A highly thermally conductive adhesive lipoic acid-based thermal interface material, method of manufacture and use

Abstract

This invention discloses a high thermal conductivity and adhesion polythiooctanoic acid-based thermal interface material, its preparation method, and its applications, belonging to the field of polymeric thermal interface materials. The key feature of this invention is the construction of a multi-supramolecular interaction system between tris(hydroxymethyl)aminomethane and a polyphenol compound in deionized water. The aromatic structure of the polyphenol molecule forms π-π conjugation and hydrogen bonding with the surface of the boron nitride thermally conductive filler, enhancing the uniform dispersion of boron nitride. Based on this, thiooctanoic acid monomers are introduced, and a cross-linked viscoelastic network containing dynamic disulfide bonds and abundant hydrogen bonds is constructed through heated ring-opening polymerization. The dynamic network achieves network structure reconstruction through reversible disulfide bond exchange reactions and dynamic hydrogen bond recombination, endowing it with excellent self-healing ability and reprocessability. Surface-modified boron nitride enhances the interfacial bonding with polythiooctanoic acid through supramolecular interfacial interactions, effectively reducing interfacial thermal resistance, constructing a highly efficient thermal conduction network, and significantly improving thermal conductivity. The abundant hydroxyl and amino groups in the composite system, through synergistic effects such as hydrogen bonding, electrostatic interactions, and van der Waals forces, impart excellent interfacial adhesion properties. The preparation method of this thermal interface material is simple, green and environmentally friendly, and it can be used as a thermal interface material in the fields of heat dissipation and flexible thermal management of electronic devices.

Description

Technical Field

[0001] This invention relates to the field of polymer thermal interface materials technology, and particularly to a method for preparing and applying a high thermal conductivity, strong adhesion polythiooctanoic acid-based thermal interface material. This thermal interface material achieves excellent thermal conductivity, self-healing properties, and reprocessability while maintaining flexibility and interfacial adaptability by constructing a viscoelastic network structure containing dynamic disulfide bonds and multiple hydrogen bond interactions, and by introducing thermally conductive fillers surface-functionalized with polyphenolic compounds. It is particularly suitable for heat dissipation and flexible thermal management in electronic devices. Background Technology

[0002] With the rapid development of consumer electronics, new energy devices, and high-power electronic devices towards higher integration, miniaturization, and higher power density, the heat generated by these devices during operation is constantly increasing. If this heat cannot be effectively conducted and dissipated in a timely manner, it will lead to an increase in the operating temperature of the devices, thereby affecting their operational stability, reliability, and lifespan. Therefore, developing thermal interface materials with high thermal conductivity, good interfacial adhesion, and structural stability has become an important research direction in the field of electronic thermal management.

[0003] Currently, common thermal interface materials typically use polymers as the matrix and introduce highly thermally conductive fillers to construct thermal conduction pathways, thereby improving the overall thermal conductivity of the material. However, to form an effective thermal conduction network, a relatively high content of thermally conductive fillers is often required. This not only significantly increases the viscosity of the material system and the processing difficulty, but may also reduce the material's flexibility and interfacial compatibility, thus affecting its application performance under complex interfacial conditions. Furthermore, a heterogeneous interface is usually formed between the thermally conductive filler and the polymer matrix. Due to insufficient interfacial compatibility, interfacial thermal resistance is easily generated, limiting the full utilization of the high intrinsic thermal conductivity of the thermally conductive filler.

[0004] In the prior art, various thermal interface materials have been proposed. For example, Chinese patent CN202410843454.9 discloses an antenna module with an anisotropic hexagonal boron nitride thermal interface, which improves the heat dissipation capacity of the device by constructing a hexagonal boron nitride thermal conductive structure. However, the thermal conductivity of such materials usually exhibits significant anisotropy, and their thermal conductivity in the thickness direction is relatively limited, requiring high standards for interface structure design and assembly conditions. Chinese patent CN202411684350.4 discloses a composite thermally conductive, insulating, and flame-retardant thermal interface material and its preparation method. It improves thermal conductivity and imparts flame-retardant properties to the material by introducing various inorganic fillers into a polymer matrix. However, such systems usually require a high filler content to form an effective thermally conductive network, which may affect the material's flexibility and interface bonding performance. Chinese patent CN202510435702.0 discloses a boron nitride nanosheet, its preparation method and application. It improves the thermal conductivity of materials by preparing two-dimensional boron nitride nanostructures. However, in practical applications, such materials still need to be used in combination with polymer matrices, and their interfacial compatibility and interfacial thermal resistance issues still need further optimization.

[0005] In recent years, dynamic covalent polymer networks have been endowed with properties such as remodeling, repairability, and recyclability due to their ability to undergo bond exchange reactions under thermal, optical, or chemical stimuli, enabling network topology rearrangement and providing new research avenues for the development of novel sustainable thermal interface materials. For example, dynamic polymer networks containing disulfide bonds can achieve self-repair and structural reconstruction through disulfide bond exchange reactions, while polyphenolic compounds, due to their abundant phenolic hydroxyl structures, can form hydrogen bonds or π–π interactions with the surfaces of various inorganic materials, thereby improving the interfacial compatibility between thermally conductive fillers and polymer matrices. However, in existing technologies, how to reduce the interfacial thermal resistance between fillers and matrices through reasonable interface control strategies while maintaining material flexibility, interfacial adhesion, and recyclability, and how to construct stable and efficient thermally conductive networks with low filler content, remain key issues that urgently need to be addressed in the field of thermal interface materials.

[0006] Therefore, there is an urgent need to develop a high thermal conductivity viscoelastic thermal interface material with good interfacial adhesion, self-healing ability, and reusability to meet the application requirements of efficient heat dissipation and sustainable development of electronic devices. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing polymer-based thermal interface materials, such as high content of thermally conductive fillers, large thermal resistance at the heterogeneous interface between the filler and the polymer matrix, poor interfacial adhesion, and difficulty in achieving self-repair and recycling. This invention provides a method for preparing a high thermal conductivity and adhesion polythioctic acid-based thermal interface material. Through molecular structure design, this invention utilizes the ring-opening polymerization of thioctic acid to construct a cross-linked viscoelastic network containing dynamic disulfide bonds and abundant hydrogen bonds. It leverages the stable supramolecular structure formed by polyphenolic compounds and tris(hydroxymethyl)aminomethane under aqueous conditions. The interaction between the aromatic structure of the polyphenol molecules and the surface of the thermally conductive filler enhances the interfacial bonding with the polythioctic acid matrix. This constructs a stable and efficient thermally conductive pathway while maintaining the material's flexibility and interfacial adhesion. The abundant hydroxyl and amino groups in the system, through synergistic effects such as hydrogen bonding, electrostatic interactions, and van der Waals forces, endow the material with excellent interfacial adhesion properties.

[0008] This dynamic network structure mainly includes two types of interactions: (1) Dynamic disulfide bond structure: Lipoic acid can undergo a reversible disulfide bond exchange reaction under certain temperature conditions, enabling the polymer network to achieve topological rearrangement under external stimulation, thereby endowing the material with good self-healing properties, reprocessable properties and recyclable characteristics.

[0009] (2) Multiple hydrogen bond interactions: The phenolic hydroxyl group in polyphenol molecules, the hydroxyl group in tris(hydroxymethyl)aminomethane and the amino group can form a rich hydrogen bond network, which not only improves the overall structural stability of the material, but also enables reversible fracture and reconstruction under external force, thus endowing the material with excellent energy dissipation ability and viscoelastic properties.

[0010] The synergistic effect of the dynamic disulfide bond and multiple hydrogen bond interactions results in a network structure with good structural controllability and interface adaptability, providing a stable dispersion environment for the thermally conductive filler while maintaining the material's flexibility.

[0011] In addition, the abundant polar groups (hydroxyl, carboxyl, ester groups) in the system provide adhesion to a variety of substrates (such as metals, ceramics, and plastics), making it suitable for interfacial wetting and bonding required for thermal interface materials.

[0012] The preparation method of the above-mentioned polythiooctanoic acid-based thermal interface material with high thermal conductivity and strong adhesion mainly includes the following steps: Preparation of S1 precursor: Add 20 parts water and 10-20 parts tris(hydroxymethyl)aminomethane to a reaction vessel, heat and stir at 70-90 °C for 5 min to fully dissolve it; then add 20-40 parts polyphenol compound, and continue stirring at 70-90 °C for 10-90 min to form a viscous precursor.

[0013] S2 Thermally Conductive Filler Introduction: Add 20-50 parts of hexagonal boron nitride to the precursor obtained in step S1, and disperse it under mechanical stirring for 1-2 hours to ensure uniform dispersion of the thermally conductive filler in the system, resulting in a homogeneous mixture. Finally, add 100 parts of thioctic acid, and continue stirring the reaction at 60-100℃ for 40 minutes to form a homogeneous viscous substance.

[0014] S3 Molding and Curing: The mixture obtained in step S2 is injected into a mold. First, it is frozen at -20 ℃ for 12-24 h to pre-fix the structure. Then, it is kept at 40-70 ℃ for 24 h. Subsequently, it is cured at 40-50 ℃ and 0.5-5 MPa pressure for 0.5-3 h. After natural cooling, a recyclable, strongly adhesive and highly thermally conductive polythiooctanoic acid-based thermal interface material is obtained.

[0015] The polyphenolic compound is at least one of tannic acid, gallic acid, dopamine or its derivatives; the boron nitride has a particle size of 10-30 μm.

[0016] The thermal interface material can be used as a thermally conductive adhesive material or a thermal management material for electronic devices to achieve heat dissipation of electronic devices.

[0017] The beneficial effects of this invention are as follows: (1) This invention constructs a viscoelastic network structure containing dynamic disulfide bonds and multiple hydrogen bonds, thereby forming a reversible dynamic cross-linking system within the material. Under external thermal stimulation, the dynamic disulfide bonds can undergo reversible exchange reactions, while the multiple hydrogen bonds can achieve rapid breakage and recombination, thus enabling the material to maintain good flexibility and structural stability while possessing excellent self-healing ability.

[0018] (2) This invention utilizes polyphenolic compounds to regulate the interface of hexagonal boron nitride thermally conductive filler. Through the π-π interaction between the aromatic structure in the polyphenol molecule and the surface of boron nitride, as well as the hydrogen bonding effect formed by the phenolic hydroxyl groups, the dispersion uniformity of the thermally conductive filler in the polymer matrix is ​​improved, and the interfacial bonding strength between the filler and the matrix is ​​enhanced, thereby significantly reducing the interfacial thermal resistance between the filler and the polymer matrix and improving the phonon transmission efficiency at the heterogeneous interface.

[0019] (3) The dynamic viscoelastic network structure constructed in this invention contains abundant polar functional groups, including hydroxyl, amino and carboxyl groups. These polar groups can form hydrogen bonds or van der Waals interactions with the surfaces of various substrates, enabling the material to have good interfacial adhesion properties between different types of substrates such as metals, ceramics and polymers. This can effectively fill the micro-voids at the interface, reduce the interfacial contact thermal resistance, and improve the actual heat dissipation efficiency of the thermal interface material.

[0020] (4) Due to the effective improvement of the interfacial compatibility between the filler and the matrix, the present invention can construct a stable and continuous three-dimensional thermal conductive network with a relatively low thermal conductive filler content, thereby achieving a significant improvement in the overall thermal conductivity of the material and avoiding the problems of increased material viscosity, difficult processing and decreased flexibility caused by excessive filler content in traditional high filler systems.

[0021] (5) The composite material prepared by the present invention has both good flexibility and viscoelastic properties. In practical applications, it can adapt to the micro-morphological changes of the surface of electronic devices and achieve stable bonding under low clamping force conditions, further improving the reliability of the material under complex thermal interface conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the crosslinking reaction of the thermal interface material system.

[0023] Figure 2 This is a schematic diagram of the adhesion mechanism of the highly thermally conductive, adhesive polythiooctanoic acid-based thermal interface material.

[0024] Figure 3 This study demonstrates the application of this highly thermally conductive and adhesive polythiooctanoic acid-based thermal interface material in heat dissipation for LED chips. Detailed Implementation

[0025] The present invention will be further described below through specific embodiments. It should be noted that the embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make non-essential improvements and adjustments to the present invention based on the above content.

[0026] Preparation of S1 precursor: Add 20 parts water and 10-20 parts tris(hydroxymethyl)aminomethane to a reaction vessel, heat and stir at 70-90 °C for 5 min to fully dissolve it; then add 20-40 parts polyphenol compound, and continue stirring at 70-90 °C for 10-90 min to form a viscous precursor.

[0027] S2 Thermally Conductive Filler Introduction: Add 20-50 parts of hexagonal boron nitride to the precursor obtained in step S1 and disperse it under mechanical stirring for 1-2 hours to ensure that the thermally conductive filler is uniformly dispersed in the system and a homogeneous mixture is obtained; finally, add 100 parts of thioctic acid and continue stirring the reaction at 60-100℃ for 40 minutes to form a uniform viscous substance in the system.

[0028] S3 Molding and Curing: The mixture obtained in step S2 is injected into a mold. First, it is frozen at -20 ℃ for 12-24 h to pre-fix the structure. Then, it is kept at 40-70 ℃ for 24 h. Subsequently, it is cured at 40-50 ℃ and 0.5-5 MPa pressure for 0.5-3 h. After natural cooling, a recyclable, strongly adhesive and highly thermally conductive polythiooctanoic acid-based thermal interface material is obtained.

[0029] Example 1 20 parts water and 10 parts tris(hydroxymethyl)aminomethane were added to a reaction vessel and heated and stirred at 80 °C for 5 min to ensure complete dissolution. Then, 20 parts tannic acid were added, and the reaction was continued at 80 °C for 30 min to form a viscous precursor. Next, 20 parts hexagonal boron nitride were added and dispersed under mechanical stirring for 1 h to ensure uniform dispersion of the thermally conductive filler in the system, resulting in a homogeneous mixture. Finally, 100 parts lipoic acid were added to the system, and the reaction was continued at 65 °C for 40 min to form a homogeneous viscous substance.

[0030] The resulting viscous material was injected into a mold and frozen at -20 °C for 12 h for structural pre-fixation. It was then held at 50 °C for 24 h, followed by curing at 45 °C and 1 MPa for 1 h. After natural cooling, a polythiooctanoic acid-based thermal interface material was obtained. This thermal interface material was adhered to the interface of a high-power LED chip to achieve heat dissipation for the electronic device.

[0031] Example 2 20 parts water and 20 parts tris(hydroxymethyl)aminomethane were added to a reaction vessel and heated and stirred at 85 °C for 5 min to ensure complete dissolution. Then, 35 parts tannic acid were added, and the reaction was continued at 85 °C for 45 min to form a viscous precursor. Next, 30 parts hexagonal boron nitride were added and dispersed under mechanical stirring for 1 h to ensure uniform dispersion of the thermally conductive filler in the system, resulting in a homogeneous mixture. Finally, 100 parts lipoic acid were added to the system, and the reaction was continued at 65 °C for 40 min to form a homogeneous viscous substance.

[0032] The resulting viscous material was injected into a mold and frozen at -20 °C for 12 h for structural pre-fixation. It was then held at 55 °C for 24 h, followed by curing at 45 °C and 1 MPa for 1 h. After natural cooling, a polythiooctanoic acid-based thermal interface material was obtained. This thermal interface material was adhered to the interface of a high-power LED chip to achieve heat dissipation for the electronic device.

[0033] Example 3 20 parts water and 20 parts tris(hydroxymethyl)aminomethane were added to a reaction vessel and heated and stirred at 90 °C for 10 min to ensure complete dissolution. Then, 40 parts dopamine were added, and the reaction was continued at 90 °C for 60 min to form a viscous precursor. Next, 40 parts hexagonal boron nitride were added and dispersed under mechanical stirring for 2 h to ensure uniform dispersion of the thermally conductive filler in the system, resulting in a homogeneous mixture. Finally, 100 parts lipoic acid were added to the system, and the reaction was continued at 70 °C for 60 min to form a homogeneous viscous substance.

[0034] The resulting viscous material was injected into a mold and frozen at -20 °C for 24 h for structural pre-fixation. It was then held at 60 °C for 24 h, followed by curing at 50 °C and 1 MPa pressure for 1 h. After natural cooling, a polythiooctanoic acid-based thermal interface material was obtained. This thermal interface material was adhered to the interface of a high-power LED chip to achieve heat dissipation for the electronic device.

[0035] Example 4 20 parts water and 20 parts tris(hydroxymethyl)aminomethane were added to a reaction vessel and heated and stirred at 85 °C for 5 min to ensure complete dissolution. Then, 30 parts tannic acid were added, and the reaction was continued at 85 °C for 60 min to form a viscous precursor. Next, 50 parts hexagonal boron nitride were added and dispersed under mechanical stirring for 2 h to ensure uniform dispersion of the thermally conductive filler in the system, resulting in a homogeneous mixture. Finally, 100 parts lipoic acid were added to the system, and the reaction was continued at 65 °C for 40 min to form a homogeneous viscous substance.

[0036] The resulting viscous material was injected into a mold and frozen at -20 °C for 24 h for structural pre-fixation. It was then held at 60 °C for 24 h, followed by curing at 50 °C and 2 MPa for 1 h. After natural cooling, a polythiooctanoic acid-based thermal interface material was obtained. This thermal interface material was adhered to the interface of a high-power LED chip to achieve heat dissipation for the electronic device.

[0037] Example 5 20 parts water and 20 parts tris(hydroxymethyl)aminomethane were added to a reaction vessel and heated and stirred at 80 °C for 5 min to ensure complete dissolution. Then, 35 parts gallic acid were added, and the reaction was continued at 80 °C for 45 min to form a viscous precursor. Next, 60 parts hexagonal boron nitride were added and dispersed under mechanical stirring for 2 h to ensure uniform dispersion of the thermally conductive filler in the system, resulting in a homogeneous mixture. Finally, 100 parts lipoic acid were added to the system, and the reaction was continued at 65 °C for 40 min to form a homogeneous viscous substance.

[0038] The resulting viscous material was injected into a mold and frozen at -20 °C for 24 h for structural pre-fixation. It was then held at 55 °C for 24 h, followed by curing at 50 °C and 2 MPa pressure for 1 h. After natural cooling, a polythiooctanoic acid-based thermal interface material was obtained. This thermal interface material was adhered to the interface of a high-power LED chip to achieve heat dissipation for the electronic device.

[0039] Comparative Example 1 20 parts water and 20 parts tris(hydroxymethyl)aminomethane were added to a reaction vessel and heated and stirred at 80 °C for 5 min to fully dissolve them. Then 30 parts tannic acid were added, and the reaction was continued at 80 °C for 30 min to form a viscous precursor. Subsequently, 100 parts lipoic acid were added to the system, and the reaction was continued at 60 °C for 30 min to form a homogeneous viscous substance.

[0040] The resulting viscous material was injected into a mold and frozen at -20 °C for 24 h for structural pre-fixation. It was then held at 55 °C for 24 h, followed by curing at 50 °C and 2 MPa pressure for 1 h. After natural cooling, a polythiooctanoic acid-based thermal interface material was obtained. This thermal interface material was adhered to the interface of a high-power LED chip to achieve heat dissipation for the electronic device.

[0041] The test results are shown in Table 1: Table 1. Performance Comparison of Polythiooctanoic Acid-Based Thermal Interface Materials

[0042] As can be seen from the results shown in Table 1, the polythioctic acid-based thermal interface material obtained in the embodiments of the present invention exhibits excellent performance in terms of thermal conductivity, interfacial adhesion, self-healing properties, and reprocessability.

[0043] First, regarding thermal conductivity, compared to Comparative Example 1 without thermally conductive filler, the thermal conductivity of the samples in Examples 1-5 of this invention is significantly improved. With the increase in the content of hexagonal boron nitride filler, a more continuous and stable thermal conductivity pathway is gradually formed, thereby significantly improving the overall thermal conductivity of the material. Second, regarding interfacial adhesion, Examples 1-5 all exhibit good interfacial adhesion. Although the adhesion strength decreases slightly with the increase in the content of thermally conductive filler, it remains at a high level overall, indicating that the viscoelastic dynamic network structure constructed by this system can effectively maintain the interfacial adhesion of the material, meeting the requirements of thermal interface materials for flexible adhesion and interfacial wettability.

[0044] Regarding self-healing properties, the composite material of this invention exhibits excellent self-repairing ability. The self-healing rates of Examples 1-5 reached 90%, 88%, 86%, 80%, and 75%, respectively, indicating that the material can rebuild its network structure through dynamic disulfide bond and hydrogen bond exchange reactions after damage, thereby restoring its material properties. Although the self-healing efficiency decreased slightly with the increase of hexagonal boron nitride filler content, it remained at a high level overall. In addition, the composite material of this invention also has good reprocessability.

[0045] In summary, this invention, by constructing a viscoelastic network structure containing dynamic disulfide bonds and multiple hydrogen bonds, and introducing hexagonal boron nitride thermally conductive filler, achieves a synergistic improvement in thermal conductivity, self-healing properties, and reprocessability while ensuring material flexibility and interfacial adhesion. Compared with traditional thermal interface materials, the composite material of this invention has significant advantages in thermal conductivity, structural stability, and sustainable utilization, and has promising application prospects.

[0046] The above embodiments have described the specific content of the present invention in detail, but the present invention is not limited to the embodiments described. Those skilled in the art can make equivalent substitutions, all of which should be covered within the protection scope of the present invention.

Claims

1. A high thermal conductivity, adhesive polythiooctanoic acid-based thermal interface material, characterized in that, This thermal interface material consists of a dynamic polythioctic acid network formed by the ring-opening polymerization of thioctic acid and a boron nitride thermally conductive filler modified with polyphenolic compounds. The polythioctic acid and polyphenolic compounds are formed in water through tris(hydroxymethyl)aminomethane to form a homogeneous system, in which strong hydrogen bonds and π-π interactions are formed. The dynamic cross-linked network contains both dynamic exchangeable disulfide bonds and multiple hydrogen bonds, thereby constructing a viscoelastic thermal interface material with self-healing properties and forming a continuous thermal conductive path inside the material.

2. The high thermal conductivity adhesive polythiooctanoic acid-based thermal interface material according to claim 1, characterized in that, The main raw materials consist of the following components, in parts by mass: 100 parts of lipoic acid 20-50 parts of hexagonal boron nitride 20-40 parts of polyphenolic compounds 10-20 parts of tris(hydroxymethyl)aminomethane 20 parts deionized water The polyphenolic compound is at least one of tannic acid, gallic acid, dopamine or its derivatives; The boron nitride particles have a diameter of 10-30 μm.

3. A method for preparing the high thermal conductivity adhesive polythiooctanoic acid-based thermal interface material according to claim 1 or 2, characterized in that, Includes the following steps: Preparation of S1 precursor: Add 20 parts water and 10-20 parts tris(hydroxymethyl)aminomethane to a reaction vessel, heat and stir at 70-90℃ for 5 min to fully dissolve it; then add 20-40 parts polyphenol compound, and continue stirring at 70-90℃ for 10-90 min to form a viscous precursor; S2 Thermally conductive filler introduction: Add 20-50 parts of hexagonal boron nitride to the precursor obtained in step S1 and disperse it under mechanical stirring for 1-2 hours to make the thermally conductive filler uniformly dispersed in the system and obtain a homogeneous mixture; finally, add 100 parts of thioctic acid and continue stirring and reacting at 60-100℃ for 40 minutes to form a uniform viscous substance in the system. S3 Molding and Curing: The mixture obtained in step S2 is injected into a mold. First, it is frozen at -20 ℃ for 12-24 h to pre-fix the structure. Then, it is kept at 40-70 ℃ for 24 h. Subsequently, it is cured at 40-50 ℃ and 0.5-5 MPa pressure for 0.5-3 h. After natural cooling, a recyclable, strongly adhesive and highly thermally conductive polythiooctanoic acid-based thermal interface material is obtained.

4. A thermal interface material obtained by the preparation method described in claim 1 or 2 or claim 3 can be used as a thermally conductive adhesive material or a thermal management material for electronic devices, and can be directly placed on the surface of heat-generating electronic devices or chips to achieve heat dissipation of electronic devices.

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