A kind of charged modified graphene thermal conductive filler and its preparation method and application

Abstract

A charged modified graphene thermal conductive filler and its preparation method and application, wherein the preparation method comprises: using ethylenediamine to modify graphene oxide with amino functionalization to obtain amino graphene oxide; using iodomethane as a modifier, the amino graphene oxide is subjected to a charging reaction to obtain charged graphene oxide; hydrazine hydrate is used to reduce the charged graphene oxide to obtain a charged modified graphene thermal conductive filler. The present invention enhances the heat transfer performance between graphene layers through the cation-π effect formed between the charged modified graphene, and the cation-π interaction can construct the strongest interaction between the fillers to effectively alleviate the interfacial thermal resistance, and interconnect between the fillers to promote the effective transfer of phonons or lattice vibrations to improve the thermal conductivity, and the charged modified graphene filler is applied to thermal conductive composite materials, thereby significantly improving the thermal conductivity of polymer composite materials.

Description

Technical Field

[0001] The present invention relates to the field of polymer composite materials, and in particular to a charged modified graphene thermal conductive filler and a preparation method and application thereof. Background Art

[0002] With the advancement of science and technology, microelectronic devices are developing towards miniaturization, high integration and high power, which puts forward new requirements and challenges for traditional thermal conductors. Therefore, an efficient thermal management system is crucial to reduce the temperature of local hot spots in high-power electronic devices. Polymer-based composites have become the best choice for thermal management materials in electronic devices due to their excellent thermal conductivity and mechanical strength. The regulation of interfacial thermal resistance and the construction of heat transfer paths in composite materials are effective ways to improve the thermal conductivity of polymer-based composites.

[0003] Modifying thermally conductive fillers is an effective way to regulate the interfacial thermal resistance between fillers. Covalent modification can regulate the interfacial thermal resistance between fillers and the matrix through chemical bonds, but the destruction of the inherent structure of the filler will affect the thermal conductivity. Non-covalent modification can effectively reduce the interfacial thermal resistance between fillers through methods such as hydrogen bond interaction, electrostatic interaction and π-π interaction on the basis of ensuring the thermal conductivity of the filler itself, so non-covalent bonds have become the mainstream method of filler modification. How to further improve the thermal conductivity of polymer-based composites through covalent modification of non-covalent bonds of thermally conductive fillers is the focus of current research. Summary of the invention

[0004] Based on this, the present invention provides a charged modified graphene thermal conductive filler and a preparation method and application thereof, aiming to cationize graphene oxide to obtain charged modified graphene, and to prepare a high thermal conductivity composite material by doctor blade coating of PVA and charged modified graphene.

[0005] To achieve the above object, the present invention provides a method for preparing a charged modified graphene thermal conductive filler, which comprises the following steps:

[0006] S1, modifying graphene oxide with amino functionalization using a modifier, ethylenediamine, to obtain amino-functionalized graphene oxide;

[0007] S2, using iodomethane as a modifier, subjecting the amination-modified graphene oxide to a charging reaction to obtain charged graphene oxide;

[0008] S3. Reducing the charged graphene oxide with hydrazine hydrate to obtain a charged modified graphene thermal conductive filler.

[0009] As a further preferred technical solution of the present invention, the graphene oxide in step S1 is prepared by the following Hummers method:

[0010] First, add 3g of graphite powder into a 250mL flask, then add 1.5g of NaNO3 and 70mL of concentrated H2SO4 in an ice bath, stir for 30min to obtain a dark green solution, slowly add 9g of KMnO4 into the solution within 1.5h, heat to 35℃, and stir for 7h;

[0011] Then slowly add 9g KMnO4, stir for 12h, cool to room temperature and pour into 400mL ice deionized water, add 5mL of 30% H2O2, so that the solution turns bright yellow;

[0012] Finally, water was added to dilute it, and the supernatant was removed after standing. Then, the solution was washed with ethanol and deionized water for multiple times to make the solution neutral, and finally, it was freeze-dried to obtain graphene oxide.

[0013] As a further preferred technical solution of the present invention, the method for preparing amination-modified graphene oxide in step S1 specifically comprises:

[0014] In a reaction vessel equipped with a reflux device, 60 mg of graphene oxide was dissolved in 12 mL of water and ultrasonically treated for 1 h to obtain a uniform graphene oxide suspension; then 10 mL of ethylenediamine and 28 mL of deionized water were added, stirred at 80°C for 12 h, and a solid product was obtained by centrifugation; finally, the fixed product was washed with ethanol and water at least three times, respectively, and then freeze-dried to obtain amino-modified graphene oxide.

[0015] As a further preferred technical solution of the present invention, the method for synthesizing charged graphene oxide in step S2 specifically includes:

[0016] In a reaction vessel equipped with a reflux device, 20 mg of amino-modified graphene oxide was dispersed in 100 mL of methanol, and ultrasonically treated for 1 h to obtain a uniform solution. Then, 0.5 mL of iodomethane was added and refluxed at 80°C for 24 h. Then, a precipitate was obtained by centrifugation, and the precipitate was washed several times with methanol and deionized water respectively, and finally, charged graphene oxide was obtained by freeze-drying.

[0017] As a further preferred technical solution of the present invention, the preparation method of the charged modified graphene thermal conductive filler in step S3 specifically includes:

[0018] 0.1 g of charged graphene oxide was dissolved in 50 mL of deionized water, and ultrasonicated for 1 h to obtain a uniform dispersion. Under ice bath conditions, 10 mL of hydrazine hydrate and 40 mL of deionized water were added, stirred for 30 min, and then reacted at 100 ° C for 30 min. After cooling to room temperature, it was washed three times with methanol and deionized water respectively, and finally freeze-dried to obtain a charged modified graphene thermal conductive filler.

[0019] According to another aspect of the present invention, the present invention further provides a charged modified graphene thermal conductive filler, which is prepared by the above-mentioned preparation method of the charged modified graphene thermal conductive filler.

[0020] According to another aspect of the present invention, the present invention also provides an application of a charged modified graphene thermal conductive filler in a composite material, PVA particles are added to deionized water, and stirred and dissolved at 90°C to obtain a PVA solution; the charged modified graphene thermal conductive filler is added to the PVA solution, stirred and dispersed evenly, and then a composite film is obtained by a doctor blade coating method, which is peeled off after drying to obtain a composite material.

[0021] As a further preferred technical solution of the present invention, the mass fraction of the PVA solution is 5wt%.

[0022] As a further preferred technical solution of the present invention, the blade coating method uses a 1000 μm blade.

[0023] The charged modified graphene thermal conductive filler and the preparation method and application thereof of the present invention can achieve the following beneficial effects by adopting the above technical scheme:

[0024] 1) The method for preparing charged modified graphene of the present invention is simple to operate and has a mild reaction, and is suitable for industrial production;

[0025] 2) The present invention enhances the heat transfer performance between graphene layers by using the cation-π interaction formed between the charged modified graphene. The cation-π interaction can build the strongest interaction in the filler and effectively alleviate the interfacial thermal resistance. The interconnection between the fillers promotes the effective transfer of phonons or lattice vibration, thereby improving the thermal conductivity. The charged modified graphene filler is applied to the thermally conductive composite material, thereby significantly improving the thermal conductivity of the polymer composite material.

[0026] 3) The present invention utilizes a blade coating method to allow graphene sheets to be naturally deposited, thereby constructing a horizontal graphene heat transfer path within the composite material. In addition, the cation-π effect formed between the charged modified graphene can greatly enhance the heat transfer performance between graphene layers. At the same time, the hydrogen bonds formed between the quaternary ammonium groups and PVA also effectively improve the compatibility between the filler and the substrate, further improving the overall thermal conductivity of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] Figure 1 This is a schematic diagram of the synthesis process of charged modified graphene (GR-N) according to Example 1 of the present invention;

[0029] Figure 2 FTIR images of graphene before and after modification in Example 1 of the present invention;

[0030] Figure 3 The thermal conductivity test results of the composite materials obtained in various embodiments and comparative examples are shown.

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0033] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0034] Example 1

[0035] In this example, 85 wt% GR-N / PVA composite material was prepared according to the following steps.

[0036] Step 1: Preparation of graphene oxide

[0037] Graphene oxide is prepared by the improved Hummers method. 3g of graphite powder is added to a 250mL flask, and then 1.5g of NaNO3 and 70mL of concentrated H2SO4 are added in an ice bath, and stirred for 30min to obtain a dark green solution. 9g of KMnO4 is slowly added to the solution within 1.5h, heated to 35°C, and stirred for 7h. Then 9g of KMnO4 is slowly added, stirred for 12h, and cooled to room temperature. Pour it into 400mL of ice deionized water, add 5mL of H2O2 (30%), and the solution becomes bright yellow. Dilute with water, remove the supernatant after standing, and then wash it three times with ethanol and deionized water respectively to wash the solution to neutrality, and finally freeze-dry to obtain graphene oxide, recorded as GO;

[0038] Step 2: Preparation of amination-modified graphene oxide

[0039] In a round-bottom flask equipped with a reflux device, 60 mg of graphene oxide was dissolved in 12 mL of water, and ultrasonic treatment was performed for 1 h to obtain a uniform graphene oxide suspension, and then 10 mL of ethylenediamine and 28 mL of deionized water were added, respectively, and stirred at 80 ° C for 12 h. The solid product was obtained by centrifugation (8000 rpm, 8 min), and washed with ethanol and water for 3 times. Finally, the amino-modified graphene oxide was obtained by freeze drying, which was recorded as NH2-GO.

[0040] Step 3: Synthesis of charged graphene oxide

[0041] In a round-bottom flask equipped with a reflux device, 20 mg of NH2-GO was dispersed in 100 mL of methanol, ultrasonically treated for 1 h to obtain a uniform solution, and then 0.5 mL of iodomethane was added and refluxed at 80 ° C for 24 h. The precipitate was obtained by centrifugation (10000 rpm, 10 min), washed three times with methanol and deionized water respectively, and finally freeze-dried to obtain charged graphene oxide, recorded as GO-N.

[0042] Step 4: Synthesis of charged modified graphene

[0043] 0.1 g GO-N was dissolved in 50 mL deionized water and ultrasonicated for 1 h to obtain a uniform dispersion. 10 mL hydrazine hydrate and 40 mL deionized water were added under ice bath conditions and stirred for 30 min. Then, the mixture was reacted at 100 °C for 30 min, cooled to room temperature, washed three times with methanol and deionized water respectively, and finally freeze-dried to obtain a charged modified graphene thermal conductive filler, recorded as GR-N.

[0044] Step 5: Preparation of charged modified graphene / polyvinyl alcohol composite film

[0045] 1 g of PVA particles were added to 20 mL of deionized water and stirred to dissolve at 90 ° C to obtain a PVA solution. GR-N was added to the PVA solution at a mass fraction of 85 wt%, and stirred to disperse evenly. Then, a GR-N / PVA composite film was prepared by a doctor blade coating method. The film was air-dried at 25 ° C and peeled off from a quartz plate to obtain a film-like GR-N / PVA composite material.

[0046] Example 2

[0047] In this example, a 90wt% GR-N / PVA composite material was prepared in the same manner as in Example 1, except that in step 5: 1g of PVA particles was added to 20mL of deionized water, and the mixture was stirred and dissolved at 90°C to obtain a PVA solution. GR-N was added to the PVA solution at a mass fraction of 90wt%, and the mixture was stirred and dispersed uniformly. Then, a GR-N / PVA composite film was obtained by a doctor blade coating method, and the film was dried in air at 25°C and peeled off from a quartz plate to obtain a film-like GR-N / PVA composite material.

[0048] Example 3

[0049] In this example, a 90wt% GR-N / PVA composite material was prepared in the same manner as in Example 1, except that in step 5: 1g of PVA particles was added to 20mL of deionized water, and the mixture was stirred and dissolved at 90°C to obtain a PVA solution. GR-N was added to the PVA solution at a mass fraction of 95wt%, and the mixture was stirred and dispersed uniformly. Then, a GR-N / PVA composite film was obtained by a doctor blade coating method, and the film was dried in air at 25°C and peeled off from a quartz plate to obtain a film-like GR-N / PVA composite material.

[0050] Example 4

[0051] In this example, a 98 wt% GR-N / PVA composite material was prepared in the same manner as in Example 1, except that in step 5: 1 g of PVA particles was added to 20 mL of deionized water, and the mixture was stirred and dissolved at 90°C to obtain a PVA solution. GR-N was added to the PVA solution at a mass fraction of 98 wt%, and the mixture was stirred and dispersed uniformly. A GR-N / PVA composite film was then obtained by a doctor blade coating method, and the film was dried in air at 25°C and peeled off from a quartz plate to obtain a film-like GR-N / PVA composite material.

[0052] Comparative Example 1

[0053] This comparative example prepared 85wt% rGO / PVA composite material according to the following steps:

[0054] Step 1: Preparation of graphene nanosheets

[0055] Add 3g of graphite powder to a 250mL flask, then add 1.5g of NaNO3 and 70mL of concentrated H2SO4 in an ice bath, stir for 30min to obtain a dark green solution, slowly add 9g of KMnO4 to the solution within 1.5h, heat to 35℃, and stir for 7h. Then slowly add 9g of KMnO4, stir for 12h, and cool to room temperature. Pour into 400mL of ice deionized water, add 5mL of H2O2 (30%), and the solution will appear bright yellow. Dilute with water, remove the supernatant after standing, and then wash with ethanol and deionized water three times respectively to wash the solution to neutrality, and finally freeze-dry to obtain graphene nanosheets, recorded as rGO.

[0056] Step 2: Preparation of rGO / PVA composite materials

[0057] 1 g of PVA particles were added to 20 mL of deionized water and stirred at 90 ° C to dissolve to obtain a PVA solution. rGO was added to the PVA solution at a mass fraction of 85 wt%, and stirred to disperse evenly. Then, an rGO / PVA composite film was obtained by a doctor blade coating method. The film was dried in air at 25 ° C and peeled off from a quartz plate to obtain a thin film of rGO / PVA composite material.

[0058] Comparative Example 2

[0059] In this example, a 90wt% rGO / PVA composite material was prepared in the same manner as in Comparative Example 1, except that step 2 was as follows: 1g of PVA particles were added to 20mL of deionized water, and the mixture was stirred and dissolved at 90°C to obtain a PVA solution. rGO was added to the PVA solution at a mass fraction of 90wt%, and the mixture was stirred and dispersed uniformly. Then, an rGO / PVA composite film was obtained by a doctor blade coating method, and the film was dried in air at 25°C and peeled off from a quartz plate to obtain a thin film of rGO / PVA composite material.

[0060] Comparative Example 3

[0061] In this example, 95wt% rGO / PVA composite material was prepared in the same manner as in Comparative Example 1, except that step 2 was as follows: 1g of PVA particles were added to 20mL of deionized water, and the PVA solution was obtained by stirring and dissolving at 90°C. rGO was added to the PVA solution at a mass fraction of 85wt%, and the mixture was stirred and dispersed uniformly. Then, an rGO / PVA composite film was obtained by a doctor blade coating method, and the film was dried in air at 25°C and peeled off from a quartz plate to obtain a thin film of rGO / PVA composite material.

[0062] Comparative Example 4

[0063] In this example, a 98wt% rGO / PVA composite material was prepared in the same manner as in Comparative Example 1, except that step 2 was as follows: 1g of PVA particles were added to 20mL of deionized water, and the mixture was stirred and dissolved at 90°C to obtain a PVA solution. rGO was added to the PVA solution at a mass fraction of 98wt%, and the mixture was stirred and dispersed uniformly. Then, an rGO / PVA composite film was obtained by a doctor blade coating method, and the film was dried in air at 25°C and peeled off from a quartz plate to obtain a thin film of rGO / PVA composite material.

[0064] Figure 1 This is a reaction mechanism diagram of charged modified graphene in Example 1.

[0065] Figure 2 The FTIR images of graphene before and after modification show that the amino functionalization has a peak at 1210 cm -1 There is an obvious carbon-nitrogen stretching vibration peak at 2818cm -1 The absorption peak of methyl group appears at , which indicates that graphene is successfully charged.

[0066] Figure 3The thermal conductivity test results of the composite materials obtained in each embodiment and the comparative example are shown in the figure. It can be seen from the figure that the GR-N / PVA composite material has a higher thermal conductivity coefficient at the same filler content, which proves that the charged modified graphene can construct a horizontal heat conduction path between the graphene layers through the cation-π effect, reduce the interface thermal resistance between the filler and the matrix, and thus greatly improve the heat transfer performance between the graphene layers. At the same time, the charged modified graphene has good interface compatibility with PVA, which will further improve the thermal conductivity of the composite material.

[0067] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. Application of a charged modified graphene thermal conductive filler in a composite material, characterized in that: 1 g of PVA particles were added to 20 mL of deionized water, and the mixture was stirred and dissolved at 90° C. to obtain a PVA solution; 98 wt % of the charged modified graphene thermal conductive filler was added to the PVA solution, and after being stirred and dispersed evenly, a composite film was obtained by a doctor blade coating method, and after drying, the composite film was peeled off to obtain a composite material; The charged modified graphene thermal conductive filler is prepared by the following steps: S1, modifying graphene oxide with amino functionalization by using ethylenediamine to obtain amino-functionalized graphene oxide; S2, using iodomethane as a modifier, subjecting the amination-modified graphene oxide to a charging reaction to obtain charged graphene oxide; S3. Using hydrazine hydrate to reduce the charged graphene oxide to obtain a charged modified graphene thermal conductive filler.

2. The use of the charged modified graphene thermal conductive filler in a composite material according to claim 1, characterized in that: The graphene oxide in step S1 is prepared by the following method: First, add 3g of graphite powder into a 250mL reaction container, then add 1.5g of NaNO3 and 70mL of concentrated H2SO4 in an ice bath, stir for 30min to obtain a dark green solution, slowly add 9g of KMnO4 into the solution within 1.5h, heat to 35℃, and stir for 7h; Then slowly add 9g KMnO4, stir for 12h, cool to room temperature and pour into 400mL ice deionized water, add 5mL H2O2 with a mass fraction of 30% to make the solution bright yellow; Finally, water was added to dilute it, and the supernatant was removed after standing. Then, the solution was washed with ethanol and deionized water for multiple times to make the solution neutral, and finally, it was freeze-dried to obtain graphene oxide.

3. The use of the charged modified graphene thermal conductive filler in a composite material according to claim 1, characterized in that: The method for preparing the amination-modified graphene oxide in step S1 specifically comprises: In a reaction vessel equipped with a reflux device, 60 mg of graphene oxide was dissolved in 12 mL of water and ultrasonically treated for 1 h to obtain a uniform graphene oxide suspension; then 10 mL of ethylenediamine and 28 mL of deionized water were added, stirred at 80 ° C for 12 h, and a solid product was obtained by centrifugation; finally, the fixed product was washed with ethanol and water at least three times, respectively, and then freeze-dried to obtain amino-modified graphene oxide.

4. The use of the charged modified graphene thermal conductive filler in a composite material according to claim 1, characterized in that: The method for synthesizing charged graphene oxide in step S2 specifically comprises: In a reaction vessel equipped with a reflux device, 20 mg of amino-modified graphene oxide was dispersed in 100 mL of methanol, and ultrasonically treated for 1 h to obtain a uniform solution. Then, 0.5 mL of iodomethane was added and refluxed at 80°C for 24 h. Then, a precipitate was obtained by centrifugation, and the precipitate was washed several times with methanol and deionized water respectively, and finally, charged graphene oxide was obtained by freeze-drying.

5. The use of the charged modified graphene thermal conductive filler in a composite material according to claim 1, characterized in that: The preparation method of the charged modified graphene thermal conductive filler in step S3 specifically comprises: 0.1 g of charged graphene oxide was dissolved in 50 mL of deionized water, and ultrasonicated for 1 h to obtain a uniform dispersion. Under ice bath conditions, 10 mL of hydrazine hydrate and 40 mL of deionized water were added, stirred for 30 min, and then reacted at 100 ° C for 30 min. After cooling to room temperature, it was washed three times with methanol and deionized water respectively, and finally freeze-dried to obtain a charged modified graphene thermal conductive filler.

6. The use of the charged modified graphene thermal conductive filler in a composite material according to claim 1, characterized in that: The doctor blade coating method uses a 1000 μm doctor blade.

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