A method for preparing a regularly arranged graphene oxide film by slit-induced self-assembly

Abstract

The application discloses a method for preparing regularly arranged graphene oxide film through slit-induced self-assembly, and belongs to the technical field of graphene oxide film preparation. The method comprises the following steps: preparing a device for containing graphene oxide solution and forming a slit condition, wherein the device comprises two polytetrafluoroethylene plates and two blocking plates; one of the polytetrafluoroethylene plates is used as a substrate, and the opposite two ends of the polytetrafluoroethylene are blocked by the two blocking plates, so that a region for containing graphene oxide solution is formed in the middle of the substrate; graphene oxide solution is contained in the middle of the substrate, then another polytetrafluoroethylene plate is placed on the top of the blocking plate, a slit condition is formed between the two polytetrafluoroethylene plates, and a regularly arranged graphene oxide film is obtained through drying. The method effectively enables graphene oxide to spontaneously arrange in a regular layer during the drying process, and greatly improves the heat transfer efficiency of the graphene oxide film.

Description

Technical Field

[0001] This invention relates to the field of graphene oxide film preparation technology, and more specifically to a method for preparing regularly arranged graphene oxide films by slit-induced self-assembly. Background Technology

[0002] Graphene, as a type of graphene, is composed of sp 2 Graphene is a stable two-dimensional atomic crystal material with a hexagonal honeycomb crystal structure composed of hybrid carbon atoms. It possesses superior properties unmatched by other materials, such as high thermal conductivity, high carrier mobility, and high mechanical strength, and has significant development prospects in the fields of materials science, electronics, photonics, energy, biomedicine, and thermal conductivity. Graphene was first discovered in 2004 by two scientists from the University of Manchester in the UK, Andre Geim and Konstantin Novoselov, who obtained a single-atom-thick graphene film by repeatedly peeling highly oriented pyrolytic graphite with adhesive tape, a method they termed mechanical exfoliation.

[0003] Mechanical exfoliation can produce high-quality graphene, but it suffers from high cost, significant human error, and low yield, failing to meet the requirements for industrial and large-scale production and currently only suitable for laboratory research. After more than a decade of development, graphene film preparation methods have made significant progress, primarily including redox methods, mechanical exfoliation, silicon carbide epitaxy, and chemical vapor deposition. Graphene oxide, an oxygen-containing derivative of graphene, possesses numerous advantages such as excellent molecular sieving ability, ease of functionalization modification, stacking into films, good chemical stability, and good thermal conductivity. Furthermore, its simple preparation method and low cost have led to its application in thermally conductive film materials.

[0004] With the development of microelectronics integration technology, the size of electronic components has been greatly reduced, and electronic devices are developing towards integration, miniaturization, and high density. However, as the integration level and power density of electronic components continue to increase, their heat generation and power dissipation density are also constantly increasing, making heat dissipation a critical issue. Commonly used thermally conductive materials are mostly metals, plastics, and some inorganic non-metallic materials. Graphene oxide film, as a novel thermally conductive and heat-dissipating material, has a unique structure with a distinct layered structure. This layered structure not only adapts well to various surfaces and shields heat sources and components but also improves the performance of electronic products. Compared with other thermally conductive materials, graphene oxide film has unique structural characteristics, such as good anisotropy and surface thermal conductivity. However, current methods for preparing graphene oxide films result in a lack of regular orientation of graphene oxide during film formation, leading to disordered orientation and hindering further improvements in thermal and electrical conductivity. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a method for preparing regularly arranged graphene oxide films through slit-induced self-assembly. The preparation method of this invention effectively enables graphene oxide to spontaneously undergo regular layered arrangement during the drying process, thereby significantly improving the heat transfer efficiency of the graphene oxide film.

[0006] The purpose of this invention is to provide a method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly, comprising the following steps:

[0007] Step 1: Prepare an apparatus for holding the graphene oxide solution and creating slit conditions.

[0008] The device includes two polytetrafluoroethylene (PTFE) plates and two sealing plates; one PTFE plate serves as a base, and the two sealing plates seal the opposite ends of the PTFE plate, thereby forming a region in the middle of the base that holds a graphene oxide solution.

[0009] Step 2: Place a graphene oxide solution in the middle of the substrate, and then cover the top of the sealing plate with another polytetrafluoroethylene plate, forming a slit between the two polytetrafluoroethylene plates. Dry to obtain a graphene oxide film with regular orientation.

[0010] Preferably, the concentration of the graphene oxide solution is 5-10 mg / ml.

[0011] Preferably, the graphene oxide solution is prepared by adding graphene oxide to water as a solvent, magnetically stirring for 10-20 minutes, ultrasonically stirring for 10-20 minutes, and repeating the magnetic stirring and ultrasonic stirring three times to obtain the solution.

[0012] Preferably, before use, the polytetrafluoroethylene (PTFE) plate is subjected to ultrasonic cleaning for 3-10 minutes and plasma cleaning to remove impurities; during plasma cleaning, the power is 50-70W and the time is 4-6 minutes.

[0013] Preferably, the contact angle of the polytetrafluoroethylene plate is 90°-120°.

[0014] Preferably, the sealing plate has a thickness of 1-6 mm, a width of 1-3 mm, and a length that is the same as the width of the polytetrafluoroethylene plate.

[0015] Preferably, the sealing plate is an acrylic plate, a glass plate, or a polytetrafluoroethylene plate.

[0016] Preferably, a vacuum drying oven is used for drying, with a drying temperature of 80-120℃ and a drying time of 24-72 hours.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention provides a method for preparing regularly arranged graphene oxide films by slit evaporation self-assembly. This method can control the evaporation self-assembly through slits to make the graphene oxide films oriented and regularly arranged. At the same time, it can also conveniently and precisely control the size and thickness of the prepared graphene oxide films, thereby preparing graphene oxide films with excellent thermal transfer properties, mechanical properties, electrical properties and other properties. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the device prepared according to the present invention;

[0020] Figure 2 This is a flowchart illustrating the preparation of graphene oxide films according to the present invention;

[0021] Figure 3 A scanning electron microscope cross-sectional image of the graphene oxide film prepared in Example 1 of this invention;

[0022] Figure 4 This is a performance comparison diagram of the graphene oxide films prepared in Example 1 of the present invention and in comparative document 1;

[0023] Figure 5 This is a scanning electron microscope cross-sectional image of the graphene oxide film prepared in Example 2 of the present invention;

[0024] Figure 6 This is a scanning electron microscope cross-sectional image of the graphene oxide film prepared in Example 3 of the present invention.

[0025] Figure label:

[0026] 1-Polytetrafluoroethylene vinyl sheet, 2-Sealing plate, 3-Drop-coated graphene oxide, 4-Graphene oxide suspension, 5-Graphene oxide film. Detailed Implementation

[0027] 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. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0028] This invention uses elongated acrylic sheets to seal both ends of the polytetrafluoroethylene (PTFE) substrate, creating a region in the center of the substrate capable of holding a graphene oxide solution. The thickness of the regularly arranged graphene oxide film can be controlled by adjusting the thickness of the elongated acrylic sheets and the graphene concentration, thereby controlling the width of the slit between the two PTFE substrates and consequently the thickness and arrangement of the regularly arranged graphene oxide film. Another PTFE substrate with a specific contact angle is placed over the solution. Due to the thickness of the acrylic sheets sealing both ends, a slit is created. Capillary forces between the liquid bridges cause the graphene oxide to arrange uniformly and regularly at the gas-liquid-solid three-phase contact line, i.e., on the surface of the graphene oxide during evaporation, forming a directionally arranged graphene oxide film. The reaction system is dried using a vacuum drying oven. After drying, a layer of the directionally arranged graphene oxide film grows on both the upper and lower PTFE substrates, which can be directly peeled off with clean tweezers without breaking. In controlling the thickness, the higher the concentration of graphene oxide, the thicker the film; the thicker the acrylic sheet, that is, the wider the slit, the thicker the film.

[0029] The graphene oxide of this invention was prepared according to the Hummers method, with the reaction system being 98% concentrated sulfuric acid containing dissolved sodium nitrate, and potassium permanganate as the oxidant. The reference is "Preparation of Graphitic Oxide" published by JrW, Offeman RE et al. in the *Journal of the American Chemical Society* (doi: 10.1021 / ja01539a017?journalCode=jacsat).

[0030] The preparation process is as follows: High-purity graphite powder is added to 98% concentrated sulfuric acid containing dissolved sodium nitrate. The reaction system is placed at 0°C, and potassium permanganate is slowly added with continuous stirring. The reaction is carried out for 5 hours at 0°C and then for 2 hours at a medium temperature of 35°C. A certain amount of deionized water is then added, and the system is placed at 98°C for another 15 minutes. After the reaction is complete, the excess potassium permanganate that did not participate in the reaction is reduced and removed using hydrogen peroxide solution. The reaction product is washed repeatedly by centrifugation with deionized water until no sulfate ions are detected.

[0031] Before using a polytetrafluoroethylene (PTFE) sheet as a substrate, the PTFE sheet is polished with a polishing agent (DNW1 type water-soluble diamond polishing paste) to obtain a PTFE sheet with a contact angle of 90-120°.

[0032] Example 1

[0033] A method for preparing regularly arranged graphene oxide films via slit evaporation self-assembly is illustrated in the flowchart below. Figure 2 As shown, it includes the following steps:

[0034] 50 mg of graphene oxide powder was dissolved in 10 ml of water. The solution was stirred with a magnetic stirrer for 15 min, followed by ultrasonic stirring for 15 min. This process was repeated three times to prepare a 5 mg / ml graphene oxide suspension. Two PTFE (polytetrafluoroethylene) plates with dimensions of 30*60*2 mm and a contact angle of 100° were selected as substrates. These substrates were ultrasonically cleaned in ultrapure water for 5 min, followed by cleaning with 60 W oxygen in a plasma cleaner for 5 min to ensure thorough cleaning. Two acrylic plates with dimensions of 30*3*5 mm were used to seal both ends of the PTFE substrates (see schematic diagram). Figure 1 (As shown). 6 ml of the above suspension was drop-coated onto the above polytetrafluoroethylene (PTFE) substrate and spread evenly. Another PTFE substrate was placed on top of the acrylic plate, forming a 5 mm wide slit. The entire reaction system was placed in a vacuum drying oven and dried at 80°C for 48 hours. After drying, the film was removed. The flow chart is shown below. Figure 2 As shown, the prepared film thickness is approximately 15 μm. Figure 3 As shown.

[0035] Example 2

[0036] A method for preparing regularly arranged graphene oxide films via slit evaporation self-assembly includes the following steps:

[0037] 100 mg of graphene oxide powder was dissolved in 10 ml of water. The solution was stirred with a magnetic stirrer for 15 min, followed by ultrasonic stirring for 15 min. This process was repeated three times to prepare a 10 mg / ml graphene oxide suspension. Two PTFE (polytetrafluoroethylene) plates with dimensions of 50 mm x 50 mm x 2 mm and a contact angle of 100° were selected as substrates. These substrates were ultrasonically cleaned in ultrapure water for 5 min, followed by cleaning with 60 W oxygen in a plasma cleaner for 5 min to ensure thorough cleaning. Two acrylic plates with dimensions of 50 mm x 3 mm x 2 mm were used to seal both ends of the PTFE substrate. 5 ml of the above suspension was drop-coated onto the PTFE substrate and spread evenly. Another PTFE substrate was placed on top of the acrylic plate, forming a 2 mm wide slit. The entire reaction system was placed in a vacuum drying oven and dried at 120°C for 72 hours. After drying, the film was removed. The thickness of the prepared film was approximately 20 μm. Figure 5 As shown.

[0038] Example 3

[0039] A method for preparing regularly arranged graphene oxide films via slit evaporation self-assembly includes the following steps:

[0040] Dissolve 70 mg of graphene oxide powder in 10 ml of water, stir with a magnetic stirrer for 15 min, then sonicate for 15 min, repeating three times to prepare a 7 mg / ml graphene oxide suspension. Use two PTFE (polytetrafluoroethylene) plates (50*30*2 mm, 100° contact angle) as substrates. Clean the substrates with ultrasonic in ultrapure water for 5 min, then clean them with oxygen at 60 W in a plasma cleaner for 5 min to ensure thorough cleaning. Seal both ends of the PTFE substrates with two acrylic plates (50*3*2 mm). Apply 4 ml of the above suspension to the PTFE substrates and spread it evenly. Place another PTFE substrate on top of the acrylic plate, forming a 2 mm wide slit. The entire reaction system was placed in a vacuum drying oven and dried at 120°C for 72 hours. After drying, the film was removed. The thickness of the prepared film was approximately 12 μm. Figure 6 As shown.

[0041] Example 4

[0042] A method for preparing regularly arranged graphene oxide films via slit evaporation self-assembly includes the following steps:

[0043] Dissolve 80 mg of graphene oxide powder in 10 ml of water, stir with a magnetic stirrer for 10 min, then sonicate for 10 min, repeating three times to prepare an 8 mg / ml graphene oxide suspension. Two PTFE plates (50*50*2 mm, 90° contact angle) were selected as substrates. These substrates were ultrasonically cleaned in ultrapure water for 3 min, then cleaned with oxygen at 50 W for 6 min in a plasma cleaner to ensure thorough cleaning. Two glass plates (50*1*6 mm) were used to seal both ends of the PTFE substrates. 4 ml of the above suspension was drop-coated onto the PTFE substrates and spread evenly. Another PTFE substrate was placed on top of the glass plates, forming a 6 mm wide slit. The entire reaction system was placed in a vacuum drying oven and dried at 100°C for 48 h. After drying, the film was removed.

[0044] Example 5

[0045] A method for preparing regularly arranged graphene oxide films via slit evaporation self-assembly includes the following steps:

[0046] Dissolve 60 mg of graphene oxide powder in 10 ml of water, stir with a magnetic stirrer for 20 min, then sonicate for 20 min, repeating three times to prepare a 6 mg / ml graphene oxide suspension. Use two PTFE plates (50*50*2 mm, 90° contact angle) as substrates. Clean the substrates with ultrasonic in ultrapure water for 3 min, then in a plasma cleaner with 50W oxygen for 6 min to ensure thorough cleaning. Use two PTFE plates (50*2*1 mm) as sealing plates to seal both ends of the PTFE substrate. Drop 4 ml of the above suspension onto the PTFE substrate and spread it evenly. Place another PTFE substrate on top of the sealing plate (PTFE plate) to form a 1 mm wide slit. The entire reaction system was placed in a vacuum drying oven and dried at 120°C for 24 hours. After drying, the film was removed.

[0047] Comparative Example 1

[0048] 100 mg of graphene oxide powder was dissolved in 10 ml of water. The solution was stirred with a magnetic stirrer for 15 min, followed by ultrasonic stirring for 15 min. This process was repeated three times to prepare a 10 mg / ml graphene oxide suspension. A 50*50*2 mm acrylic sheet was used as the substrate and washed in ultrapure water for 5 min to ensure thorough cleaning. The edges of the acrylic sheet were sealed with tape to create an area suitable for holding the graphene oxide suspension. 4 ml of the suspension was drop-coated onto the acrylic substrate and spread evenly. The entire reaction system was placed in a vacuum drying oven and dried at 120°C for 72 h. After drying, the film was removed to form a conventional graphene oxide film for comparison.

[0049] Figure 3 This is a scanned image of the graphene oxide film prepared in Example 1, from... Figure 3 It can be seen that the graphene oxide film prepared by this method is oriented and regularly arranged, and the layered structure formed by self-assembly is obvious. It can also be seen that the graphene oxide film prepared by this method is uniform and the thickness is controllable.

[0050] Figure 4 This is a performance comparison graph of the graphene oxide films prepared in Example 1 and Comparative Example 1, from... Figure 4 It can be seen that the graphene oxide film prepared by the method (Example 1) has better heat transfer effect and more uniform temperature than the graphene oxide film prepared by the conventional method (Comparative Example 1). Under the same heat source, the temperature at the end of the film has a certain difference, and the thermal diffusivity is improved to a certain extent.

[0051] This invention utilizes the regularly oriented graphene oxide film to prepare a graphene oxide heat dissipation film with a high thermal diffusivity. A portion of this graphene oxide film is then adhered to a heat source, such as a mobile phone CPU or GPU. Heat can be transferred from the heat source to the surface of the graphene oxide film and then rapidly and uniformly transferred to the outer casing or other components in contact with air for heat dissipation, thus enabling the CPU, GPU, and other chips to operate normally. Furthermore, due to the excellent flexibility of the graphene oxide film, it can be bent and even bent in multiple layers, making it suitable for irregularly shaped heat sources, greatly improving the limitations of traditional heat dissipation methods.

[0052] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0053] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly, characterized in that, Includes the following steps: Step 1: Prepare an apparatus for holding the graphene oxide solution and creating slit conditions. The device includes two polytetrafluoroethylene (PTFE) plates (1) and two sealing plates (2); one of the PTFE plates (1) serves as a substrate, and the two sealing plates (2) seal the opposite ends of the PTFE plate (1), so that a region for holding graphene oxide solution is formed in the middle of the substrate; the contact angle of the PTFE plate (1) is 90°-120°; Step 2: Place a graphene oxide solution in the middle of the substrate, and then cover the top of the sealing plate (2) with another polytetrafluoroethylene plate (1). A slit is formed between the two polytetrafluoroethylene plates (1). Dry to obtain a graphene oxide film with oriented specifications. The concentration of the graphene oxide solution is 5-10 mg / ml.

2. The method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly according to claim 1, characterized in that, The graphene oxide solution was prepared by adding graphene oxide to water as a solvent, magnetically stirring for 10-20 minutes, then ultrasonically stirring for 10-20 minutes, and repeating the magnetic stirring and ultrasonic stirring three times to obtain the solution.

3. The method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly according to claim 1, characterized in that, Before use, the polytetrafluoroethylene plate (1) is subjected to ultrasonic cleaning for 3-10 minutes and plasma cleaning to remove impurities; during plasma cleaning, the power is 50-70w and the time is 4-6 minutes.

4. The method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly according to claim 1, characterized in that, The sealing plate (2) has a thickness of 1-6 mm, a width of 1-3 mm, and a length that is the same as the width of the polytetrafluoroethylene plate.

5. The method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly according to claim 1, characterized in that, The sealing plate (2) is an acrylic plate, a glass plate or a polytetrafluoroethylene plate.

6. The method for preparing regularly arranged graphene oxide thin films by slit-induced self-assembly according to claim 1, characterized in that, The drying process is carried out using a vacuum drying oven at a temperature of 80-120℃ for 24-72 hours.

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