Covalently-bonded high-thermal-conductivity insulating polyimide composite material and preparation method thereof
By covalently bonding functionalized carbon nanofibers with aminated two-dimensional sheet-like insulating and highly thermally conductive fillers, a three-dimensional interpenetrating network is constructed, which solves the problems of filler dispersion and interfacial bonding in polyimide composites, and achieves simultaneous improvement in high thermal conductivity, insulation and mechanical properties.
Patent Information
- Application Number
- CN202511697265.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-02-17
AI Technical Summary
Existing technologies struggle to achieve uniform dispersion and covalent interfacial bonding of fillers in polyimide composites, making it difficult to simultaneously optimize thermal conductivity, insulation, and mechanical properties. Furthermore, existing modification methods have limited effectiveness.
A three-dimensional interpenetrating network structure was constructed by covalently bonding functionalized carbon nanofibers with aminated two-dimensional sheet-like insulating and highly thermally conductive fillers to prepare covalently bonded highly thermally conductive insulating polyimide composite materials.
Achieving simultaneous improvement in high thermal conductivity (122.5 W/(m·K) and high tensile strength (245 MPa), with a volume resistivity higher than 1.2×10¹⁵ Ω·cm, a synergistic three-dimensional hybrid filler network was constructed.
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Figure CN121537787A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of polyimide composites, in particular to a covalently bonded high-thermal-conductivity insulating polyimide composite and a preparation method thereof. BACKGROUND
[0002] Polyimide (PI) as a high-performance polymer material, with its excellent thermal stability, outstanding mechanical properties, good chemical inertness and excellent electrical insulation performance, plays an irreplaceable role in the fields of aerospace, microelectronic packaging, flexible display and high-temperature filter. Especially today, as electronic devices are constantly developing towards miniaturization, high power density and high frequency, the heat generated during the operation of the devices increases sharply, which puts unprecedented high requirements on the heat dissipation capacity of packaging and insulating materials. Therefore, the development of polyimide composites with high thermal conductivity, high insulation and excellent mechanical strength has become a research hotspot and urgent demand in the fields of material science and electronic engineering.
[0003] In order to improve the intrinsic thermal conductivity of polyimide, the conventional technical means is to introduce high-thermal-conductivity fillers into its matrix. Current research mainly focuses on two types of fillers: one type is one-dimensional carbon-based materials such as carbon nanofibers and carbon nanotubes, which have extremely high intrinsic thermal conductivity and can effectively build thermal conduction paths; the other type is two-dimensional sheet-shaped insulating fillers such as boron nitride nanosheets (BNNS) and boron fluoride nanosheets, which not only have excellent thermal conductivity, but also have ideal high insulation.
[0004] However, existing methods for preparing polyimide composites through simple blending have many inherent drawbacks, limiting further improvements in their overall performance. Firstly, there are issues with filler dispersibility and interfacial compatibility: whether carbon-based materials or two-dimensional sheet fillers, due to their high specific surface area and strong van der Waals forces, they are prone to agglomeration in the polymer matrix, making uniform dispersion difficult. This not only reduces mechanical properties but also hinders the formation of an efficient thermally conductive network. Secondly, there is the contradiction between thermal conductivity and insulation performance. While one-dimensional carbon materials have excellent thermal conductivity, their electrical conductivity severely compromises the electrical insulation of the composite material, failing to meet the stringent insulation requirements of high-frequency circuits. While single two-dimensional insulating fillers can ensure insulation, achieving high thermal conductivity requires very high filler amounts, often leading to a sharp increase in material viscosity, processing difficulties, and severe damage to the material's flexibility and mechanical strength. Furthermore, there is the issue of interfacial thermal resistance. The interface between the filler and the polyimide matrix is typically a weak physical adsorption bond, resulting in significant phonon scattering and extremely high interfacial thermal resistance. Even with a high intrinsic thermal conductivity of the filler, the overall improvement in the thermal conductivity of the composite material is very limited. In addition, it is difficult to construct a synergistic filler network. Most existing technologies use single fillers or simple physical mixtures, lacking effective means to control the spatial structure of fillers of different dimensions within the matrix. The lack of strong connections between one-dimensional and two-dimensional fillers makes it impossible to construct a complete and efficient "three-dimensional interpenetrating thermal conductive network" at low filler concentrations, making it difficult to simultaneously optimize thermal conductivity, insulation, and mechanical properties.
[0005] To address the aforementioned issues, while some studies have attempted to improve dispersibility by modifying the surface of the filler or by combining different fillers, the modification effects are often limited, and the interfacial bonding problems between the filler and the matrix, as well as between fillers themselves, have not been fundamentally resolved. In particular, a systematic approach is lacking that can establish a covalent bridge between one-dimensional conductive fillers and two-dimensional insulating fillers, while simultaneously enabling both to form a strong covalent interfacial bond with the polyimide matrix.
[0006] To address this, a covalently bonded high thermal conductivity insulating polyimide composite material and its preparation method are provided. Through interface design, while achieving uniform dispersion of fillers, a three-dimensional hybrid filler network with synergistic effects connected by covalent bonds is constructed, thereby preparing a novel polyimide composite material with significantly improved comprehensive performance. Summary of the Invention
[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a covalently bonded high thermal conductivity insulating polyimide composite material and its preparation method, thereby solving the problems mentioned in the background art.
[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a covalently bonded high thermal conductivity and insulating polyimide composite material, comprising the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of the functionalized carbon nanofibers to the aminated two-dimensional sheet-like insulating high thermal conductivity filler is 1:5 to 2:1. Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: Add a capping agent to the polyamic acid composite slurry obtained in Step 2, and then perform chemical imidization treatment to obtain the high thermal conductivity polyimide composite material. The total mass fraction of the hybrid filler in the composite material is 5% to 35%.
[0009] As a preferred embodiment of the present invention, the two-dimensional sheet-like insulating high thermal conductivity filler in step 1.3 is one or more of boron nitride nanosheets and alumina nanosheets; the modifier used for the amination modification is an amino-containing silane coupling agent.
[0010] As a preferred embodiment of the present invention, the end-capping agent in step 3 is one or more of phthalic anhydride, maleic anhydride, phthalic anhydride, and hexafluorophthalic anhydride; the amount of the end-capping agent added is 1% to 10% of the mass of the diamine monomer.
[0011] A covalently bonded high thermal conductivity insulating polyimide composite material prepared by the method described above, the composite material comprising a polyimide matrix and a hybrid filler uniformly dispersed therein; The hybrid filler includes: Functionalized carbon nanofibers with fluorinated aromatic ester structures covalently grafted onto their surface via ester bonds, wherein unreacted active anhydride groups are retained on the surface of the functionalized carbon nanofibers. The surface is bonded with an aminated two-dimensional sheet-like insulating and highly thermally conductive filler via a silane coupling agent; The functionalized carbon nanofibers have active anhydride groups on their surface that are covalently bonded to the polyimide molecular chains; the amino groups on the surface of the aminated two-dimensional sheet-like insulating and highly thermally conductive filler are covalently bonded to the polyimide molecular chains; and the functionalized carbon nanofibers and the aminated two-dimensional sheet-like insulating and highly thermally conductive filler are spatially bridged and separated from each other, forming a three-dimensional interpenetrating network structure in the polyimide matrix.
[0012] As a preferred embodiment of the present invention, the three-dimensional interpenetrating network structure enables the composite material to simultaneously possess the following properties: an in-plane thermal conductivity of 122.5 W / (m·K) at 25°C, a tensile strength of not less than 245 MPa, and a volume resistivity higher than 1.2 × 10⁻⁶. 15 Ω·cm.
[0013] As a preferred embodiment of the present invention, the polyimide matrix is polymerized from 9,9-bis(trifluoromethyl)oxanthracene-2,3,6,7-tetracarboxylic dianhydride and p-phenylenediamine.
[0014] A heat dissipation management element for high-power electronic devices or an insulating component for high-frequency circuits is made of the covalently bonded, highly thermally conductive, insulating polyimide composite material described above.
[0015] Compared with the prior art, the beneficial effects of the present invention are: The composite material of this invention incorporates a hybrid filler prepared by mixing functionalized carbon nanofibers with aminated two-dimensional sheet-like insulating high thermal conductivity filler. The hybrid filler influences the morphology of the three-dimensional thermally conductive network and the interfacial thermal resistance, thereby further affecting the overall performance of the composite material. The higher the total mass fraction of the hybrid filler in the composite material, the higher the thermal conductivity, tensile strength, and volume resistivity of the sample. The lower the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet-like insulating high thermal conductivity filler, the higher the thermal conductivity, tensile strength, and volume resistivity of the sample, and the better the overall performance of the material.
[0016] In this invention, the active anhydride groups on the surface of the functionalized carbon nanofibers are covalently bonded to the polyimide molecular chains; the amino groups on the surface of the aminated two-dimensional sheet-like insulating and highly thermally conductive filler are covalently bonded to the polyimide molecular chains; furthermore, the functionalized carbon nanofibers and the aminated two-dimensional sheet-like insulating and highly thermally conductive filler are spatially bridged and separated from each other, forming a three-dimensional interpenetrating network structure in the polyimide matrix. This three-dimensional interpenetrating network structure enables the composite material to simultaneously possess the following properties: an in-plane thermal conductivity of 122.5 W / (m·K) at 25°C, a tensile strength of not less than 245 MPa, and a volume resistivity higher than 1.2 × 10⁻⁶. 15 Ω·cm. Attached Figure Description
[0017] Figure 1This is an external view of the high thermal conductivity polyimide composite material of the present invention; Figure 2 This is an appearance diagram of the functionalized carbon nanofibers of the present invention; Figure 3 This is an external view of the aminated boron nitride nanosheets of the present invention; Figure 4 This is a three-dimensional structural diagram of the thermal conductivity pathway of the composite material of the present invention. Detailed Implementation
[0018] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.
[0019] like Figures 1-4 The following steps are shown: A method for preparing a covalently bonded, highly thermally conductive, insulating polyimide composite material. Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of the functionalized carbon nanofibers to the aminated two-dimensional sheet-like insulating high thermal conductivity filler is 1:5 to 2:1. Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: Add a capping agent to the polyamic acid composite slurry obtained in Step 2, and then perform chemical imidization treatment to obtain the high thermal conductivity polyimide composite material. The total mass fraction of the hybrid filler in the composite material is 5% to 35%.
[0020] Example 1: Preparation of Sample 1; Includes the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet-like insulating high thermal conductivity filler is 2:1.
[0021] Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: Add a capping agent to the polyamic acid composite slurry obtained in Step 2, and then perform chemical imidization treatment to obtain the high thermal conductivity polyimide composite material as Sample 1. The total mass fraction of hybrid filler in the composite material in Sample 1 is 5%.
[0022] Example 2: Preparation of Sample 2; Includes the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet-like insulating high thermal conductivity filler is 1:1.
[0023] Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: Add a capping agent to the polyamic acid composite slurry obtained in Step 2, and then perform chemical imidization treatment to obtain the high thermal conductivity polyimide composite material as Sample 2. The total mass fraction of hybrid filler in the composite material in Sample 2 is 10%.
[0024] Example 3: Preparation of Sample 3; Includes the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet-like insulating high thermal conductivity filler is 1:3.
[0025] Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: An end-capping agent is added to the polyamic acid composite slurry obtained in Step 2, followed by chemical imidization treatment to obtain the high thermal conductivity polyimide composite material as Sample 3. The total mass fraction of the hybrid filler in the composite material in Sample 3 is 20%.
[0026] Example 4: Preparation of Sample 4; Includes the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet-like insulating high thermal conductivity filler is 1:5.
[0027] Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: An end-capping agent is added to the polyamic acid composite slurry obtained in Step 2, followed by chemical imidization treatment to obtain the high thermal conductivity polyimide composite material as Sample 4. The total mass fraction of hybrid filler in the composite material in Sample 4 is 35%.
[0028] Comparative Example 1: Preparation of Sample 5; including the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet-like insulating high thermal conductivity filler is 5:1.
[0029] Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: Add a capping agent to the polyamic acid composite slurry obtained in step 2, and then perform chemical imidization treatment to obtain the high thermal conductivity polyimide composite material as sample 5. The total mass fraction of hybrid filler in the composite material in sample 5 is 1%.
[0030] Comparative Example 2: Samples not prepared using this method (Sample 6 purchased from the market without the addition of hybrid fillers) Experimental Testing: Thermal Conductivity Analysis (Thermal Conductivity Tester): Netzsch LFA447 (Netzsch, Germany). The in-plane thermal conductivity of the test sample at 25 °C was measured in "In-plane" mode. The test sample was a circle with a diameter of 25.4 mm and a thickness ranging from 0.1 to 0.5 mm. Thermal conductivity Lambda (W·m) -1 ·K -1 The thermal conductivity is calculated using the following formula: Lambda = Rho × Cp × α in, Rho It is the density of the material, and the unit is g·cm. -3 , Cp It is specific heat capacity, and the unit is J·g. -1 ·K -1 , α It is the thermal diffusivity of the composite material, measured in mm. 2 ·s -1 For each composite material, at least three samples should be prepared for testing and the average value should be calculated.
[0031] Tensile strength: Mechanical property testing (universal testing machine): CMT5105 (Meters Industrial, China), stress-strain testing was performed.
[0032] Volume resistivity: Four-probe conductivity meter: RTS-11 dual-electrical-measurement four-probe meter (RTS-11, China). Before testing, the sample was polished smooth to expose the CF in the sample. Each group of samples was tested 3 times and the average value was taken.
[0033] Table 1: Performance Comparison of Examples 1-4 and Comparative Examples 1-2
[0034] In summary, the table above shows that the higher the total mass fraction of hybrid fillers in the composite material, the greater the thermal conductivity, tensile strength, and volume resistivity of the sample. The smaller the mass ratio of functionalized carbon nanofibers to aminated two-dimensional sheet insulating high thermal conductivity fillers, the greater the thermal conductivity, tensile strength, and volume resistivity of the sample. Therefore, the higher the content of hybrid fillers, the better the performance of the sample.
[0035] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.
Claims
1. A method for preparing a covalently bonded high thermal conductivity insulating polyimide composite material, characterized in that, Includes the following steps: Step 1: Preparation and surface functionalization of hybrid fillers: Step 1.1: Carbon nanofibers were used, and polydopamine was used to modify their surface to obtain PDA@CNFs; Step 1.2: The phenolic hydroxyl groups on the surface of the PDA@CNFs obtained in Step 1.1 are subjected to a ring-opening esterification reaction with 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) to prepare functionalized carbon nanofibers with active anhydride groups retained on the surface. Step 1.3: Amide modification of the surface of the two-dimensional sheet-like insulating high thermal conductivity filler; Step 1.4: Mix the functionalized carbon nanofibers obtained in Step 1.2 with the aminated two-dimensional sheet-like insulating high thermal conductivity filler obtained in Step 1.3 to obtain the hybrid filler; the mass ratio of the functionalized carbon nanofibers to the aminated two-dimensional sheet-like insulating high thermal conductivity filler is 1:5 to 2:
1. Step 2: Preparation of polyamic acid composite slurry: The hybrid filler, diamine monomer, and dianhydride monomer obtained in step 1.4 are polymerized in situ in a polar aprotic solvent; Step 3: Chemical imidization and molding: Add a capping agent to the polyamic acid composite slurry obtained in Step 2, and then perform chemical imidization treatment to obtain the high thermal conductivity polyimide composite material. The total mass fraction of the hybrid filler in the composite material is 5% to 35%.
2. The preparation method according to claim 1, characterized in that, The two-dimensional sheet-like insulating high thermal conductivity filler in step 1.3 is one or more of boron nitride nanosheets and alumina nanosheets; the modifier used for the amination modification is an amino-containing silane coupling agent.
3. The preparation method according to claim 1, characterized in that, The capping agent in step 3 is one or more of phthalic anhydride, maleic anhydride, phthalic anhydride, and hexafluorophthalic anhydride; the amount of capping agent added is 1% to 10% of the mass of the diamine monomer.
4. A covalently bonded, highly thermally conductive, insulating polyimide composite material prepared by the method of any one of claims 1-3, characterized in that, The composite material includes a polyimide matrix and a hybrid filler uniformly dispersed therein; The hybrid filler includes: Functionalized carbon nanofibers with fluorinated aromatic ester structures covalently grafted onto their surface via ester bonds, wherein unreacted active anhydride groups are retained on the surface of the functionalized carbon nanofibers. The surface is bonded with an aminated two-dimensional sheet-like insulating and highly thermally conductive filler via a silane coupling agent; The functionalized carbon nanofibers have active anhydride groups on their surface that are covalently bonded to the polyimide molecular chains; the amino groups on the surface of the aminated two-dimensional sheet-like insulating and highly thermally conductive filler are covalently bonded to the polyimide molecular chains; and the functionalized carbon nanofibers and the aminated two-dimensional sheet-like insulating and highly thermally conductive filler are spatially bridged and separated from each other, forming a three-dimensional interpenetrating network structure in the polyimide matrix.
5. The covalently bonded high thermal conductivity insulating polyimide composite material according to claim 4, characterized in that, The three-dimensional interpenetrating network structure enables the composite material to simultaneously possess the following properties: an in-plane thermal conductivity of 122.5 W / (m·K) at 25°C, a tensile strength of not less than 245 MPa, and a volume resistivity higher than 1.2 × 10⁻⁶. 15 Ω·cm.
6. The covalently bonded high thermal conductivity insulating polyimide composite material according to claim 4, characterized in that, The polyimide matrix is polymerized from 9,9-bis(trifluoromethyl)oxanthracene-2,3,6,7-tetracarboxylic dianhydride and p-phenylenediamine.
7. A heat dissipation management element for high-power electronic devices or an insulating component for high-frequency circuits, made of a covalently bonded high thermal conductivity insulating polyimide composite material as described in any one of claims 4-6.