Nitrogen-containing heterocyclic diamine compound as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of new materials, and particularly relates to a nitrogen-containing heterocyclic diamine compound as well as a preparation method and application thereof. The compound has unique molecular design, can realize surface metallization of the polyimide film, and overcomes the problems of complexity, weak interface bonding and the like of the traditional process. According to the technical scheme, the nitrogen heterocyclic ring diamine compound has the advantages that firstly, the nitrogen heterocyclic ring structure in the nitrogen heterocyclic ring diamine compound provides efficient coordination active sites, and anchoring of metal ions can be achieved under mild conditions; secondly, the polyimide film prepared on the basis of the compound can be directly subjected to metallization treatment, an additional surface modification step is not needed, and the problem of sudden change of surface roughness is avoided; and finally, the method can simultaneously realize metallization of a macroscopic pattern and a fine structure (line width lt and 10 [mu] m), the thickness of a metal layer can be accurately regulated and controlled, the bonding strength of a metal-matrix interface is remarkably improved (reaching the grade of 4B or above), and the conductivity is excellent.

Description

Technical Field

[0001] This application belongs to the field of new materials technology, and more specifically, relates to a class of nitrogen-containing heterocyclic diamine compounds, their preparation methods and applications. Background Technology

[0002] Metallization of dielectric substrates is a core process in modern electronics, widely used in microelectronic devices, integrated circuits, flexible displays, and biomedical implants. Among flexible electronic substrate materials, polyimide (PI) is the preferred material due to its excellent mechanical strength (tensile strength 100-300 MPa), outstanding flexibility (bending radius <1 mm), excellent thermal cycling dimensional stability (CTE typically 20-40 ppm / K), and superior chemical stability. However, the high chemical inertness of polyimide surfaces makes direct surface metallization extremely difficult, which is a key bottleneck limiting its application in high-end flexible electronics.

[0003] Vacuum physical vapor deposition (PVD) is one of the mainstream metallization technologies. This technology typically requires a high-temperature environment above 300°C. Due to the low surface energy and strong chemical inertness of polyimide, the interfacial bonding strength between the metal layer and polyimide is generally insufficient (usually below 3B grade). During thermal cycling and mechanical bending, delamination is prone to occur, severely affecting the reliability and lifespan of flexible electronic devices. Traditional chemical metallization processes use a two-step activation method of stannous chloride / palladium chloride. However, since the polyimide surface cannot provide sufficient nucleation sites, surface pretreatment is necessary. These pretreatment methods typically include strong alkali treatment, plasma treatment, or laser / chemical roughening.

[0004] Strong alkali treatment uses strong bases such as KOH or NaOH to hydrolyze the polyimide surface, destroying the imide ring structure and introducing carboxyl and amide groups to enhance surface hydrophilicity. However, this method leads to partial breakage of the polyimide molecular chains, significantly reducing the material's mechanical strength. Plasma treatment uses oxygen, nitrogen, or argon plasma to bombard the polyimide surface, introducing polar groups or creating nanoscale roughness. However, the surface activation effect is not lasting, and the equipment is expensive and energy-intensive. Laser or chemical roughening treatments provide mechanical interlocking points by increasing surface roughness; however, the surface morphology control precision is low, easily leading to over-roughening and irreversible structural damage to the polyimide substrate.

[0005] Existing technologies typically require 5-8 processing steps, including surface pretreatment, sensitization, activation, electroless plating, and electroplating, which are not only complex but also costly. Furthermore, the minimum linewidth of traditional processes is generally greater than 50 μm, making it difficult to meet the requirements of high-density integrated circuits for micro-wires (<20 μm). Although researchers have attempted novel methods such as electron beam direct writing and photo-reduction of metals, these technologies have not yet simultaneously solved key problems such as insufficient metal-polymer interface bonding strength, protection of the intrinsic properties of polyimide substrates, simplification of process steps, and high-precision metal patterning. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this application is to provide a class of nitrogen-containing heterocyclic diamine compounds, their preparation methods, and applications. The nitrogen-containing heterocyclic diamine compounds of this invention can achieve intrinsic metallization of polyimide films through molecular design strategies without compromising the intrinsic properties of polyimide. This solves key technical problems in existing polyimide film surface metallization technologies, such as insufficient interfacial bonding strength, complex processes, and limited precision, thereby meeting the urgent need for high-density, high-reliability metal interconnects in next-generation flexible electronic devices.

[0007] To achieve the above objectives, in a first aspect, this application provides a class of nitrogen-containing heterocyclic diamine compounds, the general structural formula of which is shown in formula (1):

[0008] Equation (1) Wherein, A is a nitrogen-containing heterocycle, selected from one of the following structures, and the "*" indicates a connection point:

[0009] B is a group containing an amino group, selected from one of the following structures, where "*" indicates a connection point: .

[0010] According to another aspect of the present invention, a method for preparing the nitrogen-containing heterocyclic diamine compound is provided, comprising the following steps: (1) Synthesis of 2,4,6-trisubstituted pyridinyl indole / azaindole compounds (slash " / " means "or"):

[0011] or

[0012] X1 is H or N, X2 is -NO2, or C is the reaction solvent, which is one or both of glacial acetic acid and pyridine; (2) Synthesis of 2,4,6-trisubstituted pyridylindole / azaindole diamine compounds (the slash " / " means "or"):

[0013] or

[0014] X1 is H or N, X2 is -NO2, or X3 is -NH2, or D is the reaction solvent, which is one or both of ethanol and DMAC, and E is the reducing agent.

[0015] According to another aspect of the invention, an application of the aforementioned nitrogen-containing heterocyclic diamine compound is provided for the preparation of polyimide films; or for metallizing the surface of the prepared polyimide film.

[0016] This invention provides a class of 2,4,6-trisubstituted pyridyl nitrogen-containing heterocyclic diamine compounds and their preparation method. These compounds are uniquely designed, containing specific coordination active sites, and can be polymerized with various dianhydride monomers to form polyimide films with special functions. The resulting films not only exhibit excellent thermodynamic and optical properties but also possess the unique ability for direct surface metallization without the need for traditional surface pretreatment steps.

[0017] The technical solution of the present invention has the following advantages: First, the nitrogen heterocyclic structure in the nitrogen-containing heterocyclic diamine compound provides highly efficient coordination active sites, which can achieve the anchoring of metal ions under mild conditions; second, the surface of the polyimide film prepared based on such compounds can be directly metallized without additional surface modification steps, thus avoiding the problem of abrupt changes in surface roughness; finally, this method can simultaneously achieve the metallization of macroscopic patterns and microstructures (linewidth <10μm), and the thickness of the metal layer can be controlled, the metal-substrate interface bonding strength is significantly improved (reaching a level of 4B or higher), and the conductivity is excellent.

[0018] The core innovation of this invention lies in introducing specific nitrogen heterocyclic structural units into the polyimide molecular chain through a molecular design strategy. The nitrogen sites serve as anchoring sites for metal ions, achieving direct metallization of the intrinsic polymer surface. Overall, compared with existing technologies, the technical solutions conceived in this application have the following beneficial effects: (1) Intrinsic thin film metallization: The polyimide thin film formed by the indole / azaindole diamine compound containing the pyridine core structure of the present invention has built-in metal coordination sites, which allows the thin film surface to be directly metal patterned without the need for traditional surface treatment steps such as plasma treatment, chemical etching or roughening, thus fundamentally avoiding the damage to the structure and properties of polyimide caused by these treatments.

[0019] (2) Enhanced interface bonding mechanism: This invention establishes a strong interaction network between polyimide and metal layer through molecular-level coordination anchoring mechanism, which significantly improves the interface bonding strength (reaching or exceeding 4B level) and effectively solves the key technical problem of insufficient metal-polymer interface adhesion in traditional methods.

[0020] (3) Multi-metal compatibility and process flexibility: The palladium anchor positioning point designed in this invention has broad applicability, not only applicable to copper metallization, but also extend to various functional metals such as nickel, gold, and silver, greatly expanding the application range. At the same time, this technology is highly compatible with various patterning strategies, including photolithography, direct writing technology, and mask irradiation, simplifying process steps and increasing operational efficiency, making it suitable for mass production.

[0021] (4) Comprehensive performance optimization and application expansion: This invention not only solves the key challenges of adhesion, process complexity and substrate protection in the metallization process of flexible materials, but also achieves the construction of fine metal patterns (linewidth can reach below 10μm) while retaining the excellent performance of polyimide substrates. This technological breakthrough provides a new approach for the manufacturing of high-performance flexible electronic components, micro-nano devices and integrated systems, and has broad application prospects in cutting-edge fields such as flexible circuits, wearable devices and flexible displays. Attached Figure Description

[0022] Figure 1 This is the 1H NMR spectrum of 4,4'-(4-(1H-indol-3-yl)pyridine-2,6-diyl)diphenylamine, the product synthesized in the third step of Example 1.

[0023] Figure 2 This is the mass spectrum of 4,4'-(4-(1H-indol-3-yl)pyridine-2,6-diyl)diphenylamine, the product synthesized in the third step of Example 1.

[0024] Figure 3 This is the 1H NMR spectrum of the product synthesized in the third step of Example 2, N'-((4-(1H-indol-3-yl)pyridine-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide).

[0025] Figure 4It is the product synthesized in the third step of Example 2, N, N'-((4-(1H-indol-3-yl)pyridine-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide).

[0026] Figure 5 This is the 1H NMR spectrum of 4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine from the third step of Example 3.

[0027] Figure 6 This is the mass spectrum of 4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine from step 3 of Example 3.

[0028] Figure 7 This is the 1H NMR spectrum of N, N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide) from step 3 of Example 4.

[0029] Figure 8 This is the mass spectrum of N, N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide) from step 3 of Example 4.

[0030] Figure 9 The images show the infrared spectra of polyimide films prepared using the PAA solutions from Examples 1-4.

[0031] Figure 10 The images show the infrared spectra of polyimide films prepared using the PAA solutions from Examples 5-8.

[0032] Figure 11 These are test graphs showing the mechanical properties of the polyimide films used in Examples 1-4.

[0033] Figure 12 These are test graphs showing the mechanical properties of the polyimide films used in Examples 5-8.

[0034] Figure 13 These are thermal performance test diagrams of the polyimide films used in Examples 1-4.

[0035] Figure 14 These are thermal performance test diagrams of the polyimide films used in Examples 5-8.

[0036] Figure 15 These are images of the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film in Application Example 3, where the film was fully metallized.

[0037] Figure 16These are SEM images of the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film of Application Example 3 after complete metallization according to the method of Application Example 9.

[0038] Figure 17 The conductivity test is performed on the contents (a) copper layer and contents (b) silver layer of the polyimide film surface that were fully metallized according to the method of Application Example 9 in Application Example 3.

[0039] Figure 18 The interface bonding strength test is performed on the polyimide film surface of Application Example 3, which is fully metallized according to the method of Application Example 9, for the content (a) copper layer and the content (b) silver layer.

[0040] Figure 19 The roughness test of the contents (a) copper layer and contents (b) silver layer of the polyimide film surface fully metallized according to the method of Application Example 9 in Application Example 3 is shown.

[0041] Figure 20 These are images of the content (a) copper layer and content (b) silver layer deposited on the surface of the polyimide film after printing using the method of Application Example 10, as shown in Example 3.

[0042] Figure 21 These are SEM images of the content (a) copper layer and content (b) silver layer deposited on the surface of the polyimide film after printing using the method of Application Example 10, as shown in Example 3.

[0043] Figure 22 This is a conductivity test of the copper layer plated on the surface of the polyimide film after being printed using the method of Example 10.

[0044] Figure 23 This is an application example 3, which tests the interfacial bonding strength of a copper layer printed on the surface of a polyimide film using the method described in application example 10.

[0045] Figure 24 These are images of the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film of Application Example 3 after photolithography using the method of Application Example 11.

[0046] Figure 25 These are SEM and optical microscope images of the polyimide film surface after photolithography and copper plating using the method described in Application Example 11, as shown in Example 3.

[0047] Figure 26 The conductivity of the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film after photolithography using the method of Example 11 is tested. Figure 27This is an interface bonding strength test of the polyimide film surface after copper plating following photolithography using the method described in Example 11. Detailed Implementation To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0048] This invention provides a class of nitrogen-containing heterocyclic diamine compounds with unique molecular designs, enabling direct metallization of intrinsic polyimide films. These compounds are highly compatible with various existing patterning techniques, including photolithographic patterning and direct-write patterning of polyimides, while overcoming the temperature limitations and weak interfacial bonding issues of traditional processes. This invention provides a novel direct metallization technology for polyimide films based on molecular design. By introducing specific nitrogen-containing heterocyclic coordination units into the polyimide molecular chain, a breakthrough method for metal patterning without traditional surface treatment is achieved. This technology overcomes several key challenges in existing metallization processes, providing an innovative solution for the fabrication of next-generation flexible electronic devices.

[0049] The present invention provides a class of nitrogen-containing heterocyclic diamine compounds, the general structural formula of which is shown in formula (1):

[0050] Equation (1) Wherein, A is a nitrogen-containing heterocycle, selected from one of the following structures, and the "*" indicates a connection point:

[0051] B is a group containing an amino group, selected from one of the following structures, where "*" indicates a connection point: .

[0052] In some embodiments, the nitrogen-containing heterocyclic diamine compounds of the present invention include, but are not limited to, compounds with structures of any one of formulas (1-1)-(1-12):

[0053]

[0054] .

[0055] In some embodiments, the method for preparing the nitrogen-containing heterocyclic diamine compound includes the following steps: (1) Synthesis of 2,4,6-trisubstituted pyridinyl indole / azaindole compounds (slash " / " means "or"):

[0056] or

[0057] X1 is H or N, X2 is -NO2, or C is the reaction solvent, which is one or both of glacial acetic acid and pyridine; (2) Synthesis of 2,4,6-trisubstituted pyridylindole / azaindole diamine compounds (the slash " / " means "or"):

[0058] or

[0059] X1 is H or N, X2 is -NO2, or X3 is -NH2, or D is the reaction solvent, which is one or both of ethanol and DMAC, and E is the reducing agent.

[0060] In some embodiments, the reaction temperature in step (1) is 120-125℃ and the reaction time is 8-12h. The reaction temperature in step (2) is 50-85℃ and the reaction time is 18-24h. The reducing agent in step (3) is any one of palladium on carbon / hydrazine hydrate, palladium on carbon / ammonium formate, or palladium on carbon / formic acid combined reducing agent (here the slash " / " means "and").

[0061] The present invention also provides the application of the aforementioned nitrogen-containing heterocyclic diamine compounds for the preparation of polyimide films; or for metallizing the surface of the prepared polyimide films.

[0062] In some embodiments, the use of the nitrogen-containing heterocyclic diamine compound of the present invention in the preparation of polyimide films includes the following steps: (S1) The diamine monomer is first dissolved in a solvent. After the diamine monomer is completely dissolved, the dianhydride monomer is added in multiple portions. The reaction is carried out at room temperature for 15-25 h to obtain a polyamic acid solution. The diamine monomer is the nitrogen-containing heterocyclic diamine compound. (S2) The polyamic acid solution obtained in step (1) is dispersed on the substrate surface by spin coating, heated to evaporate the solvent in the polyamic acid solution, and heated further to cause the polyamic acid to undergo a dehydration cyclization reaction to obtain a polyimide film.

[0063] In some embodiments, the dianhydride monomer in step (S1) is one or more of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride (BPADA), 4,4'-oxobisphthalic anhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), and 1,2,4,5-pyromellitic dianhydride (PMDA); and the solvent is N,N-dimethylacetamide (DMAC) and / or N-methylpyrrolidone (NMP).

[0064] In some embodiments, the molar ratio of the diamine monomer, solvent, and dianhydride monomer in step (S1) is 1:(24-70):1.01.

[0065] In some embodiments, step (S2) involves heating the polyamic acid solution to evaporate the solvent at a temperature of 75-85°C, followed by further heating to induce a dehydration and cyclization reaction in the polyamic acid at a temperature of 100-400°C for 2-5 hours.

[0066] This invention constructs a highly efficient coordination active site network within the polyimide molecular chain by introducing specific nitrogen-containing heterocyclic structures. These active sites can form stable coordination bonds with metal ions, enabling direct metallization of the polyimide film surface. This method offers significant process and performance advantages: firstly, it enables the construction of metal patterns ranging from macroscopic to micron-level fine structures, with the metal layer thickness precisely controllable through reaction conditions; secondly, the resulting metal-polyimide interface exhibits significantly enhanced bonding strength while maintaining excellent conductivity. In terms of process, the method is simplified and highly efficient, and highly compatible with various existing patterning techniques, including photolithographic patterning, printing, and direct writing of polyimides. This molecular-level coordination strategy fundamentally solves key challenges in traditional metallization methods, such as poor adhesion, complex processes, and substrate damage, achieving direct construction, selective control, and interface strengthening of metal patterns while fully preserving the superior performance characteristics of the polyimide substrate.

[0067] This invention provides a class of compounds in which nitrogen heterocycles provide active sites for strong coordination, which can be directly used for the preparation and selective metallization of polyimide films. This invention effectively solves the dual challenges of substrate compatibility and processing precision faced by traditional metallization processes in the manufacture of flexible electronic devices, overcoming the limitations of high-temperature processing (>300 ℃) on heat-sensitive substrates and insufficient metal-substrate interface bonding strength (below 3B grade) in existing technologies. Compared with existing surface modification methods, this invention avoids the problem of abrupt changes in surface roughness, breaks through the linewidth limitation (less than 10 μm), and achieves synergistic optimization of controllable metal pattern thickness, strong adhesion, and excellent conductivity. The polyimide films and their metallized products of this invention can be widely used in optoelectronic fields such as flexible sensors, flexible detectors, flexible solar cells, flexible transparent electrodes, microelectronic packaging, aerospace equipment, medical implants, touch systems, and electromagnetic shielding.

[0068] The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0069] 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.

[0070] The process parameters in the following examples, unless otherwise specified, are generally performed under conventional conditions.

[0071] The embodiments of this application are described below with reference to the accompanying drawings.

[0072] The following is an example: Example 1 The preparation method of the 2,4,6-trisubstituted pyridinyl indole compound with the following structure includes the following steps: Equation (1-2) (1) 19.5 g of indole-3-carboxaldehyde (0.135 mol), 45 g of 4-nitroacetophenone (0.273 mol), and 140 g of ammonium acetate (1.818 mol) were added to a 1000 ml two-necked flask, followed by 300 ml of acetic acid. The mixture was refluxed at 125 °C with magnetic stirring for 12 h. After cooling to room temperature, the mixture was filtered. The product was washed three times with acetic acid, filtered while hot, and dried at 80 °C. It was recrystallized with DMAC at 125 °C, dissolved, and allowed to cool naturally. The crystallization process was repeated three times, and the product was filtered and dried to obtain a yellowish-brown crystalline product. The yield was 85%.

[0073] (2) 10.42 g of indolepyridine-4-dinitro (23.88 mmol) was added to 140 ml of ethanol and 75 ml of DMAC in a 500 ml two-necked flask. Nitrogen gas was introduced and the temperature was raised to 60 °C until the reactants dissolved. 1 g of Pd / C was added and the temperature was raised to 70 °C. 14 ml of hydrazine hydrate was slowly added through a separatory funnel and the temperature was raised to 85 °C. After reacting for 2 h, 4 ml of hydrazine hydrate was added and the reaction was continued for 24 h. The mixture was filtered while hot, dried, and crystallized three times with DMAC. After filtration and vacuum drying, 8.3 g of the product was obtained, with a yield of 92.5%.

[0074] Example 2 The preparation method of the 2,4,6-trisubstituted pyridinyl indole compound with the following structure includes the following steps: Equation (1-4) (1) Weigh 17.4192 g of indole-3-carboxaldehyde (0.12 mol), 68.2056 g of 4-nitroamide acetophenone (0.24 mol), and 210 g (2.7243 mol) of ammonium acetate, add them to a 500 ml two-necked flask, then add 450 ml of pyridine solvent and 250 ml of acetic acid, heat to 110 °C with stirring, and react for 15 h. After cooling, filter, wash with ethanol, heat and stir at 85 °C for 3 h. Repeat the operation 3 times, dry under vacuum, and obtain 36.5 g of sample, yield: 47.1%.

[0075] (2) Weigh 15 g (23.21 mmol) of reactants and 1.2 g of 10% Pd / C, add 180 ml of ethanol and 80 ml of DMAC, purge with nitrogen and stir at 50 °C for 10 min, then add 22.5 g of ammonium formate, raise the temperature to 65 °C and react for 24 h. Filter while hot, pour the filtrate into hot water, stir for 3 min, then quickly begin vacuum filtration, dry under vacuum at 50 °C. 13.31 g of product was obtained, with a yield of 93.3%.

[0076] Example 3 The preparation method of the 2,4,6-trisubstituted pyridylazaindole compound with the following structure includes the following steps: Equation (1-6) (1) Weigh 7.3075 g of 7-N-hexaindole-3-carboxaldehyde (0.05 mol), 17.3408 g of 4-nitroacetophenone (0.105 mol), and 96.35 g (1.25 mol) of ammonium acetate, add 80 ml of acetic acid and 140 ml of pyridine. Stir vigorously at 110 °C for 20 h. Filter the product while hot, collect the filter cake, wash with ethanol, and dry. Pour the filter cake into ethanol and stir vigorously at 82 °C for 1 h. After filtration, pour the filter cake into DMAC again and stir vigorously at 120 °C for 5 h. After filtration, wash with ethanol to obtain the filter cake, and dry to obtain a yellow product. 32.85 g, yield 75.1%.

[0077] (2) Weigh 10.5 g (24 mmol) of nitro reactant and 1.2 g of Pd / C (10%), add 50 ml of ethanol and 50 ml of DMAC, purge with nitrogen, stir at 50 °C for 10 min, add 22.5 g of ammonium formate, heat to 65 °C, and react for 24 h. Filter while hot, pour the filtrate into hot water, stir for 3 min, and then quickly begin vacuum filtration. After drying under vacuum at 50 °C, 8.72 g was obtained, with a yield of 96.3%.

[0078] Example 4 The preparation method of the 2,4,6-trisubstituted pyridylazaindole compound with the following structure includes the following steps: Equation (1-10) (1) Weigh 14.615 g of 7-N-hexaindole-3-carboxaldehyde (0.1 mol), 56.838 g (0.2 mol) of nitroamide ketone, and 138.636 g (1.8 mol) of ammonium acetate. Add 250 ml of pyridine and 100 ml of acetic acid, and react at 115 °C for 20 h. Filter the product while hot, collect the filter cake, wash with ethanol, and dry. Pour the filter cake into ethanol and stir vigorously at 82 °C for 1 h. Filter again and pour the filter cake into DMAC and stir vigorously at 120 °C for 5 h. Filter, wash with ethanol to obtain the filter cake, and dry to obtain a yellow product. 32.65 g, yield 48.4%.

[0079] (2) Weigh 15 g (22.22 mmol) of nitro reactant and 1.2 g of Pd / C (10%), add 100 ml of DMAC and 120 ml of ethanol, purge with nitrogen and stir at 50 °C for 10 min, add 22.5 g of ammonium formate, heat to 65 °C, and react for 24 h. Filter while hot, pour the filtrate into hot water, stir for 3 min, and then quickly begin vacuum filtration. After drying under vacuum at 50 °C, 12.96 g was obtained, with a yield of 95%.

[0080] The following are application examples of a single monomer: Application Example 1 Preparation of 3,3',4,4'-benzophenone tetracarboxylic dianhydride-4,4'-(4-(1H-indol-3-yl)pyridine-2,6-diyl)diphenylamine polyimide film.

[0081] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of 4,4'-(4-(1H-indol-3-yl)pyridin-2,6-diyl)diphenylamine from Example 1 and 8 mL of anhydrous DMAc were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was added in three portions, along with additional DMAc, to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0082] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BTDA-IPA.

[0083] Application Example 2 Preparation of 3,3',4,4'-benzophenone tetracarboxylic dianhydride-N,N'-((4-(1H-indol-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide)polyimide film.

[0084] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of N,N'-((4-(1H-indol-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide) from Example 2 and 8 mL of anhydrous DMAc were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was added in three portions, along with additional DMAc, to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0085] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BTDA-IPPA.

[0086] Application Example 3 Preparation of 3,3',4,4'-benzophenone tetracarboxylic dianhydride-4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine polyimide film.

[0087] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of 4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine from Example 3 and 8 mL of anhydrous DMAc were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was added in three portions, with additional DMAc added to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0088] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BTDA-PPA.

[0089] Application Example 4 Preparation of 3,3',4,4'-benzophenone tetracarboxylic dianhydride-N,N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide)polyimide film.

[0090] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of N, N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide) and 8 mL of anhydrous DMAc from Example 4 were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was added in three portions, with additional DMAc added to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0091] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BTDA-PPPA.

[0092] Application Example 5 Preparation of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride-4,4'-(4-(1H-indol-3-yl)pyridine-2,6-diyl)diphenylamine polyimide film.

[0093] S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of 4,4'-(4-(1H-indol-3-yl)pyridin-2,6-diyl)diphenylamine from Example 1 and 8 mL of anhydrous DMAc were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride (BPADA) was added in three portions, with additional DMAc added to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0094] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BPADA-IPA.

[0095] Application Example 6 Preparation of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride-N,N'-((4-(1H-indol-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide)polyimide film.

[0096] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of N,N'-((4-(1H-indol-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide) from Example 2 and 8 mL of anhydrous DMAc were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride (BPADA) was added in three portions, with additional DMAc added to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0097] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BPADA-IPPA.

[0098] Application Example 7 Preparation of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride-4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine polyimide film.

[0099] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of 4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine from Example 3 and 8 mL of anhydrous DMAc were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride (BPADA) was added in three portions, with additional DMAc added to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0100] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BPADA-PPA.

[0101] Application Example 8 Preparation of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride-N,N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide)polyimide film.

[0102] (S1) Under a nitrogen atmosphere and with magnetic stirring, 2 mmol of N, N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide) and 8 mL of anhydrous DMAc from Example 4 were added to a two-necked flask equipped with a magnetic stirrer. After complete dissolution, 2.02 mmol of 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride (BPADA) was added in three portions, with additional DMAc added to achieve a solid content of 15% by mass. The mixture was stirred continuously at room temperature for 24 h to obtain a PAA solution.

[0103] (S2) The PAA solution obtained in step (S1) is uniformly dispersed on the surface of a glass plate and dried at 80 °C for 1 h. Subsequently, these glass plates are placed in an oven and imidized by heating at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C and 320 °C for 0.5 h to obtain a polyimide film, denoted as BPADA-PPPA.

[0104] Results and Discussion: Figure 1This is the 1H NMR spectrum of 4,4'-(4-(1H-indol-3-yl)pyridine-2,6-diyl)diphenylamine, the product synthesized in the second step of Example 1. Figure 1 It can be seen that, 1 H NMR (600 MHz, DMSO) δ 11.67 (s, 1H), 8.16 (d, J = 2.6Hz, 1H), 8.06 (d, J = 6.9 Hz, 1H), 8.00 (d, J = 8.5 Hz, 4H), 7.85 (s, 2H), 7.52 (dd, J = 6.5, 2.0 Hz, 1H), 7.24 – 7.19 (m, 2H), 6.71 (d, J = 8.5 Hz, 4H), 5.41 s, 4H. The synthesized target product is consistent with the spectrum.

[0105] Figure 2 This is the mass spectrum of 4,4'-(4-(1H-indol-3-yl)pyridine-2,6-diyl)diphenylamine, the product synthesized in the second step of Example 1. Figure 2 It can be seen that the relative molecular mass of the synthesized target product is consistent with the spectrum.

[0106] Figure 3 This is the 1H NMR spectrum of the product synthesized in the second step of Example 2, N'-((4-(1H-indol-3-yl)pyridine-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide). Figure 3 It can be seen that, 1 H NMR (600 MHz, DMSO) δ11.78 (s, 1H), 9.98 (s, 2H), 8.31 (dd, J = 11.6, 5.6 Hz, 5H), 8.16 (d, J = 5.9Hz, 3H), 7.99 (d, J = 8.6 Hz, 4H), 7.80 (d, J = 8.5 Hz, 4H), 7.58 – 7.52 (m, 1H), 7.25 (p, J = 5.5 Hz, 2H), 6.65 (d, J = 8.5 Hz (4H), 5.81 (s, 4H). The synthesized target product is consistent with the spectrum.

[0107] Figure 4This is the mass spectrum of N,N'-((4-(1H-indol-3-yl)pyridine-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide), the product synthesized in the second step of Example 2. Figure 4 It can be seen that the relative molecular mass of the synthesized target product is consistent with the spectrum.

[0108] Figure 5 This is the 1H NMR spectrum of 4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine, the product synthesized in the second step of Example 3. Figure 5 It can be seen that, 1 H NMR (600 MHz, DMSO) δ 12.18 (s, 1H), 8.49 (d, J = 7.8 Hz, 1H), 8.43 – 8.25 (m, 2H), 8.15 – 7.71 (m, 6H), 7.26 (dd, J = 7.9,4.6 Hz, 1H), 6.71 (d, J = 8.5 Hz (4H), 5.41 (s, 4H). The synthesized target product is consistent with the spectrum.

[0109] Figure 6 This is the mass spectrum of 4,4'-(4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridine-2,6-diphenylamine, the product synthesized in the second step of Example 3. Figure 6 It can be seen that the relative molecular mass of the synthesized target product is consistent with the spectrum.

[0110] Figure 7 This is the 1H NMR spectrum of the product N, N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide), synthesized in the second step of Example 4. Figure 7 It can be seen that, 1 H NMR (600MHz, DMSO) δ 12.18 (s, 1H), 8.49 (d, J = 7.8 Hz, 1H), 8.43 – 8.25 (m, 2H), 8.15 – 7.71 (m, 6H), 7.26 (dd, J = 7.9, 4.6 Hz, 1H), 6.71 (d, J = 8.5 Hz, 4H), 5.41 s, 4H. The synthesized target product is consistent with the spectrum.

[0111] Figure 8This is the mass spectrum of the product N, N'-((4-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyridin-2,6-diyl)bis(4,1-phenylene))bis(4-aminobenzamide), synthesized in the second step of Example 4. Figure 8 It can be seen that the relative molecular mass of the synthesized target product is consistent with the spectrum.

[0112] The target product of the corresponding embodiment was successfully synthesized.

[0113] Figure 9 These are the infrared spectra of the polyimide films used in Examples 1-4. Figure 9 It can be seen that the amide bond characteristic peak of PAA disappears, and the carbonyl characteristic peak of the imine ring is at 1715 and 1775 cm⁻¹. -1 The presence of this indicates that PAA has been completely imidized to form polyimide.

[0114] Figure 10 These are the infrared spectra of the polyimide films used in Examples 5-8. Figure 10 It can be seen that the amide bond characteristic peak of PAA disappears, and the carbonyl characteristic peak of the imine ring is at 1715 and 1775 cm⁻¹. -1 The presence of this indicates that PAA has been completely imidized to form polyimide.

[0115] Figure 11 These are test graphs showing the mechanical properties of the polyimide films used in Examples 1-4. Figure 11 It can be seen that different monomers result in certain differences in the mechanical properties of the polyimide films prepared, but in general, all the prepared polyimide films have excellent mechanical properties.

[0116] Figure 12 These are mechanical property test diagrams for the polyimide films used in Examples 5-8. Figure 12 It can be seen that the prepared polyimide films all have excellent mechanical properties.

[0117] Figure 13 These are thermal performance test graphs of the polyimide films used in Examples 1-4. Figure 13 It can be seen that the prepared polyimide films all have excellent thermal properties.

[0118] Figure 14 These are thermal performance test graphs for the polyimide films used in Examples 5-8. (From...) Figure 14 It can be seen that the prepared polyimide films all have excellent thermal properties.

[0119] The following are examples of applications of direct surface metallization / patterning of the prepared polyimide films: Application Example 9 Complete metallization of the surface of polyimide films.

[0120] (S1) The films from Application Examples 1-8 were ultrasonically cleaned in ethanol, and a 10 mM / L H2PdCl2 solution and a 100 mM / L dimethylaminoborane (DMAB) solution were prepared.

[0121] (S2) The polyimide films of Examples 1-8, after cleaning in step (S1), are respectively immersed in the prepared H2PdCl2 solution. After 60 min, the films are removed, rinsed with deionized water, and dried with nitrogen. The films of Examples 1-8, after cleaning in step (S1), are respectively immersed in the prepared DMAB solution for reduction for 30 min, then the films are removed, rinsed with deionized water, and dried with nitrogen.

[0122] (S3) Copper plating solution preparation: Solution A consists of copper sulfate (0.052 mol / L), potassium sodium tartrate (0.077 mol / L), and sodium hydroxide (0.3 mol / L), while Solution B contains formaldehyde (0.33 mol / L). They are mixed at a volume ratio of 10:1 and deposited at 30 °C. Potassium sodium tartrate acts as a complexing agent, and formaldehyde acts as a reducing agent.

[0123] (S4) Nickel plating solution preparation: Solution A contains nickel sulfate hexahydrate (0.244 mol / L), sodium citrate (0.185 mol / L) and lactic acid (0.139 mol / L), and Solution B contains dimethylamine borane (0.170 mol / L). When using, mix them at a volume ratio of 4:1 and adjust the pH to about 8 with ammonia water. Deposition is carried out at 30 ℃. Sodium citrate is used as a complexing agent and dimethylamine borane is used as a reducing agent.

[0124] (S5) Cobalt plating solution preparation: Solution A consists of cobalt sulfate (0.05 mol / L), sodium hypophosphite (0.05 mol / L), sodium citrate (0.1 mol / L) and boric acid (0.05 mol / L), and Solution B is a sodium hydroxide (0.01 mol / L) solution. They are mixed in a volume ratio of 50:3 and deposited at 50 °C. Sodium citrate is used as a complexing agent and sodium hypophosphite is used as a reducing agent.

[0125] (S6) Preparation of silver plating solution: Chemical silver plating requires three solutions: Solution A is silver nitrate (0.29 mol / L), Solution B contains sodium hydroxide (0.0125 mol / L) and ammonia (8.2 ml / L), and Solution C is composed of DL-tartaric acid (0.267 mol / L), α-D-glucose (0.153 mol / L) and anhydrous ethanol (500 mL / L). When using, mix them in a volume ratio of 1:2:1 and react at 30℃. Glucose acts as a reducing agent to produce a silver mirror reaction.

[0126] (S7) The polyimide film reduced in step (S2) of Application Example 9 is immersed in the mixture of A and B in (S3)-(S5) above, and the mixture of A, B and C in (S6). The immersion time is adjusted according to the coating thickness requirements (generally 3-20 min). Finally, the substrate with the whole metal film is cleaned with deionized water and dried with nitrogen.

[0127] Application Example 10 Printed metal patterning on the surface of polyimide film.

[0128] (S1) The films from Examples 1-8 were ultrasonically cleaned in ethanol, and a 100 mM dimethylaminoborane (DMAB) solution was prepared. At the same time, a 10 mM / L H2PdCl2 solution was prepared. The H2PdCl2 solution was mixed with glycerol at a volume ratio of 3:1, and 1% wt sodium dodecyl sulfate was added. After dissolving, the solution was prepared as printing ink.

[0129] (S2) Load the printing ink from (S1) into the printer, place the cleaned films of Examples 1-8 into the printer, design the pattern, and print with H2PdCl2 ink. After printing, let the films stand for 60 minutes, wash them several times with deionized water, and then dry them with nitrogen. Immerse the films of Examples 1-8 in the prepared DMAB solution for 30 minutes to reduce them, remove the films, rinse them with deionized water, and then dry them with nitrogen.

[0130] (S3) Copper plating solution preparation: Solution A consists of copper sulfate (0.052 mol / L), potassium sodium tartrate (0.077 mol / L), and sodium hydroxide (0.3 mol / L), while Solution B contains formaldehyde (0.33 mol / L). They are mixed at a volume ratio of 10:1 and deposited at 30 °C. Potassium sodium tartrate acts as a complexing agent, and formaldehyde acts as a reducing agent.

[0131] (S4) Nickel plating solution preparation: Solution A contains nickel sulfate hexahydrate (0.244 mol / L), sodium citrate (0.185 mol / L) and lactic acid (0.139 mol / L), and Solution B contains dimethylamine borane (0.170 mol / L). When using, mix them at a volume ratio of 4:1 and adjust the pH to about 8 with ammonia water. Deposition is carried out at 30℃. Sodium citrate is used as a complexing agent and dimethylamine borane is used as a reducing agent.

[0132] (S5) Cobalt plating solution preparation: Solution A consists of cobalt sulfate (0.05 mol / L), sodium hypophosphite (0.05 mol / L), sodium citrate (0.1 mol / L) and boric acid (0.05 mol / L), and Solution B is a sodium hydroxide (0.01 mol / L) solution. They are mixed in a volume ratio of 50:3 and deposited at 50 °C. Sodium citrate is used as a complexing agent and sodium hypophosphite is used as a reducing agent.

[0133] (S6) Preparation of silver plating solution: Chemical silver plating requires three solutions: Solution A is silver nitrate (0.29 mol / L), Solution B contains sodium hydroxide (0.0125 mol / L) and ammonia (8.2 ml / L), and Solution C is composed of DL-tartaric acid (0.267 mol / L), α-D-glucose (0.153 mol / L) and anhydrous ethanol (500 mL / L). When using, mix them in a volume ratio of 1:2:1 and react at 30 ℃. Glucose acts as a reducing agent to produce the silver mirror reaction.

[0134] (S7) The polyimide film reduced in Application Example 10 (S2) is immersed in the mixture of A and B in (S3)-(S5) above, and the mixture of A, B and C in (S6). The immersion time is adjusted according to the coating thickness requirements (generally 3-20 min). Finally, the substrate with the patterned metal film is cleaned with deionized water and dried with nitrogen.

[0135] Application Example 11 Photolithographic metal patterning on the surface of polyimide thin film.

[0136] (S1) The films from Examples 1-8 were ultrasonically cleaned in ethanol, and a 100 mM dimethylaminoborane (DMAB) solution was prepared, along with a 10 mM / L H2PdCl2 solution.

[0137] (S2) The films of Examples 1-8, after cleaning as described in (S1), are photolithographically patterned according to the designed pattern. Then, the photolithographically patterned films of Examples 1-8 are immersed in the prepared H2PdCl2 solution. After 60 min, the films are removed, rinsed with deionized water, and dried with nitrogen. The films of Examples 1-8 are then immersed in the prepared DMAB solution for reduction for 30 min, removed, rinsed with deionized water, and dried with nitrogen.

[0138] (S3) Copper plating solution preparation: Solution A consists of copper sulfate (0.052 mol / L), potassium sodium tartrate (0.077 mol / L), and sodium hydroxide (0.3 mol / L), while Solution B contains formaldehyde (0.33 mol / L). They are mixed at a volume ratio of 10:1 and deposited at 30 °C. Potassium sodium tartrate acts as a complexing agent, and formaldehyde acts as a reducing agent.

[0139] (S4) Nickel plating solution preparation: Solution A contains nickel sulfate hexahydrate (0.244 mol / L), sodium citrate (0.185 mol / L) and lactic acid (0.139 mol / L), and Solution B contains dimethylamine borane (0.170 mol / L). When using, mix them at a volume ratio of 4:1 and adjust the pH to about 8 with ammonia water. Deposition is carried out at 30 ℃. Sodium citrate is used as a complexing agent and dimethylamine borane is used as a reducing agent.

[0140] (S5) Cobalt plating solution preparation: Solution A consists of cobalt sulfate (0.05 mol / L), sodium hypophosphite (0.05 mol / L), sodium citrate (0.1 mol / L) and boric acid (0.05 mol / L), and Solution B is a sodium hydroxide (0.01 mol / L) solution. They are mixed in a volume ratio of 50:3 and deposited at 50 °C. Sodium citrate is used as a complexing agent and sodium hypophosphite is used as a reducing agent.

[0141] (S6) Preparation of silver plating solution: Chemical silver plating requires three solutions: Solution A is silver nitrate (0.29 mol / L), Solution B contains sodium hydroxide (0.0125 mol / L) and ammonia (8.2 ml / L), and Solution C is composed of DL-tartaric acid (0.267 mol / L), α-D-glucose (0.153 mol / L) and anhydrous ethanol (500 mL / L). When using, mix them in a volume ratio of 1:2:1 and react at 30 ℃. Glucose acts as a reducing agent to produce the silver mirror reaction.

[0142] (S7) The polyimide film reduced in Application Example 11 (S2) is immersed in the mixture of A and B in (S3)-(S5) above, and the mixture of A, B and C in (S6). The immersion time is adjusted according to the coating thickness requirements (generally 3-20 min). Finally, the substrate with the patterned metal film is cleaned with deionized water and dried with nitrogen.

[0143] Patterned metal films were prepared from the polyimide films obtained in Application Examples 1 to 8 according to the methods in Application Examples 9 to 11, and their performance was characterized. Taking the patterned metal film obtained by copper and silver plating in Application Example 3 as an example, the characterization results are shown in the figure and analyzed as follows: Figure 15 Images show the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film in Application Example 3, after complete metallization. The immersion time was 4 min, and the coating thicknesses were 400 nm and 450 nm, respectively. Figure 15 It can be seen that there are no obvious defects in the copper and silver plating layers on the surface.

[0144] Figure 16These are SEM images of the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film in Application Example 3, where the film was fully metallized. Figure 16 It can be seen that both the copper and silver layers plated on the surface have obvious density.

[0145] Figure 17 This refers to the conductivity test of the contents (a) copper layer and (b) silver layer deposited on the fully metallized polyimide film surface in Example 3. Figure 17 It can be seen that both the copper and silver layers plated on the surface have good electrical conductivity.

[0146] Figure 18 This refers to the interfacial bonding strength test of the contents (a) copper layer and contents (b) silver layer deposited on the fully metallized polyimide film surface in Example 3. Figure 18 It can be seen that both the copper and silver layers on the surface have excellent adhesion.

[0147] Figure 19 This is a roughness test of the content (a) copper layer and content (b) silver layer deposited on the surface of the polyimide film with complete metallization as described in Example 3. Figure 19 It can be seen that the roughness of the copper and silver layers plated on the surface is about 10 nm.

[0148] Figure 20 Images of the printed content (a) copper layer and (b) silver layer on the surface of the polyimide film in Application Example 3, after printing. The immersion time was 4 min, and the coating thicknesses were 400 nm and 450 nm, respectively. Figure 20 It can be seen that there are no obvious defects in the copper and silver plating layers on the surface.

[0149] Figure 21 These are SEM images of the content (a) copper layer and content (b) silver layer deposited on the surface of the polyimide film after printing, as described in Application Example 3. Figure 21 It can be seen that both the copper and silver layers plated on the surface have obvious density.

[0150] Figure 22 This is an application example 3, testing the conductivity of the printed copper layer on the surface of the polyimide film, by... Figure 22 It can be seen that the copper layer plated on the surface has good conductivity.

[0151] Figure 23 This refers to the interfacial bonding strength test of the printed copper layer on the surface of the polyimide film in Example 3, conducted by... Figure 23 It can be seen that the copper plating layer on the surface has excellent adhesion.

[0152] Figure 24Images show the contents (a) copper layer and (b) silver layer deposited on the surface of the polyimide film after photolithography in Application Example 3. The immersion time was 4 min, and the coating thicknesses were 400 nm and 450 nm, respectively. Figure 24 It can be seen that there are no obvious defects in the copper and silver plating layers on the surface.

[0153] Figure 25 These are SEM and optical microscope images of the polyimide film surface after photolithography and copper plating in Application Example 3. The dimensions marked in the right image are [6] 10.51 μm, [2] 9.53 μm, [5] 10.45 μm, [1] 9.50 μm, [4] 10.64 μm, and [3] 9.58 μm, respectively. Figure 25 It can be seen that the copper layer plated on the surface has obvious density and has achieved the construction of fine metal patterns with line widths of less than 10μm.

[0154] Figure 26 The conductivity of the (a) copper layer and (b) silver layer deposited on the surface of the polyimide film after photolithography in Example 3 was tested. Figure 26 It can be seen that both the copper and silver layers plated on the surface have good electrical conductivity.

[0155] Figure 27 This refers to the interfacial bonding strength test of copper plating on the polyimide film surface after photolithography in Example 3. Figure 27 It can be seen that the copper plating layer on the surface has excellent adhesion.

[0156] from Figure 15 , Figure 20 and Figure 24 As can be seen, the embodiments of the present invention can realize the construction of metal patterns from the macroscopic scale to the micrometer-level fine structure, and from Figure 25 It can be seen that the linewidth of the metal pattern reaches less than 10μm; moreover, the thickness of the metal layer can be precisely controlled by adjusting the immersion time in step S7; from Figure 18 The interfacial bonding strength test shows that the embodiments of the present invention establish a strong interaction network between polyimide and metal layer through molecular-level coordination anchoring mechanism, which significantly improves the interfacial bonding strength (exceeding 4B or reaching 5B level), effectively solving the key technical problem of insufficient metal-polymer interfacial adhesion in traditional methods.

[0157] In the field of flexible electronic device manufacturing, traditional metallization processes face the dual challenges of substrate compatibility and processing precision. In existing technologies, physical vapor deposition (PVD) requires operation at temperatures above 300°C, severely limiting its application on heat-sensitive flexible substrates. It also suffers from insufficient metal-substrate interfacial bonding strength (typically below 3B grade). While existing research has improved the metal bonding performance of polyimide through surface modification, these methods often lead to a significant increase in surface roughness and limited patterning precision (linewidths generally greater than 50 μm), affecting the high-frequency transmission characteristics of devices and failing to meet the development requirements of high-density flexible circuits. This invention achieves direct metallization of polyimide film surfaces by introducing specific nitrogen heterocyclic structures into the polyimide molecular chain as metal coordination active sites. This allows for the fabrication of large-area metal layers and the realization of fine patterned structures, with controllable metal layer thickness, high interfacial bonding strength, and excellent conductivity. This method is simple, compatible with various patterning strategies, and effectively solves key technical challenges in traditional methods such as interfacial adhesion, process complexity, and substrate protection.

[0158] This invention specifically relates to a class of nitrogen-containing heterocyclic diamine compounds, their preparation methods, and applications. These nitrogen-containing heterocyclic diamine compounds can be directly used in the preparation of polyimide films. The nitrogen-containing heterocyclic structure possesses strong metal ion coordination ability, serving as active sites to achieve direct metallization of polyimide films without additional surface treatment. The method of this invention can prepare both large-size metal patterns and micron-level fine structures, with controllable metal layer thickness, strong adhesion, and excellent conductivity. This technology can be applied to optoelectronic fields such as flexible sensors, flexible detectors, flexible solar cells, flexible transparent electrodes, microelectronic packaging, aerospace equipment, medical implants, touch systems, and electromagnetic shielding. In summary, the polyimide films prepared in the embodiments of this invention, through the metal ion coordination provided by the nitrogen-containing heterocyclic structure, can achieve direct surface metallization patterns, suitable for multi-scale pattern preparation from large areas to microstructures. The thickness of the formed metal layer can be precisely controlled, exhibiting excellent bonding strength and conductivity. This technology has broad application prospects in flexible electronics, optoelectronic devices, microelectronic packaging, aerospace, medical implants, and electromagnetic shielding.

[0159] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A class of nitrogen-containing heterocyclic diamine compounds, characterized in that, Its general structural formula is shown in equation (1): Equation (1) Wherein, A is a nitrogen-containing heterocycle, selected from one of the following structures, and "*" indicates a connection point: B is a group containing an amino group, selected from one of the following structures, where "*" indicates a connection point: 。 2. The method for preparing the nitrogen-containing heterocyclic diamine compound according to claim 1, characterized in that, Includes the following steps: (1) Synthesis of 2,4,6-trisubstituted pyridylindole / azaindole compounds: or X1 is H or N, X2 is -NO2, or C is the reaction solvent, which is one or both of glacial acetic acid and pyridine; (2) Synthesis of 2,4,6-trisubstituted pyridylindole / azaindole diamine compounds: or X1 is H or N, X2 is -NO2, or X3 is -NH2, or D is the reaction solvent, which is one or both of ethanol and DMAC, and E is the reducing agent.

3. The preparation method according to claim 2, characterized in that, The reaction temperature in step (1) is 120-125℃ and the reaction time is 8-12h.

4. The preparation method according to claim 2, characterized in that, In step (2), the reaction temperature is 50-85℃ and the reaction time is 18-24h.

5. The preparation method according to claim 2, characterized in that, The reducing agent mentioned in step (3) is one of palladium on carbon / hydrazine hydrate, palladium on carbon / ammonium formate, or a combination of palladium on carbon / formic acid reducing agents.

6. The application of the nitrogen-containing heterocyclic diamine compound as described in claim 1, characterized in that, Used for the preparation of polyimide films; or for metallizing the surface of the prepared polyimide films.

7. The application as described in claim 6, characterized in that, The preparation of polyimide films includes the following steps: (S1) The diamine monomer is first dissolved in a solvent. After the diamine monomer is completely dissolved, the dianhydride monomer is added in multiple portions. The reaction is carried out at room temperature for 15-25 h to obtain a polyamic acid solution. The diamine monomer is the nitrogen-containing heterocyclic diamine compound as described in claim 1. (S2) The polyamic acid solution obtained in step (1) is dispersed on the substrate surface by spin coating, heated to evaporate the solvent in the polyamic acid solution, and heated further to cause the polyamic acid to undergo a dehydration cyclization reaction to obtain a polyimide film.

8. The application as described in claim 7, characterized in that, The dianhydride monomer in step (S1) is one or more of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride, 4,4'-oxobisphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, and 1,2,4,5-pyromellitic dianhydride; the solvent is N,N-dimethylacetamide and / or N-methylpyrrolidone.

9. The application as described in claim 7, characterized in that, The molar ratio of the diamine monomer, solvent, and dianhydride monomer in step (S1) is 1:(24-70):1.01.

Images