Diamine monomers containing adamantane structures, methods for preparing the same, polyimides, methods for preparing the same, and applications of the polyimides, and polyimide films

Abstract

This invention relates to the field of high-temperature resistant, low-dielectric polymer materials technology, and particularly to a diamine monomer containing an adamantane structure and its preparation method, polyimides and their preparation methods and applications, and polyimide films. The adamantane-containing diamine monomer has the following structure: wherein R1, R2, and R3 are the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl, or -Br. This invention introduces an adamantane alkyl group and a flexible ether bond into an aromatic diamine monomer, enabling the reaction of the diamine monomer with dianhydrides as a raw material for preparing polyimides to obtain polyimides with high solubility, high transparency, and low dielectric constant.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant and low-dielectric polymer materials technology, and in particular to a diamine monomer containing an adamantane structure and its preparation method, polyimide and its preparation method and application, and polyimide film. Background Technology

[0002] With the increasing demand for high-performance materials driven by technological advancements, specialty engineering plastics have emerged. Common commercially available specialty plastics include polyimide (PI), polyetheretherketone (PEEK), polyethersulfone (PES), and polyphenylene sulfide (PPS). These materials possess properties such as high temperature resistance, high strength, high modulus, corrosion resistance, wear resistance, and lightweight. Polyimide's molecular chain contains numerous aromatic heterocyclic structures, which endow it with excellent heat resistance, making it the specialty engineering plastic with the highest heat resistance rating. Compared to polyimide, materials like PEEK and PPS have relatively lower glass transition temperatures, generally not exceeding 200°C, which limits their application at higher temperatures.

[0003] Generally, polyimide (PI) is a polymer material obtained by polycondensation reaction of diamine and dianhydride monomers. Due to the strong intermolecular interactions of traditional polyimides, most polyimides are insoluble in certain solvents. This insolubility limits the processing and application of polyimides in many fields; for example, the poor solubility of polyimides increases the difficulty of fabricating polyimide films. Traditional polyimides often have a deep color due to electronic conjugation and the formation of intermolecular and intramolecular charge-transfer complexes (CTCs), which hinders their application as optical films. Furthermore, the widespread charge transfer effect in PI leads to poor dielectric and dielectric loss properties at high frequencies. For example, commercially available Kapton films have poor processing performance, low transparency, and high dielectric constant, which severely limits their application range.

[0004] Therefore, how to obtain polyimides with high solubility, high transparency and low dielectric constant is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned shortcomings in the existing technology, the present invention aims to provide a diamine monomer containing an adamantane structure and its preparation method, a polyimide and its preparation method and application, and a polyimide film. The present invention introduces an adamantane alkyl group and a flexible ether bond into an aromatic diamine monomer, enabling the diamine monomer to react with dianhydride as a raw material for preparing polyimide, thereby obtaining a polyimide with high solubility, high transparency and low dielectric constant.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a diamine monomer containing an adamantane structure, wherein the diamine monomer containing the adamantane structure has the following structure:

[0008]

[0009] Among them, R1, R2 and R3 may be the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl or -Br.

[0010] This invention introduces adamantyl alkyl groups and flexible ether bonds into aromatic diamine monomers, enabling the reaction of these monomers with dianhydrides as raw materials for polyimide preparation. This process yields polyimides with high solubility, high transparency, and low dielectric constant.

[0011] In a second aspect, the present invention provides a method for preparing a diamine monomer containing an adamantane structure as described in the first aspect, the method comprising the following steps:

[0012] S1. Under a protective atmosphere, 1,3-adamantanediol, phenolic compounds and a first catalyst are added to a reaction vessel equipped with a mechanical stirrer and the reaction is carried out. After the reaction is completed, the adamantane bisphenol compound is obtained through post-treatment.

[0013] S2. The adamantyl bisphenol compound, the halogen-containing and nitro compounds, and the base are mixed in a first organic solvent to carry out a substitution reaction to obtain a dinitro compound.

[0014] S3. The dinitro compound, hydrogenation catalyst, second organic solvent and reducing agent are mixed and subjected to catalytic hydrogenation reaction to obtain the diamine monomer containing the adamantane structure.

[0015] Furthermore, in step S1, the protective atmosphere includes at least one of a nitrogen atmosphere and an inert gas atmosphere;

[0016] And / or, in step S1, the phenolic compound includes one of phenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2,6-isopropylphenol, 2,6-tert-butylphenol, 2-chlorophenol, 2-bromophenol, 2-fluorophenol, 2-methylphenol, 2-methoxyphenol, 2-isopropylphenol, 2-tert-butylphenol, and 2-phenylphenol;

[0017] And / or, in step S1, the first catalyst includes at least one of concentrated sulfuric acid, trifluoroacetic acid, methanesulfonic acid, and trifluoromethanesulfonic acid;

[0018] And / or, in step S1, the molar ratio of the 1,3-adamantanediol to the phenolic compound is 1:(2-8);

[0019] And / or, in step S1, the mass ratio of the 1,3-adamantanediol to the first catalyst is 1:(0.5-2);

[0020] And / or, in step S1, the reaction temperature is 80-90°C, the reaction time is 6-12 h, and the post-treatment includes sedimentation, filtration, drying, and recrystallization;

[0021] And / or, in step S2, the halogen- and nitro-containing compound includes one of p-chloronitrobenzene, 1-chloro-2-methyl-4-nitrobenzene, 1-chloro-2-trifluoromethyl-4-nitrobenzene, 1-chloro-2-fluoro-4-nitrobenzene, 1,2-dichloro-4-nitrobenzene, and 1-chloro-2-bromo-4-nitrobenzene;

[0022] And / or, in step S2, the alkali includes at least one of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, sodium bicarbonate, and potassium bicarbonate;

[0023] And / or, in step S2, the first organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide;

[0024] And / or, in step S2, the molar ratio of the adamantyl bisphenol compound to the halogen- and nitro-containing compound is 1:2 to 2.2;

[0025] And / or, in step S2, the molar ratio of the adamantyl bisphenol compound to the base is 1:1.2 to 3.0;

[0026] And / or, in step S2, the mass ratio of the adamantyl bisphenol compound to the volume ratio of the first organic solvent is 1 g: 5 to 11 mL;

[0027] And / or, in step S2, the temperature of the substitution reaction is 80–120°C, and the time of the substitution reaction is 8–12 h;

[0028] And / or, in step S3, the hydrogenation catalyst includes at least one of palladium on carbon, platinum on carbon, rhodium on carbon, and active nickel;

[0029] And / or, in step S3, the second organic solvent includes at least one of tetrahydrofuran, ethanol, methanol, isopropanol, N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, 1,4-dioxane, ethyl acetate, benzene, toluene, and xylene.

[0030] And / or, in step S3, the reducing agent includes hydrazine hydrate;

[0031] And / or, in step S3, the mass of the hydrogenation catalyst is 2-10% of the mass of the dinitro compound;

[0032] And / or, in step S3, the mass ratio of the dinitro compound to the volume ratio of the second organic solvent is 1 g:(5-10) mL;

[0033] And / or, in step S3, the molar ratio of the dinitro compound to the reducing agent is 1:4 to 12;

[0034] And / or, in step S3, the temperature of the catalytic hydrogenation reaction is 40–100°C, and the time of the catalytic hydrogenation reaction is 8–12 h;

[0035] And / or, in step S3: the order of mixing the dinitro compound, hydrogenation catalyst, second organic solvent, and reducing agent is as follows: the dinitro compound, hydrogenation catalyst, and second organic solvent are first mixed to obtain a mixture; then the temperature is raised to the temperature of the catalytic hydrogenation reaction, and the reducing agent is added dropwise to the mixture; the dropwise addition is completed within 30 minutes; after the catalytic hydrogenation reaction is completed, the reaction solution obtained from the catalytic hydrogenation reaction is subjected to thermal solid-liquid separation, and then the obtained filtrate is mixed with water for precipitation. The obtained precipitate is dried to obtain a diamine monomer containing an adamantane structure. The drying is vacuum drying, and the drying temperature is 75-85°C.

[0036] Thirdly, the present invention provides a polyimide, wherein the diamine monomer raw material used to synthesize the polyimide includes the adamantane-containing diamine monomer described in the first aspect or the adamantane-containing diamine monomer obtained by the preparation method described in the second aspect.

[0037] Furthermore, the polyimide includes the following repeating structural units:

[0038]

[0039] Among them, R1, R2 and R3 may be the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl or -Br;

[0040] A has a structure shown by any of the following formulas:

[0041]

[0042] And / or, the number average molecular weight of the polyimide is 4.3-9.4 × 10⁻⁶. 4 g / mol;

[0043] And / or, the glass transition temperature of the polyimide is 253-329°C;

[0044] And / or, the polyimide has a 5% thermal weight loss temperature of 474-491°C;

[0045] And / or, the temperature at which the polyimide loses 10% of its thermal weight is 485-501°C;

[0046] And / or, the dielectric constant of the polyimide at 15 GHz is 2.53-2.86;

[0047] And / or, the cutoff wavelength of the polyimide is 333-365 nm;

[0048] And / or, the polyimide is soluble in an aprotic polar solvent, the aprotic polar solvent including at least one of N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, m-cresol, butyrolactone, and sulfolane, preferably including at least one of N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, and m-cresol.

[0049] Fourthly, the present invention provides a method for preparing polyimide as described in the third aspect, the method comprising the following steps:

[0050] Under a protective atmosphere, the diamine monomer containing the adamantane structure described in the first aspect or the diamine monomer containing the adamantane structure prepared by the preparation method described in the second aspect and the aromatic dianhydride monomer are added to a third organic solvent to carry out a polycondensation reaction to obtain a polyamic acid solution.

[0051] The obtained polyamic acid solution was imidized to obtain the polyimide.

[0052] Furthermore, the protective atmosphere includes a nitrogen atmosphere;

[0053] And / or, the aromatic dianhydride monomer includes one of diphenyl ether tetracarboxylic dianhydride, biphenyl dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, hexafluoro dianhydride, and bisphenol A dianhydride;

[0054] And / or, the molar ratio of the diamine monomer containing the adamantane structure to the aromatic dianhydride monomer is 1:1 to 1.3;

[0055] And / or, the third organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,4-butyrolactone;

[0056] And / or, the solid content of the mixture obtained by mixing the adamantane-containing diamine monomer, the aromatic dianhydride monomer and the third organic solvent is 10-25%;

[0057] And / or, the temperature of the polycondensation reaction is 23℃-28℃, and the time of the polycondensation reaction is greater than or equal to 24h;

[0058] And / or, the imidization is performed by thermal imidization or chemical imidization.

[0059] Furthermore, the thermal imidization includes a dehydration cyclization reaction of the polyamic acid solution by gradient heating, wherein the gradient heating includes heating at 60-80°C for 4-8 hours, followed by drying in vacuum ovens at 100°C, 150°C, 200°C, 250°C and 300°C for 30 minutes each.

[0060] And / or, the chemical imidization includes adding a dehydrating agent and a catalyst to the polyamic acid solution, stirring at 80-100°C for 8-12 hours, pouring the resulting mixed solution into a polar solvent for precipitation, filtering and drying to obtain the polyimide, wherein the polar solvent includes at least one of methanol, ethanol and water, the catalyst includes one or more of pyridine, isoquinoline, and triethylamine, and the dehydrating agent includes acetic anhydride.

[0061] Fifthly, the present invention provides the application of polyimide as described in the third aspect or polyimide prepared by the preparation method described in the fourth aspect in the preparation of polyimide film materials or electronic packaging materials.

[0062] In a sixth aspect, the present invention provides a polyimide film, wherein the polyimide in the film includes the polyimide described in the third aspect or the polyimide prepared by the preparation method described in the fourth aspect.

[0063] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0064] (1) This invention introduces adamantyl and flexible ether bonds into the aromatic diamine monomer, so that the diamine monomer can be used as a raw material for preparing polyimide and react with dianhydride to prepare polyimide with high solubility, high transparency and low dielectric constant.

[0065] (2) The adamantyl alkyl aromatic diamine monomer prepared by the present invention has inexpensive and readily available raw materials, a simple synthesis route, and the product is easy to recrystallize, purify and separate, with a yield of more than 80% and stable at room temperature.

[0066] (3) The present invention can use two cyclization methods, namely chemical imide method and thermal imide method, to obtain polyimide film. The synthesis and preparation process is simple and easy to industrialize.

[0067] (4) The polyimide prepared by the present invention includes adamantyl alkyl aromatic diamine monomer, which not only has high solubility and high glass transition temperature in specific solvents, but also has excellent optical properties and low dielectric constant, and can be used to prepare polyimide films and electronic packaging materials. Attached Figure Description

[0068] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0069] Figure 1 The infrared spectra of the intermediate dinitro compound 1,3-bis[3,5-dimethyl-4-(4-nitrophenoxy)phenyl]adamantane (AMTCDT) and the aromatic diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane (AMTCDM) in Example 1 of this invention are shown.

[0070] Figure 2 The infrared spectra of polyimides prepared by reacting the aromatic diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane (AMTCDM) provided in this invention with diphenyl ether tetracarboxylic dianhydride (ODPA), α-biphenyltetracarboxylic dianhydride (α-BPDA), biphenyltetracarboxylic dianhydride (BPDA), and bisphenol A dianhydride (BPADA), respectively.

[0071] Figure 3 The thermal property curves (DSC diagrams) of polyimides prepared by reacting the aromatic diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane (AMTCDM) with diphenyl ether tetracarboxylic dianhydride (ODPA), α-biphenyl tetracarboxylic dianhydride (α-BPDA), biphenyl dianhydride (BPDA), hexafluoro dianhydride (6FDA), and bisphenol A dianhydride (BPADA) are shown in the figure.

[0072] Figure 4 The thermal property curves (TGA diagrams) of polyimides prepared by reacting the aromatic diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane (AMTCDM) with diphenyl ether tetracarboxylic dianhydride (ODPA), biphenyl tetracarboxylic dianhydride (BPDA), α-biphenyl tetracarboxylic dianhydride (α-BPDA), hexafluoro dianhydride (6FDA), and bisphenol A dianhydride (BPADA) are shown in the figure. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0074] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0075] In a first aspect, the present invention provides a diamine monomer containing an adamantane structure, wherein the diamine monomer containing the adamantane structure has the following structure:

[0076]

[0077] Wherein, R1, R2 and R3 may be the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl or -Br, preferably -H or -CH3.

[0078] C1-6 alkyl refers to straight-chain or branched alkyl groups containing 1-6 carbons, such as methyl, ethyl, propyl, n-butyl, isobutyl, 2,2-dimethylbutane, etc. Halogenated C1-6 alkyl refers to straight-chain or branched alkyl groups containing 1-6 carbons in which the hydrogen atoms are replaced by halogens, such as trifluoromethyl.

[0079] This invention introduces adamantyl and flexible ether bonds into an aromatic diamine monomer, enabling the diamine monomer to react with dianhydrides as a raw material for preparing polyimides, thereby producing polyimides with high solubility, high transparency, and low dielectric constant.

[0080] This invention introduces a large-volume adamantyl group and flexible ether bonds into an aromatic diamine monomer. When used to prepare polyimides, this effectively improves the solubility of polyimides in specific solvents. Specifically, the adamantyl group in the aromatic diamine monomer provided by this invention has an alicyclic structure. This structure hinders the close packing of polyimide molecular chains, making it easier for solvents to diffuse between chains, thereby increasing solubility and optical properties. Furthermore, the presence of the flexible ether group can change the twist angle of the polyimide molecule, which is beneficial to the rotation of the aromatic ring, further improving the solubility of the polyimide prepared from it. In addition, because the adamantyl group in the aromatic diamine monomer provided by this invention has a large volume, the free volume of the polyimide prepared from it is increased, and the number of polarized groups per unit volume is reduced, thereby lowering the dielectric constant of the polyimide. Moreover, since adamantane has excellent heat resistance, introducing adamantane units into polyimides can also increase the glass transition temperature of the material.

[0081] In one optional embodiment, the diamine monomer containing the adamantane structure is used as a raw material for preparing polyimide.

[0082] In a second aspect, the present invention provides a method for preparing a diamine monomer containing an adamantane structure as described in the first aspect, the method comprising the following steps:

[0083] S1. Under a protective atmosphere, 1,3-adamantanediol, phenolic compounds and a first catalyst are added to a reaction vessel equipped with a mechanical stirrer and the reaction is carried out. After the reaction is completed, the adamantane bisphenol compound is obtained through post-treatment.

[0084] S2. The adamantyl bisphenol compound, the halogen-containing and nitro compounds, and the base are mixed in a first organic solvent to carry out a substitution reaction to obtain a dinitro compound.

[0085] S3. The dinitro compound, hydrogenation catalyst, second organic solvent and reducing agent are mixed and subjected to catalytic hydrogenation reaction to obtain the diamine monomer containing the adamantane structure (a semi-aromatic diamine monomer containing the adamantane structure).

[0086] In step S1, the present invention does not have any special limitation on the protective atmosphere, and any conventional protective atmosphere can be used. In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S1, the protective atmosphere includes at least one of nitrogen atmosphere and inert gas atmosphere.

[0087] In the above-mentioned method for preparing diamine monomers containing adamantane structures, as an optional embodiment, in step S1, the phenolic compound includes one of phenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2,6-isopropylphenol, 2,6-tert-butylphenol, 2-chlorophenol, 2-bromophenol, 2-fluorophenol, 2-methylphenol, 2-methoxyphenol, 2-isopropylphenol, 2-tert-butylphenol, and 2-phenylphenol.

[0088] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S1, the first catalyst includes at least one of concentrated sulfuric acid, trifluoroacetic acid, methanesulfonic acid, and trifluoromethanesulfonic acid, preferably trifluoromethanesulfonic acid.

[0089] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S1, the molar ratio of 1,3-adamantanediol to the phenolic compound is 1:(2-8), for example, it can be 1:2, 1:4, 1:6 or 1:8.

[0090] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S1, the mass ratio of 1,3-adamantanediol to the first catalyst is 1:(0.5-2), for example, it can be 1:0.5, 1:1, 1:1.5 or 1:2.

[0091] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S1, the reaction temperature is 80-90℃ (for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃), the reaction time is 6-12h (for example, it can be 6h, 8h, 10h or 12h), and the post-treatment includes sedimentation, filtration, drying and recrystallization.

[0092] In the above-mentioned method for preparing diamine monomers containing adamantane structures, as an optional embodiment, in step S2, the halogen- and nitro-containing compounds include one of p-chloronitrobenzene, 1-chloro-2-methyl-4-nitrobenzene, 1-chloro-2-trifluoromethyl-4-nitrobenzene, 1-chloro-2-fluoro-4-nitrobenzene, 1,2-dichloro-4-nitrobenzene, and 1-chloro-2-bromo-4-nitrobenzene.

[0093] In the above-described method for preparing diamine monomers containing adamantane structures, as an optional embodiment, in step S2, the base includes at least one selected from potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, sodium bicarbonate, and potassium bicarbonate. The base acts as a catalyst, promoting the substitution reaction; when the base is two or more of the specific selections mentioned above, they can be mixed in any proportion.

[0094] In the above-described method for preparing adamantane-containing diamine monomers, as an optional embodiment, in step S2, the first organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide. When the first organic solvent is two or more of the specific selections mentioned above, they can be mixed in any proportion. This invention does not have a special limitation on the amount of the first organic solvent used, as long as it ensures the smooth progress of the reaction.

[0095] In the above-mentioned method for preparing diamine monomers containing adamantane structures, as an optional embodiment, in step S2, the molar ratio of the adamantane bisphenol compound to the halogen- and nitro-containing compound is 1:2 to 2.2.

[0096] In the above-mentioned method for preparing diamine monomers containing adamantane structures, as an optional embodiment, in step S2, the molar ratio of the adamantane bisphenol compound to the base is 1:1.2 to 3.0.

[0097] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S2, the mass ratio of the adamantane bisphenol compound to the volume of the first organic solvent is 1g:5 to 11mL, for example, 1g:5mL, 1g:7mL, 1g:9mL, or 1g:11mL.

[0098] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S2, the temperature of the substitution reaction is 80-120°C (for example, 80°C, 90°C, 100°C, 110°C or 120°C), and the time of the substitution reaction is 8-12h (for example, 8h, 10h or 12h).

[0099] In the above-described method for preparing diamine monomers containing adamantane structures, as an optional embodiment, in step S3, the hydrogenation catalyst includes at least one of palladium on carbon, platinum on carbon, rhodium on carbon, and active nickel. When the hydrogenation catalyst is two or more of the specific selections mentioned above, they can be mixed in any proportion.

[0100] In the above-described method for preparing adamantane-containing diamine monomers, as an optional embodiment, in step S3, the second organic solvent includes at least one selected from tetrahydrofuran, ethanol, methanol, isopropanol, N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, 1,4-dioxane, ethyl acetate, benzene, toluene, and xylene. When the second organic solvent is two or more of the specific selections mentioned above, they can be mixed in any proportion.

[0101] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3, the reducing agent includes hydrazine hydrate, preferably added in the form of an aqueous solution of hydrazine hydrate, and the mass concentration of the aqueous solution of hydrazine hydrate is 80-99% (for example, 80%, 85%, 90%, 99%), preferably 98%.

[0102] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3, the mass percentage of metal elements in the palladium on carbon, platinum on carbon, and rhodium on carbon is 5-10%, for example, it can be 5%, 7%, 9%, or 10%.

[0103] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3, the mass of the hydrogenation catalyst is 2-10% of the mass of the dinitro compound.

[0104] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3, the mass ratio of the dinitro compound to the volume ratio of the second organic solvent is 1g:(5-10)mL, for example, it can be 1g:5mL, 1g:6mL, 1g:8mL or 1g:10mL.

[0105] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3, the molar ratio of the dinitro compound to the reducing agent is 1:4 to 12, for example, it can be 1:4, 1:6, 1:8, 1:10 or 1:12, preferably 1:10.

[0106] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3, the temperature of the catalytic hydrogenation reaction is 40-100°C (for example, 40°C, 60°C, 80°C or 100°C), and the time of the catalytic hydrogenation reaction is 8-12h (for example, 8h, 10h or 12h).

[0107] In the above-mentioned method for preparing diamine monomers containing adamantane structure, as an optional embodiment, in step S3: the preferred order of mixing the dinitro compound, hydrogenation catalyst, second organic solvent and reducing agent is as follows: the dinitro compound, hydrogenation catalyst and second organic solvent are first mixed to obtain a mixture; then the temperature is raised to the temperature of the catalytic hydrogenation reaction, and then the reducing agent is added dropwise to the mixture; the dropwise addition is preferably completed within 30 minutes. In this invention, since the reduction reaction that occurs when the reducing agent is added dropwise releases a large amount of heat and generates a large number of bubbles, hydrazine hydrate needs to be added slowly to prevent excessively rapid addition. The time for the catalytic hydrogenation reaction is calculated from the time when the dinitro compound, hydrogenation catalyst, second organic solvent, and reducing agent are completely mixed. In the embodiments provided by this invention, the time is calculated from the time when the reducing agent is completely added. After the catalytic hydrogenation reaction is completed, the present invention may optionally perform thermal solid-liquid separation on the reaction liquid obtained from the catalytic hydrogenation reaction (i.e., perform solid-liquid separation directly at the temperature of the catalytic hydrogenation reaction), and then mix the obtained filtrate with water to precipitate. The obtained precipitate is dried to obtain a diamine monomer containing an adamantane structure. The drying is vacuum drying, and the drying temperature is 75-85°C, preferably 80°C.

[0108] Thirdly, the present invention provides a polyimide, wherein the diamine monomer raw material used to synthesize the polyimide includes the adamantane-containing diamine monomer described in the first aspect or the one described in the second aspect.

[0109] The diamine monomer containing adamantane structure was prepared by the method described above.

[0110] This polyimide has high solubility, high transparency, and low dielectric constant.

[0111] In one optional embodiment of the above-mentioned polyimide, the polyimide includes the following repeating structural units:

[0112]

[0113] Wherein, R1, R2 and R3 may be the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl or -Br, preferably -H or -CH3;

[0114] A has a structure shown by any of the following formulas:

[0115]

[0116] In one optional embodiment of the above-mentioned polyimide, the number-average molecular weight of the polyimide is 4.3-9.4 × 10⁻⁶. 4 g / mol, for example, could be 4.3 × 10⁻⁶ g / mol.4 g / mol, 5.4×10 4 g / mol, 6.4×10 4 g / mol, 7.4×10 4 g / mol or 9.4×10 4 g / mol.

[0117] In the above-mentioned polyimide, as an optional embodiment, the glass transition temperature (Tg) of the polyimide is 253-329°C.

[0118] In the above-mentioned polyimide, as an optional embodiment, the temperature at which the polyimide loses 5% of its thermal weight is 474-491°C.

[0119] In the above-mentioned polyimide, as an optional embodiment, the temperature at which the polyimide experiences 10% thermal weight loss is 485-501°C.

[0120] In the above-mentioned polyimide, as an optional embodiment, the dielectric constant of the polyimide at 15 GHz is 2.53-2.86.

[0121] In the above-mentioned polyimide, as an optional embodiment, the cutoff wavelength of the polyimide is 333-365nm.

[0122] In one optional embodiment of the above-mentioned polyimide, the polyimide is soluble in an aprotic polar solvent, the aprotic polar solvent including at least one of N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, m-cresol, butyrolactone, and sulfolane, preferably including at least one of N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, and m-cresol.

[0123] Fourthly, the present invention provides a method for preparing polyimide as described in the third aspect, the method comprising the following steps:

[0124] Under a protective atmosphere, the diamine monomer containing the adamantane structure described in the first aspect or the diamine monomer containing the adamantane structure prepared by the preparation method described in the second aspect and the aromatic dianhydride monomer are added to a third organic solvent to carry out a polycondensation reaction to obtain a polyamic acid solution.

[0125] The obtained polyamic acid solution was imidized to obtain the polyimide.

[0126] This invention does not impose any particular limitation on the mixing order of the aromatic diamine monomer, the dianhydride monomer, and the third organic solvent; a mixing order well known to those skilled in the art can be used. In the embodiments provided by this invention, the preferred mixing order of the aromatic diamine monomer, the third organic solvent, and the dianhydride monomer is to mix the aromatic diamine monomer and the third organic solvent, and then mix the resulting mixture with the dianhydride monomer.

[0127] In the above-mentioned method for preparing polyimide, as an optional embodiment, the protective atmosphere includes a nitrogen atmosphere.

[0128] In the above-mentioned method for preparing polyimide, as an optional embodiment, the aromatic dianhydride monomer includes one of diphenyl ether tetracarboxylic dianhydride, biphenyl dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, hexafluoro dianhydride, and bisphenol A dianhydride.

[0129] In the above-mentioned method for preparing polyimide, as an optional embodiment, the molar ratio of the diamine monomer containing the adamantane structure and the aromatic dianhydride monomer is 1:1 to 1.3.

[0130] In the above-described method for preparing polyimide, as an optional embodiment, the third organic solvent includes at least one selected from N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,4-butyrolactone. When the third organic solvent is selected from two or more of the above solvents, the present invention does not impose any special limitation on the specific ratio of the above substances; they can be mixed in any ratio. The present invention does not impose any special limitation on the amount of the third organic solvent used, as long as it ensures the smooth progress of the reaction. In the embodiments provided by the present invention, the amount of the third organic solvent is preferably based on the solid content of the mixture obtained by mixing the aromatic diamine monomer, the dianhydride monomer, and the third organic solvent.

[0131] In the above-mentioned method for preparing polyimide, as an optional embodiment, the solid content of the mixture obtained by mixing the diamine monomer containing the adamantane structure, the aromatic dianhydride monomer, and the third organic solvent is 10-25%, for example, it can be 10%, 15%, 20%, or 25%.

[0132] In the above-mentioned method for preparing polyimide, as an optional embodiment, the temperature of the polycondensation reaction is 23℃-28℃, and the time of the polycondensation reaction is greater than or equal to 24h, for example, 24-36h.

[0133] In the above-mentioned method for preparing polyimide, as an optional embodiment, the imidization is carried out by thermal imidization or chemical imidization, preferably chemical imidization, as polyimide prepared by chemical imidization has better optical properties.

[0134] In the above-mentioned method for preparing polyimide, as an optional embodiment, the thermal imidization includes a dehydration cyclization reaction of the polyamic acid solution through a gradient heating process. The gradient heating includes first heating at 60-80℃ (e.g., 60℃, 65℃, 70℃, 75℃, or 80℃) for 4-8 hours (e.g., 4 hours, 6 hours, or 8 hours), followed by drying in a vacuum oven at 100℃, 150℃, 200℃, 250℃, and 300℃ for 30 minutes each. Compared to direct heat treatment at high temperatures, the gradient heating method of this invention can slowly remove the solvent, resulting in superior membrane performance and avoiding pore defects on the membrane.

[0135] In the above-mentioned method for preparing polyimide, as an optional embodiment, the chemical imidization includes adding a dehydrating agent and a catalyst to the polyamic acid solution, stirring at 80-100°C (e.g., 80°C, 85°C, 90°C, 95°C, or 100°C) for 8-12 hours (e.g., 8 hours, 10 hours, or 12 hours), then pouring the resulting mixed solution into a polar solvent for sedimentation, filtering, and drying to obtain the polyimide, wherein the polar solvent includes at least one of methanol, ethanol, and water.

[0136] In the above-mentioned method for preparing polyimide, as an optional embodiment, the catalyst includes one or more of pyridine, isoquinoline, and triethylamine; the dehydrating agent includes acetic anhydride.

[0137] Fifthly, the present invention provides the application of polyimide as described in the third aspect or polyimide prepared by the preparation method described in the fourth aspect in the preparation of polyimide film materials or electronic packaging materials.

[0138] Sixthly, the present invention provides a polyimide film, wherein the polyimide in the film includes the polyimide described in the third aspect or the polyimide prepared by the preparation method described in the fourth aspect. That is, the present invention uses the polyimide described in the above technical solutions as a raw material and forms a film by a film-forming method to obtain a polyimide film.

[0139] In this invention, the film-forming method is not particularly limited and can be any conventional film-forming method in the art. Specifically, the film-forming method in this invention is as follows:

[0140] S1. Dissolve the polyimide in a solvent to obtain a polyimide solution;

[0141] S2. The polyimide solution is coated onto a substrate and cured to form a polyimide wet film;

[0142] S3. Peel the polyimide wet film from the substrate to obtain a polyimide film;

[0143] The solvent is an organic solvent, including one or more of tetrahydrofuran, dichloromethane, trichloromethane, m-cresol, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and γ-butyrolactone. The solid content of the polyimide solution is 5wt% to 15wt%. In step S2, a doctor blade is used to uniformly coat the polyimide solution onto the substrate; the substrate is a clean substrate. In step S2, the curing temperature is preferably 60 to 300°C, for example, 60°C, 100°C, 150°C, 200°C, 250°C, or 300°C.

[0144] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0145] Example 1

[0146] The preparation method of the monomer containing adamantane structure and side-methyl aromatic diamine provided in this embodiment includes the following steps:

[0147] S1. Under nitrogen purging, add 16.5 g of 1,3-adamantanediol (0.10 mol) and 97 g of 2,6-dimethylphenol (0.8 mol) to a 250 ml three-necked flask equipped with a mechanical stirrer. Heat to 90 °C. After the 2,6-dimethylphenol melts, add 9.6 g of methanesulfonic acid (0.10 mol) while stirring. React at this temperature for 8 hours. Then pour the reaction mixture into 800 ml of deionized water, precipitating a white-pink precipitate. Filter the product and wash several times with deionized water. Dissolve the washed precipitate in 300 ml of ethyl acetate, then add 600 ml of n-heptane solution, precipitating a white precipitate. Stir at room temperature for 30 min and then filter. The crude product was recrystallized from toluene and then dried under vacuum at 100°C for 8 hours to obtain 31.6 g of the intermediate adamantyl bisphenol compound 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)adamantane (white crystals), with a yield of 84% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0148] 1,3-Bis(3,5-dimethyl-4-hydroxyphenyl)adamantane:

[0149]

[0150] S2. Under nitrogen protection, 11.7 g of the adamantyl bisphenol compound 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)adamantane (31.2 mmol) and 60 ml of DMF were added to a 250 ml three-necked flask equipped with a magnetic stirrer. After the solid was completely dissolved, 8.6 g of anhydrous K2CO3 (62.4 mmol) was added. At this time, the colorless solution turned into a white turbid liquid. After reacting at 100 °C for 30 min, 9.83 g of p-chloronitrobenzene (62.4 mmol) was added. The solution turned yellow-green. After reacting at this temperature for 8 h, the solution was cooled and poured into a methanol-water (volume ratio 1:1) solution, and a white-yellow precipitate was formed. The crude product was filtered and recrystallized from tetrahydrofuran-water (volume ratio 1:3) to give 17.1 g of 1,3-bis[3,5-dimethyl-4-(4-nitrophenoxy)phenyl]adamantane, with a yield of 89% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0151] 1,3-Bis[3,5-Dimethyl-4-(4-nitrophenoxy)phenyl]adamantane:

[0152]

[0153] The 1,3-bis[3,5-dimethyl-4-(4-nitrophenoxy)phenyl]adamantane obtained in this example was characterized by NMR, and the results are as follows: 1 H NMR (600MHz, CDCl3)δ:8.18-8.16(d,4H),7.15(s,4H),6.86-6.84(d,4H),2.37(s,2H),2.11(s,12H),2.03-1.95(m,10H),1.82(s,2H).

[0154] S3. In a 250 mL three-necked flask equipped with a stirrer and a spherical condenser, add 8.85 g of the dinitro compound 1,3-bis[3,5-dimethyl-4-(4-nitrophenoxy)phenyl]adamantane (14.3 mmol) dissolved in 80 mL of ethanol. Using 0.2 g Pd / C (10 wt% Pd content) as a catalyst, heat to reflux (80 °C). Then, over 30 min, add 10 g of an aqueous solution of hydrazine hydrate (hydrazine hydrate in the aqueous solution is 80% by mass). The reaction system was then kept at a constant temperature for 8 hours. The reaction was confirmed to be complete by TLC. The palladium on carbon was removed by hot filtration, water was added to precipitate the residue, the precipitate was washed, filtered, and finally the obtained solid was dried in a vacuum oven at 80°C to obtain 7.35 g of white powdery diamine monomer, which was 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane, with a yield of 92% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0155] 1,3-Bis[3,5-Dimethyl-4-(4-aminophenoxy)phenyl]adamantane:

[0156]

[0157] The 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane obtained in this example was characterized by NMR, and the results are as follows: 1 H NMR (600MHz, CDCl3) δ: 7.08 (s, 4H), 6.57 (s, 8H), 3.40 (s, 4H), 2.32 (s, 2H), 2.12 (s, 12H), 2.01-1.93 (m, 10H), 1.78 (s, 2H).

[0158] Figure 1 Infrared spectra of 1,3-bis[3,5-dimethyl-4-(4-nitrophenoxy)phenyl]adamantane (AMTCDT) and the aromatic diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane (AMTCDM), as shown below. Figure 1 As shown, the range is 3687-3228cm. -1 The peak at 2905 cm⁻¹ represents the stretching vibration peak of the amino group (NH₄⁺), confirming the successful reduction reaction. -1 and 2851cm -1 The peak represents the CH vibration absorption peak on adamantane, at 1332 cm⁻¹. -1 The peak at 1271 cm⁻¹ represents the absorption peak of the stretching vibration of the nitro group; after reduction, the characteristic absorption of the nitro group disappears. -1 The absorption vibration peak representing CO is at 1132 cm⁻¹. -1The peak represents the vibrational absorption peak of -O-.

[0159] Example 2

[0160] The preparation method of the adamantane-containing diamine monomer provided in this embodiment includes the following steps:

[0161] S1. Under nitrogen purging, 16.5 g of 1,3-adamantanediol (0.10 mol) and 75 g of phenol (0.8 mol) were added to a 250 mL three-necked flask equipped with a mechanical stirrer. The temperature was raised to 80 °C. After the phenol melted, 10 g of concentrated sulfuric acid was added while stirring. The reaction was carried out at this temperature for 8 h. The reaction mixture was then poured into 500 mL of deionized water, and a white-pink precipitate was formed. The product was filtered and washed several times with deionized water. The washed precipitate was dissolved in 200 mL of ethyl acetate, and then 500 mL of n-heptane solution was added. A white precipitate was formed. The mixture was stirred at room temperature for 30 min and then filtered. The crude product was recrystallized from toluene and then dried under vacuum at 100 °C for 8 h to obtain the intermediate adamantyl bisphenol compound 1,3-bis(4-hydroxyphenyl)adamantane (white crystals) with a yield of 87% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0162] 1,3-Bis(4-hydroxyphenyl)adamantane:

[0163]

[0164] S2. Under nitrogen protection, 10 g of the adamantyl bisphenol compound 1,3-bis(4-hydroxyphenyl)adamantane (31.2 mmol) and 50 ml of DMF were added to a 250 ml three-necked flask equipped with a magnetic stirrer. After the solid was completely dissolved, 8.6 g of anhydrous K2CO3 (62.4 mmol) was added. At this point, the colorless solution turned into a white turbid liquid. The temperature was raised to 120 °C and reacted for 30 min. Then, 9.83 g of p-chloronitrobenzene (62.4 mmol) was added, and the solution turned yellow-green. After reacting at this temperature for 8 h, the solution was cooled and poured into a methanol-water (volume ratio 1:1), resulting in a white-yellow precipitate. The crude product was filtered and recrystallized from tetrahydrofuran-water (volume ratio 1:3) to give 1,3-bis[4-(4-nitrophenoxy)phenyl]adamantane, with a yield of 86% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0165] 1,3-Bis[4-(4-nitrophenoxy)phenyl]adamantane:

[0166]

[0167] S3. In a 250 mL three-necked flask equipped with a stirrer and a spherical condenser, 10 g of the dinitro compound 1,3-bis[4-(4-nitrophenoxy)phenyl]adamantane was dissolved in 60 mL of ethanol. Using 0.2 g Pd / C (Pd content 10 wt%) as a catalyst, the mixture was heated to reflux (85 °C). Then, within 30 min, 10 g of an aqueous solution of hydrazine hydrate (hydrazine hydrate in the aqueous solution was 80% by mass) was added to the reaction system. The reaction was continued at a constant temperature for 10 h. The reaction was confirmed to be complete by TLC. The palladium on carbon was removed by hot filtration, water was added to precipitate, the precipitate was washed, filtered, and finally the obtained solid was dried in a vacuum oven at 80 °C to obtain a white powdery diamine monomer, 1,3-bis[4-(4-aminophenoxy)phenyl]adamantane, with a yield of 89% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0168] 1,3-Bis[4-(4-aminophenoxy)phenyl]adamantane:

[0169]

[0170] Example 3

[0171] The method for preparing the aromatic diamine monomer containing adamantane structure and trifluoromethyl groups provided in this embodiment includes the following steps:

[0172] S1. Under nitrogen purging, add 16.5 g of 1,3-adamantanediol (0.10 mol) and 75 g of 2,6-dimethylphenol (0.6 mol) to a 250 ml three-necked flask equipped with a mechanical stirrer. Heat to 90 °C. After the 2,6-dimethylphenol melts, add 30 g of trifluoromethanesulfonic acid (0.20 mol) while stirring. React at this temperature for 6 hours. Then pour the reaction mixture into 500 ml of deionized water, precipitating a white-pink precipitate. Filter the product and wash repeatedly with deionized water. Dissolve the washed precipitate in 200 ml of ethyl acetate, then add 500 ml of n-heptane solution, precipitating a white precipitate. Stir at room temperature for 30 minutes and then filter. The crude product was recrystallized from toluene and then dried under vacuum at 100°C for 8 hours to obtain the intermediate adamantyl bisphenol compound 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)adamantane (white crystals) in a yield of 86% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0173] S2. Under nitrogen protection, 10g of the adamantyl bisphenol compound 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)adamantane (26.56mmol) and 50ml of DMF were added to a 250ml three-necked flask equipped with a magnetic stirrer. After the solid was completely dissolved, 8.6g of anhydrous K2CO3 (62.4mmol) was added. At this time, the colorless solution turned into a white turbid liquid. After reacting at 100℃ for 30min, 12g of 1-chloro-2-trifluoromethyl-4-nitrobenzene (53.12mmol) was added. The solution turned yellow-green. After reacting at this temperature for 8h, the solution was cooled and poured into a methanol-water (volume ratio 1:1) solution, and a white-yellow precipitate was formed. The crude product was filtered and recrystallized from tetrahydrofuran-water (volume ratio 1:3) to give 1,3-bis[3,5-dimethyl-4-(2-trifluoromethyl-4-nitrophenoxy)phenyl]adamantane in 88% yield (yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0174] S3. In a 250mL three-necked flask equipped with a stirrer and a spherical condenser, add 10g of the dinitro compound 1,3-bis[3,5-dimethyl-4-(2-trifluoromethyl-4-nitrophenoxy)phenyl]adamantane dissolved in 80mL of ethanol, and then add 0.4g of the solution. Using Pd / C (10wt% Pd content) as a catalyst, the temperature was raised to reflux (80℃). Then, 10g of hydrazine hydrate aqueous solution (hydrazine hydrate in the aqueous solution was 80% by mass) was added to the reaction system within 30min, and the reaction was continued at a constant temperature for 8h. The reaction was confirmed to be complete by TLC. The palladium on carbon was removed by hot filtration, water was added to precipitate, the precipitate was washed, filtered, and finally the obtained solid was dried in a vacuum oven at 80℃ to obtain 8.4g of yellow powdered diamine monomer, which was 1,3-bis[3,5-dimethyl-4-(2-trifluoromethyl-4-aminophenoxy)phenyl]adamantane, with a yield of 91% (the yield here is obtained by the ratio of the actual mass of the intermediate compound obtained to the theoretical mass of the intermediate compound).

[0175] 1,3-Bis[3,5-Dimethyl-4-(2-trifluoromethyl-4-aminophenoxy)phenyl]adamantane:

[0176]

[0177] Example 4

[0178] The preparation method of the diamine monomer containing the adamantane structure provided in this embodiment is basically the same as that in Example 1, except that in step S1, 0.8 mol of 2,6-dimethylphenol is replaced with 0.8 mol of 2,6-dimethoxyphenol.

[0179] The structure of the diamine monomer containing the adamantane structure prepared in this embodiment is shown below:

[0180]

[0181] The yields and purities of the aromatic diamine monomers (diamine monomers containing adamantane structures) obtained in Examples 1-4 are shown in Table 1.

[0182] Table 1

[0183]

[0184] As shown in Table 1, the diamine monomer synthesized in Example 1 has a high yield and high purity, making it suitable for industrial production.

[0185] Example 5

[0186] This embodiment uses the aromatic diamine monomer prepared in Example 1 to prepare polyimide polymers via both the thermal imide method and the chemical imide method. Because the diamine monomer containing an adamantane structure prepared in Example 1 introduces a large volume of adamantane, excellent light transmittance and dielectric properties are expected. The diamine monomers prepared in Examples 2-4 have similar structures to those prepared in Example 1, all introducing a large volume of adamantane structure, which is beneficial for increasing the solubility of the polymer.

[0187] The polyimide provided in this embodiment includes the following repeating structural units:

[0188]

[0189] The above-mentioned polyimide films were prepared using both the thermal imide method and the chemical imide method, specifically including:

[0190] (1) Thermal imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone with stirring. 1 mmol of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride was added at 25°C. After stirring at 25°C for 24 hours, the solution was filtered and cast onto a glass plate. The glass plate was heated on a hot plate at 60°C for 8 hours, and then dried in vacuum ovens at 100°C, 150°C, 200°C, 250°C, and 300°C for 30 minutes each. After cooling, the film was immersed in deionized water, peeled off, and then dried at 150°C for 2 hours to obtain a polyimide film (AMTCDM+ODPA(T)) with Mn of 9.2 × 10⁻⁶. 4 g / mol.

[0191] (2) Chemical imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone under stirring. 1 mmol of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride was added at 25°C. After stirring at 25°C for 24 hours, 4 ml of a mixture of acetic anhydride and 2 ml of pyridine was added. The mixture was heated to 80°C and stirred for 12 hours. The solution was poured into a large amount of ethanol, filtered, and dried under vacuum at 80°C to obtain polyimide. The dried polyimide was dissolved in NMP to prepare a PI solution with a solid content of 15%. The polyimide film was then laid on a glass plate using a doctor blade and evaporated at 60°C for 8 hours. The film was then vacuum-dried at 140°C for 5 hours and at 200°C for 5 hours to completely remove the solvent. The glass plate with the polyimide film was then immersed in deionized water, peeled off, and dried at 150°C for 2 hours to obtain the polyimide film. (AMTCDM+ODPA(C)), Mn is 9.4×10⁻⁶ 4 g / mol.

[0192] Table 2 shows the optical, dielectric, and thermal properties of the polyimide synthesized in this embodiment; Table 3 shows the mechanical properties of the polyimide synthesized in this embodiment; and Table 4 shows the solubility of the polyimide synthesized in this embodiment. The specific test methods are as follows:

[0193] Differential scanning calorimetry (DSC) was performed on a Mettler DSC instrument to evaluate the glass transition temperature (Tg) of the PI film (polyimide film) at a nitrogen gas flow rate of 50 mL / min and a heating rate of 20 mL / min, where Tg was taken from the second heating trajectory to eliminate thermal history.

[0194] Thermogravimetric analysis (TGA) was performed on a Mettler TGA machine at a nitrogen flow rate of 50 mL / min in N2 at a rate of 20 °C / min within the range of 50–800 °C to evaluate the TGA properties of PI films (polyimide films). 5％ (Temperature at which 5% thermal weight loss occurs) and T 10％ (Temperature at which 10% thermal weight loss occurs).

[0195] Mechanical properties of a 20mm×6mm×0.05mm thin film sample were tested using an Instron 5567A universal testing machine. The sensor was 100N, the tensile rate was 5mm / min, and five sets of tests were performed, with the average value taken.

[0196] The solubility was determined by dissolving 10 mg of polyimide film in the appropriate solvent (1 ml) at 25 °C for 24 hours.

[0197] The UV-Vis spectrum of the polyimide film was recorded in transmission mode within the wavelength range of 250–800 nm using a UV / Vis / NIR spectrophotometer to determine the cutoff wavelength λ of the polyimide film. cut off and transmittance T at 450nm 450 .

[0198] The dielectric properties of the polyimide film were tested using a network analyzer at 15 GHz and the dielectric constant and dielectric loss at room temperature.

[0199] Figure 2 The infrared spectra of polyimides (AMTCDM+ODPA(C), AMTCDM+ODPA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (ODPA) are shown. It can be seen that at 2923 cm⁻¹... -1 and 2836cm -1 The peak is -CH at 1779 cm⁻¹. -1 and 1727cm -1 The peak is -C=O at 1375cm. -1 The peak is -CN.

[0200] Figure 3 The DSC curves show the thermal properties of polyimides (AMTCDM+ODPA(C) and AMTCDM+ODPA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (ODPA). The glass transition temperature of AMTCDM+ODPA(C) is 291 °C.

[0201] Figure 4 The thermal properties of polyimides (AMTCDM+ODPA(C) and AMTCDM+ODPA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (ODPA) are shown in the TGA graph. The 5% and 10% thermogravimetric temperatures of AMTCDM+ODPA(C) are 482℃ and 492℃, respectively.

[0202] Example 6

[0203] In this embodiment, the aromatic diamine monomer prepared in Example 1 was used to prepare polyimide polymers by thermal imide method and chemical imide method, respectively.

[0204] The polyimide provided in this embodiment includes the following repeating structural units:

[0205]

[0206] The above-mentioned polyimide films were prepared using both the thermal imide method and the chemical imide method, specifically including:

[0207] (1) Thermal imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was dissolved in N-methylpyrrolidone with stirring. 1 mmol of bisphenol A dianhydride was added at 25°C, and the mixture was stirred at 25°C for 24 hours. The solution was then filtered and cast onto a glass plate. The glass plate was heated on a hot plate at 60°C for 8 hours, and then dried in vacuum ovens at 100°C, 150°C, 200°C, 250°C, and 300°C for 30 minutes each. After cooling, the film was immersed in deionized water, peeled off, and then dried at 150°C for 2 hours to obtain a polyimide film (AMTCDM+BPADA(T)) with Mn of 7.0 × 10⁻⁶. 4 g / mol.

[0208] (2) Chemical imide method: Under nitrogen protection, 1 mmol of diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone under stirring. 1 mmol of bisphenol A dianhydride was added at 25°C and stirred at 25°C for 24 hours. Then, a mixture of 4 ml of acetic anhydride and 2 ml of pyridine was added, and the mixture was heated to 80°C and stirred for 12 hours. The solution was poured into a large amount of ethanol, filtered, and dried under vacuum at 80°C to obtain polyimide. The dried polyimide was dissolved in NMP to prepare a PI solution with a solid content of 15%. Subsequently, a film was laid on a glass plate using a scraper. After evaporation at 60°C for 8 hours, the film was vacuum dried at 140°C for 5 hours and at 200°C for 5 hours to completely remove the solvent. The glass plate with the polyimide film was then immersed in deionized water and peeled off to obtain the polyimide film (AMTCDM+BPADA(C)). n 8.8×10 4 g / mol.

[0209] Table 2 shows the optical, dielectric, and thermal properties of the polyimide synthesized in this embodiment. Table 3 shows the mechanical properties of the polyimide synthesized in this embodiment. Table 4 shows the solubility of the polyimide synthesized in this embodiment. The specific test methods are the same as in Example 5.

[0210] Figure 2The infrared spectra of polyimides (AMTCDM+BPADA(C), AMTCDM+BPADA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with bisphenol A dianhydride (BPADA) show that at 2923 cm⁻¹... -1 and 2836cm -1 The peak is -CH at 1779 cm⁻¹. -1 and 1727cm -1 The peak is -C=O at 1375cm. -1 The peak is -CN.

[0211] Figure 3 The DSC plots show the thermal properties of polyimides (AMTCDM+BPADA(C) and AMTCDM+BPADA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with bisphenol A dianhydride (BPADA). The glass transition temperature of AMTCDM+BPADA(C) is 253 °C.

[0212] Figure 4 The thermal properties of polyimides (AMTCDM+BPADA(C) and AMTCDM+BPADA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with bisphenol A dianhydride (BPADA) are shown in the TGA graph. The 5% and 10% thermogravimetric losses of AMTCDM+BPADA(C) are 478℃ and 489℃, respectively.

[0213] Example 7

[0214] In this embodiment, the aromatic diamine monomer prepared in Example 1 was used to prepare polyimide polymers by thermal imide method and chemical imide method, respectively.

[0215] The polyimide provided in this embodiment includes the following repeating structural units:

[0216]

[0217] The above-mentioned polyimide films were prepared using both the thermal imide method and the chemical imide method, specifically including:

[0218] (1) Thermal imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone with stirring. 1 mmol of 2,3,3',4'-biphenyltetracarboxylic dianhydride was added at 25°C. After stirring at 25°C for 24 hours, the solution was filtered and cast onto a glass plate. The glass plate was heated on a hot plate at 60°C for 8 hours, and then dried in vacuum ovens at 100°C, 150°C, 200°C, 250°C, and 300°C for 30 minutes each. After cooling, the film was immersed in deionized water, peeled off, and then dried at 150°C for 2 hours to obtain a polyimide film (AMTCDM+α-BPDA(T)) with Mn of 9.4 × 10⁻⁶. 4 g / mol.

[0219] (2) Chemical imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone under stirring. 1 mmol of 2,3,3',4'-biphenyltetracarboxylic dianhydride was added at 25°C. After stirring at 25°C for 24 hours, a mixture of 4 ml of acetic anhydride and 2 ml of pyridine was added. The mixture was heated to 80°C and stirred for 12 hours. The solution was poured into a large amount of ethanol, filtered, and dried under vacuum at 80°C to obtain polyimide. The dried polyimide was dissolved in NMP to prepare a PI solution with a solid content of 15%. The polyimide film was then laid on a glass plate using a doctor blade and evaporated at 60°C for 8 hours. The film was then vacuum-dried at 140°C for 5 hours and at 200°C for 5 hours to completely remove the solvent. The glass plate with the polyimide film was then immersed in deionized water and peeled off to obtain the polyimide film (AMTCDM+α-BPDA(C)), with a Mn content of 8.7 × 10⁻⁶. 4 g / mol.

[0220] Table 2 shows the optical, dielectric, and thermal properties of the polyimide synthesized in this embodiment. Table 3 shows the mechanical properties of the polyimide synthesized in this embodiment. Table 4 shows the solubility of the polyimide synthesized in this embodiment. The specific test methods are the same as in Example 5.

[0221] Figure 2 The infrared spectra of polyimides (AMTCDM+α-BPDA(C), AMTCDM+α-BPDA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with α-biphenyltetraic dianhydride (α-BPDA) show that at 2923 cm⁻¹... -1and 2836cm -1 The peak is -CH at 1779 cm⁻¹. -1 and 1727cm -1 The peak is -C=O at 1375cm. -1 The peak is -CN.

[0222] Figure 3 The thermal properties of polyimides (AMTCDM+α-BPDA(C) and AMTCDM+α-BPDA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with α-biphenyltetraic dianhydride (α-BPDA) are shown in the DSC curves. AMTCDM+α-BPDA(C) has a glass transition temperature of 319 °C.

[0223] Figure 4 The thermal properties of polyimides (AMTCDM+α-BPDA(C) and AMTCDM+α-BPDA(T)) prepared by the reaction of 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with α-biphenyltetraic dianhydride (α-BPDA) are shown in the TGA graph. The 5% and 10% thermogravimetric temperatures of AMTCDM+α-BPDA(C) are 486℃ and 497℃, respectively.

[0224] Example 8

[0225] In this embodiment, the aromatic diamine monomer prepared in Example 1 was used to prepare polyimide polymers by thermal imide method and chemical imide method, respectively.

[0226] The polyimide provided in this embodiment includes the following repeating structural units:

[0227]

[0228] The above-mentioned polyimide films were prepared using both the thermal imide method and the chemical imide method, specifically including:

[0229] (1) Thermal imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was dissolved in N-methylpyrrolidone with stirring. 1 mmol of hexafluorodianhydride was added at 25°C, and the mixture was stirred at 25°C for 24 hours. The solution was then filtered and cast onto a glass plate. The glass plate was heated on a hot plate at 60°C for 8 hours, and then dried in vacuum ovens at 100°C, 150°C, 200°C, 250°C, and 300°C for 30 minutes each. After cooling, the film was immersed in deionized water, peeled off, and then dried at 150°C for 2 hours to obtain a polyimide film (AMTCDM+6FDA(T)) with Mn of 7.6 × 10⁻⁶.4 g / mol.

[0230] (2) Chemical imide method: Under nitrogen protection, 1 mmol of diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone under stirring. 1 mmol of hexafluorodianhydride was added at 25°C. After stirring at 25°C for 24 hours, 4 ml of acetic anhydride and 2 ml of pyridine mixture were added. The mixture was heated to 80°C and stirred for 12 hours. The solution was poured into a large amount of ethanol, filtered, and dried under vacuum at 80°C to obtain polyimide. The dried polyimide was dissolved in NMP to prepare a PI solution with a solid content of 15%. The film was then laid on a glass plate using a doctor blade and evaporated at 60°C for 8 hours. The film was then vacuum-dried at 140°C for 5 hours and at 200°C for 5 hours to completely remove the solvent. The glass plate with the polyimide film was then immersed in deionized water and peeled off to obtain the polyimide film (AMTCDM+6FDA(C)), with Mn of 8.5 × 10⁻⁶. 4 g / mol.

[0231] Table 2 shows the optical, dielectric, and thermal properties of the polyimide synthesized in this embodiment. Table 3 shows the mechanical properties of the polyimide. Table 4 shows the solubility of the polyimide. The specific test methods are the same as in Example 5.

[0232] Figure 3 The DSC curves of the thermal properties of polyimides (AMTCDM+6FDA(C) and AMTCDM+6FDA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with hexafluorodianhydride (6FDA) are shown. The glass transition temperature of AMTCDM+6FDA(C) is 304 °C.

[0233] Figure 4 The thermal properties of polyimides (AMTCDM+6FDA(C) and AMTCDM+6FDA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with hexafluorodianhydride (6FDA) are shown in the TGA graph. The 5% and 10% thermogravimetric temperatures of AMTCDM+6FDA(C) are 491℃ and 501℃, respectively.

[0234] Example 9

[0235] In this embodiment, the aromatic diamine monomer prepared in Example 1 was used to prepare polyimide polymers by thermal imide method and chemical imide method, respectively.

[0236] The polyimide provided in this embodiment includes the following repeating structural units:

[0237]

[0238] The above-mentioned polyimide films were prepared using both the thermal imide method and the chemical imide method, specifically including:

[0239] (1) Thermal imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was dissolved in N-methylpyrrolidone with stirring. 1 mmol of biphenyl dianhydride (BPDA) was added at 25°C, and the mixture was stirred at 25°C for 24 hours. The solution was then filtered and cast onto a glass plate. The glass plate was heated on a hot plate at 60°C for 8 hours, and then dried in vacuum ovens at 100°C, 150°C, 200°C, 250°C, and 300°C for 30 minutes each. After cooling, the film was immersed in deionized water, peeled off, and then dried at 150°C for 2 hours to obtain a polyimide film (AMTCDM+BPDA(T)) with Mn of 5.5 × 10⁻⁶. 4 g / mol.

[0240] (2) Chemical imide method: Under nitrogen protection, 1 mmol of diamine monomer 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone under stirring. 1 mmol of biphenyl dianhydride (BPDA) was added at 25°C. After stirring at 25°C for 24 hours, a mixture of 4 ml of acetic anhydride and 2 ml of pyridine was added. The mixture was heated to 80°C and stirred for 12 hours. The solution was poured into a large amount of ethanol, filtered, and dried under vacuum at 80°C to obtain polyimide. The dried polyimide was dissolved in NMP to prepare a PI solution with a solid content of 15%. The polyimide film was then laid on a glass plate using a doctor blade and evaporated at 60°C for 8 hours. The film was then vacuum-dried at 140°C for 5 hours and at 200°C for 5 hours to completely remove the solvent. The glass plate with the polyimide film was then immersed in deionized water and peeled off to obtain the polyimide film (AMTCDM+BPDA(C)), with a Mn content of 6.5 × 10⁻⁶. 4 g / mol.

[0241] Table 2 shows the optical, dielectric, and thermal properties of the polyimide synthesized in this embodiment. Table 3 shows the mechanical properties of the polyimide. Table 4 shows the solubility of the polyimide. The specific test methods are the same as in Example 5.

[0242] Figure 2 The infrared spectra of polyimides (AMTCDM+BPDA(C), AMTCDM+BPDA(T)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with biphenyltetraic dianhydride (BPDA) show that at 2923 cm⁻¹... -1 and 2836cm -1 The peak is -CH at 1779 cm⁻¹. -1 and 1727cm -1 The peak is -C=O at 1375cm. -1 The peak is -CN.

[0243] Figure 3 The thermal properties of polyimides (AMTCDM+BPDA(T) and AMTCDM+BPDA(C)) prepared by reacting 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with biphenyltetraic dianhydride (BPDA) are shown in the DSC curves. The glass transition temperature of AMTCDM+BPDA(T) is 329 °C.

[0244] Figure 4 The thermal properties of polyimides (AMTCDM+BPDA(T) and AMTCDM+BPDA(C)) prepared by the reaction of 1,3-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]adamantane with biphenyltetraic dianhydride (BPDA) are shown in the TGA graph. The 5% and 10% thermogravimetric temperatures of AMTCDM+BPDA(T) are 481℃ and 493℃, respectively.

[0245] Example 10

[0246] In this embodiment, the aromatic diamine monomer prepared in Example 2 was used to prepare polyimide polymers by thermal imide method and chemical imide method, respectively.

[0247] The polyimide provided in this embodiment includes the following repeating structural units:

[0248]

[0249] The above-mentioned polyimide films were prepared using both the thermal imide method and the chemical imide method, specifically including:

[0250] (1) Thermal imide method: Under nitrogen protection, 1 mmol of the diamine monomer 1,3-bis[4-(4-aminophenoxy)phenyl]adamantane was dissolved in N-methylpyrrolidone with stirring. 1 mmol of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride was added at 25°C. After stirring at 25°C for 24 hours, the solution was filtered and cast onto a glass plate. The glass plate was heated on a hot plate at 60°C for 8 hours, and then dried in vacuum ovens at 100°C, 150°C, 200°C, 250°C, and 300°C for 30 minutes each. After cooling, the film was immersed in deionized water, peeled off, and then dried at 150°C for 2 hours to obtain a polyimide film (AMTDM+ODPA(T)) with Mn of 7.96 × 10⁻⁶. 4 g / mol.

[0251] (2) Chemical imide method: Under nitrogen protection, 1 mmol of diamine monomer 1,3-bis[4-(4-aminophenoxy)phenyl]adamantane was fully dissolved in N-methylpyrrolidone with stirring. 1 mmol of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride was added at 25°C. After stirring at 25°C for 24 hours, 4 ml of acetic anhydride and 2 ml of pyridine mixture were added. The mixture was heated to 80°C and stirred for 12 hours. The solution was poured into a large amount of ethanol, filtered, and dried under vacuum at 80°C to obtain polyimide. The dried polyimide was dissolved in NMP to prepare a PI solution with a solid content of 15%. The polyimide film was then laid on a glass plate using a doctor blade and evaporated at 60°C for 8 hours. The film was then vacuum-dried at 140°C for 5 hours and at 200°C for 5 hours to completely remove the solvent. The glass plate with the polyimide film was then immersed in deionized water and peeled off to obtain the polyimide film (AMTDM+ODPA(C)), with a Mn content of 8.97 × 10⁻⁶. 4 g / mol.

[0252] Table 2 shows the optical, dielectric, and thermal properties of the polyimide synthesized in this embodiment. Table 3 shows the mechanical properties of the polyimide. Table 4 shows the solubility of the polyimide. The specific test methods are the same as in Example 5.

[0253] Comparative Example 1

[0254] This comparative example is a commercially available Kapton film in the prior art. Its optical properties, dielectric properties, thermal properties, mechanical properties and solubility were tested using the same test methods as in Examples 5-10, as shown in Tables 2-4.

[0255] Comparative Example 2

[0256] The polyimide provided in this comparative example includes the following repeating structural units:

[0257]

[0258] The polyimide film described above was prepared by the chemical imide method, which is basically the same as that in Example 5, except that the diamine monomer in Example 5 was replaced with a diamine monomer with the structure shown in formula (a).

[0259]

[0260] Comparative Example 3

[0261] The polyimide provided in this comparative example includes the following repeating structural units:

[0262]

[0263] The polyimide film described above was prepared by the chemical imide method, which is basically the same as that in Example 5, except that the diamine monomer in Example 5 was replaced with a diamine monomer with the structure shown in formula (b).

[0264]

[0265] Comparative Example 4

[0266] The polyimide provided in this comparative example includes the following repeating structural units:

[0267]

[0268] The polyimide film described above was prepared by the chemical imide method, which is basically the same as that in Example 5, except that the diamine monomer in Example 5 was replaced with a diamine monomer with the structure shown in formula (c).

[0269]

[0270] Table 2. Optical, dielectric, and thermal properties of the polyimides synthesized in Examples 5-10 and Comparative Examples 1-4.

[0271]

[0272]

[0273] Table 3 Mechanical properties of the polyimides synthesized in Examples 5-10 and Comparative Examples 1-4

[0274]

[0275]

[0276] Table 4. Solubility of Polyimide synthesized in Examples 5-10 and Comparative Examples 1-4

[0277]

[0278] Note: +: dissolves at room temperature; +-: partially dissolves or swells; -: does not dissolve.

[0279] As can be seen from Table 2, the polyimides prepared in Examples 5-10 of the present invention exhibit superior optical performance compared to Comparative Example 1, indicating that the polyimides prepared by the present invention have better optical transparency and can meet the requirements for polyimide films in the optical field.

[0280] As can be seen from Table 2, the polyimides prepared in Examples 5-10 of the present invention exhibit superior dielectric properties compared to Comparative Example 1, indicating that the polyimides prepared by the present invention have a lower dielectric constant. The lower the dielectric constant, the better the charge transfer effect, and thus it can be used in electronic packaging materials.

[0281] As can be seen from Table 2, the polyimides prepared in Examples 5-10 of the present invention have little difference in thermal properties compared with Comparative Example 1, indicating that the polyimides prepared by the present invention all have high glass transition temperatures and can be used at higher temperatures, thus having wider applicability.

[0282] As can be seen from Table 3, the polyimides prepared in Examples 5-10 of the present invention exhibit superior mechanical properties compared to Comparative Example 1.

[0283] As can be seen from Table 4, the polyimides prepared in Examples 5-10 of the present invention have better solubility in specific solvents compared with Comparative Example 1, indicating that the polyimides prepared by the present invention are easier to process and have wider applicability.

[0284] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diamine monomer containing an adamantane structure, characterized in that, The diamine monomer containing the adamantane structure has the following structure: Among them, R1, R2 and R3 may be the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl or -Br.

2. A method for preparing a diamine monomer containing an adamantane structure as described in claim 1, characterized in that, The preparation method includes the following steps: S1. Under a protective atmosphere, 1,3-adamantanediol, phenolic compounds and a first catalyst are added to a reaction vessel equipped with a mechanical stirrer and the reaction is carried out. After the reaction is completed, the adamantane bisphenol compound is obtained through post-treatment. S2. The adamantyl bisphenol compound, the halogen-containing and nitro compounds, and the base are mixed in a first organic solvent to carry out a substitution reaction to obtain a dinitro compound. S3. The dinitro compound, hydrogenation catalyst, second organic solvent and reducing agent are mixed and subjected to catalytic hydrogenation reaction to obtain the diamine monomer containing the adamantane structure.

3. The method for preparing a diamine monomer containing an adamantane structure according to claim 2, characterized in that, In step S1, the protective atmosphere includes at least one of nitrogen atmosphere and inert gas atmosphere; And / or, in step S1, the phenolic compound includes one of phenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2,6-isopropylphenol, 2,6-tert-butylphenol, 2-chlorophenol, 2-bromophenol, 2-fluorophenol, 2-methylphenol, 2-methoxyphenol, 2-isopropylphenol, 2-tert-butylphenol, and 2-phenylphenol; And / or, in step S1, the first catalyst includes at least one of concentrated sulfuric acid, trifluoroacetic acid, methanesulfonic acid, and trifluoromethanesulfonic acid; And / or, in step S1, the molar ratio of the 1,3-adamantanediol to the phenolic compound is 1:(2-8); And / or, in step S1, the mass ratio of the 1,3-adamantanediol to the first catalyst is 1:(0.5-2); And / or, in step S1, the reaction temperature is 80-90°C, the reaction time is 6-12 h, and the post-treatment includes sedimentation, filtration, drying, and recrystallization; And / or, in step S2, the halogen- and nitro-containing compound includes one of p-chloronitrobenzene, 1-chloro-2-methyl-4-nitrobenzene, 1-chloro-2-trifluoromethyl-4-nitrobenzene, 1-chloro-2-fluoro-4-nitrobenzene, 1,2-dichloro-4-nitrobenzene, and 1-chloro-2-bromo-4-nitrobenzene; And / or, in step S2, the alkali includes at least one of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, sodium bicarbonate, and potassium bicarbonate; And / or, in step S2, the first organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide; And / or, in step S2, the molar ratio of the adamantyl bisphenol compound to the halogen- and nitro-containing compound is 1:2 to 2.2; And / or, in step S2, the molar ratio of the adamantyl bisphenol compound to the base is 1:1.2 to 3.0; And / or, in step S2, the mass ratio of the adamantyl bisphenol compound to the volume ratio of the first organic solvent is 1 g: 5 to 11 mL; And / or, in step S2, the temperature of the substitution reaction is 80–120°C, and the time of the substitution reaction is 8–12 h; And / or, in step S3, the hydrogenation catalyst includes at least one of palladium on carbon, platinum on carbon, rhodium on carbon, and active nickel; And / or, in step S3, the second organic solvent includes at least one of tetrahydrofuran, ethanol, methanol, isopropanol, N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, 1,4-dioxane, ethyl acetate, benzene, toluene, and xylene. And / or, in step S3, the reducing agent includes hydrazine hydrate; And / or, in step S3, the mass of the hydrogenation catalyst is 2-10% of the mass of the dinitro compound; And / or, in step S3, the mass ratio of the dinitro compound to the volume ratio of the second organic solvent is 1 g:(5-10) mL; And / or, in step S3, the molar ratio of the dinitro compound to the reducing agent is 1:4 to 12; And / or, in step S3, the temperature of the catalytic hydrogenation reaction is 40–100°C, and the time of the catalytic hydrogenation reaction is 8–12 h; And / or, in step S3: the order of mixing the dinitro compound, hydrogenation catalyst, second organic solvent, and reducing agent is as follows: the dinitro compound, hydrogenation catalyst, and second organic solvent are first mixed to obtain a mixture; then the temperature is raised to the temperature of the catalytic hydrogenation reaction, and the reducing agent is added dropwise to the mixture; the dropwise addition is completed within 30 minutes; after the catalytic hydrogenation reaction is completed, the reaction solution obtained from the catalytic hydrogenation reaction is subjected to thermal solid-liquid separation, and then the obtained filtrate is mixed with water for precipitation. The obtained precipitate is dried to obtain a diamine monomer containing an adamantane structure. The drying is vacuum drying, and the drying temperature is 75-85°C.

4. A polyimide, characterized in that, The diamine monomer raw materials used to synthesize the polyimide include the diamine monomer containing adamantane structure as described in claim 1 or the diamine monomer containing adamantane structure prepared by any one of claims 2 to 3.

5. The polyimide according to claim 4, characterized in that, The polyimide comprises the following repeating structural units: Among them, R1, R2 and R3 may be the same or different, and each independently represents -H, C1-6 alkyl, halogenated C1-6 alkyl, methoxy, phenyl, -F, -Cl or -Br; A has a structure shown by any of the following formulas: And / or, the number average molecular weight of the polyimide is 4.3-9.4 × 10⁻⁶. 4 g / mol; And / or, the glass transition temperature of the polyimide is 253-329°C; And / or, the polyimide has a 5% thermal weight loss temperature of 474-491°C; And / or, the temperature at which the polyimide loses 10% of its thermal weight is 485-501°C; And / or, the dielectric constant of the polyimide at 15 GHz is 2.53-2.86; And / or, the cutoff wavelength of the polyimide is 333-365 nm; And / or, the polyimide is soluble in an aprotic polar solvent, the aprotic polar solvent including at least one of N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, m-cresol, butyrolactone, and sulfolane, preferably including at least one of N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, and m-cresol.

6. A method for preparing polyimide as described in claim 4 or 5, characterized in that, The preparation method of the polyimide includes the following steps: Under a protective atmosphere, the diamine monomer containing the adamantane structure as described in claim 1, or the diamine monomer containing the adamantane structure prepared by the preparation method described in claim 2 or 3, and the aromatic dianhydride monomer are added to a third organic solvent to carry out a polycondensation reaction to obtain a polyamic acid solution. The obtained polyamic acid solution was imidized to obtain the polyimide.

7. The method for preparing polyimide according to claim 6, characterized in that, The protective atmosphere includes a nitrogen atmosphere; And / or, the aromatic dianhydride monomer includes one of diphenyl ether tetracarboxylic dianhydride, biphenyl dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, hexafluoro dianhydride, and bisphenol A dianhydride; And / or, the molar ratio of the diamine monomer containing the adamantane structure to the aromatic dianhydride monomer is 1:1 to 1.3; And / or, the third organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,4-butyrolactone; And / or, the solid content of the mixture obtained by mixing the adamantane-containing diamine monomer, the aromatic dianhydride monomer and the third organic solvent is 10-25%; And / or, the temperature of the polycondensation reaction is 23℃-28℃, and the time of the polycondensation reaction is greater than or equal to 24h; And / or, the imidization is performed by thermal imidization or chemical imidization.

8. The method for preparing polyimide according to claim 7, characterized in that, The thermal imidization includes a dehydration cyclization reaction of the polyamic acid solution by gradient heating, wherein the gradient heating includes heating at 60-80°C for 4-8 hours, followed by drying in vacuum ovens at 100°C, 150°C, 200°C, 250°C and 300°C for 30 minutes each. And / or, the chemical imidization includes adding a dehydrating agent and a catalyst to the polyamic acid solution, stirring at 80-100°C for 8-12 hours, pouring the resulting mixed solution into a polar solvent for precipitation, filtering and drying to obtain the polyimide, wherein the polar solvent includes at least one of methanol, ethanol and water, the catalyst includes one or more of pyridine, isoquinoline, and triethylamine, and the dehydrating agent includes acetic anhydride.

9. The use of a polyimide as described in any one of claims 4 to 5 or a polyimide prepared by the preparation method as described in any one of claims 6 to 8 in the preparation of polyimide film materials or electronic packaging materials.

10. A polyimide film, characterized in that, The polyimide in the film includes the polyimide according to any one of claims 4 to 5 or the polyimide prepared by any one of claims 6 to 8.

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