Highly thermally conductive poly(phthalazinone) polymers, films, and methods of making and using the same

Abstract

The application relates to a high-thermal-conductivity polyaromatic oxadiazole polymer, a film, a preparation method and application, and belongs to the technical field of high polymer materials. The preparation method is as follows: fuming sulfuric acid is mixed with phosphoric acid to obtain a composite acid solvent; under the condition of inert gas, POD monomers and a thermal conductive filler are added into the composite acid solvent; a gradient temperature polymerization reaction is carried out to obtain a polymerization liquid containing the polyaromatic oxadiazole polymer; the surface of the thermal conductive filler is modified with amino, hydroxyl or carboxyl functional groups; and the polymerization reaction temperature is less than or equal to 80 DEG C. The preparation method of the high-thermal-conductivity polyaromatic oxadiazole polymer can obtain the polyaromatic oxadiazole polymer with excellent thermal conductive performance, mechanical property and high-temperature stability through a low-temperature polymerization mode. 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 application 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. BACKGROUND

[0002] With the rapid development of modern technologies such as 5G communication technology, artificial intelligence chips and high-power electronic devices, the power density and integration of electronic devices are continuously improved, and the heat accumulation problem is increasingly prominent. According to statistics, the reliability of electronic components will decrease by 50% for every 10℃ increase in temperature, which makes high-efficiency heat dissipation materials one of the key factors restricting the development of electronic technology. In particular, in the fields of 5G millimeter wave communication (24-100GHz) and high-performance computing, not only is it required that the heat dissipation material has excellent thermal conductivity, but also it is required that the heat dissipation material has extremely low dielectric constant and dielectric loss to avoid the decline in signal transmission quality.

[0003] Traditional heat dissipation materials such as metals (copper, aluminum, etc.) have excellent thermal conductivity, but their disadvantages such as high density, easy corrosion and difficult processing limit their application in the microelectronic field. Common polymer-based heat dissipation materials generally have the problem of low thermal conductivity (usually <1W / mK). As a high-performance aromatic heterocyclic polymer, polyaryloxadiazole (POD) has excellent heat resistance (decomposition temperature >500℃), mechanical strength (tensile strength >100MPa) and chemical stability due to its unique molecular structure, and is considered to be a new type of heat dissipation matrix material with great development potential. The rigid aromatic ring structure and strong polar azole ring in the molecular chain can theoretically construct an efficient phonon transmission channel, providing the possibility of achieving high thermal conductivity.

[0004] However, the practical application of POD materials faces three major technical bottlenecks: first, the traditional synthesis method needs to react in a strong corrosive medium (such as fuming sulfuric acid) at a high temperature (>120℃), which leads to molecular chain breakage and performance degradation; second, the thermal conductivity of pure POD (about 2-4W / mK) still cannot meet the needs of high-end applications; third, existing modification techniques often have difficulty in balancing high thermal conductivity and low dielectricity. These problems seriously restrict the practical application of POD in the field of electronic heat dissipation, and new synthesis methods and composite technologies need to be developed to break through these limitations. In recent years, although there have been several patents trying to solve these problems, each has obvious limitations, and an ideal solution has not yet been found.

[0005] In the prior art, patent application CN102731795A discloses a process for preparing POD by high-temperature polycondensation. This patent uses single fuming sulfuric acid as a solvent and conducts polymerization at a high temperature of 120-140°C. Although this method can obtain a POD polymer with a higher molecular weight, the high reaction temperature easily leads to molecular chain rupture and crosslinking, affecting the mechanical properties of the product. More critically, the thermal conductivity of the obtained film can only reach 4.3 W / mK, which is difficult to meet the heat dissipation requirements of modern electronic devices. In addition, this method has very high requirements for equipment corrosion resistance, increasing production costs.

[0006] Patent application CN105131492A proposes to improve the thermal conductivity of POD films by adding carbon nanotubes. This patent uses an in-situ polymerization method to introduce multi-walled carbon nanotubes during the synthesis of POD. Although this method can increase the thermal conductivity to 6.8 W / mK, the electrical conductivity of carbon nanotubes leads to a significant increase in the dielectric constant of the material (>5), which will cause serious signal loss in high-frequency circuit applications. In addition, the dispersion of carbon nanotubes in the matrix also affects the performance stability of the product, and agglomeration easily occurs, reducing the mechanical strength of the material.

[0007] Patent application CN110527118A develops a relatively mild method for synthesizing POD, using ionic liquids as reaction media to reduce the polymerization temperature to around 100°C. Although this process reduces energy consumption and equipment requirements, it has obvious limitations: first, the cost of ionic liquids is high, which is not conducive to large-scale production; second, a complex purification step is needed to remove the ionic liquid after the reaction, increasing the process complexity. The thermal conductivity of the obtained film is only 5.2 W / mK, which still cannot meet the requirements of high-end applications.

[0008] Patent application JP2018123274A reports a method for preparing a POD / boron nitride composite material. This patent uses mechanical blending to mix hexagonal boron nitride (h-BN) microparticles with POD. Although this method is simple, the interface compatibility between micron-sized h-BN and the polymer matrix is poor, and the thermal conductivity network is not well constructed, limiting the improvement in thermal conductivity (up to 6.1 W / mK). At the same time, large-sized h-BN fillers can lead to a decrease in the flexibility of the film, limiting its application in the field of flexible electronics.

[0009] Patent application with publication number US2017032762A1 proposes a multi-stage warming POD synthesis process. The patent adopts a step-by-step warming strategy, first initiates the reaction at a lower temperature, and then gradually increases the temperature to complete the polymerization. Although this method improves the molecular weight distribution to some extent, it still needs to complete the final reaction above 110℃, and cannot completely avoid the negative effects of high temperature. Moreover, the patent does not involve any heat conduction enhancement technology, and the thermal conductivity performance of the obtained product has no breakthrough.

[0010] Therefore, a low-temperature polymerization and a preparation method of a polyaryloxadiazole polymer with excellent thermal conductivity performance, mechanical property and high-temperature stability performance are provided, which provides more new technical paths for the development of high-performance heat dissipation materials. SUMMARY

[0011] The present application provides a high-heat-conducting polyaryloxadiazole polymer, a film, a preparation method and an application, and the preparation method of the high-heat-conducting polyaryloxadiazole polymer can obtain a polyaryloxadiazole polymer with excellent thermal conductivity performance, mechanical property and high-temperature stability performance through low-temperature polymerization.

[0012] The technical scheme for solving the above technical problems is as follows: a preparation method of a high-heat-conducting polyaryloxadiazole polymer, the preparation method is:

[0013] S1, mixing oleum and phosphoric acid to obtain a composite acid solvent;

[0014] S2, under the condition of inert gas, adding POD monomer and heat-conducting filler into the composite acid solvent; performing gradient warming polymerization reaction to obtain a polymerization liquid containing the polyaryloxadiazole polymer;

[0015] The surface of the heat-conducting filler is modified with amino, hydroxyl or carboxyl functional groups; and the polymerization reaction temperature is ≤80℃.

[0016] Further, the mass content of SO3 in the oleum is 10% to 30%, and the mass concentration of the phosphoric acid is 75% to 85%;

[0017] In the composite acid solvent, the volume ratio of the oleum to the phosphoric acid is 1: (0.5-2).

[0018] Further, the POD monomer includes terephthalic acid, isophthalic acid and hydrazine sulfate.

[0019] Further, the molar ratio of the terephthalic acid, isophthalic acid and hydrazine sulfate is 1: (0.5-2): (1-3).

[0020] Further, the heat-conductive filler is selected from at least one of boron nitride quantum dots, boron nitride nanosheets and boron nitride nanotubes with amino, hydroxyl or carboxyl functional groups on the surface.

[0021] Further, the particle size of the heat-conductive filler is 2-50 nm, and the addition amount of the heat-conductive filler is 1%-5% of the total mass of the POD monomers.

[0022] Further, the polymerization process is: first, reacting at 40-60 DEG C for 4-6 hours, and then increasing the temperature to 70-80 DEG C for 2-6 hours.

[0023] Further, the viscosity of the polymerization solution of the high-thermal-conductivity polyaromatic oxadiazole polymer is 20000-30000 Cp.

[0024] The application further discloses a high-thermal-conductivity polyaromatic oxadiazole polymer prepared by the preparation method.

[0025] The application further discloses a film prepared from the high-thermal-conductivity polyaromatic oxadiazole polymer.

[0026] The application further discloses an application of the film, and the film is applied to electronic device heat dissipation, flexible circuit or high-frequency communication material.

[0027] The application has the following beneficial effects:

[0028] The preparation method adopts a composite acid solvent system of oleum and phosphoric acid, adjusts the protonation degree of the reaction system to make the polycondensation reaction more balanced, improves the molecular chain orientation parameter, reduces the polymerization reaction temperature to below 80 DEG C, adopts a gradient temperature polymerization process, realizes a controllable polymerization process of chain formation at low temperature and ring closure at high temperature, effectively avoids the molecular chain rupture problem caused by the traditional high-temperature process, and simultaneously realizes in-situ composite technology of the heat-conductive filler, constructs a three-dimensional heat-conductive network by the action of the surface functional groups of the heat-conductive filler and the POD molecular chain, significantly improves the heat conduction performance of the material, and obtains a high-quality polymer.

[0029] The polymeric liquid containing the polyaryl-oxadiazole polymer prepared by the preparation method is directly cast into a film, the thermal conductivity of the POD film is greater than or equal to 7.5 W / (m*K); the dielectric constant of the POD film is less than or equal to 2.73 (test frequency 10 GHz), and the tensile strength of the POD film is greater than or equal to 114 MPa; preferably, the thermal conductivity of the POD film is greater than or equal to 8.6 W / (m*K); the dielectric constant of the POD film is less than or equal to 2.6 (test frequency 10 GHz), and the tensile strength of the POD film is greater than or equal to 125 MPa, and the elongation at break of the POD film is greater than or equal to 15%, the film has excellent mechanical properties and high-temperature stability (the thermal conductivity retention rate is greater than 95% after 2 hours of heat treatment at 300 DEG C). The material is suitable for heat dissipation applications in the fields of 5G high-frequency circuits, flexible electronic devices and the like, and has the advantages of simple process, excellent performance and moderate cost. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objectives, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0032] A preparation method of a high-thermal-conductivity polyaryl-oxadiazole polymer, the preparation method is:

[0033] S1, mixing oleum and phosphoric acid to obtain a composite acid solvent;

[0034] S2, under the condition of inert gas, adding POD monomers and thermal conductive fillers into the composite acid solvent; performing gradient temperature rising polymerization to obtain a polymeric liquid containing the polyaryl-oxadiazole polymer;

[0035] The surface of the thermal conductive filler is modified with amino, hydroxyl or carboxyl functional groups; the polymerization temperature is less than or equal to 80 DEG C, and the reaction time is 6-12 hours.

[0036] Specifically, the mass content of SO3 in the oleum is 10%-30%, and the mass concentration of the phosphoric acid is 75%-85%;

[0037] In the composite acid solvent, the volume ratio of the oleum to the phosphoric acid is 1: (0.5-2).

[0038] Specifically, the POD monomer comprises terephthalic acid, isophthalic acid and hydrazine sulfate.

[0039] Specifically, the molar ratio of the terephthalic acid, isophthalic acid and hydrazine sulfate is 1: (0.5-2): (1-3).

[0040] Specifically, the thermally conductive filler is selected from at least one of boron nitride quantum dots (BNQDs, Xi'an Qiyue Biological Technology Co., Ltd.) surface modified with amino, hydroxyl or carboxyl functional groups, boron nitride nanosheets (BNNS, Suzhou Napor Material Technology Co., Ltd.), and hydroxylated boron nitride nanotubes (BNNTs, Dalian Yibang Technology Co., Ltd.).

[0041] Specifically, the particle size of the thermally conductive filler is 2-50 nm, and the addition amount of the thermally conductive filler is 1%-5% of the total mass of the POD monomer.

[0042] Preferably, the polymerization process is: first reacting at 40-60℃ for 4-6 hours, and then increasing the temperature to 70-80℃ for 2-6 hours.

[0043] Preferably, the final viscosity of the polymerization solution of the high-thermal-conductivity polyaryloxadiazole polymer is 20,000-30,000 Cp (80℃).

[0044] The application also discloses a high-thermal-conductivity polyaryloxadiazole polymer prepared by the preparation method.

[0045] The application also discloses a film prepared from the high-thermal-conductivity polyaryloxadiazole polymer.

[0046] The application also discloses an application of the film, and the film is applied to electronic device heat dissipation, flexible circuit or high-frequency communication material.

[0047] Example 1

[0048] S1, a composite acid solvent 42L is prepared by adding oleum and phosphoric acid in a reaction kettle, wherein the volume ratio of the oleum to the phosphoric acid is 1:1, the mass content of SO3 in the oleum is 20%, and the mass concentration of the phosphoric acid is 80%;

[0049] S2, under the protection of nitrogen, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added into the composite acid solvent, 0.28 kg of amino-modified BNQDs (particle size 5-8 nm) was slowly injected into the reaction kettle through a metering pump, stirring was started at a speed of 45 rpm, the temperature was raised to 50°C at a rate of 1°C / min, and reacted for 6 hours, then the temperature was raised to 80°C and reacted for 4 hours, the final viscosity of the reaction system reached 25000 Cp, after the reaction was completed, the material was deaerated and then pumped directly into a casting machine for casting film, and the thickness of the dried film was 120 μm.

[0050] Example 2

[0051] S1, a composite acid solvent 42L was prepared by adding oleum and phosphoric acid in a reaction kettle, wherein the volume ratio of oleum to phosphoric acid was 1:1, the mass content of SO3 in oleum was 10%, and the mass concentration of phosphoric acid was 75%;

[0052] S2, under the protection of nitrogen, 0.84 kg of hydroxylated boron nitride nanosheet (thickness 2-5 nm) was pre-dispersed in the composite acid solvent by a high-shear disperser at a speed of 10000 rpm to obtain a mixture, the mixture was added to the reaction kettle, then 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added, stirring was started at a speed of 45 rpm, the temperature was raised to 40°C at a rate of 1°C / min, and reacted for 6 hours, then the temperature was raised to 70°C and reacted for 6 hours, the final viscosity of the reaction system reached 20000 Cp, after the reaction was completed, the material was deaerated and then pumped directly into a casting machine for casting film, and the thickness of the dried film was 120 μm.

[0053] Example 3

[0054] S1, a composite acid solvent 42L was prepared by adding oleum and phosphoric acid in a reaction kettle, wherein the volume ratio of oleum to phosphoric acid was 1:1, the mass content of SO3 in oleum was 30%, and the mass concentration of phosphoric acid was 85%;

[0055] S2, under the protection of nitrogen, 1.4 kg of carboxylated boron nitride nanotube was pre-mixed with the composite acid solvent by a static mixer to obtain a mixture, the mixture was added to the reaction kettle, then 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added, stirring was started at a speed of 45 rpm, the temperature was raised to 60°C at a rate of 1°C / min, and reacted for 4 hours, then the temperature was raised to 80°C and reacted for 4 hours, the final viscosity of the reaction system reached 30000 Cp, after the reaction was completed, the material was deaerated and then pumped directly into a casting machine for casting film, and the thickness of the dried film was 120 μm.

[0056] Example 4

[0057] S1, add oleum and phosphoric acid to prepare a composite acid solvent 42L in a reaction kettle, wherein the volume ratio of oleum to phosphoric acid is 1:2; the mass content of SO3 in oleum is 25%, and the mass concentration of phosphoric acid is 80%;

[0058] S2, under the protection of nitrogen, add 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) to the composite acid solvent, slowly inject 0.42 kg of amino-modified BNQDs (particle size 5-8 nm) into the reaction kettle through a metering pump, start stirring at a speed of 45 rpm, and increase to 80 rpm in the later stage, heat to 40℃ at a rate of 1℃ / min and react for 4 hours, and finally react at 80℃ for 4 hours. The final viscosity of the reaction system reaches 28000Cp. After the reaction is completed, the material is treated by degassing and then pumped directly into a casting machine for casting film. The thickness of the dried film is 120μm.

[0059] Example 5

[0060] S1, add oleum and phosphoric acid to prepare a composite acid solvent 42L in a reaction kettle, wherein the volume ratio of oleum to phosphoric acid is 1:0.5; the mass content of SO3 in oleum is 25%, and the mass concentration of phosphoric acid is 80%;

[0061] S2, under the protection of nitrogen, add 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) to the composite acid solvent, slowly inject 0.42 kg of amino-modified BNQDs (particle size 5-8 nm) into the reaction kettle through a metering pump, start stirring at a speed of 45 rpm, and increase to 80 rpm in the later stage, heat to 40℃ at a rate of 1℃ / min and react for 4 hours, and finally react at 80℃ for 4 hours. The final viscosity of the reaction system reaches 28000Cp. After the reaction is completed, the material is treated by degassing and then pumped directly into a casting machine for casting film. The thickness of the dried film is 120μm.

[0062] Comparative Example 1

[0063] Comparative Example 1 uses a traditional high-temperature polymerization method to prepare a polymer, and the specific preparation process is as follows:

[0064] In the reaction kettle, add 42L of oleum (SO3 content 20%), under the protection of nitrogen, add 2.8kg of terephthalic acid, 1.7kg of isophthalic acid and 2.7kg of hydrazine sulfate, start stirring at a speed of 40rpm, heat to 120℃ at a rate of 1℃ / min and maintain for 8 hours, the pressure in the kettle during the reaction is controlled at 0.25MPa, the final viscosity of the reaction system reaches 26000Cp, after the reaction is completed, the material is treated by degassing and then pumped directly into a casting machine for casting film. The thickness of the dried film is 120μm.

[0065] Comparative Example 2

[0066] The same method as in Example 2 was used to prepare the polymer, except that no heat-conducting filler was added in Comparative Example 2, and the preparation process was as follows:

[0067] S1, a composite acid solvent of 42 L was prepared by adding oleum and phosphoric acid in a reaction kettle, wherein the volume ratio of oleum to phosphoric acid was 1:1, the mass content of SO3 in the oleum was 10%, and the mass concentration of the phosphoric acid was 75%;

[0068] S2, under nitrogen protection, the mixture was added to the reaction kettle, then 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added, stirring was started at a speed of 45 rpm, the temperature was raised to 40°C at a rate of 1°C / min, and reacted for 6 hours, then the temperature was raised to 70°C and reacted for 6 hours, the final viscosity of the reaction system reached 21000 Cp, after the reaction was completed, the material was treated by degassing and then pumped directly to the casting machine for casting film, and the thickness of the dried film was 120 μm.

[0069] Comparative Example 3

[0070] The same method as in Example 1 was used to prepare the polyaryoxadiazole polymer, except that no phosphoric acid was added in Comparative Example 3, and the preparation process was as follows:

[0071] 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 oleum (SO3 mass content of 20%), 0.28 kg of amino-modified BNQDs (particle size of 5-8 nm) was slowly injected into the reaction kettle through a metering pump, stirring was started at a speed of 45 rpm, the temperature was raised to 80°C at a rate of 1°C / min, and reacted for 6 hours, then the temperature was raised to 120°C and reacted for 4 hours, the final viscosity of the reaction system reached 27000 Cp, after the reaction was completed, the material was treated by degassing and then pumped directly to the casting machine for casting film, and the thickness of the dried film was 120 μm.

[0072] Comparative Example 4

[0073] The same method as in Example 1 was used to prepare the polyaryoxadiazole polymer, except that no oleum was added in Comparative Example 4, and the preparation process was as follows:

[0074] Under the protection of nitrogen, 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%) in the reaction kettle, and 0.28 kg of amino-modified BNQDs (particle size of 5-8 nm) was slowly injected into the reaction kettle through a metering pump. The stirring was started at a speed of 45 rpm, and the temperature was raised to 50°C at a rate of 1°C / min for 6 hours and then 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.

[0075] Comparative Example 5

[0076] The same method as in Example 1 was used to prepare the polyaromatic oxadiazole polymer, except that in Comparative Example 5, the volume ratio of oleum to phosphoric acid was 1:4 (which is not within the range of the present application), and the specific preparation process was as follows:

[0077] S1, oleum and phosphoric acid were added to the reaction kettle to prepare a composite acid solvent 42 L, wherein the volume ratio of oleum to phosphoric acid was 1:4; the mass content of SO3 in oleum was 20%, and the mass concentration of phosphoric acid was 80%;

[0078] S2, under the protection of nitrogen, 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%) in the reaction kettle, and 0.28 kg of amino-modified BNQDs (particle size of 5-8 nm) was slowly injected into the reaction kettle through a metering pump. The stirring was started at a speed of 45 rpm, and the temperature was raised to 50°C at a rate of 1°C / min for 6 hours and then 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.

[0079] Comparative Example 6

[0080] The same method as in Example 1 was used to prepare the polyaromatic oxadiazole polymer, except that in Comparative Example 6, the surface of the heat-conducting filler added was not modified with amino, hydroxyl or carboxyl functional groups. The specific preparation process was as follows:

[0081] S1, oleum and phosphoric acid were added to the reaction kettle to prepare a composite acid solvent 42 L, wherein the volume ratio of oleum to phosphoric acid was 1:1; the mass content of SO3 in oleum was 20%, and the mass concentration of phosphoric acid was 80%;

[0082] S2, under the protection of nitrogen, 2.8 kg of terephthalic acid, 1.4 kg of isophthalic acid and 2.2 kg of hydrazine sulfate were added into the composite acid solvent, 0.28 kg of boron nitride nanosheet without hydroxyl modification was slowly added into the reaction kettle, stirring was started at a speed of 50 rpm, the temperature was raised to 50℃ at a rate of 1℃ / min, and reacted for 6 hours, then the temperature was raised to 80℃ and reacted for 4 hours, the final viscosity of the reaction system reached 25000 Cp, after the reaction was completed, the material was deaerated and directly pumped into a casting machine for casting film, and the thickness of the dried film was 120μm.

[0083] The films prepared in the above examples and comparative examples were tested for performance, and the specific test results are shown in Table 1 below, and the test methods involved are as follows:

[0084] Thermal conductivity: ASTM E1461 laser flash method (sample thickness 120±5μm);

[0085] High temperature stability: thermal conductivity retention rate after 300℃ heat treatment for 2 hours;

[0086] Dielectric constant: SPDR method (10GHz, 23±1℃);

[0087] Tensile strength: ASTM D882 (tensile rate 50mm / min);

[0088] Elongation at break: ASTM D882 (tensile rate 50mm / min).

[0089] Table 1 Performance test results

[0090]

[0091] As can be seen from the above table data: the high-thermal-conductivity polyaryloxadiazole (POD) polymer films prepared by the preparation method of the present application in examples 1-5 have excellent mechanical properties and high temperature stability. In the preparation method of the high-thermal-conductivity polyaryloxadiazole polymer of the present application, a truly low-temperature polymerization (≤80℃) is achieved by using a composite acid solvent system; a high-efficiency three-dimensional thermal conduction network is constructed by using in-situ composite technology of thermal conductive fillers; and the polymerization process is precisely controlled by gradient temperature rising process. These innovations not only solve the technical bottlenecks of traditional methods, but also greatly improve the comprehensive performance of the products.

[0092] As can be seen from the comparison of the results of comparative example 1 and examples 1-5: the mechanical properties and thermal conductivity of the high-thermal-conductivity polyaryloxadiazole polymer films prepared by the preparation method of the present application are significantly better than those of the polyaryloxadiazole polymer films prepared by conventional and traditional methods.

[0093] From the comparison of the results of Comparative Example 2 and Example 2, it can be seen that the use of the heat-conductive filler with the surface modified with the amino, hydroxyl or carboxyl functional group and the POD molecular chain in the preparation method of the application can construct a three-dimensional heat-conductive network, significantly improve the thermal conductivity of the material, and also be beneficial to the improvement of the mechanical properties of the polyarene oxadiazole polymer film.

[0094] From the comparison of the results of Comparative Example 3 and Example 1, it can be seen that if the phosphoric acid is not added and only the oleum is used, the first-stage polymerization temperature needs to be increased to 80℃ and the second-stage polymerization temperature needs to be increased to 120℃ to obtain the polymerization stock solution capable of preparing the film, the increase of the reaction temperature can cause the non-expected crosslinking or branching reaction or the increase of the side reaction, result in the inhomogeneous polymer structure, and possibly aggravate the corrosion of the reaction kettle and shorten the service life of the equipment.

[0095] From the comparison of the results of Comparative Example 4, Comparative Example 5 and Example 1, it can be seen that if the oleum is not added and only the phosphoric acid is used, or the use ratio of the oleum and the phosphoric acid is not appropriate, the system cannot normally react and the viscosity required for film preparation cannot be reached, and therefore the use of the composite acid solvent defined in the application is more beneficial to obtain the polyarene oxadiazole polymer with excellent comprehensive performance.

[0096] From the comparison of the results of Comparative Example 6 and Example 1, it can be seen that if the heat-conductive filler with the surface not modified with the amino, hydroxyl or carboxyl functional group is used, the heat-conductive filler will appear the agglomeration phenomenon, affect the uniformity of the system, make the polymerization reaction difficult to control, cause the decrease of the thermal conductivity, affect the heat-conductive effect, and the unmodified filler is not chemically bonded with the POD molecular chain and only relies on the physical adsorption, and is easy to cause the interface slip under the heat or stress, resulting in the decrease of the thermal conductivity retention rate, and therefore the use of the heat-conductive filler with the surface modified with the amino, hydroxyl or carboxyl functional group to prepare the polyarene oxadiazole polymer is more beneficial to obtain the POD film with excellent comprehensive performance.

[0097] The technical features of the above-described embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the description.

[0098] The above-described embodiments only express several implementation manners of the application, the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the application. It should be pointed out that for the ordinary skilled in the art, several modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for preparing a high thermal conductivity polyarylene oxadiazole polymer, characterized in that, The preparation method is as follows: S1. Mix fuming sulfuric acid with phosphoric acid to obtain a composite acid solvent; S2. Under inert gas conditions, polyarylene oxadiazole monomer and thermally conductive filler are added to the composite acid solvent; a gradient temperature polymerization reaction is carried out 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℃; The SO3 content of fuming sulfuric acid is 10%~30% by mass, and the mass concentration of phosphoric acid is 75%~85% by mass. In the composite acid solvent, the volume ratio of fuming sulfuric acid to phosphoric acid is 1:(0.5-2). The thermally conductive filler is selected from at least one of boron nitride quantum dots, boron nitride nanosheets, and hydroxylated boron nitride nanotubes with surface modified with amino, hydroxyl, or carboxyl functional groups. The polymerization process is as follows: first react at 40-60℃ for 4-6 hours, then raise the temperature to 70-80℃ and react for 2-6 hours.

2. The method for preparing a high thermal conductivity polyarylene diazole polymer according to claim 1, characterized in that, The polyarylexadiazole monomers include terephthalic acid, isophthalic acid, and hydrazine sulfate.

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

4. The method for preparing a high thermal conductivity polyarylene diazole polymer according to claim 1, characterized in that, The thermally conductive filler has a particle size of 2~50 nm, and the amount of thermally conductive filler added is 1%~5% of the total mass of polyarylexadiazole monomer.

5. The method for preparing a high thermal conductivity polyaromatic oxadiazole polymer according to claim 1, characterized in that, The polymer solution viscosity of the high thermal conductivity polyaromatic oxadiazole polymer is 20,000-30,000 Cp.

6. A high thermal conductivity polyarylene diazole polymer, characterized in that, The high thermal conductivity polyaromatic oxadiazole polymer is prepared according to the preparation method described in any one of claims 1-5.

7. A thin film, characterized in that, The polymer solution of the polyarylene oxadiazole polymer prepared by any one of claims 1-5 is used to obtain the film by casting.

8. An application of the thin film according to claim 7, characterized in that, The thin film is used in heat dissipation of electronic devices, flexible circuits, or high-frequency communication materials.

Images