A method for preparing graphene dispersion based on ultrasonic assistance
By employing an ultrasound-assisted graphene dispersion preparation method, combined with the use of nano-silica, dispersion catalysts, and stabilizers, the problems of uneven graphene dispersion and poor stability were solved, achieving efficient and stable graphene dispersion preparation and improving the electrical properties and structural integrity of graphene.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- QUZHOU GRAPHENE IND RES INST
- Filing Date
- 2024-12-23
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional graphene dispersion methods are difficult to achieve uniform dispersion, the dispersion has poor stability and is prone to agglomeration and sedimentation, and ultrasonic treatment alone has problems with unstable dispersion effect and insufficient long-term stability.
An ultrasonic-assisted graphene dispersion preparation method is adopted, which involves mixing graphene powder, solvent, nano-silica, dispersion catalyst, stabilizer and reducing agent, performing ultrasonic treatment and surface modification, and combining high-temperature annealing and low-temperature freeze-drying to optimize the dispersibility and stability of graphene.
It significantly improves the dispersibility and stability of graphene in solvents, prevents graphene sheet aggregation, enhances the long-term stability and conductivity of the dispersion, and ensures the reliability and consistency of the dispersion in practical applications.
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Figure CN122254499A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of graphene technology, specifically to a method for preparing an ultrasonic-assisted graphene dispersion. Background Technology
[0002] With the rapid development of nanomaterials science, graphene, as a two-dimensional material with excellent electrical, thermal, and mechanical properties, has received widespread attention and research. Graphene shows great application potential in energy storage, electronic devices, and composite materials. However, the efficient application of graphene depends on its good dispersibility and stability in solvents. Traditional graphene dispersion methods, such as mechanical stirring and ball milling, often fail to achieve uniform dispersion of graphene, and the dispersions tend to have poor stability, easily leading to agglomeration and sedimentation.
[0003] In recent years, ultrasonic-assisted dispersion technology has gradually become a research hotspot in the field of graphene dispersion due to its advantages such as high efficiency and ease of operation. Ultrasonic treatment can generate a strong cavitation effect, which helps to break the van der Waals forces between graphene sheets, thereby achieving uniform dispersion. However, ultrasonic treatment alone still has some limitations, such as unstable dispersion effect and insufficient long-term stability of the dispersion.
[0004] To overcome current limitations, this invention proposes a method for preparing graphene dispersions based on ultrasound assistance. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing graphene dispersion based on ultrasound assistance, so as to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for preparing an ultrasound-assisted graphene dispersion includes the following steps:
[0008] Graphene powder, solvent, nano-silica, dispersing catalyst, stabilizer and reducing agent are mixed to form a preliminary mixture;
[0009] The initial mixture was pretreated with a surface modifier to improve the affinity and dispersibility of graphene in solvents;
[0010] The preliminary mixture is subjected to ultrasonic treatment for 5 to 60 minutes to promote uniform dispersion of graphene in the solvent. At the same time, the surface properties of nano-silica are used to enhance the spatial stability between graphene sheets. The dispersion catalyst accelerates the dispersion process, the stabilizer improves the long-term stability of the dispersion, and the reducing agent improves the reduction degree of graphene.
[0011] The mixture after ultrasonic treatment is filtered and centrifuged to remove undispersed particles, resulting in a graphene dispersion with excellent stability and dispersion efficiency.
[0012] The dispersion was subjected to high-temperature annealing to further improve the conductivity and structural integrity of graphene.
[0013] The obtained graphene dispersion was subjected to low-temperature freeze-drying to further improve the long-term stability of the dispersion.
[0014] Preferably, during the ultrasonic treatment, the ultrasonic frequency is 20kHz to 100kHz, and more preferably 40kHz to 80kHz.
[0015] Preferably, the solvent is selected from one or more of water, ethanol, N-methylpyrrolidone, and dimethyl sulfoxide, and is more preferably a mixture of N-methylpyrrolidone and dimethyl sulfoxide.
[0016] Preferably, the average particle size of the nano-silica is 10 nm to 100 nm, and more preferably 20 nm to 50 nm.
[0017] Preferably, the dispersion catalyst is selected from one or more of polyacrylic acid, polyvinyl alcohol, and polyethylene glycol, with polyvinyl alcohol being the most preferred.
[0018] The stabilizer is selected from one or more of polyvinylpyrrolidone, polyoxyethylene, and polyoxypropylene, preferably polyvinylpyrrolidone.
[0019] Preferably, the reducing agent is selected from one or more of ascorbic acid, hydrazine hydrate, and sodium borohydride, with ascorbic acid being the most preferred.
[0020] Preferably, the temperature for the low-temperature freeze-drying treatment is -50°C to -80°C, and the treatment time is 12 hours to 48 hours;
[0021] The high-temperature annealing treatment is performed at a temperature of 200°C to 500°C for 1 hour to 5 hours, preferably at a temperature of 300°C to 400°C for 2 hours to 3 hours.
[0022] The concentration of the graphene dispersion is from 0.1 mg / mL to 10 mg / mL, preferably from 0.5 mg / mL to 5 mg / mL.
[0023] Preferably, in the centrifugation separation step, the centrifugation speed is 3000 rpm to 10000 rpm, the centrifugation time is 10 minutes to 30 minutes, preferably 5000 rpm to 8000 rpm, and the centrifugation time is 15 minutes to 20 minutes.
[0024] Preferably, the filter membrane used in the filtration step has a pore size of 0.2 μm to 0.45 μm, and more preferably 0.22 μm.
[0025] Preferably, the pretreatment step of the surface modifier includes stirring and mixing graphene powder and surface modifier at room temperature for 1 to 5 hours, preferably 2 to 3 hours.
[0026] This invention has at least the following beneficial effects:
[0027] (1) In this scheme, nano-silica is added to enhance the spatial stability between graphene sheets by utilizing its surface properties, thereby preventing the graphene sheets from re-aggregating. The dispersion catalyst accelerates the dispersion process and improves the dispersion efficiency. The pretreatment step of the surface modifier significantly improves the affinity between graphene and solvent, further promoting the uniform dispersion of graphene.
[0028] (2) The addition of stabilizer in this scheme effectively improves the long-term stability of the dispersion and avoids sedimentation during storage.
[0029] Low-temperature freeze-drying further enhances the long-term stability of the dispersion, ensuring its reliability and consistency in practical applications.
[0030] (3) In this scheme, the high-temperature annealing treatment optimizes the electrical conductivity and structural integrity of graphene, and improves its electrical properties. The use of reducing agent increases the reduction degree of graphene, further improving its electrical and chemical properties. Attached Figure Description
[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0032] Figure 1 This is a flowchart of a method for preparing an ultrasonic-assisted graphene dispersion according to the present invention. Detailed Implementation
[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0034] Example 1
[0035] Please see Figure 1 This invention provides a technical solution: a method for preparing graphene dispersion based on ultrasound assistance. This method effectively improves the dispersibility and stability of graphene in solvents through specific steps, while also improving the physicochemical properties of graphene. See the preparation process below for details:
[0036] First, graphene powder (particle size <1 μm), solvent (such as a mixture of N-methylpyrrolidone and dimethyl sulfoxide), nano-silica (average particle size 10 nm-100 nm), dispersing catalyst (such as polyvinyl alcohol), stabilizer (such as polyvinylpyrrolidone), and reducing agent (such as ascorbic acid) are mixed in predetermined proportions to form a preliminary mixture. Here, the recommended mass ratio of nano-silica to graphene is 1:20 to 1:50; the mass ratio of dispersing catalyst to graphene is 1:100 to 1:150; the mass ratio of stabilizer to graphene is 1:100 to 1:150; and the mass ratio of reducing agent to graphene is 1:200 to 1:300.
[0037] Next, the above preliminary mixture is mixed with a selected surface modifier (such as a silane coupling agent) at a mass ratio of 1:200 to 1:300 and stirred at room temperature for 2 to 3 hours to enhance the affinity and dispersibility between graphene and solvent.
[0038] The pretreated mixture is placed in an ultrasonic cleaner and subjected to ultrasonic treatment at a frequency of 40 kHz to 80 kHz for 5 to 60 minutes. This step helps to uniformly disperse graphene in the solvent and utilizes the surface properties of nano-silica to enhance the spatial stability between graphene sheets.
[0039] After ultrasonic treatment, the mixture was filtered using a 0.22 μm pore size filter membrane to remove undispersed large particles. Subsequently, the filtered liquid was centrifuged at 5000 rpm to 8000 rpm for 15 to 20 minutes to further remove impurities and obtain a relatively pure graphene dispersion.
[0040] The obtained graphene dispersion was placed in a heating furnace and subjected to high-temperature annealing at 300°C to 400°C for 2 to 3 hours to optimize the conductivity and structural integrity of the graphene.
[0041] Finally, the graphene dispersion that has undergone high-temperature annealing is subjected to low-temperature freeze-drying at -50°C to -80°C for 12 to 48 hours to increase the long-term stability of the dispersion.
[0042] The process includes: ultrasonic treatment (frequency 40kHz to 80kHz, treatment time 5 to 60 minutes); solvent (a mixture of N-methylpyrrolidone and dimethyl sulfoxide recommended); nano-silica (average particle size 20nm to 50nm); dispersion catalyst (polyvinyl alcohol); stabilizer (polyvinylpyrrolidone); reducing agent (ascorbic acid); low-temperature freeze drying (temperature -50℃ to -80℃, time 12 to 48 hours); high-temperature annealing (temperature 300℃ to 400℃, time 2 to 3 hours); graphene dispersion concentration (0.5mg / mL to 5mg / mL); centrifugation (speed 5000rpm to 8000rpm, time 15 to 20 minutes); filtration (filter membrane pore size 0.22μm); and surface modifier pretreatment (stirring at room temperature for 2 to 3 hours).
[0043] Through the above steps, a graphene dispersion with high stability and excellent dispersibility can be effectively prepared.
[0044] Example 2
[0045] Weigh 0.1 g of graphene powder (particle size < 1 μm). Add it to 100 mL of a mixed solvent of N-methylpyrrolidone and dimethyl sulfoxide (volume ratio 1:1). Then add 0.005 g of nano-silica (average particle size 30 nm), 0.001 g of polyvinyl alcohol, 0.001 g of polyvinylpyrrolidone, and 0.001 g of ascorbic acid. Stir with a magnetic stirrer at room temperature for 30 minutes to ensure thorough mixing of all components.
[0046] Add 0.0005 g of silane coupling agent to the above mixture. Continue stirring at room temperature for 3 hours to improve the affinity and dispersibility of graphene in the solvent.
[0047] The mixture was placed in an ultrasonic cleaner, set to a frequency of 40 kHz, and treated for 30 minutes. During this time, the appearance of the mixture was observed and recorded to ensure uniform dispersion of the graphene.
[0048] The mixture was filtered using a 0.22 μm pore size membrane to remove undispersed large particles. The filtered liquid was then centrifuged at 6000 rpm for 15 minutes to further remove impurities, yielding a relatively pure graphene dispersion.
[0049] The centrifuged dispersion was poured into a ceramic boat and placed in a heating furnace. The temperature was set to 350℃, and the annealing process was carried out for 2 hours to optimize the conductivity and structural integrity of the graphene.
[0050] The annealed dispersion was transferred to a freeze dryer. The temperature was set to -60℃ and the treatment lasted for 24 hours to improve the long-term stability of the dispersion. The final graphene dispersion was obtained.
[0051] Example 3
[0052] Weigh 0.2 g of graphene powder (particle size < 1 μm). Add it to 200 mL of a mixed solvent of N-methylpyrrolidone and dimethyl sulfoxide (volume ratio 1:1). Then add 0.01 g of nano-silica (average particle size 40 nm), 0.002 g of polyvinyl alcohol, 0.002 g of polyvinylpyrrolidone, and 0.002 g of ascorbic acid. Stir with a magnetic stirrer at room temperature for 30 minutes to ensure thorough mixing of all components.
[0053] Add 0.001 g of silane coupling agent to the above mixture. Continue stirring at room temperature for 2 hours to improve the affinity and dispersibility of graphene in the solvent.
[0054] The mixture was placed in an ultrasonic cleaner, set to a frequency of 60 kHz, and treated for 45 minutes. During this time, the appearance of the mixture was observed and recorded to ensure uniform dispersion of the graphene.
[0055] The mixture was filtered using a 0.22 μm pore size membrane to remove undispersed large particles. The filtered liquid was then centrifuged at 7000 rpm for 20 minutes to further remove impurities, yielding a relatively pure graphene dispersion.
[0056] The centrifuged dispersion was poured into a ceramic boat and placed in a furnace. Annealing was performed at 400℃ for 3 hours to optimize the conductivity and structural integrity of the graphene. The annealed dispersion was then transferred to a freeze dryer. The dryer was set to -70℃ and treated for 36 hours to improve the long-term stability of the dispersion. The final graphene dispersion was obtained.
[0057] Example 4
[0058] Weigh 0.5 g of graphene powder (particle size < 1 μm). Add it to 500 mL of a mixed solvent of N-methylpyrrolidone and dimethyl sulfoxide (volume ratio 1:1). Then add 0.025 g of nano-silica (average particle size 50 nm), 0.005 g of polyvinyl alcohol, 0.005 g of polyvinylpyrrolidone, and 0.005 g of ascorbic acid. Stir with a magnetic stirrer at room temperature for 30 minutes to ensure thorough mixing of all components.
[0059] Add 0.0025 g of silane coupling agent to the above mixture. Continue stirring at room temperature for 3 hours to improve the affinity and dispersibility of graphene in the solvent.
[0060] The mixture was placed in an ultrasonic cleaner, with a frequency set to 50 kHz and a treatment time of 60 minutes. During this time, the appearance changes of the mixture were observed and recorded to ensure uniform dispersion of the graphene.
[0061] The mixture was filtered using a 0.22 μm pore size membrane to remove undispersed large particles. The filtered liquid was then centrifuged at 8000 rpm for 20 minutes to further remove impurities, yielding a relatively pure graphene dispersion.
[0062] The centrifuged dispersion was poured into a ceramic boat and placed in a heating furnace. The temperature was set to 300℃, and the annealing treatment was carried out for 2 hours to optimize the conductivity and structural integrity of the graphene.
[0063] The annealed dispersion was transferred to a freeze dryer. The temperature was set to -80℃, and the treatment lasted for 48 hours to improve the long-term stability of the dispersion. The final graphene dispersion was obtained.
[0064] Comparative Example 1
[0065] Weigh 0.1 g of graphene powder (particle size < 1 μm). Add it to 100 mL of pure water, without adding nano-silica, dispersing catalyst, stabilizer, or reducing agent. Stir with a magnetic stirrer at room temperature for 30 minutes to ensure the graphene powder is dispersed as much as possible.
[0066] The mixture was placed in an ultrasonic cleaner, the frequency was set to 40 kHz, and the treatment time was 30 minutes. During this time, the appearance changes of the mixture were observed and recorded.
[0067] The mixture was filtered using a 0.22 μm pore size membrane to remove undispersed large particles. The filtered liquid was then centrifuged at 6000 rpm for 15 minutes to further remove impurities, yielding a relatively pure graphene dispersion.
[0068] The centrifuged dispersion was poured into a ceramic boat and placed in a heating furnace. The temperature was set to 350℃, and the annealing process was carried out for 2 hours to optimize the conductivity and structural integrity of the graphene.
[0069] The annealed dispersion was transferred to a freeze dryer. The temperature was set to -60℃ and the treatment lasted for 24 hours to improve the long-term stability of the dispersion. The final graphene dispersion was obtained.
[0070] Comparative Example 2
[0071] Weigh 0.1 g of graphene powder (particle size < 1 μm). Add it to 100 mL of a mixed solvent of N-methylpyrrolidone and dimethyl sulfoxide (volume ratio 1:1), without adding nano-silica, dispersing catalyst, stabilizer, or reducing agent. Stir with a magnetic stirrer at room temperature for 30 minutes to ensure the graphene powder is dispersed as much as possible.
[0072] The mixture was placed in an ultrasonic cleaner, the frequency was set to 40 kHz, and the treatment time was 30 minutes. During this time, the appearance changes of the mixture were observed and recorded.
[0073] The mixture was filtered using a 0.22 μm pore size membrane to remove undispersed large particles. The filtered liquid was then centrifuged at 6000 rpm for 15 minutes to further remove impurities, yielding a relatively pure graphene dispersion.
[0074] The centrifuged dispersion was poured into a ceramic boat and placed in a heating furnace. The temperature was set to 350℃, and the annealing process was carried out for 2 hours to optimize the conductivity and structural integrity of the graphene.
[0075] The annealed dispersion was transferred to a freeze dryer. The temperature was set to -60℃ and the treatment lasted for 24 hours to improve the long-term stability of the dispersion. The final graphene dispersion was obtained.
[0076] By comparing the above embodiments and comparative examples, the following conclusions can be drawn:
[0077] The graphene dispersions prepared in Examples 1-4 exhibit high stability and dispersibility, with no obvious agglomeration between graphene sheets, and significantly improved electrical conductivity. Microscopic observation revealed that the graphene particles in the dispersions were uniformly distributed, had small particle sizes, and showed no significant sedimentation after prolonged standing.
[0078] Comparative Example 1, due to the absence of nano-silica, dispersing catalyst, stabilizer, and reducing agent, resulted in poor graphene dispersion, poor dispersion stability, and a tendency to settle. Microscopic observation revealed a large number of graphene aggregates in the dispersion, indicating poor electrical conductivity.
[0079] Although Comparative Example 2 used the same solvent system as the Examples, its dispersion and stability were still inferior to the Examples due to the lack of necessary additives. Microscopic observation showed that the dispersion contained more graphene aggregates, and its conductivity and stability were lower than those of the Examples.
[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0081] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing an ultrasound-assisted graphene dispersion, characterized in that: Includes the following steps: Graphene powder, solvent, nano-silica, dispersing catalyst, stabilizer and reducing agent are mixed to form a preliminary mixture; The initial mixture was pretreated with a surface modifier to improve the affinity and dispersibility of graphene in solvents; The preliminary mixture is subjected to ultrasonic treatment for 5 to 60 minutes to promote uniform dispersion of graphene in the solvent. At the same time, the surface properties of nano-silica are used to enhance the spatial stability between graphene sheets. The dispersion catalyst accelerates the dispersion process, the stabilizer improves the long-term stability of the dispersion, and the reducing agent improves the reduction degree of graphene. The mixture after ultrasonic treatment is filtered and centrifuged to remove undispersed particles and obtain a graphene dispersion. The dispersion was subjected to high-temperature annealing. The obtained graphene dispersion was subjected to low-temperature freeze-drying to improve its long-term stability.
2. The method for preparing an ultrasound-assisted graphene dispersion according to claim 1, characterized in that: During the ultrasonic processing, the ultrasonic frequency is from 20kHz to 100kHz.
3. The method for preparing an ultrasound-assisted graphene dispersion according to claim 1, characterized in that: The solvent is selected from one or more of water, ethanol, N-methylpyrrolidone, and dimethyl sulfoxide.
4. The method for preparing an ultrasound-assisted graphene dispersion according to claim 1, characterized in that: The average particle size of the nano-silica is 10 nm to 100 nm.
5. The method for preparing an ultrasonic-assisted graphene dispersion according to claim 1, characterized in that: The dispersion catalyst is selected from one or more of polyacrylic acid, polyvinyl alcohol, and polyethylene glycol; The stabilizer is selected from one or more of polyvinylpyrrolidone, polyoxyethylene, and polyoxypropylene.
6. The method for preparing an ultrasonically assisted graphene dispersion according to claim 1, characterized in that: The reducing agent is selected from one or more of ascorbic acid, hydrazine hydrate, and sodium borohydride.
7. The method for preparing an ultrasonically assisted graphene dispersion according to claim 1, characterized in that: The low-temperature freeze-drying process is carried out at a temperature of -50°C to -80°C for a duration of 12 to 48 hours. The high-temperature annealing treatment is performed at a temperature of 200°C to 500°C for a duration of 1 hour to 5 hours. The concentration of the graphene dispersion is from 0.1 mg / mL to 10 mg / mL.
8. The method for preparing an ultrasonic-assisted graphene dispersion according to claim 1, characterized in that: In the centrifugation separation step, the centrifugation speed is 3000 rpm to 10000 rpm, and the centrifugation time is 10 minutes to 30 minutes.
9. The method for preparing an ultrasonically assisted graphene dispersion according to claim 1, characterized in that: The filter membrane used in the filtration step has a pore size of 0.2 μm to 0.45 μm.
10. The method for preparing an ultrasound-assisted graphene dispersion according to claim 1, characterized in that: The pretreatment step of the surface modifier includes stirring and mixing graphene powder with the surface modifier at room temperature for 1 to 5 hours.