High-thermal-conductivity polyaryloxadiazole polymer, film, preparation method and application

Abstract

The invention relates to a high-thermal-conductivity polyaryloxadiazole polymer, a film, a preparation method and application, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: mixing fuming sulfuric acid and phosphoric acid to obtain a composite acid solvent; adding a POD monomer and a heat-conducting filler into the composite acid solvent under the condition of inert gas; carrying out gradient heating polymerization reaction to obtain a polymerization solution containing the polyaryloxadiazole polymer; the surface of the heat-conducting filler is modified with amino, hydroxyl or carboxyl functional groups; the polymerization reaction temperature is less than or equal to 80 DEG C. According to the preparation method of the high-thermal-conductivity polyaryloxadiazole polymer, the polyaryloxadiazole polymer with relatively excellent thermal conductivity, mechanical property and high-temperature stability can be obtained in a low-temperature polymerization manner. The material is suitable for heat dissipation application in the fields of 5G high-frequency circuits, flexible electronic devices and the like, and has the advantages of simple process, excellent performance, moderate cost and the like.

Description

Technical Field

[0001] The invention relates to a high-thermal-conductivity polyarylene oxadiazole polymer, a film, a preparation method and an application thereof, and belongs to the technical field of polymer materials. Background Art

[0002] With the rapid development of modern technologies such as 5G communications, artificial intelligence chips, and high-power electronic devices, the power density and integration of electronic devices are constantly increasing, and the resulting heat accumulation problem is becoming increasingly prominent. According to statistics, for every 10°C increase in electronic component temperature, the reliability of the component decreases by 50%. This makes high-efficiency heat dissipation materials a key factor restricting the development of electronic technology. In particular, in the fields of 5G millimeter-wave communications (24-100GHz) and high-performance computing, heat dissipation materials must not only have excellent thermal conductivity but also maintain extremely low dielectric constant and dielectric loss to avoid degradation of signal transmission quality.

[0003] While traditional heat dissipation materials such as metals (copper, aluminum, etc.) offer excellent thermal conductivity, their high density, susceptibility to corrosion, and difficulty in processing limit their application in microelectronics. Common polymer-based heat dissipation materials also suffer from low thermal conductivity (typically <1W / mK). Polyaryl oxadiazole (POD), a high-performance aromatic heterocyclic polymer, possesses excellent heat resistance (decomposition temperature >500°C), mechanical strength (tensile strength >100MPa), and chemical stability due to its unique molecular structure, making it a promising new heat dissipation matrix material. The rigid aromatic ring structure and highly polar oxadiazole rings in its molecular chain theoretically enable the formation of efficient phonon transmission channels, making it possible to achieve high thermal conductivity.

[0004] However, the practical application of POD materials faces three major technical bottlenecks: First, traditional synthesis methods require high-temperature reactions (>120°C) in highly corrosive media (such as fuming sulfuric acid), leading to molecular chain breakage and performance degradation; second, the thermal conductivity of pure POD (approximately 2-4 W / mK) still cannot meet the requirements of high-end applications; and third, existing modification technologies often struggle to achieve both high thermal conductivity and low dielectric properties. These issues severely restrict the practical application of POD in electronic cooling, necessitating the development of new synthesis methods and composite technologies to overcome these limitations. Although several patents have been filed in recent years to address these issues, each has significant limitations, and an ideal solution has yet to be found.

[0005] In the prior art, a patent application with publication number CN102731795A discloses a process for preparing POD by a high-temperature polycondensation method. This patent uses a single fuming sulfuric acid as a solvent and carries out a polymerization reaction at a high temperature of 120-140°C. Although this method can obtain POD polymers with a higher molecular weight, due to the high reaction temperature, it is easy to cause molecular chain breakage and cross-linking, affecting the mechanical properties of the product. More importantly, the thermal conductivity of the resulting film can only reach 4.3W / mK, which is difficult to meet the heat dissipation requirements of modern electronic devices. In addition, this method has extremely high requirements on the corrosion resistance of the equipment, which increases production costs.

[0006] Patent application publication number CN105131492A proposes improving the thermal conductivity of POD films by adding carbon nanotubes. This patent utilizes an in-situ polymerization method to introduce multi-walled carbon nanotubes during the POD synthesis process. While this method can increase thermal conductivity to 6.8 W / mK, the conductive properties of carbon nanotubes significantly increase the dielectric constant of the material (>5), resulting in severe signal loss in high-frequency circuit applications. Furthermore, the dispersion of carbon nanotubes in the matrix affects the product's performance stability, making them prone to agglomeration and reducing the material's mechanical strength.

[0007] Patent application CN110527118A develops a relatively mild POD synthesis method using an ionic liquid as the reaction medium, lowering the polymerization temperature to around 100°C. While this process reduces energy consumption and equipment requirements, it has significant limitations. First, the high cost of the ionic liquid makes it unsuitable for large-scale production. Second, complex purification steps are required to remove the ionic liquid after the reaction, further complicating the process. The resulting film has a thermal conductivity of only 5.2 W / mK, still insufficient for high-end applications.

[0008] Patent application JP2018123274A reports a method for preparing a POD / boron nitride composite material. This patent utilizes mechanical blending to combine hexagonal boron nitride (h-BN) micronized flakes with POD. While this method is simple, due to the poor interfacial compatibility between the micron-sized h-BN and the polymer matrix, the thermal conductivity network is imperfect, resulting in limited improvement in thermal conductivity (maximum 6.1 W / mK). Furthermore, the large size of the h-BN filler reduces the film's flexibility, limiting its application in flexible electronics.

[0009] Patent application publication number US2017032762A1 proposes a multi-stage heating process for POD synthesis. This patent employs a step-by-step heating strategy, initiating the reaction at a lower temperature before gradually increasing the temperature to complete polymerization. While this method improves molecular weight distribution to a certain extent, the final reaction still requires temperatures above 110°C, which cannot completely avoid the negative effects of high temperatures. Furthermore, the patent does not involve any thermal conductivity enhancement technology, and the resulting product exhibits no breakthrough in thermal conductivity.

[0010] Therefore, providing a method for preparing polyaromatic oxadiazole polymers that can be polymerized at low temperature and have relatively excellent thermal conductivity, mechanical properties, and high-temperature stability provides more new technical paths for the development of high-performance heat dissipation materials. Summary of the Invention

[0011] The present invention addresses the deficiencies in the prior art and provides a high thermal conductivity poly(arylene oxadiazole) polymer, a film, a preparation method, and applications thereof. The preparation method of the high thermal conductivity poly(arylene oxadiazole) polymer can obtain a poly(arylene oxadiazole) polymer having relatively excellent thermal conductivity, mechanical properties, and high-temperature stability by low-temperature polymerization.

[0012] The technical solution of the present invention to solve the above technical problems is as follows: a method for preparing a high thermal conductivity polyarylene oxadiazole polymer, the preparation method comprising: S1, mixing fuming sulfuric acid and phosphoric acid to obtain a composite acid solvent; S2. Under inert gas conditions, adding POD monomer and thermal conductive filler to the composite acid solvent; performing a gradient temperature polymerization reaction to obtain a polymer solution containing the polyarylene oxadiazole polymer; The surface of the thermally conductive filler is modified with amino, hydroxyl or carboxyl functional groups; and the polymerization reaction temperature is ≤80°C.

[0013] Furthermore, the mass content of SO3 in oleum is 10% to 30%, and the mass concentration of phosphoric acid is 75% to 85%; In the composite acid solvent, the volume ratio of fuming sulfuric acid to phosphoric acid is 1:(0.5-2).

[0014] Furthermore, the POD monomers include terephthalic acid, isophthalic acid and hydrazine sulfate.

[0015] Furthermore, the molar ratio of terephthalic acid, isophthalic acid and hydrazine sulfate is 1: (0.5-2): (1-3).

[0016] Furthermore, the thermally conductive filler is selected from at least one of boron nitride quantum dots, boron nitride nanosheets, and hydroxylated boron nitride nanotubes, the surfaces of which are modified with amino, hydroxyl, or carboxyl functional groups.

[0017] Furthermore, the particle size of the thermally conductive filler is 2-50 nm, and the added amount of the thermally conductive filler is 1%-5% of the total mass of the POD monomer.

[0018] Furthermore, the polymerization reaction process is: first react at 40-60°C for 4-6 hours, then heat to 70-80°C for 2-6 hours.

[0019] Furthermore, the viscosity of the polymer solution of the high thermal conductivity polyarylene oxadiazole polymer is 20,000-30,000 Cp.

[0020] The present invention also discloses a high thermal conductivity polyarylene oxadiazole polymer, which is prepared according to the preparation method of the present invention.

[0021] The present invention also discloses a film using the high thermal conductivity polyoxadiazole polymer, and the film is obtained by using a casting method on the polymer solution of the polyoxadiazole polymer obtained by the preparation method of the present invention.

[0022] The invention also discloses the application of the film, which is applied to heat dissipation of electronic devices, flexible circuits or high-frequency communication materials.

[0023] The beneficial effects of the present invention are: The preparation method of the present invention adopts a composite acid solvent system of fuming sulfuric acid and phosphoric acid, adjusts the protonation degree of the reaction system to make the condensation reaction more balanced, and at the same time improves the molecular chain orientation parameters, reduces the polymerization reaction temperature to below 80°C, and adopts a gradient temperature rise polymerization process to achieve a controllable polymerization process of first low-temperature chain formation and then high-temperature cyclization, effectively avoiding the problem of molecular chain breakage caused by traditional high-temperature processes; at the same time, by introducing the in-situ composite technology of thermal conductive fillers, the surface functional groups of the thermal conductive fillers and the POD molecular chains are used to construct a three-dimensional thermal conductive network, which significantly improves the thermal conductivity performance of the material and obtains high-quality polymers.

[0024] The poly(aryl oxadiazole) polymer prepared by the preparation method of the present invention is directly cast into a film. The POD film has a thermal conductivity of ≥7.5 W / (m•K), a dielectric constant of ≤2.73 (tested at 10 GHz), and a tensile strength of ≥114 MPa. Under preferred conditions, the POD film has a thermal conductivity of ≥8.6 W / (m•K), a dielectric constant of ≤2.6 (tested at 10 GHz), a tensile strength of ≥125 MPa, and an elongation at break of ≥15%. The film exhibits both excellent mechanical properties and high-temperature stability (thermal conductivity retention >95% after heat treatment at 300°C for 2 hours). This material is suitable for heat dissipation applications in 5G high-frequency circuits, flexible electronic devices, and other fields, offering advantages such as simple processing, excellent performance, and reasonable cost. DETAILED DESCRIPTION

[0025] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] A method for preparing a high thermal conductivity polyarylene oxadiazole polymer, the preparation method comprising: S1, mixing fuming sulfuric acid and phosphoric acid to obtain a composite acid solvent; S2. Under inert gas conditions, adding POD monomer and thermal conductive filler to the composite acid solvent; performing a gradient temperature polymerization reaction to obtain a polymer solution containing the polyarylene oxadiazole polymer; The surface of the thermally conductive filler is modified with amino, hydroxyl or carboxyl functional groups; the polymerization reaction temperature is ≤80° C., and the reaction time is 6 to 12 hours.

[0028] Specifically, the mass content of SO3 in fuming sulfuric acid is 10% to 30%, and the mass concentration of phosphoric acid is 75% to 85%; In the composite acid solvent, the volume ratio of fuming sulfuric acid to phosphoric acid is 1:(0.5-2).

[0029] Specifically, the POD monomers include terephthalic acid, isophthalic acid and hydrazine sulfate.

[0030] Specifically, the molar ratio of terephthalic acid, isophthalic acid and hydrazine sulfate is 1: (0.5-2): (1-3).

[0031] Specifically, the thermally conductive filler is selected from at least one of boron nitride quantum dots (BNQDs, Xi'an Qiyue Biotechnology Co., Ltd.) whose surfaces are modified with amino, hydroxyl or carboxyl functional groups, boron nitride nanosheets (BNNS, Suzhou Napu Material Technology Co., Ltd.), and hydroxylated boron nitride nanotubes (BNNTs, Dalian Yibang Technology Co., Ltd.).

[0032] Specifically, the particle size of the thermally conductive filler is 2-50 nm, and the added amount of the thermally conductive filler is 1%-5% of the total mass of the POD monomer.

[0033] Preferably, the polymerization reaction process is: first react at 40-60°C for 4-6 hours, then heat to 70-80°C for 2-6 hours.

[0034] Preferably, the final viscosity of the polymer solution of the high thermal conductivity polyarylene oxadiazole polymer is 20,000-30,000 Cp (80° C.).

[0035] The present invention also discloses a high thermal conductivity polyarylene oxadiazole polymer, which is prepared according to the preparation method of the present invention.

[0036] The present invention also discloses a film using the high thermal conductivity polyoxadiazole polymer, and the film is obtained by using a casting method on the polymer solution of the polyoxadiazole polymer obtained by the preparation method of the present invention.

[0037] The invention also discloses the application of the film, which is applied to heat dissipation of electronic devices, flexible circuits or high-frequency communication materials.

[0038] Example 1 S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:1; the mass content of SO3 in fuming sulfuric acid is 20%, and the mass concentration of phosphoric acid is 80%; S2. Under nitrogen protection, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added to the composite acid solvent, and 0.28 kg of amino-modified BNQDs (particle size 5-8 nm) was slowly injected into the reactor through a metering pump. The stirring was started at 45 rpm, and the temperature was raised to 50 ° C at 1 ° C / min for 6 hours, and then raised to 80 ° C for 4 hours. The final viscosity of the reaction system reached 25000 Cp. After the reaction was completed, the material was degassed and directly pumped to the casting machine for casting film. The thickness of the film after drying was 120 μm.

[0039] Example 2 S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:1; the mass content of SO3 in fuming sulfuric acid is 10%, and the mass concentration of phosphoric acid is 75%; S2. Under nitrogen protection, 0.84 kg of hydroxylated boron nitride nanosheets (thickness 2-5 nm) were pre-dispersed in a composite acid solvent at a speed of 10,000 rpm by a high shear disperser to obtain a mixture, and the mixture was added to a reactor. 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added. The mixture was stirred at a speed of 45 rpm, and the temperature was raised to 40°C at a speed of 1°C / min for 6 hours, and then raised to 70°C for 6 hours. The final viscosity of the reaction system reached 20,000 Cp. After the reaction was completed, the material was degassed and then directly pumped to a casting machine for casting film formation. The thickness of the film after drying was 120 μm.

[0040] Example 3 S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:1; the mass content of SO3 in fuming sulfuric acid is 30%, and the mass concentration of phosphoric acid is 85%; S2. Under nitrogen protection, 1.4 kg of carboxylated boron nitride nanotubes were pre-mixed with a composite acid solvent in a static mixer to obtain a mixture, the mixture was added to a reactor, and then 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added. The stirring was started at 45 rpm, the temperature was raised to 60 ° C at 1 ° C / min and the reaction was carried out for 4 hours, and then the temperature was raised to 80 ° C and the reaction was carried out for 4 hours. The final viscosity of the reaction system reached 30000 Cp. After the reaction was completed, the material was degassed and then directly pumped to a casting machine for casting film. The thickness of the film after drying was 120 μm.

[0041] Example 4 S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:2; the mass content of SO3 in fuming sulfuric acid is 25%, and the mass concentration of phosphoric acid is 80%; S2. Under nitrogen protection, 2.1 kg of terephthalic acid, 1.6 kg of isophthalic acid, and 2.5 kg of hydrazine sulfate (molar ratio 1:1.5:2) were added to the composite acid solvent, and 0.42 kg of amino-modified BNQDs (particle size 5-8 nm) was slowly injected into the reactor through a metering pump. The stirring was started at 45 rpm, and later increased to 80 rpm. The temperature was raised to 40°C at 1°C / min for 4 hours, and finally reacted at 80°C for 4 hours. The final viscosity of the reaction system reached 28,000 Cp. After the reaction was completed, the material was degassed and directly pumped to a casting machine for casting film formation. The thickness of the film after drying was 120 μm.

[0042] Example 5 S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:0.5; the mass content of SO3 in fuming sulfuric acid is 25%, and the mass concentration of phosphoric acid is 80%; S2. Under nitrogen protection, 4.2 kg of terephthalic acid, 2.1 kg of isophthalic acid and 3.3 kg of hydrazine sulfate were added to the composite acid solvent, and 1.26 kg of amino-modified BNQDs (particle size 5-8 nm) were slowly injected into the reactor through a metering pump. The stirring was started at 60 rpm and the auxiliary dispersion disk was used for high-speed shearing at 1500 rpm. The temperature was raised to 30 ° C at 1 ° C / min for pre-dissolution for 2 hours, and the mixture was reacted at 50 ° C for 6 hours. The temperature was then raised to 80 ° C for reaction for 2 hours. The final viscosity of the reaction system reached 28000 Cp. After the reaction was completed, the material was degassed and then directly pumped to the casting machine for casting film. The thickness of the film after drying was 120 μm.

[0043] Comparative Example 1 This comparative example 1 adopts the traditional high temperature polymerization method to prepare the polymer, and the specific preparation process is as follows: 42L of fuming sulfuric acid (SO3 content 20%) was added to the reactor, and 2.8kg of terephthalic acid, 1.7kg of isophthalic acid and 2.7kg of hydrazine sulfate were added under nitrogen protection. The stirring was started at 40rpm, and the temperature was raised to 120℃ at 1℃ / min and the reaction was maintained for 8 hours. During the reaction, the pressure in the reactor was controlled at 0.25MPa, and the final viscosity of the reaction system reached 26000Cp. After the reaction was completed, the material was degassed and directly pumped to the casting machine for casting film. The thickness of the film after drying was 120μm.

[0044] Comparative Example 2 The polymer was prepared by the same method as in Example 2, except that no thermal conductive filler was added in this comparative example 2. The specific preparation process is as follows: S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:1; the mass content of SO3 in fuming sulfuric acid is 10%, and the mass concentration of phosphoric acid is 75%; S2. Under nitrogen protection, the mixture was added to the reactor, and then 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added. The stirring was started at 45 rpm, and the temperature was raised to 40 ° C at 1 ° C / min for 6 hours, and then the temperature was raised to 70 ° C for 6 hours. The final viscosity of the reaction system reached 21000 Cp. After the reaction was completed, the material was degassed and directly pumped to the casting machine for casting film. The thickness of the film after drying was 120 μm.

[0045] Comparative Example 3 The same method as in Example 1 was used to prepare a polyarylene oxadiazole polymer, except that phosphoric acid was not added in this comparative example 3. The specific preparation process is as follows: Under nitrogen protection, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added to 42 L of fuming sulfuric acid (SO3 mass content is 20%), and 0.28 kg of amino-modified BNQDs (particle size 5-8 nm) were slowly injected into the reactor through a metering pump. The stirring was turned on at 45 rpm, and the temperature was raised to 80 ° C at 1 ° C / min for 6 hours and then raised to 120 ° C for 4 hours. The final viscosity of the reaction system reached 27000 Cp. After the reaction was completed, the material was degassed and directly pumped to the casting machine for casting film. The thickness of the film after drying was 120 μm.

[0046] Comparative Example 4 The same method as in Example 1 was used to prepare a polyarylene oxadiazole polymer, except that fuming sulfuric acid was not added in this comparative example 4. The specific preparation process is as follows: Under nitrogen protection, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added to 42 L of phosphoric acid (mass concentration of 80%), and 0.28 kg of amino-modified BNQDs (particle size 5-8 nm) were slowly injected into the reactor through a metering pump. The stirring was started at 45 rpm, and the temperature was raised to 50 ° C at 1 ° C / min for 6 hours and then raised to 80 ° C for 4 hours. The viscosity of the polymer stock solution did not meet the requirements and could not be made into a film.

[0047] Comparative Example 5 The polyarylene oxadiazole polymer was prepared by the same method as in Example 1, except that the volume ratio of fuming sulfuric acid to phosphoric acid in Comparative Example 5 was 1:4 (not within the ratio range defined in the present invention). The specific preparation process was as follows: S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:4; the mass content of SO3 in fuming sulfuric acid is 20%, and the mass concentration of phosphoric acid is 80%; S2. Under nitrogen protection, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added to the composite acid solvent, and 0.28 kg of amino-modified BNQDs (particle size 5-8 nm) were slowly injected into the reactor through a metering pump. The stirring was started at 45 rpm, and the temperature was raised to 50°C at 1°C / min for 6 hours and then raised to 80°C for 4 hours. The viscosity of the polymer stock solution did not meet the requirements and a film could not be made.

[0048] Comparative Example 6 The polyarylene oxadiazole polymer was prepared by the same method as in Example 1, except that the surface of the thermally conductive filler added in this comparative example 6 was not modified with amino, hydroxyl or carboxyl functional groups. The specific preparation process is as follows: S1. Add fuming sulfuric acid and phosphoric acid into a reactor to prepare 42 L of a composite acid solvent, wherein the volume ratio of fuming sulfuric acid to phosphoric acid is 1:1; the mass content of SO3 in fuming sulfuric acid is 20%, and the mass concentration of phosphoric acid is 80%; S2. Under nitrogen protection, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added to the composite acid solvent, and 0.28 kg of boron nitride nanosheets that had not been hydroxylated were slowly added to the reactor. The stirring was started at 50 rpm, and the temperature was raised to 50 ° C at 1 ° C / min for 6 hours and then raised to 80 ° C for 4 hours. The final viscosity of the reaction system reached 25000 Cp. After the reaction was completed, the material was degassed and directly pumped to a casting machine for casting film. The thickness of the film after drying was 120 μm.

[0049] The films prepared in the above examples and comparative examples were subjected to performance tests. The specific test results are shown in Table 1 below. The test methods involved are as follows: Thermal conductivity: ASTM E1461 laser flash method (sample thickness 120 ± 5 μm); High temperature stability: thermal conductivity retention after heat treatment at 300℃ for 2 hours; Dielectric constant: SPDR method (10 GHz, 23 ± 1 ° C); Tensile strength: ASTM D882 (tensile rate 50 mm / min); Elongation at break: ASTM D882 (tensile rate 50 mm / min).

[0050] Table 1 Performance test results

[0051] The data in the table above demonstrate that the highly thermally conductive poly(aryl oxadiazole) (POD) polymer films produced using the methods described herein, as used in Examples 1-5, exhibit both excellent mechanical properties and high-temperature stability. This method utilizes a complex acid solvent system to achieve true low-temperature polymerization (≤80°C); employs in-situ thermal filler compounding to construct an efficient three-dimensional thermally conductive network; and utilizes a gradient temperature ramping process to precisely control the polymerization process. These innovations not only address technical bottlenecks of traditional methods but also significantly enhance the overall performance of the product.

[0052] From the comparison of the results of Comparative Example 1 and Examples 1-5, it can be seen that the mechanical properties and thermal conductivity of the high thermal conductivity poly(arylene oxadiazole) polymer film prepared by the preparation method of the present invention are significantly better than those of the poly(arylene oxadiazole) polymer film prepared by conventional traditional preparation methods.

[0053] From the comparison of the results of Comparative Example 2 and Example 2, it can be seen that the use of thermally conductive fillers modified with amino, hydroxyl or carboxyl functional groups and POD molecular chains in the preparation method of the present invention can construct a three-dimensional thermal conductive network, which significantly improves the thermal conductivity of the material and is also beneficial to the improvement of the mechanical properties of the polyaryl oxadiazole polymer film.

[0054] From the comparison of the results of Comparative Example 3 and Example 1, it can be seen that if phosphoric acid is not added and only fuming sulfuric acid is used, in order to obtain a polymerization stock solution capable of preparing a film, the first-stage polymerization reaction temperature needs to be increased to 80°C, and the second-stage polymerization reaction temperature needs to be increased to 120°C. The increase in reaction temperature may trigger unexpected cross-linking or branching reactions or an increase in side reactions, resulting in an uneven polymer structure. At the same time, the corrosion to the reactor may be aggravated, shortening the equipment life.

[0055] From the comparison of the results of Comparative Examples 4 and 5 with Example 1, it can be seen that if only phosphoric acid is used without adding fuming sulfuric acid, or if the ratio of fuming sulfuric acid to phosphoric acid is inappropriate, the system cannot react normally and the viscosity required for film formation cannot be achieved. Therefore, the use of the composite acid solvent defined in the present invention is more conducive to obtaining a polyarylene oxadiazole polymer with excellent comprehensive properties.

[0056] From the comparison of the results of Comparative Example 6 and Example 1, it can be seen that if the surface of the thermally conductive filler used is not modified with amino, hydroxyl or carboxyl functional groups, the thermally conductive filler will agglomerate, affecting the uniformity of the system, making the polymerization reaction difficult to control, resulting in a decrease in the thermal conductivity coefficient and affecting the thermal conductivity effect. At the same time, the unmodified filler has no chemical bond with the POD molecular chain and relies only on physical adsorption. When heated or stressed, interfacial slip is likely to occur, resulting in a decrease in the thermal conductivity retention rate. Therefore, the use of thermally conductive fillers whose surface is modified with amino, hydroxyl or carboxyl functional groups to prepare polyarylene oxadiazole polymers is more conducive to obtaining POD films with excellent comprehensive performance.

[0057] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a high thermal conductivity polyarylene oxadiazole polymer, characterized in that: The preparation method is: S1, mixing fuming sulfuric acid and phosphoric acid to obtain a composite acid solvent; S2. Under inert gas conditions, adding POD monomer and thermal conductive filler to the composite acid solvent; performing a gradient temperature polymerization reaction to obtain a polymer solution containing the polyarylene oxadiazole polymer; The surface of the thermally conductive filler is modified with amino, hydroxyl or carboxyl functional groups; and the polymerization reaction temperature is ≤80°C.

2. The method for preparing a high thermal conductivity polyarylene oxadiazole polymer according to claim 1, characterized in that: The mass content of SO3 in fuming sulfuric acid is 10%~30%, and the mass concentration of phosphoric acid is 75%~85%; In the composite acid solvent, the volume ratio of fuming sulfuric acid to phosphoric acid is 1:(0.5-2).

3. The method for preparing a high thermal conductivity polyarylene oxadiazole polymer according to claim 1, characterized in that: The POD monomers include terephthalic acid, isophthalic acid and hydrazine sulfate.

4. The method for preparing a high thermal conductivity polyarylene oxadiazole polymer according to claim 3, characterized in that: The molar ratio of terephthalic acid, isophthalic acid and hydrazine sulfate is 1: (0.5-2): (1-3).

5. The method for preparing a high thermal conductivity polyarylene oxadiazole polymer according to claim 1, wherein: The thermally conductive filler is selected from at least one of boron nitride quantum dots, boron nitride nanosheets, and hydroxylated boron nitride nanotubes whose surfaces are modified with amino, hydroxyl or carboxyl functional groups.

6. The method for preparing a high thermal conductivity polyarylene oxadiazole polymer according to claim 1, wherein: The particle size of the thermal conductive filler is 2-50 nm, and the addition amount of the thermal conductive filler is 1%-5% of the total mass of the POD monomer.

7. The method for preparing a high thermal conductivity polyarylene oxadiazole polymer according to claim 1, characterized in that: The polymerization reaction process is: first react at 40-60°C for 4-6 hours, then heat to 70-80°C for 2-6 hours; The viscosity of the polymer liquid of the high thermal conductivity polyarylene oxadiazole polymer is 20,000-30,000 Cp.

8. A highly thermally conductive poly(arylene oxadiazole) polymer, characterized in that: The high thermal conductivity polyarylene oxadiazole polymer is prepared according to the preparation method according to any one of claims 1 to 7.

9. A film, characterized in that The film is obtained by using a casting method to prepare the polymer solution of the polyarylene oxadiazole polymer prepared by the preparation method according to any one of claims 1 to 7.

10. Use of the film according to claim 9, characterized in that: The film is used in heat dissipation of electronic devices, flexible circuits or high-frequency communication materials.

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