 2 The images show scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectra of the modified graphene prepared in Example 2 of this invention.
[0020] Figure 3 The image shows the X-ray diffraction pattern of the modified graphene prepared in Example 2 of this invention. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0022] Example 1: A method for preparing highly dispersible modified graphene, comprising: Step 1: Modification of Nano-Silica: First, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane are added sequentially to an ethanol solution. The volume ratio of 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane is 6.5:1.5:0.8, and the volume ratio of 3-aminopropyltrimethoxysilane to the ethanol solution is 6.5:200. The ethanol solution used is an 80% ethanol solution (the ethanol solution can be prepared by anhydrous ethanol and deionized water, and the volume ratio of anhydrous ethanol to deionized water is 8:2). The pH is adjusted to 4.0 using a 1 mol / L hydrochloric acid solution. The mixture is stirred in a water bath at 60–80°C (stirring speed 200 rpm), with a reflux condenser installed to achieve stirring and reflux. The mixture is stirred for 3.5 hours to obtain a silane solution. Next, nano-silica particles (50-100 nm in diameter) were ultrasonically dispersed in anhydrous ethanol for 18 min. The mass-to-volume ratio of nano-silica particles to anhydrous ethanol was 0.8 g:4.5 mL, and the volume ratio of anhydrous ethanol to ethanol solution was 4.5:200. Silane solution was slowly poured in, and the mixture was stirred (at 60°C and 200 rpm) and refluxed for 4.5 h. Finally, modified nano-silica was obtained by centrifugation, filtration, washing, and drying. Centrifugation was performed at 8000 rpm for 10 min; filtration was carried out using a ceramic vacuum filter; washing was performed by repeatedly washing with deionized water and anhydrous ethanol three times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water); and drying was performed under vacuum at 60°C for 24 h.
[0023] Step 2: Graphene Nanosheet Modification: First, graphene nanosheets were added to a mixed solvent of toluene and ethanol at a mass-to-volume ratio of 18 mg:16 mL:1.5 mL. The mixture was ultrasonically dispersed for 20 min to form a black suspension. Then, styrenetrimethoxysilane was added under a nitrogen atmosphere at a mass-to-volume ratio of 18 mg:6.5 mL. The mixture was stirred and refluxed at 60°C for 4.5 h (stirring rate 200 rpm). After centrifugation, filtration, washing, and drying, the first modified graphene was obtained. The centrifugation step was performed at 8000 rpm for 10 min. The filtration step was performed using a ceramic vacuum filter. The washing step involved repeated washing with deionized water and anhydrous ethanol three times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water). The drying step involved vacuum drying at 60°C for 24 h.
[0024] Subsequently, under a nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane and isobutyltrimethoxysilane were added to a DMF solution, with a volume ratio of γ-glycidoxypropyltrimethoxysilane, isobutyltrimethoxysilane to DMF solution of 7.5:1.5:145; then, first-modified graphene was added, with a volume-to-mass ratio of γ-glycidoxypropyltrimethoxysilane to first-modified graphene of 7.5 mL:98 mg; the mixture was ultrasonically dispersed for 20 min, and then dibutyltin dilaurate was added and stirred, with a mass ratio of dibutyltin dilaurate to first-modified graphene of 1:98. The stirring speed was 200 rpm, the stirring time was 3.5 h, and the stirring temperature was 60 °C. Modified graphene nanosheets were obtained by centrifugation, filtration, washing, and drying. The centrifugation step was carried out in a centrifuge at 8000 rpm for 10 min; the filtration step was carried out using a ceramic vacuum filter; the washing step was carried out by repeatedly washing with deionized water and anhydrous ethanol three times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water); and the drying step was carried out by vacuum drying at 60℃ for 24 h.
[0025] Step 3: Preparation of Composite Material: Modified graphene nanosheets were added to a DMF solution at a mass-to-volume ratio of 14 mg:9 mL. The mixture was stirred at room temperature for 20 min (stirring speed 200 rpm) and then ultrasonically dispersed for 18 min to obtain a suspension. Modified nano-silica was then added to the suspension at a mass ratio of 1:2.9 to the modified graphene nanosheets. The mixture was stirred at room temperature for 20 min (stirring speed 200 rpm) and then ultrasonically dispersed for 18 min. The mixture was then stirred in a 90°C oil bath for 8 h (stirring speed 200 rpm). After cooling to room temperature, the mixture was filtered, washed, and dried sequentially to obtain the composite material. The filtration step used a microporous membrane; the washing step involved repeated washing three times with distilled water and anhydrous ethanol; and the drying step involved vacuum drying at 60°C for 24 h.
[0026] Example 2: A method for preparing highly dispersible modified graphene, comprising: Step 1, Modification of Nano-Silica: First, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane are added sequentially to an ethanol solution with a volume ratio of 7:2:1 and a volume ratio of 3-aminopropyltrimethoxysilane to ethanol solution of 7:200. The ethanol solution used is an 80% ethanol solution (which can be prepared by mixing anhydrous ethanol and deionized water with a volume ratio of anhydrous ethanol to deionized water of 8:2). The pH is adjusted to 3.5 using a 1 mol / L hydrochloric acid solution. The mixture is stirred in a 70°C water bath at a stirring speed of 250 rpm, with a reflux condenser installed to achieve stirring and reflux. The mixture is stirred for 3 hours to obtain a silane solution. Next, nano-silica particles (50-100 nm in diameter) were ultrasonically dispersed in anhydrous ethanol for 20 min. The mass-to-volume ratio of nano-silica particles to anhydrous ethanol was 1 g:5 mL, and the volume ratio of anhydrous ethanol to ethanol solution was 5:200. Silane solution was slowly poured in, and the mixture was stirred (at 70°C and 250 rpm) and refluxed for 4 h. Finally, the modified nano-silica was obtained by centrifugation, filtration, washing, and drying. Centrifugation was performed at 90,000 rpm for 9 min; filtration was carried out using a ceramic vacuum filter; washing was performed by repeatedly washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and drying was performed under vacuum at 70°C for 21 h.
[0027] Step 2, Graphene Nanosheet Modification: First, graphene nanosheets were added to a mixed solvent of toluene and ethanol, with a mass-to-volume ratio of 20 mg: 18 mL: 2 mL. The mixture was ultrasonically dispersed for 25 min to form a black suspension. Then, styrenetrimethoxysilane was added under a nitrogen atmosphere, with a mass-to-volume ratio of 20 mg: 7 mL. The mixture was stirred and refluxed at 70°C for 4 h (stirring rate 250 rpm). After centrifugation, filtration, washing, and drying, the first modified graphene was obtained. The centrifugation step was performed in a centrifuge at 9000 rpm for 9 min. The filtration step was performed using a ceramic vacuum filter. The washing step involved repeated washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol). The drying step involved vacuum drying at 70°C for 21 h.
[0028] Subsequently, under a nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane and isobutyltrimethoxysilane were added to a DMF solution, with a volume ratio of γ-glycidoxypropyltrimethoxysilane, isobutyltrimethoxysilane to DMF solution of 8:2:150; then, first-modified graphene was added, with a volume-to-mass ratio of γ-glycidoxypropyltrimethoxysilane to first-modified graphene of 8 mL:100 mg; the mixture was ultrasonically dispersed for 25 min, and then dibutyltin dilaurate was added and stirred, with a mass ratio of dibutyltin dilaurate to first-modified graphene of 1.5:100. The stirring speed was 250 rpm, the stirring time was 3 h, and the stirring temperature was 70 °C. Modified graphene nanosheets were obtained by centrifugation, filtration, washing, and drying. The centrifugation step was carried out in a centrifuge at 9000 rpm for 9 min; the filtration step was carried out using a ceramic vacuum filter; the washing step was carried out by repeatedly washing with deionized water and anhydrous ethanol 4 times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and the drying step was carried out by vacuum drying at 70℃ for 21 h.
[0029] Step 3: Preparation of Composite Material: Modified graphene nanosheets were added to a DMF solution at a mass-to-volume ratio of 15 mg:10 mL. The mixture was stirred at room temperature for 17 min (stirring speed 250 rpm) and then ultrasonically dispersed for 20 min to obtain a suspension. Modified nano-silica was then added to the suspension at a mass ratio of 1:3 to the modified graphene nanosheets. The mixture was stirred at room temperature for 17 min (stirring speed 250 rpm) and then ultrasonically dispersed for 20 min. The mixture was then stirred in an oil bath at 100 °C for 6.5 h (stirring speed 250 rpm). After cooling to room temperature, the mixture was filtered, washed, and dried sequentially to obtain the composite material. The filtration step used a microporous membrane; the washing step involved repeated washing with distilled water and anhydrous ethanol four times; and the drying step involved vacuum drying at 70 °C for 21 h.
[0030] To investigate the morphology and structure of silica-modified graphene materials, SEM combined with EDS was used to characterize the original graphene and the materials prepared in this embodiment; the surface morphology of the original graphene material is as follows: Figure 2 (a) Figure 2 As shown in (b), graphene exhibits a typical translucent sheet structure, with some areas showing curling and wrinkling, which is due to the stacking of sheets during the dispersion process; from Figure 2 (e) The EDS spectrum of the graphene material showed a large amount of C and O elements. The surface morphology of the silica-modified graphene in this embodiment is as follows: Figure 2 (c) Figure 2As shown in (d), it is clear that fine particles are densely distributed in the curled and wrinkled areas. (Comparison) Figure 2 (e) and Figure 2 The EDS spectrum of (f) shows that in addition to C and O elements, a large amount of Si elements were detected on the surface of the modified graphene, indicating that nano-SiO2 was successfully and uniformly and densely loaded on the surface of the sheet-like graphene, that is, nano-silica successfully modified the graphene nanosheets.
[0031] Figure 3 Analysis of the X-ray diffraction patterns of the composite material and the original graphene prepared in this embodiment reveals a sharp diffraction peak at 2θ = 11.20°, corresponding to the characteristic diffraction peak of the graphene crystal plane. This is one of the unique diffraction features of graphene. For the silica-modified graphene sample in this embodiment, an additional diffraction peak appears at 2θ = 22.27°, consistent with the reflection of amorphous silicon. A new peak exists at 2θ = 7.06° in the composite material, attributed to a slight leftward shift in the position of the graphene diffraction peak relative to the graphene nanosheet diffraction peak. This shift may be due to the loading of a large amount of SiO2 during the graphene modification process, resulting in a larger interlayer spacing. The interlayer spacing of the nanomaterials can be evaluated using Bragg's law. d This also confirms this conclusion: ; Where n represents the diffraction order, Indicates the wavelength of X-rays. d The interplanar spacing of nanomaterials is represented by this value. According to this calculation, the interplanar spacing of unmodified graphene is 0.79 nm, while the interplanar spacing of silica-modified graphene composites is 1.25 nm. This means that silica modification makes the tightly packed graphene structure more loose and expanded, which has a favorable effect on the dispersion behavior of composite materials.
[0032] Example 3: A method for preparing highly dispersible modified graphene, comprising: Step 1: Modification of Nano-Silica: First, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane are added sequentially to an ethanol solution. The volume ratio of 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane is 7.5:2.5:1.2, and the volume ratio of 3-aminopropyltrimethoxysilane to the ethanol solution is 7.5:200. The ethanol solution used is an 80% ethanol solution (the ethanol solution can be prepared by anhydrous ethanol and deionized water, and the volume ratio of anhydrous ethanol to deionized water is 8:2). The pH is adjusted to 3.0 using a 1 mol / L hydrochloric acid solution. The mixture is stirred in an 80℃ water bath (stirring speed 300 rpm) while a reflux condenser is installed to achieve stirring and reflux. The mixture is stirred for 2.5 hours to obtain a silane solution. Next, nano-silica particles (50-100 nm in diameter) were ultrasonically dispersed in anhydrous ethanol for 22 min. The mass-to-volume ratio of nano-silica particles to anhydrous ethanol was 1.2 g: 5.5 mL, and the volume ratio of anhydrous ethanol to ethanol solution was 5.5: 200. Silane solution was slowly poured in, and the mixture was stirred (at 80 °C and 300 rpm) and refluxed for 3.5 h. Finally, modified nano-silica was obtained by centrifugation, filtration, washing, and drying. Centrifugation was performed at 10,000 rpm for 8 min; filtration was performed using a ceramic vacuum filter; washing was performed by repeatedly washing with deionized water and anhydrous ethanol five times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol-deionized water); and drying was performed under vacuum at 80 °C for 18 h.
[0033] Step 2: Graphene Nanosheet Modification: First, graphene nanosheets were added to a mixed solvent of toluene and ethanol at a mass-to-volume ratio of 22 mg: 20 mL: 2.5 mL. The mixture was ultrasonically dispersed for 30 min to form a black suspension. Then, styrenetrimethoxysilane was added under a nitrogen atmosphere at a mass-to-volume ratio of 22 mg: 7.5 mL. The mixture was stirred and refluxed at 80°C for 3.5 h (stirring rate 300 rpm). After centrifugation, filtration, washing, and drying, the first modified graphene was obtained. The centrifugation step was performed at 10,000 rpm for 8 min. The filtration step was performed using a ceramic vacuum filter. The washing step involved repeated washing with deionized water and anhydrous ethanol five times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol-deionized water). The drying step involved vacuum drying at 80°C for 18 h.
[0034] Subsequently, under a nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane and isobutyltrimethoxysilane were added to a DMF solution, with a volume ratio of γ-glycidoxypropyltrimethoxysilane, isobutyltrimethoxysilane to DMF solution of 8.5:2.5:155; then, first-modified graphene was added, with a volume-to-mass ratio of γ-glycidoxypropyltrimethoxysilane to first-modified graphene of 8.5 mL:102 mg; the mixture was ultrasonically dispersed for 30 min, and then dibutyltin dilaurate was added and stirred, with a mass ratio of dibutyltin dilaurate to first-modified graphene of 2:102. The stirring speed was 300 rpm, the stirring time was 2.5 h, and the stirring temperature was 80 °C. Modified graphene nanosheets were obtained by centrifugation, filtration, washing, and drying. The centrifugation step was carried out in a centrifuge at 10,000 rpm for 8 min; the filtration step was carried out using a ceramic vacuum filter; the washing step was carried out by repeatedly washing with deionized water and anhydrous ethanol 5 times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol-deionized water); and the drying step was carried out by vacuum drying at 80℃ for 18 h.
[0035] Step 3: Preparation of Composite Material: Modified graphene nanosheets were added to a DMF solution at a mass-to-volume ratio of 16 mg:11 mL. The mixture was stirred at room temperature for 15 min (stirring speed 300 rpm) and then ultrasonically dispersed for 22 min to obtain a suspension. Modified nano-silica was then added to the suspension at a mass ratio of 1:3.1 to the modified graphene nanosheets. The mixture was stirred at room temperature for 15 min (stirring speed 300 rpm) and then ultrasonically dispersed for 22 min. The mixture was then stirred in an oil bath at 110°C for 5 h (stirring speed 300 rpm). After cooling to room temperature, the mixture was filtered, washed, and dried sequentially to obtain the composite material. The filtration step used a microporous membrane; the washing step involved repeated washing with distilled water and anhydrous ethanol five times; and the drying step involved vacuum drying at 80°C for 18 h.
[0036] Example 4: As a preferred embodiment of the present invention, based on any one of Examples 1 to 3, in order to further enhance the grafting efficiency of the silane coupling agent, before the graphene nanosheets are modified in step two, the graphene nanosheets can be preferentially oxidized by hydrogen peroxide with a concentration of 30% and concentrated sulfuric acid with a concentration of 98%. The volume ratio of hydrogen peroxide to concentrated sulfuric acid is 1:3. The hydrogen peroxide and concentrated sulfuric acid are mixed in an ice bath environment below 10°C, and the mixed hydrogen peroxide is slowly added dropwise to the concentrated sulfuric acid. The oxidation process is carried out at room temperature, first by ultrasonic dispersion for 1 hour, then by stirring at a stirring rate of 300 rpm for 2 hours. After the reaction, the mixture is quenched in 100 mL of ice water, and then centrifuged, filtered, washed, and vacuum dried in sequence. Comparative Example 1: A method for preparing modified graphene, comprising: Step 1, Modification of Nano-Silica: First, 3-aminopropyltriethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane are added sequentially to an ethanol solution. The volume ratio of 3-aminopropyltriethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane is 7:2:1, and the volume ratio of 3-aminopropyltriethoxysilane to the ethanol solution is 7:200. The ethanol solution used is an 80% ethanol solution (the ethanol solution can be prepared by anhydrous ethanol and deionized water, and the volume ratio of anhydrous ethanol to deionized water is 8:2). The pH is adjusted to 3.5 using a 1 mol / L hydrochloric acid solution. The mixture is stirred in a 70℃ water bath (stirring speed 250 rpm), with a reflux condenser installed to achieve stirring and reflux. The mixture is stirred for 3 hours to obtain a silane solution. Next, nano-silica particles (50-100 nm in diameter) were ultrasonically dispersed in anhydrous ethanol for 20 min. The mass-to-volume ratio of nano-silica particles to anhydrous ethanol was 1 g:5 mL, and the volume ratio of anhydrous ethanol to ethanol solution was 5:200. Silane solution was slowly poured in, and the mixture was stirred (at 70°C and 250 rpm) and refluxed for 4 h. Finally, the modified nano-silica was obtained by centrifugation, filtration, washing, and drying. Centrifugation was performed at 90,000 rpm for 9 min; filtration was carried out using a ceramic vacuum filter; washing was performed by repeatedly washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and drying was performed under vacuum at 70°C for 21 h.
[0037] Step 2, Graphene Nanosheet Modification: Same as Step 2 in Example 2.
[0038] Step 3, preparation of composite materials: consistent with step 3 in Example 2.
[0039] Comparative Example 2: A method for preparing modified graphene, comprising: Step 1, Modification of Nano-Silica: First, add 3-aminopropyltrimethoxysilane and methyltrimethoxysilane sequentially to an ethanol solution. The volume ratio of 3-aminopropyltrimethoxysilane to methyltrimethoxysilane is 7:2, and the volume ratio of 3-aminopropyltrimethoxysilane to ethanol solution is 7:200. The ethanol solution used is an 80% ethanol solution (the ethanol solution can be prepared by anhydrous ethanol and deionized water, and the volume ratio of anhydrous ethanol to deionized water is 8:2). Adjust the pH to 3.5 with a 1 mol / L hydrochloric acid solution. In a 70℃ water bath heating environment, stir and mix (stirring speed 250 rpm), while installing a reflux condenser to achieve stirring and reflux. Stir for 3 hours to obtain a silane solution. Next, nano-silica particles (50-100 nm in diameter) were ultrasonically dispersed in anhydrous ethanol for 20 min. The mass-to-volume ratio of nano-silica particles to anhydrous ethanol was 1 g:5 mL, and the volume ratio of anhydrous ethanol to ethanol solution was 5:200. Silane solution was slowly poured in, and the mixture was stirred (at 70°C and 250 rpm) and refluxed for 4 h. Finally, the modified nano-silica was obtained by centrifugation, filtration, washing, and drying. Centrifugation was performed at 90,000 rpm for 9 min; filtration was carried out using a ceramic vacuum filter; washing was performed by repeatedly washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and drying was performed under vacuum at 70°C for 21 h.
[0040] Step 2, Graphene Nanosheet Modification: Same as Step 2 in Example 2.
[0041] Step 3, preparation of composite materials: consistent with step 3 in Example 2.
[0042] Comparative Example 3: A method for preparing modified graphene, comprising: Step 1, Modification of Nano-Silica: First, add 3-aminopropyltrimethoxysilane and phenyltrimethoxysilane sequentially to an ethanol solution, with a volume ratio of 7:1 for 3-aminopropyltrimethoxysilane and 7:200 for ethanol solution. The ethanol solution used is an 80% concentration ethanol solution (which can be prepared by mixing anhydrous ethanol and deionized water, with a volume ratio of 8:2 for anhydrous ethanol and deionized water). Adjust the pH to 3.5 using a 1 mol / L hydrochloric acid solution. Mix the mixture in a 70℃ water bath with stirring (stirring speed 250 rpm), while simultaneously installing a reflux condenser to achieve stirring and reflux. Stir for 3 hours to obtain a silane solution. Next, nano-silica particles (50-100 nm in diameter) were ultrasonically dispersed in anhydrous ethanol for 20 min. The mass-to-volume ratio of nano-silica particles to anhydrous ethanol was 1 g:5 mL, and the volume ratio of anhydrous ethanol to ethanol solution was 5:200. Silane solution was slowly poured in, and the mixture was stirred (at 70°C and 250 rpm) and refluxed for 4 h. Finally, the modified nano-silica was obtained by centrifugation, filtration, washing, and drying. Centrifugation was performed at 90,000 rpm for 9 min; filtration was carried out using a ceramic vacuum filter; washing was performed by repeatedly washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and drying was performed under vacuum at 70°C for 21 h.
[0043] Step 2, Graphene Nanosheet Modification: Same as Step 2 in Example 2.
[0044] Step 3, preparation of composite materials: consistent with step 3 in Example 2.
[0045] Comparative Example 4: A method for preparing modified graphene, comprising: Step 1, Modification of nano-silica: Same as Step 1 in Example 2.
[0046] Step 2, Graphene Nanosheet Modification: First, graphene nanosheets were added to a mixed solvent of toluene and ethanol, with a mass-to-volume ratio of 20 mg: 18 mL: 2 mL. The mixture was ultrasonically dispersed for 25 min to form a black suspension. Then, styrenetrimethoxysilane was added under a nitrogen atmosphere, with a mass-to-volume ratio of 20 mg: 7 mL. The mixture was stirred and refluxed at 70°C for 4 h (stirring rate 250 rpm). After centrifugation, filtration, washing, and drying, the first modified graphene was obtained. The centrifugation step was performed in a centrifuge at 9000 rpm for 9 min. The filtration step was performed using a ceramic vacuum filter. The washing step involved repeated washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol). The drying step involved vacuum drying at 70°C for 21 h.
[0047] Subsequently, under a nitrogen atmosphere, 3-glycidyl etheroxypropyltriethoxysilane and isobutyltrimethoxysilane were added to a DMF solution, with a volume ratio of 3-glycidyl etheroxypropyltriethoxysilane, isobutyltrimethoxysilane, and DMF solution of 8:2:150. Then, first-modified graphene was added, with a volume-to-mass ratio of 3-glycidyl etheroxypropyltriethoxysilane to first-modified graphene of 8 mL:100 mg. The mixture was ultrasonically dispersed for 25 min, and then dibutyltin dilaurate was added and stirred. The mass ratio of dibutyltin dilaurate to first-modified graphene was 1.5:100. The stirring speed was 250 rpm, the stirring time was 3 h, and the stirring temperature was 70 °C. Modified graphene nanosheets were obtained by centrifugation, filtration, washing, and drying. The centrifugation step was carried out in a centrifuge at 9000 rpm for 9 min; the filtration step was carried out using a ceramic vacuum filter; the washing step was carried out by repeatedly washing with deionized water and anhydrous ethanol 4 times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and the drying step was carried out by vacuum drying at 70℃ for 21 h.
[0048] Step 3, preparation of composite materials: consistent with step 3 in Example 2.
[0049] Comparative Example 5: A method for preparing modified graphene, comprising: Step 1, Modification of nano-silica: Same as Step 1 in Example 2.
[0050] Step 2: Graphene nanosheet modification: Under a nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane and isobutyltrimethoxysilane were added to a DMF solution, with a volume ratio of γ-glycidoxypropyltrimethoxysilane, isobutyltrimethoxysilane to DMF solution of 8:2:150; then graphene nanosheets were added, with a volume-to-mass ratio of γ-glycidoxypropyltrimethoxysilane to graphene nanosheets of 8 mL:100 mg; the mixture was ultrasonically dispersed for 25 min, and then dibutyltin dilaurate was added and stirred to mix, with a mass ratio of dibutyltin dilaurate to graphene nanosheets of 1.5:100. The stirring speed was 250 rpm, the stirring time was 3 h, and the stirring temperature was 70 °C. Modified graphene nanosheets were obtained by centrifugation, filtration, washing, and drying. The centrifugation step was carried out in a centrifuge at 9000 rpm for 9 min; the filtration step was carried out using a ceramic vacuum filter; the washing step was carried out by repeatedly washing with deionized water and anhydrous ethanol 4 times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and the drying step was carried out by vacuum drying at 70℃ for 21 h.
[0051] Step 3, preparation of composite materials: consistent with step 3 in Example 2.
[0052] Comparative Example 6: A method for preparing modified graphene, comprising: Step 1, Modification of nano-silica: Same as Step 1 in Example 2.
[0053] Step 2, Graphene Nanosheet Modification: First, graphene nanosheets were added to a mixed solvent of toluene and ethanol, with a mass-to-volume ratio of 20 mg: 18 mL: 2 mL. The mixture was ultrasonically dispersed for 25 min to form a black suspension. Then, styrenetrimethoxysilane was added under a nitrogen atmosphere, with a mass-to-volume ratio of 20 mg: 7 mL. The mixture was stirred and refluxed at 70°C for 4 h (stirring rate 250 rpm). After centrifugation, filtration, washing, and drying, the first modified graphene was obtained. The centrifugation step was performed in a centrifuge at 9000 rpm for 9 min. The filtration step was performed using a ceramic vacuum filter. The washing step involved repeated washing with deionized water and anhydrous ethanol four times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol). The drying step involved vacuum drying at 70°C for 21 h.
[0054] Subsequently, under a nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane was added to a DMF solution at a volume ratio of γ-glycidoxypropyltrimethoxysilane to DMF solution of 8:150; then, first-modified graphene was added at a volume-to-mass ratio of γ-glycidoxypropyltrimethoxysilane to first-modified graphene of 8 mL:100 mg; the mixture was ultrasonically dispersed for 25 min, and then dibutyltin dilaurate was added and stirred to mix, with a mass ratio of dibutyltin dilaurate to first-modified graphene of 1.5:100. The stirring speed was 250 rpm, the stirring time was 3 h, and the stirring temperature was 70 °C. Modified graphene nanosheets were obtained by centrifugation, filtration, washing, and drying. The centrifugation step was carried out in a centrifuge at 9000 rpm for 9 min; the filtration step was carried out using a ceramic vacuum filter; the washing step was carried out by repeatedly washing with deionized water and anhydrous ethanol 4 times (i.e., repeated washing with deionized water-anhydrous ethanol-deionized water-anhydrous ethanol); and the drying step was carried out by vacuum drying at 70℃ for 21 h.
[0055] Step 3, preparation of composite materials: consistent with step 3 in Example 2.
[0056] The modified graphene materials prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to a 10-day dispersibility test and a Zeta potential test in xylene. The results are shown in the table below:
[0057] As can be seen from the above, the absolute values of the Zeta potential in Comparative Examples 1 to 6 are relatively small, and the dispersibility is poor, making them prone to agglomeration and sedimentation. In contrast, the absolute values of the Zeta potential in Examples 1 to 3 are large, which significantly improves the dispersibility of the graphene material.
Claims
1. A method for preparing highly dispersible modified graphene, characterized in that: include: Step 1: Modification of nano-silica: First, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane are added sequentially to an ethanol solution, the pH is adjusted to 3.0-4.0, and the mixture is stirred to obtain a silane solution; then, nano-silica particles are ultrasonically dispersed in anhydrous ethanol, and the silane solution is slowly poured in and stirred to mix; finally, the mixture is centrifuged, filtered, washed, and dried sequentially to obtain modified nano-silica; Step 2, Graphene Nanosheet Modification: First, graphene nanosheets are added to a mixed solvent of toluene and ethanol and ultrasonically dispersed to form a black suspension; then, under a nitrogen atmosphere, styryltrimethoxysilane is added, stirred and mixed, and after centrifugation, filtration, washing and drying, the first modified graphene is obtained. Subsequently, under a nitrogen atmosphere, γ-glycidyl etheroxypropyltrimethoxysilane and isobutyltrimethoxysilane were added to a DMF solution, followed by the addition of the first-modified graphene, ultrasonic dispersion, addition of a catalyst, stirring and mixing, centrifugation, filtration, washing, and drying to obtain modified graphene nanosheets. Step 3: Preparation of composite material: Modified graphene nanosheets are added to DMF solution, stirred and mixed, and ultrasonically dispersed to obtain a suspension; then modified nano-silica is added to the suspension, stirred and mixed, and ultrasonically dispersed; after that, the mixed solution is stirred and reacted in an oil bath, cooled to room temperature, and then filtered, washed and dried to obtain the composite material.
2. The method for preparing highly dispersible modified graphene according to claim 1, characterized in that: The volume ratio of 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltrimethoxysilane is 6.5–7.5:1.5–2.5:0.8–1.2, and the volume ratio of 3-aminopropyltrimethoxysilane to ethanol solution is 6.5–7.5:200; the ethanol solution used is an 80% ethanol solution.
3. The method for preparing highly dispersible modified graphene according to claim 1 or 2, characterized in that: The pH value in step one is achieved using a 1 mol / L hydrochloric acid solution.
4. The method for preparing highly dispersible modified graphene according to claim 1 or 3, characterized in that: The mass-to-volume ratio of the nano-silica particles to anhydrous ethanol is 0.8–1.2 g: 4.5–5.5 mL, and the volume ratio of anhydrous ethanol to ethanol solution is 4.5–5.5:
200.
5. A method for preparing highly dispersible modified graphene according to claim 1 or 3, characterized in that: The centrifugation steps in both steps one and two are performed in a centrifuge at 8000-10000 rpm for 8-10 minutes; the filtration steps are performed using a ceramic vacuum filter; the washing steps are performed by repeatedly washing with deionized water and anhydrous ethanol 3-5 times; and the drying steps are performed by vacuum drying at 60-80℃ for 18-24 hours.
6. The method for preparing highly dispersible modified graphene according to claim 1, characterized in that: The mass-to-volume ratio of graphene nanosheets, toluene, and ethanol is 18–22 mg: 16–20 mL: 1.5–2.5 mL; the mass-to-volume ratio of graphene nanosheets to styrenetrimethoxysilane is 18–22 mg: 6.5–7.5 mL.
7. The method for preparing highly dispersible modified graphene according to claim 1, characterized in that: The catalyst is dibutyltin dilaurate, and the mass ratio of dibutyltin dilaurate to the first modified graphene is 1-2:98-102.
8. The method for preparing highly dispersible modified graphene according to claim 1, characterized in that: The mass ratio of modified nano-silica to modified graphene nanosheets is 1:2.9-3.1, and the mass-to-volume ratio of modified graphene nanosheets to DMF solution is 14-16 mg:9-11 mL.
9. The method for preparing highly dispersible modified graphene according to claim 1, characterized in that: In step three, the filtration step uses a microporous membrane for filtration; the washing step involves repeatedly washing with distilled water and anhydrous ethanol 3 to 5 times; and the drying step involves vacuum drying at 60 to 80°C for 18 to 24 hours.