A dielectric composition, polyimide dielectric film and method of making and use

Abstract

The application relates to the technical field of energy storage materials, and particularly discloses a dielectric composition, a polyimide dielectric film, a preparation method and application. The dielectric composition provided by the application is a naphthylamine block polyamide acid, a naphthalene anhydride block polyamide acid, a polyamide acid and a transition metal phthalocyanine-based covalent organic framework material. The polyimide dielectric film prepared from the dielectric composition can still maintain a high energy density under a high-temperature environment, and the energy storage density under a 150 DEG C condition can reach 2.70 J / mm 2 The breakdown field strength can reach 350 kV / mm or more, and the Young's modulus can reach 2.2 GPa or more, so that the balance between the high-temperature energy storage performance and the mechanical performance is achieved, and the polyimide dielectric film can be widely applied to the fields of high-temperature energy storage devices, aerospace power systems, high-temperature industrial sensors and the like, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage materials, and particularly relates to a dielectric composition, a polyimide dielectric film and a preparation method and application. BACKGROUND

[0002] With the vigorous development of new energy vehicles, aerospace and other fields, higher requirements are put forward for polymer film capacitors serving under extreme conditions. Under the coupling of heat, electricity and other fields, the conduction loss of traditional polymer films will rapidly increase, resulting in serious deterioration of their electrical insulation and energy storage performance. Although the most widely used biaxially oriented polypropylene (BOPP) exhibits high breakdown strength at room temperature, its working temperature is only 105 DEG C. When the temperature continues to rise, the leakage current density in the material rapidly rises, resulting in a sharp decline in the charge and discharge efficiency and energy density of the capacitor. Therefore, the traditional polymer dielectric cannot meet the growing power demand in harsh environments.

[0003] Polyimide is one of the high polymer materials with good comprehensive performance, and its long-term working temperature range is -200-300 DEG C, and it can withstand high temperature above 400 DEG C. Compared with the most widely used BOPP dielectric film, it has a natural advantage in the application of extreme temperature environment, and it has a dielectric constant of 3.3 (BOPP is 2.2), which also indicates that polyimide has great potential in the application of dielectric film for capacitors. However, the energy storage density of polyimide dielectric film at high temperature is low, which greatly limits its application in the field of high-temperature dielectric energy storage. The existing technology generally adds a small amount of inorganic nanoparticles with wide band gap to improve the breakdown field strength of polyimide and reduce the electrical conduction loss of polyimide film at high temperature, thereby improving its high-temperature energy storage performance. However, the introduction of inorganic nanoparticles will reduce the flexibility and mechanical properties of the polyimide dielectric film. Therefore, it is urgent to develop a polyimide dielectric film with excellent high-temperature energy storage performance and mechanical properties. SUMMARY

[0004] In view of the problem that the polyimide film in the prior art cannot have high-temperature energy storage performance and mechanical properties, the present application provides a dielectric composition, a polyimide dielectric film and a preparation method and application. The polyimide dielectric film provided by the present application has few defects, has high electron affinity performance, can effectively capture carriers at high temperature, and can significantly inhibit electron conduction, thereby having excellent high-temperature energy storage performance, and also has good mechanical properties, and has a wide application prospect in the field of capacitors.

[0005] To solve the above technical problems, the technical scheme provided by the present application is:

[0006] In a first aspect, the present application provides a dielectric composition comprising a naphthylamine block polyamic acid represented by formula (I), a naphthyl anhydride block polyamic acid represented by formula (II), a polyamic acid represented by formula (III), and a transition metal phthalocyanine-based covalent organic framework material;

[0007]

[0008] Compared with the prior art, the dielectric composition provided by the present application has good compatibility among the naphthylamine block polyamic acid, the naphthyl anhydride block polyamic acid and the polyamic acid, which can reduce various defects of the naphthalene-containing polyimide film prepared therefrom; the molecular chain of the naphthalene-containing polyimide prepared therefrom is more rigid and has a more ordered packing, has a smaller free volume, and has better crystallization performance, thus being beneficial to improving the energy storage density and charge-discharge efficiency of the polyimide film and reducing the electrical conduction loss of the polyimide film; the naphthalene-containing polyimide has good heat resistance and can maintain good energy storage performance at high temperature; at the same time, the naphthalene-containing polyimide prepared from the above three polyamic acids has a large conjugated structure, which is beneficial to improving the electronic conductivity, and the conduction band and valence band electron levels and the band gap of the conjugated structure can effectively regulate the movement mode and path of the carriers (holes and electrons), thereby improving the energy storage performance; further, the addition of the transition metal phthalocyanine-based covalent organic framework material can increase the polarization ability of the polyimide film, thereby improving the dielectric constant thereof, and the transition metal phthalocyanine-based covalent organic framework material can form a good interfacial interaction with the polyimide, effectively dispersing the electric field stress, thereby improving the breakdown strength of the polyimide film; in addition, the energy level difference between the transition metal phthalocyanine-based covalent organic framework material and the naphthalene-containing polyimide is large, which can produce a large energy barrier, which is helpful for free charge scattering and hinders the transfer of charges, so that the energy storage device can maintain good performance in a wider temperature range, at the same time, the large energy barrier can make the electrode material more effectively store charges during the charging process, therefore, the introduction of the transition metal phthalocyanine-based covalent organic framework material is also beneficial to further improving the energy storage density; in addition, after the transition metal phthalocyanine-based covalent organic framework material is compounded with the naphthalene-containing polyimide, the flexibility and processability of the naphthalene-containing polyimide film can be effectively improved.

[0009] The polyimide film prepared from the dielectric composition provided by the present application achieves a good balance among the high-temperature energy storage performance, mechanical properties and thermal stability of the polyimide film, overcomes the problem that the traditional polyimide film improves one performance while other performances decrease, is beneficial to widening the application range of the polyimide material, can be applied to various high-performance material demand scenes under complex working conditions, and has high practical value.

[0010] Further, the structure of the transition metal phthalocyanine-based covalent organic framework material is represented by formula (IV):

[0011]

[0012] wherein M is Zn, Cu, Ni or Co.

[0013] The preferred transition metal phthalocyanine-based covalent organic framework material has certain similarities in molecular structure and chemical properties with the polyimide, and good compatibility and interface interaction can be formed between the two. This compatibility helps to improve the dispersibility and binding force of the covalent organic framework material in the polyimide film, so as to fully exert the energy storage performance thereof, and the above-mentioned transition metal phthalocyanine macrocyclic structure itself has high stability, which can maintain stable structure and performance in a wide temperature range and different chemical environments, so that the energy storage device can still work normally under high temperature conditions, which is beneficial to the preparation of an energy storage device with excellent high-temperature energy storage performance and mechanical properties.

[0014] Further, the naphthylamine block polyamide acid represented by formula (I) is formed by polycondensation reaction of 1,4,5,8-naphthalene tetracarboxylic anhydride and a diamine monomer; wherein the diamine monomer includes at least one of 4,4'-diaminodiphenyl methane, m-phenylenediamine, p-phenylenediamine, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 2-bis[4-(4-aminophenoxyphenyl)]propane or 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene.

[0015] As a specific embodiment of the present application, the preparation method of the naphthylamine block polyamide acid represented by formula (I) includes the following steps:

[0016] 1,4,5,8-naphthalene tetracarboxylic anhydride and diamine monomer are added to an organic solvent, and stirred to react to obtain a naphthylamine block polyamide acid solution.

[0017] Specifically, the organic solvent is N,N-dimethylacetamide or N-methyl pyrrolidone; the stirring reaction temperature is 0℃-5℃, and the stirring reaction time is 2h-4h.

[0018] Specifically, the molar ratio of the 1,4,5,8-naphthalene tetracarboxylic anhydride and the diamine monomer is 1:1000-1:100.

[0019] Specifically, the molar ratio of the diamine monomer to the organic solvent is 1:50-1:66.

[0020] Further, the naphthalene anhydride block polyamic acid shown in formula (II) is formed by polycondensation reaction of 2,2'-diphenyl biphenyl-4,4'-diamine and dianhydride monomers; wherein the dianhydride monomers are selected from at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, bisphenol A type diether dianhydride, 4,4'-oxybisphthalic anhydride or bicyclohexyl-3,4',3,4'-tetracarboxylic dianhydride.

[0021] It should be noted that 2,2'-diphenyl biphenyl-4,4'-diamine is synthesized according to the literature High thermal stability and rigid rod of novel organosoluble polyimides and polyamides based on bulky and noncoplanar naphthalene-biphenyldiamine.

[0022] As a specific embodiment of the present application, the preparation method of the naphthalene anhydride block polyamic acid shown in formula (II) comprises the following steps:

[0023] 2,2'-diphenyl biphenyl-4,4'-diamine and dianhydride monomers are added to an organic solvent, and stirred to react to obtain a naphthalene anhydride block polyamic acid solution.

[0024] Specifically, the organic solvent is N,N-dimethylacetamide or N-methyl pyrrolidone; the stirring reaction temperature is 0-5°C, and the stirring reaction time is 5-6h.

[0025] Specifically, the molar ratio of 2,2'-diphenyl biphenyl-4,4'-diamine and dianhydride monomers is 1:1000-1:100.

[0026] Specifically, the molar ratio of the dianhydride monomers and the organic solvent is 1:40-1:50.

[0027] Further, the polyamic acid shown in formula (III) is formed by polycondensation reaction of diamine monomers and dianhydride monomers; wherein the diamine monomers include at least one of 4,4'-diaminodiphenylmethane, m-phenylenediamine, p-phenylenediamine, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 2,2-bis[4-(4-aminophenoxyphenyl)]propane or 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene;

[0028] The dianhydride monomer is selected from at least one of pyromellitic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bisphenol A type diether dianhydride, 4,4'-oxydiphthalic anhydride or bicyclohexyl-3,4',3,4'-tetracarboxylic dianhydride.

[0029] As a specific embodiment of the present application, the preparation method of the polyamic acid represented by formula (III) comprises the following steps:

[0030] The diamine monomer and the dianhydride monomer are added to an organic solvent, and stirred to react to obtain a polyamic acid solution.

[0031] Specifically, the organic solvent is N,N-dimethylacetamide or N-methylpyrrolidone; the temperature of the stirring reaction is 0-5°C, and the time of the stirring reaction is 5-6h.

[0032] Specifically, the molar ratio of the diamine monomer and the dianhydride monomer is 1:1-1:1.2.

[0033] Specifically, the molar ratio of the diamine monomer and the organic solvent is 1:50-1:66.

[0034] As a specific embodiment of the present application, the preparation method of the transition metal phthalocyanine-based covalent organic framework material comprises the following steps:

[0035] The tetraamino phthalocyanine transition metal salt and 1,4-naphthoquinone are dissolved in an organic solvent, anhydrous magnesium sulfate is added, and the reaction is carried out under an inert atmosphere by refluxing, followed by solid-liquid separation, washing and drying to obtain a transition metal phthalocyanine-based covalent organic framework material.

[0036] Specifically, the molar ratio of the tetraamino phthalocyanine transition metal salt, 1,4-naphthoquinone and anhydrous magnesium sulfate is 1:(4-4.2):(4-6).

[0037] Specifically, the tetraamino phthalocyanine transition metal salt is tetraamino zinc phthalocyanine, tetraamino copper phthalocyanine, tetraamino nickel phthalocyanine or tetraamino cobalt phthalocyanine.

[0038] Specifically, the molar ratio of the tetraamino phthalocyanine transition metal salt and the organic solvent is 1:10-1:15.

[0039] Specifically, the organic solvent is N,N-dimethylformamide.

[0040] Specifically, the temperature of the heating reflux is 60-66°C, and the reaction time is 50-52h.

[0041] It should be noted that the prepared transition metal phthalocyanine-based covalent organic framework material is dispersed in an organic solvent to obtain a transition metal phthalocyanine-based covalent organic framework material solution for standby use. The molar ratio of the transition metal phthalocyanine-based covalent organic framework material to the organic solvent is 1:900-1:1100.

[0042] In a second aspect, the present application also provides the use of the above-mentioned dielectric composition in the preparation of a polyimide dielectric film.

[0043] In a third aspect, the present application also provides a polyimide dielectric film prepared from any of the above-mentioned dielectric compositions.

[0044] The polyimide dielectric film provided by the present application can still maintain a relatively high energy density under high temperature environment, and the energy storage density under the condition of 150℃ can reach 2.70J / mm 2 The above-mentioned polyimide dielectric film has a breakdown field strength of 350kV / mm or more, and also has good mechanical properties, with a Young's modulus of 2.2GPa or more, achieving a balance between high-temperature energy storage performance and mechanical properties, and can be widely used in high-temperature energy storage devices, aerospace power systems, high-temperature industrial sensors and other fields, and has a wide application prospect.

[0045] Further, the thickness of the polyimide dielectric film is 8μm-16μm.

[0046] In a fourth aspect, the present application provides a preparation method of a polyimide dielectric film, comprising the following steps:

[0047] The naphthylamine block polyamic acid shown in formula (I), the naphthalimide block polyamic acid shown in formula (II), the polyamic acid shown in formula (III) and the transition metal phthalocyanine-based covalent organic framework material are uniformly mixed, and after polycondensation reaction, a film is cast, then the film is subjected to high-temperature imidization, and the film is peeled off from the substrate to obtain a polyimide dielectric film.

[0048] Further, the temperature of the polycondensation reaction is 0℃-5℃, and the time of the polycondensation reaction is 10h-12h.

[0049] As a specific embodiment of the present application, the preparation method of the polyimide dielectric film comprises the following steps:

[0050] S1, preparing a naphthylamine block polyamic acid solution: adding 1,4,5,8-naphthalic anhydride and the diamine monomer into an organic solvent, stirring and reacting to obtain a naphthylamine block polyamic acid solution (solution a);

[0051] S2, preparing a polyamic acid solution: adding the diamine monomer and the dianhydride monomer into an organic solvent, stirring and reacting to obtain a polyamic acid solution (solution b);

[0052] S3, preparing a naphthalic anhydride block polyamide acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and the dianhydride monomer are added to an organic solvent, the reaction is stirred to obtain a naphthalic anhydride block polyamide acid solution (solution c);

[0053] S4, dissolving a transition metal phthalocyanine and 1,4-naphthoquinone in an organic solvent, adding anhydrous magnesium sulfate, and heating and refluxing under an inert atmosphere, then solid-liquid separation, washing, and drying to obtain a transition metal phthalocyanine-based covalent organic framework material; dispersing the prepared transition metal phthalocyanine-based covalent organic framework material in an organic solvent to obtain a transition metal phthalocyanine-based covalent organic framework material solution (solution d);

[0054] S5, casting and high-temperature imidization: after the polycondensation reaction of solution a, solution b, solution c and solution d, a film is cast on a substrate, the film is heat treated, and the film is peeled off from the substrate to obtain a polyamide-imide dielectric film.

[0055] Specifically, in S5, the volume ratio of solution a, solution b, solution c and solution d is 1:(1-2):1:(1-2).

[0056] Specifically, in S5, the heat treatment adopts a gradient heating mode, and the specific steps are: first, heat preservation at 60-80℃ for 2-5h, then heat preservation at 100-120℃ for 2-5h, heat preservation at 150-180℃ for 2-5h, heat preservation at 200-240℃ for 2-5h, and finally heat preservation at 280-300℃ for 1-2h.

[0057] By using the preferred gradient heating mode, the polyimide molecular chain can gradually arrange and crosslink at different temperature stages, so that the molecular structure of the film is more regular, the internal stress distribution is more uniform, and the mechanical properties of the film are improved. At the same time, by gradient heating, the polyimide molecules can fully undergo imidization reaction at different temperatures to form more stable imide ring structures, improve the thermal stability and high-temperature resistance of the film, and enable the film to maintain good performance in a wider temperature range. At the same time, it is also beneficial to reduce various defects on the surface and inside of the film, and improve the performance of the polyimide film.

[0058] The preparation process of the polyimide film provided by the application is simple and suitable for large-scale industrial production and application.

[0059] In a fifth aspect, the application further provides an application of the above-mentioned polyimide dielectric film in the field of energy storage capacitors.

[0060] In a sixth aspect, the application provides an energy storage capacitor comprising the above-mentioned polyimide dielectric film.

[0061] Compared with the prior art, the naphthalene-containing polyimide film provided by the application has strong charge capture capacity, can bind carriers in a trap region, is favorable for improving the breakdown field strength of the dielectric film, and has the advantages of stronger molecular chain rigidity, more ordered stacking, smaller free volume, better crystallization performance, good flexibility and mechanical properties of the polymer, and still has a high energy storage density under high temperature and strong electric field, so that the application of the naphthalene-containing polyimide in the development of energy storage devices has important research significance and practical value. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 A breakdown field strength diagram of a polyimide dielectric film prepared for the application examples 1 to 4 and the comparative examples 1 to 3;

[0063] Figure 2 A breakdown field strength diagram of a polyimide dielectric film prepared for the application examples 5 to 8 and the comparative examples 4 to 6. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0065] Example 1

[0066] The present embodiment provides a preparation method of a polyimide dielectric film, comprising the following steps:

[0067] Step 1: preparing a naphthalene amine block polyamide acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and 2,2-bis[4-(4-aminophenoxyphenyl)]propane are dissolved in N-methyl pyrrolidone in a molar ratio of 1:1000, and a naphthalene amine block polyamide acid solution (solution a) is obtained after magnetic stirring reaction at 2℃ for 3h;

[0068] Step 2: preparing a polyamide acid solution: 2,2-bis[4-(4-aminophenoxyphenyl)]propane and 3,3',4,4'-benzophenonetetracarboxylic dianhydride are dissolved in N-methyl pyrrolidone in a molar ratio of 1:1.2, and a polyamide acid solution (solution b) is obtained after magnetic stirring reaction at 3℃ for 6h;

[0069] Step 3: Preparation of naphthalic anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and 3,3',4,4'-benzophenonetetracarboxylic dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 40:1 at 5°C, and the reaction was stirred magnetically for 5h to obtain a naphthalic anhydride block polyamic acid solution (solution c);

[0070] Step 4: Preparation of covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed in a molar ratio of 1:4, dissolved in DMF with a molar ratio of 10:1 to tetraamino zinc phthalocyanine, and then 4:1 molar ratio of anhydrous magnesium sulfate to tetraamino zinc phthalocyanine was added. The mixture was heated to reflux at 60°C under nitrogen for 52h, then filtered, and the obtained solid was washed with distilled water, benzene and anhydrous ethanol, and vacuum dried for 12h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:600 to 2,2-bis[4-(4-aminophenoxyphenyl)]propane monomer was dissolved in N-methyl pyrrolidone with a molar ratio of 1000:1 to N-ZnPc COF, and the solution was stirred magnetically at 0°C for 10h to obtain a covalent organic framework solution (solution d);

[0071] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed in a volume ratio of 1:1:1:1.2, and the mixture was cast into a film on a substrate after stirring magnetically at 0°C for 10h. The film was then subjected to high-temperature imidization by heat treatment, and the temperature was maintained at 70°C for 3h, 110°C for 4h, 165°C for 3h, 215°C for 3h and 280°C for 2h. The film was then peeled off from the substrate to obtain the naphthalene block type polyimide / covalent organic framework dielectric film.

[0072] Example 2

[0073] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0074] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and 4,4'-diaminodiphenylmethane were dissolved in N-methyl pyrrolidone with a molar ratio of 58:1 at 5°C, and the reaction was stirred magnetically for 4h to obtain a naphthalene amine block polyamic acid solution (solution a);

[0075] Step 2: Preparation of polyamic acid solution: 4,4'-diaminodiphenylmethane and 4,4'-oxybisphthalic anhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 58:1 at 5°C, and the reaction was stirred magnetically for 6h to obtain a polyamic acid solution (solution b);

[0076] Step 3: Preparation of naphthalic anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and 4,4'-oxybisphthalic anhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 45:1 at 5°C, and the naphthalic anhydride block polyamic acid solution (solution c) was obtained after magnetic stirring for 6h;

[0077] Step 4: Preparation of covalent organic framework solution: zinc tetraaminophthalocyanine and 1,4-naphthoquinone were mixed in a molar ratio of 1:4, dissolved in DMF with a molar ratio of 15:1 to zinc tetraaminophthalocyanine, and then anhydrous magnesium sulfate was added in a molar ratio of 4:1 to zinc tetraaminophthalocyanine. The mixture was heated to reflux at 60°C under nitrogen for 52h, followed by suction filtration. The obtained solid was washed with distilled water, benzene and anhydrous ethanol, respectively, and vacuum dried for 24h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:400 to 4,4'-diaminodiphenylmethane monomer was dissolved in N-methyl pyrrolidone with a molar ratio of 1000:1 to N-ZnPc COF, and the covalent organic framework solution (solution d) was obtained after magnetic stirring at 5°C for 10h.

[0078] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed in a volume ratio of 1:1:1:1.2, and then cast into a film on a substrate after magnetic stirring at 5°C for 12h. The film was then subjected to high-temperature imidization by heat treatment, i.e., 60°C for 4h, 115°C for 3h, 170°C for 4h, 230°C for 4h and 300°C for 1h. After being peeled off from the substrate, the naphthalene block type polyimide / covalent organic framework dielectric film was obtained.

[0079] Example 3

[0080] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0081] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and m-phenylenediamine were dissolved in N-methyl pyrrolidone with a molar ratio of 63:1 to m-phenylenediamine at 0°C, and the naphthalene amine block polyamic acid solution (solution a) was obtained after magnetic stirring for 2h.

[0082] Step 2: Preparation of polyamic acid solution: m-phenylenediamine and bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 63:1 to m-phenylenediamine at 0°C, and the polyamic acid solution (solution b) was obtained after magnetic stirring for 5h.

[0083] Step 3: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 46:1 at 0°C, and the naphthalene anhydride block polyamic acid solution (solution c) was obtained after magnetic stirring for 5h;

[0084] Step 4: Preparation of covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed in a molar ratio of 1:5, dissolved in DMF with a molar ratio of 12:1 to tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate was added with a molar ratio of 4:1 to tetraamino zinc phthalocyanine. After heating and refluxing at 63°C under nitrogen for 51h, the obtained solid was washed with distilled water, benzene and anhydrous ethanol respectively, and vacuum dried for 15h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:200 to m-phenylenediamine monomer was dissolved in N-methyl pyrrolidone with a molar ratio of 1000:1 to N-ZnPc COF, and the covalent organic framework solution (solution d) was obtained after magnetic stirring at 2°C for 12h.

[0085] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed in a volume ratio of 1:1.5:1:1.5, and after magnetic stirring at 0°C for 10h, a film was cast on a substrate, and then the film was subjected to high-temperature imidization by heat treatment, 75°C for 4h, 105°C for 5h, 155°C for 3h, 220°C for 5h, and 290°C for 1h. After peeling off from the substrate, the naphthalene block type polyimide / covalent organic framework dielectric film was obtained.

[0086] Example 4

[0087] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0088] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and 4,4'-diaminodiphenyl sulfone were dissolved in N-methyl pyrrolidone with a molar ratio of 1:100, and the naphthalene amine block polyamic acid solution (solution a) was obtained after magnetic stirring at 3°C for 2h.

[0089] Step 2: Preparation of polyamic acid solution: 4,4'-diaminodiphenyl sulfone and bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 66:1 to 4,4'-diaminodiphenyl sulfone at 3°C, and the polyamic acid solution (solution b) was obtained after magnetic stirring for 6h.

[0090] Step 3: Preparation of naphthalene anhydride poly-block amic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 50:1 to bisphenol A type diether dianhydride, and a naphthalene anhydride block polyamide acid solution (solution c) was obtained after magnetic stirring at 3°C for 5h;

[0091] Step 4: Preparation of covalent organic framework solution: zinc tetraaminophthalocyanine and 1,4-naphthoquinone were mixed in a molar ratio of 1:6, dissolved in DMF with a molar ratio of 13:1 to zinc tetraaminophthalocyanine, and anhydrous magnesium sulfate was added in a molar ratio of 4:1 to zinc tetraaminophthalocyanine. The mixture was heated to reflux at 60°C under nitrogen for 52h, followed by suction filtration. The obtained solid was washed with distilled water, benzene and anhydrous ethanol, respectively, and vacuum dried for 15h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:100 to 4,4'-diaminodiphenyl sulfone monomer was dissolved in N-methyl pyrrolidone with a molar ratio of 1000:1 to N-ZnPc COF, and a covalent organic framework solution (solution d) was obtained after magnetic stirring at 0°C for 10h.

[0092] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed in a volume ratio of 1:2:1:2, and a film was cast on a substrate after magnetic stirring at 2°C for 11h. The film was then subjected to high-temperature imidization by heat treatment, with 65°C for 4h, 115°C for 3h, 160°C for 4h, 230°C for 3h and 285°C for 2h. After peeling off from the substrate, the naphthalene block type polyimide / covalent organic framework dielectric film was obtained.

[0093] Example 5

[0094] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0095] Step 1: Naphthalene amine block polyamide acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and p-phenylenediamine were dissolved in N-methyl pyrrolidone with a molar ratio of 60:1 to p-phenylenediamine, and a naphthalene amine block polyamide acid solution (solution a) was obtained after magnetic stirring at 2°C for 4h.

[0096] Step 2: Preparation of polyamide acid solution: p-phenylenediamine and 3,3',4,4'-biphenyl tetracarboxylic dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 60:1 to p-phenylenediamine, and a polyamide acid solution (solution b) was obtained after magnetic stirring at 0°C for 5h.

[0097] Step 3: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and 3,3',4,4'-biphenyl tetracarboxylic dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1000, and a naphthalene anhydride block polyamic acid solution (solution c) was obtained after magnetic stirring at 2°C for 5h;

[0098] Step 4: Preparation of covalent organic framework solution: zinc tetraaminophthalocyanine and 1,4-naphthoquinone were mixed at a molar ratio of 1:4, dissolved in DMF at a molar ratio of 10:1 with zinc tetraaminophthalocyanine, and anhydrous magnesium sulfate was added at a molar ratio of 4:1 with zinc tetraaminophthalocyanine. The mixture was heated to reflux at 66°C under nitrogen for 50h, followed by suction filtration. The obtained solid was washed with distilled water, benzene and anhydrous ethanol, respectively, and vacuum dried for 24h to obtain N-ZnPc COF. N-ZnPc COF at a molar ratio of 1:600 with p-phenylenediamine monomer was dissolved in N-methyl pyrrolidone at a molar ratio of 1000:1 with N-ZnPc COF, and a covalent organic framework solution (solution d) was obtained after magnetic stirring at 0°C for 12h.

[0099] Step 5: Casting and high-temperature imidization, the volume ratio of solution a, solution b, solution c, solution d is 1:1.2:1:1.5, after magnetic stirring at 0°C for 12h, the film is cast on the substrate, and then the film is subjected to high-temperature imidization by heat treatment, 60°C for 4h, 110°C for 3h, 170°C for 3h, 230°C for 2h, and 285°C for 1h. After peeling off from the substrate, the naphthalene block type polyimide / covalent organic framework dielectric film is obtained.

[0100] Example 6

[0101] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0102] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene were dissolved in N-methyl pyrrolidone at a molar ratio of 1:500, and a naphthalene amine block polyamic acid solution (solution a) was obtained after magnetic stirring at 5°C for 3h.

[0103] Step 2: Preparation of polyamic acid solution: 1,3-bis[2-(4-aminophenyl)-2- propyl]benzene and bicyclohexyl-3,4',3,4'-tetraoic dianhydride were dissolved in N- methylpyrrolidone with a molar ratio of 1:1.2 to 1,3-bis[2-(4-aminophenyl)-2- propyl]benzene, and the reaction was stirred magnetically at 3°C for 6h to obtain a polyamic acid solution (solution b);

[0104] Step 3: Preparation of naphthalic anhydride block polyamic acid solution: 2,2'- dinaphthyl biphenyl-4,4'-diamine and bicyclohexyl-3,4',3,4'-tetraoic dianhydride were dissolved in N-methylpyrrolidone with a molar ratio of 1:500 to bicyclohexyl-3,4',3,4'- tetraoic dianhydride, and the reaction was stirred magnetically at 2°C for 5h to obtain a naphthalic anhydride block polyamic acid solution (solution c);

[0105] Step 4: Preparation of covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed with a molar ratio of 1:5, dissolved in DMF with a molar ratio of 15:1 to tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate was added with a molar ratio of 4.2:1 to tetraamino zinc phthalocyanine, heated to reflux at 60°C under nitrogen for 52h, followed by suction filtration, and the obtained solid was washed with distilled water, benzene and anhydrous ethanol, and vacuum dried for 20h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:400 to 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene monomer was dissolved in N-methylpyrrolidone with a molar ratio of 1000:1 to N-ZnPc COF, and the reaction was stirred magnetically at 0°C for 10h to obtain a covalent organic framework solution (solution d);

[0106] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed with a volume ratio of 1:1:1:1, and the reaction was stirred magnetically at 5°C for 10h to form a film on a substrate, and then the film was subjected to high-temperature imidization by heat treatment, 70°C for 3h, 110°C for 3h, 160°C for 3h, 220°C for 3h, and 290°C for 2h, and then peeled off from the substrate to obtain the naphthalene block type polyimide / covalent organic framework dielectric film.

[0107] Example 7

[0108] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0109] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalenetetracarboxylic anhydride and 1,3-bis(4-aminophenoxy)benzene were dissolved in N-methylpyrrolidone at a molar ratio of 1:200, and the reaction was stirred magnetically at 0°C for 2h to obtain a naphthalene amine block polyamic acid solution (solution a);

[0110] Step 2: Preparation of polyamic acid solution: 1,3-bis(4-aminophenoxy)benzene and 1,2,4,5-cyclohexanetetracarboxylic dianhydride were dissolved in N-methylpyrrolidone at a molar ratio of 1:1.2, and the reaction was stirred magnetically at 2°C for 6h to obtain a polyamic acid solution (solution b);

[0111] Step 3: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and 1,2,4,5-cyclohexanetetracarboxylic dianhydride were dissolved in N-methylpyrrolidone at a molar ratio of 1:200, and the reaction was stirred magnetically at 0°C for 5h to obtain a naphthalene anhydride block polyamic acid solution (solution c);

[0112] Step 4: Preparation of covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed at a molar ratio of 1:4, dissolved in DMF at a molar ratio of 10:1 with respect to tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate was added at a molar ratio of 4.1:1 with respect to tetraamino zinc phthalocyanine. The mixture was heated to reflux at 65°C under nitrogen for 50h, followed by suction filtration. The obtained solid was washed with distilled water, benzene and anhydrous ethanol, and vacuum dried for 15h to obtain N-ZnPc COF. N-ZnPc COF was dissolved in N-methylpyrrolidone at a molar ratio of 1000:1 with respect to N-ZnPc COF, and the solution was stirred magnetically at 5°C for 12h to obtain a covalent organic framework solution (solution d);

[0113] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed at a volume ratio of 1:1:1:1.2, and the mixture was cast into a film on a substrate after being stirred magnetically at 0°C for 11h. The film was then subjected to high-temperature imidization by heat treatment, i.e., 80°C for 2h, 20°C for 2h, 180°C for 2h, 240°C for 2h and 300°C for 1h. After being peeled off from the substrate, the naphthalene block-containing polyimide / covalent organic framework dielectric film was obtained.

[0114] Example 8

[0115] The present embodiment provides a method for preparing a polyimide dielectric film, comprising the following steps:

[0116] Step 1: Preparation of naphthylamine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and 4,4'-diaminodiphenyl ether were dissolved in N-methyl pyrrolidone with a molar ratio of 1:100 at 0°C, and the reaction was stirred magnetically for 2h to obtain a naphthylamine block polyamic acid solution (solution a);

[0117] Step 2: Preparation of polyamic acid solution: 4,4'-diaminodiphenyl ether and pyromellitic dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 1:1.1 at 0°C, and the reaction was stirred magnetically for 5h to obtain a polyamic acid solution (solution b);

[0118] Step 3: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinitrophenyl biphenyl-4,4'-diamine and pyromellitic dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 1:100 at 0°C, and the reaction was stirred magnetically for 5h to obtain a naphthalene anhydride block polyamic acid solution (solution c);

[0119] Step 4: Preparation of covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed with a molar ratio of 1:4, dissolved in DMF with a molar ratio of 10:1 to tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate with a molar ratio of 4:1 to tetraamino zinc phthalocyanine was added. The mixture was heated to reflux at 60°C under nitrogen for 50h, then filtered, and the obtained solid was washed with distilled water, benzene and anhydrous ethanol, and vacuum dried for 18h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:100 to 4,4'-diaminodiphenyl ether monomer was dissolved in N-methyl pyrrolidone with a molar ratio of 1:1000 to N-ZnPc COF, and the reaction was stirred magnetically for 11h at 0°C to obtain a covalent organic framework solution (solution d);

[0120] Step 5: Casting and high-temperature imidization: solutions a, b, c and d were mixed with a volume ratio of 1:1:1:1.2, and the mixture was cast into a film on a substrate after stirring magnetically at 5°C for 12h. The film was then subjected to high-temperature imidization by heat treatment, i.e. 60°C for 5h, 100°C for 5h, 150°C for 5h, 200°C for 5h and 280°C for 2h. After being peeled off from the substrate, the naphthalene block-containing polyimide / covalent organic framework dielectric film was obtained.

[0121] Comparative Example 1

[0122] This comparative example provides a method for preparing a polyimide dielectric film, which is different from Example 3 only in that no solution a, solution c and solution d are added during the preparation process, and specifically comprising the following steps:

[0123] Step 1: Preparation of polyamic acid solution: m-phenylenediamine and bisphenol A diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 1:1.2 to m-phenylenediamine, and the polyamic acid solution (solution b) was obtained after magnetic stirring at 0°C for 5h;

[0124] Step 2: Casting and high-temperature imidization: solution b was cast into a film on a substrate, and then the film was subjected to high-temperature imidization by heat treatment, 75°C for 4h, 105°C for 5h, 155°C for 3h, 220°C for 5h, 290°C for 1h, and the naphthalene block type polyimide / covalent organic framework dielectric film was obtained after peeling off from the substrate.

[0125] Comparative Example 2

[0126] The present comparative example provides a preparation method of a polyimide dielectric film, which is different from Example 3 only in that solution d is not added during the preparation process, and specifically comprises the following steps:

[0127] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and m-phenylenediamine were dissolved in N-methyl pyrrolidone with a molar ratio of 1:200 to m-phenylenediamine, and the naphthalene amine block polyamic acid solution (solution a) was obtained after magnetic stirring at 0°C for 2h;

[0128] Step 2: Preparation of polyamic acid solution: m-phenylenediamine and bisphenol A diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 1:1.2 to m-phenylenediamine, and the polyamic acid solution (solution b) was obtained after magnetic stirring at 0°C for 5h;

[0129] Step 3: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and bisphenol A diether dianhydride were dissolved in N-methyl pyrrolidone with a molar ratio of 1:200 to bisphenol A diether dianhydride, and the naphthalene anhydride block polyamic acid solution (solution c) was obtained after magnetic stirring at 0°C for 5h;

[0130] Step 4: Casting and high-temperature imidization: solution a, solution b, and solution c were cast into a film on a substrate in a volume ratio of 1:1.5:1 after magnetic stirring at 0°C for 10h, and then the film was subjected to high-temperature imidization by heat treatment, 75°C for 4h, 105°C for 5h, 155°C for 3h, 220°C for 5h, 290°C for 1h, and the naphthalene block type polyimide / covalent organic framework dielectric film was obtained after peeling off from the substrate.

[0131] Comparative Example 3

[0132] The comparative example provides a preparation method of a polyimide dielectric film, which is different from example 3 only in that no solution a is added in the preparation process, and specifically comprises the following steps:

[0133] Step 1: Preparation of polyamic acid solution: m-phenylenediamine and bisphenol A type diether dianhydride are dissolved in N-methylpyrrolidone with a molar ratio of 63:1 to m-phenylenediamine, and a polyamic acid solution (solution b) is obtained after magnetic stirring at 0°C for 5h;

[0134] Step 2: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and bisphenol A type diether dianhydride are dissolved in N-methylpyrrolidone with a molar ratio of 46:1 to bisphenol A type diether dianhydride, and a naphthalene anhydride block polyamic acid solution (solution c) is obtained after magnetic stirring at 0°C for 5h;

[0135] Step 3: Preparation of covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone are mixed according to a molar ratio of 1:5, dissolved in DMF with a molar ratio of 12:1 to tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate with a molar ratio of 4:1 to tetraamino zinc phthalocyanine is added, heated to reflux at 63°C under nitrogen for 51h, then filtered, and the obtained solid is washed with distilled water, benzene and anhydrous ethanol respectively, and vacuum dried for 15h to obtain N-ZnPc COF. N-ZnPc COF with a molar ratio of 1:200 to m-phenylenediamine monomer is dissolved in N-methylpyrrolidone with a molar ratio of 1000:1 to N-ZnPc COF, and a covalent organic framework solution (solution d) is obtained after magnetic stirring at 2°C for 12h;

[0136] Step 4: Casting and high-temperature imidization: solutions b, c and d are mixed in a volume ratio of 1.5:1:1.5, and after magnetic stirring at 0°C for 10h, a film is cast on a substrate, and then the film is subjected to high-temperature imidization by heat treatment, 75°C for 4h, 105°C for 5h, 155°C for 3h, 220°C for 5h, and 290°C for 1h, and then peeled off from the substrate to obtain the naphthalene block type polyimide / covalent organic framework dielectric film.

[0137] Comparative example 4

[0138] The comparative example provides a preparation method of a polyimide dielectric film, which specifically comprises the following steps:

[0139] Step 1: Preparation of anhydride-terminated flexible polyamic acid precursor A: Flexible diamine 4,4'-diaminodiphenyl ether and flexible dibasic anhydride bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.2 to 4,4'-diaminodiphenyl ether, and stirred at 0°C under nitrogen protection for 4h to obtain anhydride-terminated flexible polyamic acid precursor A;

[0140] Step 2: Preparation of amine-terminated flexible polyamic acid precursor B: Flexible diamine 4,4'-diaminodiphenyl ether and flexible dibasic anhydride bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.1 to 4,4'-diaminodiphenyl ether, and stirred at 0°C under nitrogen protection for 4h to obtain amine-terminated flexible polyamic acid precursor B;

[0141] Step 3: Preparation of amine-terminated rigid polyamic acid precursor D: Rigid diamine p-phenylenediamine and rigid dibasic anhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.2 to p-phenylenediamine, and stirred at 0°C under nitrogen protection for 4h to obtain amine-terminated rigid polyamic acid precursor D;

[0142] Step 4: Preparation of covalent organic framework solution: Tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed at a molar ratio of 1:4, dissolved in DMF at a molar ratio of 10:1 to tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate was added at a molar ratio of 4:1 to tetraamino zinc phthalocyanine, heated to reflux at 66°C under nitrogen for 50h, followed by suction filtration, and the obtained solid was washed with distilled water, benzene and anhydrous ethanol, and vacuum dried for 24h to obtain N-ZnPc COF. N-ZnPc COF at a molar ratio of 1:600 to p-phenylenediamine monomer was dissolved in N-methyl pyrrolidone at a molar ratio of 1000:1 to N-ZnPc COF, and stirred magnetically at 0°C for 12h to obtain a covalent organic framework solution (solution d);

[0143] Step 5: Casting and high-temperature imidization, the volume ratio of anhydride-terminated flexible polyamic acid precursor A, amine-terminated flexible polyamic acid precursor B, amine-terminated rigid polyamic acid precursor D, and solution d was 1:1.2:1:1.5, and after magnetic stirring at 0°C for 12h, a film was cast on a substrate, and then the film was subjected to high-temperature imidization by heat treatment, 60°C for 4h, 110°C for 3h, 170°C for 3h, 230°C for 2h, and 285°C for 1h, and after being peeled off from the substrate, the naphthalene block type polyimide / covalent organic framework dielectric film was obtained.

[0144] Comparative Example 5

[0145] The present comparative example provides a preparation method of a polyimide dielectric film, specifically comprising the following steps:

[0146] Step 1: Preparation of anhydride-terminated flexible polyamic acid precursor A: flexible diamine 4,4'-diamino diphenyl ether and flexible dianhydride bisphenol A type diether dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.2 with 4,4'-diamino diphenyl ether at a molar ratio of 50:1, and stirred at 0°C under nitrogen protection for 4h to obtain anhydride-terminated flexible polyamic acid precursor A;

[0147] Step 2: Preparation of amine-terminated rigid polyamic acid precursor C: rigid diamine p-phenylenediamine and rigid dianhydride 3,3',4,4'-biphenyl tetracarboxylic dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.1 with p-phenylenediamine at a molar ratio of 50:1, and stirred at 0°C under nitrogen protection for 4h to obtain amine-terminated flexible polyamic acid precursor C;

[0148] Step 3: Preparation of amine-terminated rigid polyamic acid precursor D: rigid diamine p-phenylenediamine and rigid dianhydride 3,3',4,4'-biphenyl tetracarboxylic dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.2 with p-phenylenediamine at a molar ratio of 50:1, and stirred at 0°C under nitrogen protection for 4h to obtain amine-terminated rigid polyamic acid precursor D;

[0149] Step 4: Preparation of a covalent organic framework solution: tetraamino zinc phthalocyanine and 1,4-naphthoquinone were mixed at a molar ratio of 1:4, dissolved in DMF at a molar ratio of 10:1 with tetraamino zinc phthalocyanine, and anhydrous magnesium sulfate was added at a molar ratio of 4:1 with tetraamino zinc phthalocyanine, heated to reflux at 66°C under nitrogen for 50h, followed by suction filtration, and the obtained solid was washed with distilled water, benzene and anhydrous ethanol, and vacuum dried for 24h to obtain N-ZnPc COF. N-ZnPc COF at a molar ratio of 1:600 with p-phenylenediamine monomer was dissolved in N-methyl pyrrolidone at a molar ratio of 1000:1 with N-ZnPc COF, and a covalent organic framework solution (solution d) was obtained after magnetic stirring at 0°C for 12h;

[0150] Step 5: Casting and high-temperature imidization, the volume ratio of anhydride-terminated flexible polyamic acid precursor A, amine-terminated flexible polyamic acid precursor C, amine-terminated rigid polyamic acid precursor D and solution d was 1:1.2:1:1.5, and after magnetic stirring at 0°C for 12h, a film was cast on a substrate, and then the film was subjected to high-temperature imidization by heat treatment, 60°C for 4h, 110°C for 3h, 170°C for 3h, 230°C for 2h, and 285°C for 1h, and after being peeled off from the substrate, the naphthalene block type polyimide / covalent organic framework dielectric film was obtained.

[0151] Comparative Example 6

[0152] This comparative example provides a method for preparing a polyimide dielectric film, which is different from Example 8 only in that the covalent organic framework N-CuPc COF is replaced by a metal-organic framework ZIF-8, and specifically comprises the following steps:

[0153] Step 1: Preparation of naphthalene amine block polyamic acid solution: 1,4,5,8-naphthalene tetracarboxylic anhydride and 4,4'-diamino diphenyl ether were dissolved in N-methyl pyrrolidone at a molar ratio of 1:100, and the solution was stirred at 0°C for 2h to obtain a naphthalene amine block polyamic acid solution (solution a);

[0154] Step 2: Preparation of polyamic acid solution: 4,4'-diamino diphenyl ether and pyromellitic dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:1.1, and the solution was stirred at 0°C for 5h to obtain a polyamic acid solution (solution b);

[0155] Step 3: Preparation of naphthalene anhydride block polyamic acid solution: 2,2'-dinaphthyl biphenyl-4,4'-diamine and pyromellitic dianhydride were dissolved in N-methyl pyrrolidone at a molar ratio of 1:100, and the solution was stirred at 0°C for 5h to obtain a naphthalene anhydride block polyamic acid solution (solution c);

[0156] Step 4: Preparation of ZIF-8 solution: 0.79g dimethyl imidazole and 0.45g zinc nitrate were dissolved in 40mL methanol respectively, then the two solutions were mixed and placed for 24h, washed with methanol and centrifuged, and dried in a 120°C oven for 12h to obtain ZIF-8. ZIF-8 and 4,4'-diamino diphenyl ether monomer were dissolved in N-methyl pyrrolidone at a molar ratio of 1:100 and 1000:1, and the solution was stirred at 0°C for 10h to obtain a metal-organic framework solution (solution e);

[0157] Step 5: Casting and high-temperature imidization: solutions a, b, c, and e were mixed at a volume ratio of 1:1:1:1.2, and the mixture was stirred at 5°C for 12h, then cast on a substrate to form a film, and the film was subjected to high-temperature imidization by heat treatment, 60°C for 5h, 100°C for 5h, 150°C for 5h, 200°C for 5h, and 280°C for 2h. After peeling off from the substrate, the naphthalene block-containing polyimide / covalent organic framework dielectric film was obtained.

[0158] To better reflect the performance of the naphthalene block-containing polyimide / covalent organic framework dielectric thin films prepared in Examples 1-8 and Comparative Examples 1-6 of the present application, the breakdown field strength and high-temperature energy storage density of each naphthalene block-containing polyimide / covalent organic framework dielectric thin film were tested at 150°C. The Young's modulus was obtained by measuring the stress-strain curve of the sample using a dynamic thermal analyzer (Discovery DMA 850). The breakdown field strength was tested using a PolyK CPE1901 ferroelectric polarization test system by applying a direct current voltage of 500 V / s until breakdown. The high-temperature energy storage density was calculated by measuring the D-E loop, which was tested using a ferroelectric analyzer (Huace FE-2000) by applying a triangular monopolar pulse voltage waveform at a frequency of 100 Hz. During the test, the instrument recorded the relationship between the electric field (E) and the electric displacement (D), thereby drawing the D-E loop, and the energy storage density was calculated from the area under the loop. The electrical measurement under high voltage was performed in a silicone oil bath. The results are shown in Table 1.

[0159] Table 1

[0160]

[0161]

[0162] The breakdown field strength in Table 1 was tested using a PolyK CPE1901 ferroelectric polarization test system by applying a direct current voltage of 500 V / s until breakdown at a temperature of 150°C.

[0163] As can be seen from the data in Table 1, the naphthalene block-containing polyimide / covalent organic framework dielectric thin films prepared in Examples 1-8 using the method in the present application have higher breakdown field strength and energy storage density at a high temperature of 150°C. Examples 1-8 all added different amounts of 1,4,5,8-naphthalene tetracarboxylic anhydride and N-ZnPc COF, Comparative Examples 1-3 did not add 1,4,5,8-naphthalene tetracarboxylic anhydride or N-ZnPc COF, Comparative Examples 4-5 prepared naphthalene block-containing polyimide / covalent organic framework dielectric thin films from rigid and flexible polyimide acid segments, and Comparative Example 6 prepared a naphthalene block-containing polyimide / metal organic framework dielectric thin film using a metal organic framework ZIF-8. The test data show that the breakdown field strength and energy storage density of the naphthalene block-containing polyimide dielectric thin film at 150°C are higher than those of the pure polyimide dielectric thin film. The monomer 1,4,5,8-naphthalene tetracarboxylic anhydride and the organic filler N-ZnPc COF in the naphthalene block-containing polyimide / covalent organic framework dielectric thin film have strong charge trapping ability at high temperatures, which binds the carriers in the trap region, significantly improving the breakdown field strength and energy storage density of the dielectric thin film.

[0164] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A polyimide dielectric film characterized by, The preparation method of the polyimide dielectric film comprises the following steps: S1, 1, 4, 5, 8-naphthalene tetracarboxylic anhydride and diamine monomer are added into an organic solvent according to a molar ratio of 1:1000-1:100, and stirred and reacted to obtain solution a; S2, diamine monomer and dianhydride monomer are added into an organic solvent, and stirred and reacted to obtain solution b; S3, 2, 2'-diphenyl biphenyl-4, 4'-diamine and dianhydride monomer are added into an organic solvent according to a molar ratio of 1:1000-1:100, and stirred and reacted to obtain solution c; S4, tetraamino phthalocyanine transition metal salt and 1, 4-naphthoquinone are dissolved in an organic solvent, anhydrous magnesium sulfate is added, and heated and refluxed under an inert atmosphere, and then solid-liquid separation, washing and drying are carried out to obtain a transition metal phthalocyanine-based covalent organic framework material; the prepared transition metal phthalocyanine-based covalent organic framework material is dispersed in an organic solvent to obtain solution d; S5, solution a, solution b, solution c and solution d are subjected to polycondensation reaction, and then cast into a film on a substrate, and the film is subjected to heat treatment and peeled off from the substrate to obtain a polyamide-imide dielectric film; said diamine monomers include 4,4' diaminodiphenylmethane, m-phenylenediamine, p-phenylenediamine, 1,3 bis(4 aminophenoxy)benzene, 4,4' diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 2,2 bis[4 (4 aminophenoxyphenyl)]propane or 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene; The dianhydride monomer is selected from at least one of pyromellitic dianhydride, 3, 3', 4, 4'-biphenyl tetracarboxylic dianhydride, 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride, 1, 2, 4, 5-cyclohexane tetracarboxylic dianhydride, bisphenol A type diether dianhydride, 4, 4'-oxybisphthalic anhydride or bicyclohexyl-3, 4', 3, 4'-tetracarboxylic dianhydride.

2. The polyimide dielectric film of claim 1, wherein, The structure of the transition metal phthalocyanine-based covalent organic framework material is shown in formula (IV): Wherein, M is Zn, Cu, Ni or Co.

3. The polyimide dielectric film of claim 1 or 2 is applied in the field of energy storage capacitors.

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