High-elasticity high-thermal-conductivity graphene-based carbon film and preparation method thereof

Abstract

The application discloses a kind of high-elastic high-thermal-conductivity graphene-based carbon films and preparation method thereof.The method is by precisely regulating the buckling microstructure of graphene skeleton, significantly reduces the hardness and modulus of carbon film, and improves its flexible characteristics;Further, the graphene skeleton is coated with organic polymer derived hard carbon, and a "soft-hard composite" carbon phase structure is constructed to achieve high resilience and excellent thermal conductivity of the material in a synergistic manner.This technology is expected to break through the bottleneck of traditional thermal conductivity materials, which is difficult to achieve both elasticity and thermal conductivity, and provide a new paradigm for the heat dissipation management of high-performance flexible electronic devices.The structural design strategy based on soft and hard carbon composite can be further expanded to other carbon-based functional material systems, promoting the upgrading of thermal conductivity materials in the fields of new energy vehicle battery modules and 5G radio frequency chips.

Description

Technical Field

[0001] This invention belongs to the field of graphene materials, specifically relating to a highly elastic and thermally conductive graphene-based carbon film and its preparation method. Background Technology

[0002] With the rapid development of 5G mobile communication, high-power integrated circuits, and new energy power systems, the heat flux density of electronic devices has exceeded 1000 W / cm², posing a revolutionary challenge to traditional thermal interface materials. Currently commercialized silicone greases (<5 W / mK) and metal-based phase change materials (rebound rate <70%) are ill-suited to the harsh conditions of high-frequency mechanical vibration, especially in large-size chip packaging and automotive-grade IGBT modules, where the surge in contact thermal resistance caused by microscopic gaps at the interface has become the primary cause of system failure. While cutting-edge materials such as vertically arrayed graphene can provide axial thermal conductivity in the range of 120 W / mK, the inherent defect of its sp² lattice layers being connected only by weak van der Waals forces inevitably leads to irreversible slip deformation under cyclic pressure loads—directly causing structural degradation such as buckling collapse and microcrack network proliferation. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing materials by providing a high-precision, low-cost, and high-efficiency method for preparing elastic, highly thermally conductive graphene-based thermal interface materials. By constructing a graphene-soft carbon framework with controllable buckling, the material achieves an ultra-low compressive modulus; simultaneously, by armoring key nodes of the wrinkles with polyimide-derived hard carbon, an elastic support network resistant to plastic deformation is formed; furthermore, the sp... 2 -sp 3 Hybridized bonds (bond energy > 2.5 eV) construct efficient phonon transport channels, ultimately achieving the material's revolutionary properties of maintaining 98% resilience and a stable thermal conductivity of 110 W / mK even under 80% compressive strain.

[0004] One of the technical solutions of the present invention is to provide a highly elastic and thermally conductive graphene-based carbon film with a sandwich structure. The intermediate body of the sandwich structure includes an intermediate layer and finned layers located on both sides of the intermediate layer. The two finned layers are symmetrical about the intermediate layer as an axis. The finned layers include fins, which are inclined relative to one side of the intermediate layer. Fins on the same side are parallel to each other. The intermediate layer and the finned layers include a graphene stacked core layer and a hard carbon layer covering the core layer. The interfacial carbon atom bonding mode between the core layer and the hard carbon layer is a sp²-sp³ mixed hybrid state. The edge body of the sandwich structure is a coating layer of organic polymer-derived hard carbon, which covers the intermediate body.

[0005] Furthermore, the graphene sheets in the middle layer and the two side fin layers are continuous.

[0006] Furthermore, the stacking density of the graphene oxide in the intermediate layer is 0.3-0.8 g / cm³. 3 .

[0007] Furthermore, the tilt angle of the fins relative to the intermediate layer is greater than 30°.

[0008] Furthermore, the organic polymer is a polyamic acid containing an aromatic ring conjugated structure.

[0009] The second technical solution of the present invention is to provide a method for preparing the above-mentioned graphene-based carbon film, comprising the following steps:

[0010] (1) Spread graphene oxide liquid crystals with a concentration in the range of 1 wt% to 15 wt% on a horizontal smooth substrate;

[0011] (2) Insert two probes, and take a point on the perpendicular bisector of the two probe insertion points as the endpoint. Drive the probes to move from the insertion point to the endpoint at the same speed to complete one flow field shearing; the moving speed is between 100-4000 cm / h.

[0012] (3) Repeat the flow field shearing in step 2 multiple times, keeping the probe's movement path parallel to that in step 2, to obtain the oriented graphene oxide liquid crystal; in each flow field shearing, the distance between the two probes is 0.5-3 mm. The distance between two adjacent movement paths is 50-500 μm.

[0013] As the V-shaped trajectory is formed, the flow field at the junction of the two probes becomes horizontal due to compression, forming a dense intermediate layer. The flow fields generated by the two probes interact at the central junction of their trajectories, changing the flow field from shear-dominated to compression-dominated. This compression effect forces the graphene oxide sheets to be highly oriented and tightly packed in the horizontal direction, thereby self-assembling in situ at the center of the predetermined buckling path to form a dense and continuous intermediate layer.

[0014] This dense layer acts like a "load-bearing beam" in a building, providing solid support for the entire porous three-dimensional buckling skeleton and preventing overall collapse during subsequent processing (such as polymer coating and drying) or actual pressing applications, thus ensuring the integrity and reliability of the macroscopic structure. Furthermore, the three-dimensional porous networks on both sides are responsible for capturing heat from the heat source and efficiently "transferring" the heat to the highly conductive pathways in the middle (the dense layer). This collaborative division of labor between "vertical heat transfer and horizontal diffusion" greatly improves the overall heat dissipation efficiency.

[0015] (4) The graphene oxide liquid crystal after orientation obtained in step (3) is dried under reduced pressure to obtain a graphene buckled skeleton.

[0016] (5) Polymer coating: The graphene bent skeleton is immersed in a polyamic acid precursor solution containing an aromatic ring conjugated structure for 2-24 h; after being taken out and cleaned, it is immersed in a poor solvent of polyamic acid for 1-24 h under the condition of oxygen content <5ppm; after being taken out, a composite skeleton with a continuous polymer shell is obtained.

[0017] (6) Carbonization-graphitization treatment: The composite skeleton with continuous polymer shell is subjected to a two-step temperature control program, first carbonized in a reducing atmosphere and then graphitized in an inert atmosphere.

[0018] Furthermore, the polyamic acid precursor containing the aromatic ring conjugated structure satisfies the following general formula characteristic:

[0019] -[Ar1-C(=O)-NH-Ar2-NH-C(=O)] n -

[0020] Wherein: Ar1 is selected from at least one of phenylene, biphenylene, and naphthyldiyl; Ar2 is selected from at least one of oxydiphenylene, thiodiphenylene, and benzophenone diyl; and n is greater than 10000.

[0021] Furthermore, the monomers used in the synthesis of polyamic acid precursors containing aromatic ring conjugated structures include:

[0022] a) Dihydride components: pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-oxobisphthalic dianhydride.

[0023] b) Diamine components: 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene.

[0024] Furthermore, the unsuitable solvent is deionized water, ethanol, methanol, acetone, or a mixture thereof.

[0025] Further, the cleaning method described in step 5 is as follows: the graphene buckled skeleton soaked in the polyamic acid precursor solution is immersed in a solvent for 4 hours for solvent replacement. The solvent is one or more of ethanol, hexanol, tert-butanol, isopropanol, water, n-hexane, and acetone; then, it is washed with anhydrous ethanol 3 times, 2 hours each time.

[0026] The advantages of this invention are as follows: This invention pioneers a soft-hard carbon composite topology design: by constructing a graphene-soft carbon framework with controllable buckling, the material achieves an ultra-low compressive modulus (0.8 GPa) similar to a spring; simultaneously, by utilizing the armoring coating of polyimide-derived hard carbon at key wrinkle nodes, an elastic support network resistant to plastic deformation is formed; furthermore, it relies on the sp... 2 -sp 3Hybridized bonds (bond energy > 2.5 eV) construct efficient phonon transport channels, ultimately achieving the disruptive performance of maintaining 98% resilience and 110 W / mK stable thermal conductivity at 80% compressive strain, providing a new generation of thermal management solutions for highly reliable optoelectronic devices, solid-state laser systems and aerospace electronic control equipment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of step 2 of the present invention.

[0028] Figure 2 This is the micro-buckling structure of Example 1.

[0029] Figure 3 The stress-strain curves for Example 1 and Comparative Example 1 are shown. Figure 3 In this context, 'a' represents the stress-strain cycle curve of the thermal interface between the soft and hard carbon composites. Figure 3 In the figure, b represents the stress-strain curve of the thermal interface of pure graphene.

[0030] Figure 4 This is the TEM of Example 2. Detailed Implementation

[0031] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0032] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0033] The embodiments of the present invention will be further described below with reference to several examples.

[0034] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0035] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0036] Example 1

[0037] (1) A 1 wt% graphene oxide liquid crystal was spread on a smooth horizontal substrate with a liquid crystal thickness of 3 mm.

[0038] (2) Insert two probes with a spacing of 0.5 mm. With the position 0.43 mm from the vertical line between the two probe insertion points as the endpoint, drive the probes to move from the insertion point to the endpoint at the same speed to complete one flow field shearing; the moving speed is 100 cm / h.

[0039] (3) Repeat the shear orientation of step (2), with adjacent sliding paths parallel to each other and a horizontal spacing of 50 μm;

[0040] (4) The oriented graphene oxide liquid crystal obtained in step (3) is dried under reduced pressure to obtain a graphene buckled skeleton.

[0041] (5) Polymer coating: The graphene bent framework is immersed in a polyamic acid precursor solution containing an aromatic ring conjugated structure for 24 hours; the polyamic acid precursor containing an aromatic ring conjugated structure is:

[0042] -[Ar1-C(=O)-NH-Ar2-NH-C(=O)] n -;

[0043] Wherein: Ar1 is phenylene; Ar2 is diphenylene oxide, and n is 10000. The composite framework was removed and immersed in a water / ethanol (5:5, v / v) mixed solution for 4 hours. Afterwards, it was washed three times with fresh anhydrous ethanol for 2 hours each time to further remove impurities and residual solvent. Permeation treatment was performed under conditions of oxygen content <5 ppm, immersing in a water:ethanol = 1:9 solution for 24 hours; a composite framework with a continuous polymer shell was obtained.

[0044] (6) Carbonization-graphitization treatment: The composite skeleton with a continuous polymer shell is first carbonized at 2000℃ in a reducing atmosphere, and then graphitized at 3200℃ in an inert atmosphere.

[0045] like Figure 2 As shown, the prepared material has a sandwich structure. The middle body of the sandwich structure includes an intermediate layer and finned layers located on both sides of the intermediate layer. The two finned layers are symmetrical about the intermediate layer as an axis. Each finned layer includes fins that are inclined relative to one side of the intermediate layer. Fins on the same side are parallel to each other. The intermediate layer and finned layers include a graphene core layer and a hard carbon layer covering the core layer. The stacking density of graphene oxide in the intermediate layer is 0.3 g / cm³. 3 .

[0046] like Figure 4As shown, at the interface between the core layer and the hard carbon layer, a continuous gradient transition from highly ordered graphitized sp² carbon to a highly disordered layer structure rich in sp³ carbon bonds can be observed. This unique microstructure cleverly synergizes the advantages of the two hybrid states: the sp² carbon domains ensure excellent phonon transport capabilities, providing ultra-high thermal conductivity; while the cross-linked sp³ carbon matrix acts as an elastic framework, endowing the material with outstanding hyperelasticity. It is this gradient evolution of chemical bonds from sp² to sp³ that enables the material to possess both thermal conductivity and elasticity. The edge body of the sandwich structure is a coating layer of organic polymer-derived hard carbon, encapsulating the intermediate body. It maintains a 98% resilience, an ultra-low compressive modulus of 0.8 GPa, and a stable thermal conductivity of 110 W / mK under 80% compressive strain.

[0047] Example 2

[0048] (1) A 15 wt% graphene oxide liquid crystal was spread on a smooth horizontal substrate with a liquid crystal thickness of 3 mm.

[0049] (2) Insert two probes, with the endpoint at 1 mm on the vertical line between the two probe insertion points with a spacing of 3 mm. Drive the probes to move from the insertion point to the endpoint at the same speed to complete one flow field shearing. The moving speed is 4000 cm / h. Specifically, immerse the lower part of the array in the graphene oxide liquid crystal and drive the upper vertical section to make the lower part of the probe slide in the liquid crystal.

[0050] (3) Repeat the shear orientation of step (2), and the horizontal spacing between adjacent sliding paths is 500 μm;

[0051] (4) The oriented graphene oxide liquid crystal obtained in step (3) is dried under reduced pressure to obtain a graphene buckled skeleton.

[0052] (5) Polymer coating: The graphene bent framework is immersed in a polyamic acid precursor solution containing an aromatic ring conjugated structure for 2 hours; the polyamic acid precursor containing an aromatic ring conjugated structure is:

[0053] -[Ar1-C(=O)-NH-Ar2-NH-C(=O)] n -;

[0054] Wherein: Ar1 is biphenylene; Ar2 is dithiobenzene, and n is 12000. The composite framework was removed and immersed in a 3:7 v / v acetone / ethanol mixture for 4 hours. Afterwards, it was washed three times with fresh anhydrous ethanol for 2 hours each time to further remove impurities and residual solvent. A permeation treatment was performed under conditions of <5 ppm oxygen content, immersing the composite framework in 100% ethanol solution for 1 hour; a composite framework with a continuous polymer shell was obtained.

[0055] (6) Carbonization-graphitization treatment: The composite skeleton with a continuous polymer shell is subjected to a two-step temperature control program, first carbonized at 1000℃ in a reducing atmosphere, and then graphitized at 3150℃ in an inert atmosphere.

[0056] The resulting material has a sandwich structure similar to that of Example 1, with the stacking density of the graphene oxide in the middle layer being 0.8 g / cm³. 3 .

[0057] Comparative Example 1

[0058] The difference from Example 1 is that it was not coated with polymer.

[0059] like Figure 3 As shown, compression-rebound cyclic performance tests were conducted on the control sample without polymer-based carbon precursor coating. The results showed that the sample exhibited significant plastic deformation characteristics rather than elasticity. After 100 cycles of compression, its stress-strain curve showed obvious hysteresis loop widening and permanent deformation, with the height retention rate dropping sharply to less than 50% of the initial value, completely losing its function as an elastic thermally conductive material.

[0060] After undergoing 100 compression-rebound cycles, the maximum stress retention rate of the graphene composite skeleton coated with polyimide shells decreased by about 15% compared to the initial state, but its overall three-dimensional network structure remained intact, and the height recovery rate could still be maintained at over 85%.

[0061] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A graphene-based carbon film with high elasticity and high thermal conductivity, characterized in that, The structure has a sandwich structure, the intermediate of which includes an intermediate layer and finned layers on both sides of the intermediate layer. The two finned layers are symmetrical about the intermediate layer as an axis. The finned layers include fins that are inclined relative to one side of the intermediate layer. Fins on the same side are parallel to each other. The intermediate layer and the finned layers include a graphene stacked core layer and a hard carbon layer covering the core layer. The interfacial carbon atom bonding mode between the core layer and the hard carbon layer is a sp²-sp³ mixed hybrid state. The edge body of the sandwich structure is a coating layer of organic polymer-derived hard carbon that covers the intermediate body.

2. The graphene-based carbon film according to claim 1, characterized in that, The graphene sheets in the middle layer and the two side fin layers are continuous.

3. The graphene-based carbon film according to claim 1, characterized in that, The stacking density of the graphene oxide in the middle layer is 0.3-0.8 g / cm³. 3 .

4. The graphene-based carbon film according to claim 1, characterized in that, The fins are tilted at an angle greater than 30° relative to the intermediate layer.

5. The graphene-based carbon film according to claim 1, characterized in that, The organic polymer is a polyamic acid containing an aromatic ring conjugated structure.

6. A method for preparing a highly elastic and thermally conductive graphene-based composite carbon film as described in claim 1, characterized in that, It includes the following steps: (1) Spread graphene oxide liquid crystals with a concentration in the range of 1 wt% to 15 wt% on a horizontal smooth substrate; (2) Insert two probes, and take a point on the perpendicular bisector of the two probe insertion points as the endpoint. Drive the probes to move from the insertion point to the endpoint at the same speed to complete one flow field shearing; the moving speed is between 100-4000 cm / h. (3) Repeat the flow field shearing of step (2) multiple times, and keep the probe moving path parallel to the moving path of step (2) to obtain the oriented graphene oxide liquid crystal. (4) The graphene oxide liquid crystal after orientation obtained in step (3) is dried under reduced pressure to obtain a graphene buckled skeleton. (5) Polymer coating: The graphene bent skeleton is immersed in a polyamic acid precursor solution containing an aromatic ring conjugated structure for 2-24 h; after being taken out and cleaned, it is immersed in a poor solvent of polyamic acid for 1-24 h under the condition of oxygen content <5ppm; after being taken out, a composite skeleton with a continuous polymer shell is obtained. (6) Carbonization-graphitization treatment: The composite skeleton with continuous polymer shell is subjected to a two-step temperature control program, first carbonized in a reducing atmosphere and then graphitized in an inert atmosphere.

7. The preparation method according to claim 6, characterized in that, During each flow field shearing, the distance between the two probes is 0.5-3 mm.

8. The preparation method according to claim 6, characterized in that, The spacing between two adjacent movement paths is set to 50-500 μm.

9. The preparation method according to claim 6, characterized in that: The polyamic acid precursor containing an aromatic ring conjugated structure has the following general formula characteristics: -[Ar1-C(=O)-NH-Ar2-NH-C(=O)] n -; Wherein: Ar1 is selected from at least one of phenylene, biphenylene, and naphthyldiyl; Ar2 is selected from at least one of oxydiphenylene, thiodiphenylene, and benzophenone diyl; and n is greater than 10000.

10. The preparation method according to claim 6, characterized in that, The cleaning method in step 5 is as follows: Immerse the graphene buckled skeleton soaked in the polyamic acid precursor solution in the solvent for 4 hours to perform solvent replacement. The solvent is one or more of ethanol, hexanol, tert-butanol, isopropanol, water, n-hexane, and acetone. After that, soak and wash with anhydrous ethanol 3 times, 2 hours each time.

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