Organic molecule bridging graphite copper composite material and preparation method thereof

Abstract

The invention discloses an organic molecule bridged graphite copper composite material and a preparation method thereof, the composite material is structurally characterized in that thiophenol molecules are introduced to the upper surface and the lower surface of a flake graphite film, copper is deposited on the flake graphite film with the thiophenol molecules, sulfydryl in the thiophenol molecules and the copper form a sulfur-copper bond, and the thiophenol molecules and the copper form an organic molecule bridged graphite copper composite material. The preparation method of the copper-flake graphite film-copper composite material specifically comprises the following steps: carrying out surface treatment on the flake graphite film; dissolving 4-aminothiophenol in o-dichlorobenzene, putting the flake graphite film, vacuumizing, carrying out nitrogen protection, and magnetically stirring uniformly; adding isoamyl nitrite into the obtained mixed solution under the protection of nitrogen, magnetically stirring uniformly, and preserving heat at 40-60 DEG C; and taking out the flake graphite film, washing the flake graphite film with N, N-dimethylformamide and absolute ethyl alcohol, performing vacuum drying, and electroplating copper on the dried flake graphite film to obtain the organic molecule bridging graphite copper composite material.

Description

Technical Field:

[0001] The present invention relates to the field of thermal management of metal matrix composites, and particularly to an organic molecule-bridged graphite copper composite material and a preparation method thereof. Technical Background:

[0002] High thermal conductivity graphite film is a functional material prepared from polyimide (PI) as a raw material through high-temperature heat treatment and graphitization processes. Its thermal conductivity is as high as 600-1200 W / (m﹒k). At the same time, the heat dissipation graphite film is light in weight and has good flexibility, which is convenient for integration with electronic components of different shapes and has broad application prospects in the field of heat dissipation of electronic devices such as smart phones, tablet computers, and notebook computers. However, due to the weak bonding between graphite layers, there is occasionally a small amount of graphite powder falling off during use, resulting in unstable operation of electronic devices. Metallization on the graphite surface can effectively prevent the graphite powder from falling off. In the prior art, a copper foil is directly pasted after covering a glue layer on the graphite surface, and the presence of the glue layer makes the thermal conductivity of the whole material not high. In the prior art, a metal coating is chemically plated on the surface of the graphite composite material. This method has a clean interface and thus the composite material has a high thermal conductivity. However, during the process of assembling with devices, especially when the graphite is bent under force in some cases, the metal coating is prone to fall off. Summary of the Invention:

[0003] The present invention provides a preparation method of an organic molecule-bridged graphite copper composite material, aiming to simultaneously solve the problems of low interfacial bonding strength between graphite and copper, insufficient in-plane thermal conductivity in the prior art solution, and the problem that the graphite debris in the graphite film is prone to fall off or crack due to difficulty in bending.

[0004] To achieve the above object, the present invention adopts the following technical solution: An organic molecule-bridged graphite copper composite material, the structure of the composite material is that benzenethiol molecules are introduced on the upper and lower surfaces of a flaky graphite film, copper is deposited on the flaky graphite film with benzenethiol molecules, and the sulfhydryl group in the benzenethiol molecule forms a sulfur-copper bond with copper to form a copper-flaky graphite film-copper composite material, also called an organic molecule-bridged graphite copper composite material.

[0005] The preparation method of the organic molecule-bridged graphite copper composite material includes the following steps:

[0006] S1, treating the surface of the flaky graphite film;

[0007] S2, dissolving 4-aminobenzenethiol in o-dichlorobenzene, putting in the flaky graphite film, pouring it into a three-necked flask, evacuating the air in the three-necked flask through a vacuum pump and then introducing nitrogen, and repeating this operation three times to make the experiment carried out under nitrogen protection, and magnetically stirring for 10 min to obtain a mixed solution;

[0008]

[0009] ​S3. Under nitrogen protection, add isoamyl nitrite to the mixed solution obtained in step S2. After magnetic stirring until evenly mixed, keep the temperature at 40 - 60 °C and carry out a heat preservation reaction for 20 - 24 h;

[0010]

[0011] S4. Take out the flaky graphite film in S3 and wash it with N,N - dimethylformamide (abbreviated as: DMF) and absolute ethanol, and then carry out vacuum drying at 50 - 100 °C for 4 - 6 h;

[0012]

[0013] S5. Electroplate copper on the dried flaky graphite film for 1 - 15 min to obtain an organic molecule - bridged graphite - copper composite material.

[0014] Furthermore, the thickness of the flaky graphite film is 10 - 300 μm, and the density is 1.7 - 2.3 g / cm 3 .

[0015] Furthermore, the surface treatment of the flaky graphite film in step S1 is specifically as follows: soak the flaky graphite film in ethanol and stir for 10 min, wash it with deionized water, dry it, and then carry out plasma surface treatment. The process parameters of the plasma surface treatment are: plasma power 10 W - 300 W, treatment atmosphere is air, gas flow rate is 100 - 800 sccm, and treatment time is 10 s - 200 min.

[0016] Furthermore, in step S2, the content of o - dichlorobenzene is 200 ml, and the mass ratio of 4 - aminothiophenol to the flaky graphite film is 2 - 10:1.

[0017] Furthermore, in step S3, the molar ratio of isoamyl nitrite to 4 - aminothiophenol is 1.8 - 2.5:1.

[0018] Furthermore, in step S5, the concentration ratio of copper sulfate pentahydrate, sodium potassium tartrate, trisodium citrate, and potassium nitrate in the electroplating solution is 8:24:4:3. Electroplating is carried out in a constant - current mode, and the current density is 1 - 8 A / dm 2 .

[0019] The principle of the present invention is as follows: 4 - aminothiophenol undergoes a diazo reaction with the diazotizing reagent isoamyl nitrite. During the diazo reaction, the amino group (-NH 2 ) of 4 - aminothiophenol will be converted into a diazo group (-N 2 + ), forming a diazonium salt intermediate - thiophenol. The thiophenol molecule contains a benzene ring, and the carbon atoms on the benzene ring adopt the sp 2 hybridization method to form a planar π - conjugate system. This π - conjugate system enables the π - electrons on the benzene ring to be delocalized within the entire conjugate system, providing a large number of electron carriers. And the graphite film is also composed of sp​​2 Composed of hybridized carbon atoms, it has planar π-conjugation properties, and its delocalized π-bond runs through the entire crystal, making the graphite film have good electrical conductivity. When benzenethiol contacts the graphite film, the π-electron system in the benzenethiol molecule can interact with the π-electron system on the graphite film and form a connection through the π-π conjugation effect. They can form a tightly ordered stacking structure through π-π stacking, and the overlap of π-orbitals between adjacent molecules further increases the charge transport performance. This reaction is usually achieved through the formation of covalent bonds, that is, the positive charge part in the diazonium salt interacts with the negative charge part or lone pair electrons of the functional group on the graphite film, thereby connecting 4-aminobenzenethiol to the graphite film.

[0020] Due to the special chemical properties of the mercapto group (-SH) of benzenethiol, it can form stable chemical bonds on the metal surface. Therefore, this conjugate connection method has broad application prospects in chemistry and materials science. By adjusting the reaction conditions and the properties of the graphite film, the effect and stability of this conjugate connection can be further optimized.

[0021] Under the action of an electric current, copper ions will migrate to the surface of the graphite film and undergo a reduction reaction on its surface to form copper atoms. The sulfur in benzenethiol has a certain copper affinity and can interact with copper atoms. This interaction may include coordination or chemical bonding between sulfur and copper, enabling benzenethiol molecules to be anchored on the copper coating during the electroplating process. As the electroplating process proceeds, copper ions are continuously reduced to copper atoms on the surface of the graphite film and tightly combine with benzenethiol molecules, eventually forming a structure in which benzenethiol is connected to copper.

[0022] Beneficial effects:

[0023] In the present invention, the surface of the graphite film is roughened by plasma activation, and at the same time, active sites are introduced. The diazo component 4-aminobenzenethiol undergoes a diazotization reaction with the diazo reagent isoamyl nitrite, and at the same time, benzenethiol molecules are introduced onto the flaky graphite film through physical and chemical adsorption. Then, copper is deposited on the graphite film by electroplating to form a copper-graphite film-copper composite material, and benzenethiol conjugate molecules are introduced between the graphite film and the copper interface by using the active sites. The benzenethiol conjugate molecules form conjugate π-bonds with graphite, and the mercapto group will form sulfur-copper bonds with copper. This two-way linked structure helps to enhance the interfacial bonding between the graphite film and the copper matrix. At the same time, the conjugate benzenethiol molecules form an electron movement with molecular connections at the interface between the graphite film and the copper, thereby effectively improving the electron mobility in the composite material, and the contribution of electron heat transfer is more obvious, making the thermal conductivity of the composite material higher. Specifically:

[0024] 1. The plasma roughens the surface of the graphite, and the roughened grooves and the copper layer form a mechanical interlock, which improves the interfacial bonding.

[0025] 2. The introduction of benzenethiol further enhances the interfacial bonding force of graphite-copper from the perspective of micro-interface design.

[0026] 3. The conjugated molecules in benzenethiol form conjugated π bonds with graphite, effectively improving the electron mobility in the composite material. The more obvious contribution of electron heat transfer makes the thermal conductivity of the composite material higher. Description of the drawings:

[0027] Figure 1 It is a schematic structural diagram of the organic molecule-bridged graphite copper composite material of this application;

[0028] Figure 2 It is the bending diagram of the composite material prepared in Example 1;

[0029] Figure 3 It is the bending diagram of the composite material prepared in Comparative Example 1;

[0030] Figure 4 It is Figure 2 The SEM image of the graphite-benzenethiol copper-plated surface at the bending part. Detailed implementation manners:

[0031] Example 1:

[0032] Select 1 g of flaky graphite film with a thickness of 70 μm and a density of 2.1 g / cm 3 . Immerse the flaky graphite film in ethanol and stir for 10 min, wash with deionized water, and dry. After drying, perform plasma treatment. Use an air atmosphere, with a gas flow rate of 300 sccm, a power of 120 W, and a treatment time of 20 s. Take 4 g of 4-aminobenzenethiol, dissolve it in 200 ml of ortho-dichlorobenzene, mix evenly, put it into the treated flaky graphite film, pour it into a three-necked flask, evacuate the air in the three-necked flask through a vacuum pump and then introduce nitrogen. This operation is repeated three times to make the experiment carried out under nitrogen protection. Magnetically stir for 10 min to obtain a mixed solution. Add 8 ml of isoamyl nitrite to the mixed solution under nitrogen protection, heat up to 60 °C, and react for 18 h. After the reaction is completed, wash three times with DMF and three times with ethanol, and vacuum dry at 60 °C for 5 h. Subsequently, electroplate the graphite at a current density of 2 A / dm 2 for 10 min to obtain a copper-coated graphite film composite material. The graphite copper-based composite material with an in-plane thermal conductivity of 1333 W / (m·K) is measured by an LFA467 HyperFlash flash thermal conductivity meter. Conduct a bending test on the composite material. Clamp both ends of the composite material and perform a bending test at a bending radius of 10 mm, a bending degree of 90°, and a rate of 20 times per minute. After 100 bends, there is no cracking. The bending diagram is shown in Figure 2 , Figure 4 It is Figure 2SEM image of the copper-plated surface of graphite-aminobenzenethiol at the bending point. As can be seen from the figure, there are no obvious voids on the microscopic surface after bending, indicating good bending performance of the material.

[0033] Example 2:

[0034] Select 1 g of flaky graphite film with a thickness of 70 μm and a density of 2.1 g / cm 3 The flaky graphite film is soaked in ethanol and stirred for 10 min, washed with deionized water, and dried; after drying, plasma treatment is carried out. Using an air atmosphere, the gas flow rate is 300 sccm, the power is 120 W, and the treatment time is 20 s. Take 4 g of 4-aminobenzenethiol, dissolve it in 200 ml of o-dichlorobenzene, mix evenly, put it into the treated flaky graphite film, pour it into a three-necked flask, evacuate the air in the three-necked flask through a vacuum pump and then introduce nitrogen. This operation is repeated three times to make the experiment carried out under nitrogen protection. Stir magnetically for 10 min to obtain a mixed solution. Under nitrogen protection, 11 ml of isoamyl nitrite is added to the mixed solution, heated to 60 °C, and reacted for 18 h. After the reaction is completed, wash three times with DMF and three times with ethanol, and dry in vacuum at 60 °C for 5 h. Subsequently, the graphite is electroplated at a current density of 2 A / dm 2 for 10 min to obtain a copper-coated graphite film composite material. The in-plane thermal conductivity of the graphite copper matrix composite material measured by the LFA467 HyperFlash flash method thermal conductivity meter is 1297 W / (m﹒k). The composite material is subjected to a bending test. The two ends of the composite material are clamped and bent at a bending radius of 10 mm, a bending degree of 90°, and a rate of 20 times per minute. After 85 bends, it does not crack.

[0035] Example 3:

[0036] Select 1 g of flaky graphite film with a thickness of 70 μm and a density of 2.1 g / cm 3 The flaky graphite film is soaked in ethanol and stirred for 10 min, washed with deionized water, and dried; after drying, plasma treatment is carried out. Using an air atmosphere, the gas flow rate is 500 sccm, the power is 50 W, and the treatment time is 1 min. 4 g of 4-aminobenzenethiol is dissolved in 200 ml of o-dichlorobenzene, mixed evenly, put it into the treated flaky graphite film, pour it into a three-necked flask, evacuate the air in the three-necked flask through a vacuum pump and then introduce nitrogen. This operation is repeated three times to make the experiment carried out under nitrogen protection. Stir magnetically for 10 min to obtain a mixed solution. Under nitrogen protection, 8 ml of isoamyl nitrite is added to the mixed solution, heated to 60 °C, and reacted for 18 h. After the reaction is completed, wash three times with DMF and three times with ethanol, and dry in vacuum at 60 °C for 5 h. Subsequently, the graphite is electroplated at a current density of 2 A / dm 2The copper-coated graphite film composite material was obtained by electroplating at a current density of 10 minutes. The in-plane thermal conductivity of the graphite copper-based composite material was measured by the LFA467HyperFlash flash method thermal conductivity meter to be 1272W / (m﹒k). The composite material was subjected to a bending test. The two ends of the composite material were bent at a bending radius of 10mm, a bending angle of 90°, and a rate of 20 times per minute. No cracking occurred after 120 bends.

[0037] Embodiment 4:

[0038] Select a thickness of 70 μm and a density of 2.1 g / cm 3 1g of flaky graphite film was soaked in ethanol and stirred for 10 minutes, washed with deionized water and dried; after drying, plasma treatment was carried out in an air atmosphere with a gas flow rate of 300sccm, a power of 120W and a treatment time of 20s. 4g of 4-aminobenzenethiophenol was dissolved in 200ml of o-dichlorobenzene and mixed evenly and put into the treated flaky graphite film, poured into a three-necked flask, the air in the three-necked flask was evacuated by a vacuum pump and then nitrogen was introduced. This operation was repeated three times so that the experiment was carried out under nitrogen protection, and a mixed solution was obtained by magnetic stirring for 10 minutes. Under nitrogen protection, 8ml of isoamyl nitrite was added to the mixed solution, the temperature was raised to 60°C, and the reaction was carried out for 18 hours. After the reaction was completed, it was washed with DMF three times, ethanol three times, and vacuum dried at 60°C for 5 hours. Then the graphite was heated at 2A / dm 2 The copper-coated graphite film composite material was obtained by electroplating at a current density of 15 minutes. The in-plane thermal conductivity of the graphite copper-based composite material was measured by the LFA467HyperFlash flash method thermal conductivity meter to be 1254W / (m﹒k). The composite material was subjected to a bending test. The two ends of the composite material were bent at a radius of 10mm, a bending angle of 90°, and a rate of 20 times per minute. No cracking occurred after 30 bends.

[0039] Comparative Example 1:

[0040] Select a thickness of 70 μm and a density of 2.1 g / cm 3 1g of graphite sheet was immersed in ethanol and stirred for 10min, washed with deionized water and dried; after drying, plasma treatment was performed using air atmosphere, gas flow rate of 300sccm, power of 120W and treatment time of 20s. 2 The copper-coated graphite film composite material was obtained by electroplating at a current density of 10 minutes. The in-plane thermal conductivity of the graphite copper-based composite material was measured by the LFA467HyperFlash flash method thermal conductivity meter to be 1231W / (m﹒k). The composite material was subjected to a bending test. The composite material was held at both ends with a bending radius of 10mm, a bending angle of 90°, and a bending rate of 20 times per minute. The composite material cracked after one bending. The bending diagram is shown inFigure 3 。

[0041] In the above embodiments, electroplating is carried out in a constant current mode, and the concentration ratio of copper sulfate pentahydrate, potassium sodium tartrate, trisodium citrate and potassium nitrate in the electroplating solution is 8:24:4:3.

[0042] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. An organic molecule bridged graphite copper composite material, characterized in that: The composite material structure is that thiophenol molecules are introduced into the upper and lower surfaces of the flaky graphite film, copper is deposited on the flaky graphite film with the thiophenol molecules, and the thiol groups in the thiophenol molecules form sulfur-copper bonds with copper to form a copper-flaky graphite film-copper composite material, also known as an organic molecule bridged graphite copper composite material.

2. A method for preparing an organic molecule bridged graphite copper composite material, characterized in that: The steps include: S1, treating the surface of the flake graphite film; S2, dissolving 4-aminothiophenol in o-dichlorobenzene, putting a flake graphite film, pouring into a three-necked flask, evacuating the air in the three-necked flask by a vacuum pump and then introducing nitrogen, the operation was repeated three times, so that the experiment was carried out under nitrogen protection, and magnetic stirring was performed for 10 minutes to obtain a mixed solution; S3, adding isoamyl nitrite to the mixed solution obtained in step S2 under nitrogen protection, stirring evenly with a magnetic stirrer, and then keeping the mixture at 40-60° C. for 20-24 hours; S4, taking out the flake graphite film in S3, washing it with N,N-dimethylformamide and anhydrous ethanol, and vacuum drying it at 50-100°C for 4-6h; S5, electroplating copper on the dried graphite film for 1-15 min to obtain an organic molecule bridged graphite copper composite Material.

3. The method for preparing the organic molecule bridged graphite copper composite material as claimed in claim 2, characterized in that: The graphite film has a thickness of 10-300 μm and a density of 1.7-2.3 g / cm 3 .

4. The method for preparing the organic molecule bridged graphite copper composite material as claimed in claim 2, characterized in that: The surface treatment of the flaky graphite film in step S1 is specifically as follows: immersing the flaky graphite film in ethanol and stirring for 10 minutes, washing with deionized water, drying, and plasma surface treatment. The plasma surface treatment process parameters are: plasma power 10W-300W, treatment atmosphere is air, gas flow rate is 100-800sccm, and treatment time is 10s-200min.

5. The method for preparing the organic molecule bridged graphite copper composite material as claimed in claim 2, characterized in that: In step S2, the content of o-dichlorobenzene is 200 ml, and the mass ratio of 4-aminothiophenol to the flaky graphite film is 2-10:

1.

6. The method for preparing the organic molecule bridged graphite copper composite material as claimed in claim 2, characterized in that: In step S3, the molar ratio of isoamyl nitrite to 4-aminothiophenol is 1.8-2.5:

1.

7. The method for preparing the organic molecule bridged graphite copper composite material as claimed in claim 2, characterized in that: In step S5, the concentration ratio of copper sulfate pentahydrate, potassium sodium tartrate, trisodium citrate and potassium nitrate in the electroplating solution is 8:24:4:3, and the electroplating adopts a constant current mode with a current density of 1-8A / dm 2 .

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