A sulfonated polyetherimide-polyetheramine copolymer, its preparation method and application

Abstract

This invention relates to the field of polymer compound technology, specifically disclosing a sulfonated polyetherimide-polyetheramine copolymer, its preparation method, and its applications. The invention uses sulfone-containing aromatic diamine, ether-containing aromatic dianhydride, and diamino-terminated polyetheramine as raw materials. A polyamic acid precursor is prepared through in-situ polycondensation, followed by stepwise thermal imidization to obtain a copolymer dielectric film. This film possesses a microscopic heterogeneous structure at the molecular level, consisting of a rigid imide matrix and flexible polyether nanodomains. This structure effectively expands the interchain spacing, inhibits the formation of charge-transfer complexes, and simultaneously introduces deep-level charge traps through the intrinsic nano-heterogeneous interface, hindering the jumping and conduction of charge carriers under high temperature and high electric field conditions. This synergistically reduces the dielectric loss of the material, improves the breakdown field strength, and enhances high-temperature energy storage efficiency. The flexible segments are covalently embedded in the polymer backbone, preventing component migration and precipitation, and ensuring the structural stability and performance reliability of the material during long-term service.

Description

Technical Field

[0001] This invention relates to the field of polymer compound technology, and in particular to a sulfonated polyetherimide-polyetheramine copolymer, its preparation method, and its application. Background Technology

[0002] With the rapid development of aerospace, new energy vehicles, and underground oil and gas exploration, there is an urgent need for high-performance energy storage devices that can operate stably in extreme environments such as high temperature, high pressure, and high frequency. Thin-film capacitors, as one of the core energy storage components, play an irreplaceable role in pulse power systems, power electronics, and new energy storage due to their advantages such as high power density, fast charging and discharging speed, and long cycle life. However, while the most widely used commercially available biaxially oriented polypropylene film has high breakdown strength and low dielectric loss, its dielectric constant is only 2.2, limiting its energy storage density. Furthermore, its maximum operating temperature is only 105℃, and its energy storage performance deteriorates sharply in high-temperature environments, making it difficult to meet the requirements of high-temperature applications.

[0003] Polyimides, as a class of high-performance polymers with an imide ring structure in their main chain, possess outstanding thermal stability, mechanical strength, and chemical resistance, and are widely recognized as highly promising high-temperature dielectric matrix materials. Among them, sulfonated polyetherimides, due to the introduction of sulfone groups and ether bonds into their molecular structure, possess certain polarity and dielectric response while maintaining high thermal stability, and are considered ideal candidate materials for high-temperature energy storage media. However, traditional sulfonated polyetherimide materials still face several performance bottlenecks in practical applications. First, the fully aromatic backbone tends to form strong intramolecular and intermolecular charge transfer complexes, resulting in a dielectric constant generally higher than 4.0 and a dielectric loss typically greater than 0.008. Under high temperature and high electric field conditions, polarization loss and conductivity loss increase sharply. Second, the dense molecular chain packing and limited free volume within the system make it easy for charge carriers to jump and conduct, resulting in a low breakdown strength, typically in the range of 350~400MV / m, which limits further improvement in energy storage density. Third, the leakage current of the material increases significantly under high temperature conditions, and the charge and discharge energy efficiency decreases sharply, failing to meet the application requirements of high temperature and high reliability.

[0004] To overcome the aforementioned shortcomings, existing technologies mainly employ the following three modification methods: First, introducing inorganic nanofillers such as boron nitride nanosheets and alumina into the polymer matrix to construct interfacial traps at the two-phase interface to suppress carrier migration; second, constructing a wide-bandgap dielectric layer on the film surface to block charge injection from the electrode side; and third, adjusting molecular polarity and band structure by introducing fluorine-containing groups and alicyclic structures through molecular structure design. However, these methods generally suffer from problems such as complex preparation processes, poor uniformity of nanofiller dispersion, poor interfacial compatibility, or easy sacrifice of the original flexibility and processing performance of the material, making it difficult to achieve synergistic optimization of comprehensive performance such as breakdown strength, dielectric loss, thermal stability, and processability.

[0005] It is worth noting that under high-temperature conditions, the dominant energy loss mechanism of polymer dielectrics gradually shifts from dipole polarization relaxation to bulk-confined hopping conduction of charge carriers. This process is directly regulated by the distribution of trap energy levels within the material and the carrier migration path. However, current conventional modification methods are insufficient to effectively control the transport behavior of charge carriers at high temperatures, failing to fundamentally alleviate the performance degradation of materials under high-temperature and high-electric-field conditions. Therefore, developing novel sulfonated polyetherimide dielectric materials that can effectively control the trap energy level distribution and improve carrier migration characteristics, so that the materials simultaneously possess low dielectric loss, high breakdown field strength, and high energy efficiency under high-temperature and high-field conditions, meeting the requirements of thin-film capacitors in extreme service environments, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] To address the problems of high dielectric loss and low breakdown field strength in existing sulfonated polyetherimide materials under high temperature and high electric field conditions, and the limited effectiveness of existing modification methods in regulating charge carrier hopping and conduction at high temperatures, this invention provides a sulfonated polyetherimide-polyetheramine copolymer, its preparation method, and its applications. This invention introduces flexible polyetheramine segments into the rigid sulfonated polyetherimide backbone via covalent bonds, constructing a microscopic heterostructure of a rigid matrix and flexible nanodomains. This allows for controllable expansion of the inter-molecular chain spacing, effectively suppressing the formation of charge transfer complexes and introducing deep-level interface traps. These improvements synergistically enhance the material's breakdown strength, reduce dielectric loss, and maintain excellent high-temperature energy storage stability.

[0007] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a sulfonated polyetherimide-polyetheramine copolymer, the structure of which is shown in formula (I): Equation (I) Ar1 is selected from or ; n≥30; m=50~100.

[0008] Compared with the prior art, the sulfonated polyetherimide-polyetheramine copolymer provided by the present invention introduces the diamino-terminated polyetheramine segments into the sulfonated polyetherimide backbone to construct a molecular structure with alternating rigid imide segments and flexible polyether segments, forming an intrinsic nano-heterogeneous interface inside the polymer, which significantly improves the dielectric energy storage performance and service stability of the material.

[0009] Among them, the polyetheramine segments have a large spatial volume, which can effectively increase the average distance between molecular chains, suppress the π-π stacking effect between aromatic rings, weaken the formation of intramolecular and intermolecular charge transfer complexes, and thus reduce the polarization loss of the material at high temperatures. Simultaneously, the ether oxygen atoms in the polyetheramine segments can act as proton acceptors, forming a rich intermolecular hydrogen bond network with the sulfone groups on the sulfonate polyetherimide backbone and the carbonyl groups in the imide rings. This introduces a large number of deep-level charge traps at the two-phase interface and inside the matrix, effectively capturing charge carriers excited under high temperature and high electric field conditions, suppressing the hopping conduction and migration processes of charge carriers, and achieving… The leakage current is reduced and the breakdown strength is improved. At the same time, the high flexibility of the polyetheramine segments can increase the free volume fraction of the system, which is beneficial to suppressing ion migration and space charge accumulation, so that the material maintains good flexibility and mechanical properties. In addition, the polyetheramine segments are chemically bonded to the polymer backbone, avoiding the problem of easy migration and precipitation of small molecule modifiers, ensuring the structural integrity and performance stability of the material during long-term high-temperature service. Ultimately, the material can simultaneously have low dielectric loss, high breakdown field strength and high energy efficiency under high temperature and high electric field conditions, which can meet the energy storage application requirements of thin film capacitors in extreme environments.

[0010] Secondly, the present invention also provides a method for preparing the above-mentioned sulfonated polyetherimide-polyetheramine copolymer, comprising the following steps: S1, the sulfone-containing aromatic diamine monomer shown in formula (a), the ether-containing aromatic dianhydride monomer shown in formula (b), and the diamino-terminated polyetheramine shown in formula (c) are subjected to a condensation reaction to obtain polyamic acid; S2, the polyamic acid is subjected to an imidization reaction to obtain the sulfonated polyetherimide-polyetheramine copolymer shown in formula (Ⅰ); (a) (b) (c) Ar1 is selected from or ; for or ; n≥30.

[0011] Compared with existing technologies, the method for preparing sulfonated polyetherimide-polyetheramine copolymers provided by this invention adopts an in-situ polycondensation combined with thermal imidization process. The condensation reaction of diamino-terminated polyetheramine with sulfone-containing aromatic diamine and ether-bonded aromatic dianhydride monomers is carried out simultaneously. The process steps are simple, and the reaction conditions are mild and controllable. The polyetheramine segments are covalently embedded in the polymer backbone, avoiding problems such as phase separation and uneven component dispersion that are common in physical blending systems. This achieves a uniform distribution of rigid imide segments and flexible polyether segments at the molecular level, ensuring the uniformity of the internal microscopic heterostructure and interface trap distribution of the material. Furthermore, this method uses a conventional thermal imidization process, requiring no complex equipment or special reagents. The raw materials are readily available, the preparation cost is low, and it is easy to achieve large-scale production. The prepared sulfonated polyetherimide-polyetheramine copolymer can achieve synergistic improvement in breakdown strength, dielectric loss reduction, and high-temperature energy storage stability.

[0012] In some specific embodiments of the present invention, the preparation method of the sulfonated polyetherimide-polyetheramine copolymer specifically includes the following steps: S1, add the sulfone-containing aromatic diamine monomer shown in formula (a) and the diamino-terminated polyetheramine shown in formula (c) to an organic solvent to obtain a mixed solution; add the ether-containing aromatic dianhydride monomer shown in formula (b) to the mixed solution to carry out a condensation reaction to obtain a polyamic acid solution; S2, the polyamic acid is subjected to an imidization reaction to obtain the sulfonated polyetherimide-polyetheramine copolymer shown in formula (Ⅰ).

[0013] Further, in S1, the molar ratio of the sulfone-containing aromatic diamine monomer to the ether-containing aromatic dianhydride monomer is 1:1 to 1:1.02.

[0014] Further, in S1, the molar ratio of the diamino-terminated polyetheramine to the sulfone-containing aromatic diamine monomer is 1:50 to 1:100.

[0015] By adopting the above molar ratio, the intrinsic rigidity and thermal stability of the sulfonated polyetherimide backbone can be preserved, while giving full play to the regulatory role of the flexible polyetherimide segments on the molecular chain stacking state and interface trap distribution, thereby achieving the effect of reducing dielectric loss and steadily improving breakdown strength. At the same time, it can avoid the decrease in heat resistance and mechanical properties of the material due to an excessively high proportion of flexible components, thus achieving a balance between energy storage performance and structural stability.

[0016] In some specific embodiments of the present invention, the sulfone-containing aromatic diamine monomer is selected from 4,4'-diaminodiphenyl sulfone or 4,4'-bis(4-aminophenoxy)diphenyl sulfone.

[0017] In some specific embodiments of the present invention, the ether-containing aromatic dianhydride monomer is selected from bisphenol A dianhydride or 4,4'-oxobisphthalic anhydride.

[0018] In some specific embodiments of the present invention, the diamino-terminated polyetheramine is a diamino-terminated D-2000 type polyetheramine, with Chemical Abstracts Service number 9046-10-0.

[0019] The D-2000 polyetheramine with diamino-terminated ends has a moderate chain length, which can effectively construct microscopic heterogeneous interfaces in the polymer matrix and introduce sufficient deep-level charge traps, resulting in a significant suppression effect on high-temperature charge carrier jumping and conduction. Its diamino-terminated reactivity is stable and controllable, allowing for uniform embedding into the sulfonated polyetherimide backbone and avoiding localized phase separation. Furthermore, D-2000 is liquid at room temperature, exhibiting good compatibility with the reaction system and enabling molecular-level homogeneous copolymerization. This avoids interfacial defects caused by uneven dispersion of inorganic fillers, facilitating the acquisition of homogeneous and highly reliable films.

[0020] Further, in S1, the organic solvent is N-methylpyrrolidone.

[0021] Further, in S1, the mass-to-volume ratio of the total mass of the solute to the volume of the solvent in the mixed solution is 0.7 g: (6~15) mL.

[0022] Further, in S1, after adding the sulfone-containing aromatic diamine monomer and the diamino-terminated polyetheramine to the organic solvent, the mixture is stirred at 0℃~5℃ for 8h~12h to obtain a mixed solution.

[0023] Furthermore, in S1, the temperature of the condensation reaction is 0℃~5℃, and the reaction time is 8h~12h.

[0024] Further, in S2, the specific steps of the imidization reaction are as follows: first, react at 60℃~80℃ for 2h~5h, then at 100℃~120℃ for 2h~5h, continue to heat to 150℃~180℃ for 2h~5h, then heat to 200℃~240℃ for 2h~5h, and finally heat to 280℃~300℃ for 1h~2h.

[0025] Thirdly, the present invention also provides a dielectric film comprising the above-described sulfonated polyetherimide-polyetheramine copolymer or a sulfonated polyetherimide-polyetheramine copolymer prepared by any of the above preparation methods.

[0026] Actual testing has shown that, compared to pure sulfonated polyetherimide films without the introduction of polyetheramine segments, the dielectric film provided by this invention exhibits significantly reduced dielectric loss and higher breakdown field strength within a temperature range of 25–150°C, especially in high-temperature environments above 120°C. This demonstrates that it effectively solves the problem of the rapid decline in energy storage capacity of traditional polymer dielectric films at high temperatures, making it an ideal high-temperature thin-film capacitor dielectric material with wide applications in aerospace, new energy vehicles, underground oil and gas exploration, and other fields.

[0027] Fourthly, the present invention also provides a method for preparing a dielectric thin film, comprising the following steps: S1, add the sulfone-containing aromatic diamine monomer shown in formula (a) and the diamino-terminated polyetheramine shown in formula (c) to an organic solvent to obtain a mixed solution; add the ether-containing aromatic dianhydride monomer shown in formula (b) to the mixed solution to carry out a condensation reaction to obtain a polyamic acid solution; (a) (b) (c) Ar1 is selected from or ; for or ; n≥30; S2, after casting the polyamic acid into a film on the substrate, an imidization reaction is carried out, and the film is peeled off from the substrate to obtain a dielectric film.

[0028] Further, in S1, the molar ratio of the sulfone-containing aromatic diamine monomer to the ether-containing aromatic dianhydride monomer is 1:1 to 1:1.02.

[0029] Further, in S1, the molar ratio of the diamino-terminated polyetheramine to the sulfone-containing aromatic diamine monomer is 1:50 to 1:100.

[0030] Further, in S1, the organic solvent is N-methylpyrrolidone.

[0031] Further, in S1, the mass-to-volume ratio of solute to solvent in the mixed solution is 0.7 g: (6~15) mL.

[0032] Furthermore, in S1, the temperature of the condensation reaction is 0℃~5℃, and the reaction time is 8h~12h.

[0033] Further, in S2, the specific steps of the imidization reaction are as follows: first, react at 60℃~80℃ for 2h~5h, then at 100℃~120℃ for 2h~5h, continue to heat to 150℃~180℃ for 2h~5h, then heat to 200℃~240℃ for 2h~5h, and finally heat to 280℃~300℃ for 1h~2h.

[0034] The imidization process employing a multi-stage stepped heating method allows the organic solvent in the system to gradually and steadily evaporate, avoiding morphological defects such as pinholes and warping in the film caused by rapid solvent escape. At the same time, the cyclization and ring-closing reaction of the amide acid is gradually promoted as the temperature gradient increases, ensuring sufficient imidization reaction and regular molecular chain structure. Ultimately, a copolymer film with a dense structure and uniform performance is obtained, effectively guaranteeing the material's breakdown stability and high-temperature service reliability.

[0035] As a preferred technical solution, the thickness of the dielectric film can be controllably adjusted within the range of 1μm to 50μm according to actual application requirements by adjusting the solid content of the solution or the film formation process. As a more specific example, to balance the energy storage density and mechanical flexibility of the capacitor, the film thickness is preferably 10μm to 20μm.

[0036] Fifthly, the present invention also provides an energy storage capacitor, comprising the dielectric thin film described above.

[0037] Specifically, the energy storage capacitor uses the sulfonated polyetherimide-polyetheramine copolymer dielectric film described above as the dielectric layer, and a conductive electrode is provided on at least one side of the dielectric layer. The conductive electrode can be a metal vapor-deposited layer, a metal foil layer, or a conductive coating, such as aluminum, zinc, silver, or their alloys, and the corresponding electrode material and thickness can be selected according to the actual application requirements.

[0038] The energy storage capacitor can be manufactured by winding or stacking the core, and after encapsulation and lead-out of terminals, the finished product is obtained. The manufacturing process is highly compatible with existing film capacitor production lines and does not require additional special equipment.

[0039] Because the copolymer dielectric film of this invention possesses low dielectric loss, high breakdown field strength, and high energy efficiency under high temperature and high electric field conditions, the energy storage capacitor prepared using this film can break through the operating temperature limit of traditional polypropylene film capacitors. It can maintain stable energy storage performance and operational reliability even in high-temperature environments above 120°C, exhibiting low leakage current, small capacity decay rate, and long cycle life at high temperatures. Furthermore, thanks to the synergistic improvement in material breakdown strength and dielectric properties, the volumetric energy density of this energy storage capacitor is significantly superior to that of conventional high-temperature polyimide film capacitors, enabling higher energy storage capacity within limited installation space and aligning with the trend towards miniaturization and lightweight equipment.

[0040] In summary, this invention provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film. Using sulfone-containing aromatic diamine, ether-bonded aromatic dianhydride, and diamino-terminated polyetheramine as raw materials, a polyamic acid precursor is prepared via in-situ polycondensation, followed by step-heat thermal imidization to obtain the copolymer dielectric film. This film possesses a microscopic heterostructure at the molecular level, consisting of a rigid imide matrix and flexible polyether nanodomains. This structure effectively expands the interchain spacing, inhibits the formation of charge transfer complexes, and introduces deep-level charge traps through intrinsic nano-heterogeneous interfaces, hindering the jumping and conduction of charge carriers under high temperature and high electric field conditions. This synergistically reduces dielectric loss, improves breakdown field strength, and enhances high-temperature energy storage efficiency. The flexible segments are covalently embedded in the polymer backbone, preventing component migration and precipitation, and ensuring the structural stability and performance reliability of the material during long-term service. The preparation process of this invention is simple and controllable, the raw materials are commercially mature, and it is easy to scale up production. The resulting dielectric film is suitable for high-temperature energy storage devices in aerospace, new energy vehicles, and underground oil and gas exploration, demonstrating promising engineering application prospects. Attached Figure Description

[0041] Figure 1 Comparison of breakdown field strengths of the dielectric thin films prepared in Examples 1 to 6; Figure 2 Comparison of the breakdown field strength of the dielectric thin films prepared in Comparative Examples 1 to 6; Figure 3 Thermogravimetric analysis (TGA) diagrams of the dielectric thin films prepared in Examples 1-3 and Comparative Example 1 are shown. Figure 4 Differential scanning calorimetry (DSC) images of the dielectric thin films prepared in Examples 1-3 and Comparative Example 1; Figure 5 This is a comparison chart of the discharge energy density and charge / discharge efficiency of the dielectric thin films prepared in Examples 1 to 6; Figure 6 The graph shows a comparison of the discharge energy density and charge / discharge efficiency of the dielectric thin films prepared in Comparative Examples 1 to 6. Figure 7 Comparison of dielectric losses of the dielectric films prepared in Examples 1 to 6; Figure 8 The graph shows a comparison of the dielectric losses of the dielectric films prepared in Comparative Examples 1 to 6. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] This invention provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film with the structure shown in formula (I), and the preparation method includes the following steps: S1, the sulfone-containing aromatic diamine monomer shown in formula (a) and the diamino-terminated polyetheramine shown in formula (c) are added to an organic solvent at a molar ratio of 50:1 to 100:1, with the total mass of solute to organic solvent ratio being 0.7 g: (6~15) mL. The mixture is stirred at 0℃ to 5℃ for 8h to 12h to obtain a mixed solution. The ether-containing aromatic dianhydride monomer shown in formula (b) is added to the mixed solution, with the molar ratio of the ether-containing aromatic dianhydride monomer to the sulfone-containing aromatic diamine monomer being 1:1 to 1.02:1. The mixture is stirred at 0℃ to 5℃ for 8h to 12h to obtain a polyamic acid solution. (a) (b) (c) Ar1 is selected from or ; for or ; n≥30; S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 60℃~80℃ for 2h~5h, then at 100℃~120℃ for 2h~5h, continuing to heat to 150℃~180℃ for 2h~5h, then at 200℃~240℃ for 2h~5h, and finally at 280℃~300℃ for 1h~2h. After cooling, the film is peeled off from the substrate to obtain a dielectric film with the structure shown in formula (I).

[0044] Equation (I) To better illustrate the present invention, further examples are provided below.

[0045] Example 1 This embodiment provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, the preparation method of which includes the following steps: S1, 4,4'-diaminodiphenyl sulfone and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 100:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 10 mL. The mixture is stirred at 0℃~5℃ for 10 h to obtain a mixed solution. Bisphenol A dianhydride is added to the mixed solution, with a molar ratio of bisphenol A dianhydride to 4,4'-diaminodiphenyl sulfone of 1.01:1. The mixture is stirred at 0℃~5℃ for 10 h to obtain a polyamic acid solution. S2, the polyamic acid is cast into a film on the substrate, and then the film is subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then heating to 220°C for 3 hours, and finally heating to 290°C for 1.5 hours. After cooling, it is peeled off from the substrate to obtain a dielectric film.

[0046] Example 2 This embodiment provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, the preparation method of which includes the following steps: S1, 4,4'-diaminodiphenyl sulfone and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 70:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 6 mL. The mixture is stirred at 0℃~5℃ for 8 h to obtain a mixed solution. Bisphenol A dianhydride is added to the mixed solution, with a molar ratio of bisphenol A dianhydride to 4,4'-diaminodiphenyl sulfone of 1.015:1. The mixture is stirred at 0℃~5℃ for 12 h to obtain a polyamic acid solution. S2, the polyamic acid is cast into a film on the substrate, and then the film is subjected to high-temperature imidization by heat treatment: reacting at 60°C for 5 hours, then at 100°C for 5 hours, continuing to heat to 150°C for 5 hours, then at 200°C for 5 hours, and finally at 280°C for 2 hours. After cooling, it is peeled off from the substrate to obtain a dielectric film.

[0047] Example 3 This embodiment provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, the preparation method of which includes the following steps: S1, 4,4'-diaminodiphenyl sulfone and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 50:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 15 mL. The mixture is stirred at 0℃~5℃ for 12 h to obtain a mixed solution. Bisphenol A dianhydride is added to the mixed solution, with a molar ratio of bisphenol A dianhydride to 4,4'-diaminodiphenyl sulfone of 1.02:1. The mixture is stirred at 0℃~5℃ for 8 h to obtain a polyamic acid solution. S2, the polyamic acid is cast into a film on the substrate, and then the film is subjected to high-temperature imidization by heat treatment: reacting at 80°C for 2 hours, then at 120°C for 2 hours, continuing to heat to 180°C for 2 hours, then heating to 240°C for 2 hours, and finally heating to 300°C for 1 hour. After cooling, it is peeled off from the substrate to obtain a dielectric film.

[0048] Example 4 This embodiment provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, the preparation method of which includes the following steps: S1, 4,4'-bis(4-aminophenoxy)diphenyl sulfone and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 100:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 12 mL. The mixture is stirred at 0℃~5℃ for 10 h to obtain a mixed solution. 4,4'-oxydiphthalic anhydride is added to the mixed solution, with the molar ratio of 4,4'-oxydiphthalic anhydride to 4,4'-bis(4-aminophenoxy)diphenyl sulfone being 1.01:1. The mixture is stirred at 0℃~5℃ for 12 h to obtain a polyamic acid solution. S2, the polyamic acid is cast into a film on the substrate, and then the film is subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then heating to 220°C for 3 hours, and finally heating to 290°C for 1.5 hours. After cooling, it is peeled off from the substrate to obtain a dielectric film.

[0049] Example 5 This embodiment provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, the preparation method of which includes the following steps: S1, 4,4'-bis(4-aminophenoxy)diphenyl sulfone and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 70:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 6 mL. The mixture is stirred at 0℃~5℃ for 12 h to obtain a mixed solution. 4,4'-oxybisphthalic anhydride is added to the mixed solution, with the molar ratio of 4,4'-oxybisphthalic anhydride to 4,4'-bis(4-aminophenoxy)diphenyl sulfone being 1.015:1. The mixture is stirred at 0℃~5℃ for 8 h~12 h to obtain a polyamic acid solution. S2, the polyamic acid is cast into a film on the substrate, and then the film is subjected to high-temperature imidization by heat treatment: reacting at 80°C for 2 hours, then at 120°C for 2 hours, continuing to heat to 180°C for 2 hours, then heating to 240°C for 2 hours, and finally heating to 300°C for 1 hour. After cooling, it is peeled off from the substrate to obtain a dielectric film.

[0050] Example 6 This embodiment provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, the preparation method of which includes the following steps: S1, 4,4'-bis(4-aminophenoxy)diphenyl sulfone and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 50:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7g:15mL. The mixture is stirred at 0℃~5℃ for 8h to obtain a mixed solution. 4,4'-oxybisphthalic anhydride is added to the mixed solution, with the molar ratio of 4,4'-oxybisphthalic anhydride to 4,4'-bis(4-aminophenoxy)diphenyl sulfone being 1:1. The mixture is stirred at 0℃~5℃ for 8h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: the polyamic acid is cast into a film on the substrate, and then the film is subjected to high-temperature imidization by heat treatment: the film is reacted at 60°C for 5 hours, then at 100°C for 5 hours, then at 150°C for 5 hours, then at 200°C for 5 hours, and finally at 280°C for 2 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0051] Comparative Example 1 This comparative example provides a sulfonated polyetherimide dielectric film, which differs from Example 1 only in that it does not contain the D-2000 type polyetherimide with diamino end-capping. The specific preparation method includes the following steps: S1, 4,4'-diaminodiphenyl sulfone and bisphenol A dianhydride were added to N-methylpyrrolidone at a molar ratio of 1:1.01, and the ratio of the total mass of solute to N-methylpyrrolidone was 0.7 g:10 mL. The mixture was stirred at 0℃~5℃ for 10 h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then at 220°C for 3 hours, and finally at 290°C for 1.5 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0052] Comparative Example 2 This comparative example provides a sulfonated polyetherimide dielectric film, which differs from Example 4 only in that it does not contain the D-2000 type polyetherimide with diamino end-capping. The specific preparation method includes the following steps: S1, 4,4'-bis(4-aminophenoxy)diphenyl sulfone and 4,4'-oxobisphthalic anhydride were added to N-methylpyrrolidone at a molar ratio of 1:1.01, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g:12 mL. The mixture was stirred at 0℃~5℃ for 12 h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then at 220°C for 3 hours, and finally at 290°C for 1.5 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0053] Comparative Example 3 This comparative example provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, which differs from Example 1 only in that the diamino-terminated D-2000 type polyetheramine is replaced with D-230 type polyetheramine. The specific preparation method includes the following steps: S1, 4,4'-diaminodiphenyl sulfone and D-230 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 100:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 10 mL. The mixture is stirred at 0℃~5℃ for 10 h to obtain a mixed solution. Bisphenol A dianhydride is added to the mixed solution, with the molar ratio of bisphenol A dianhydride to 4,4'-diaminodiphenyl sulfone being 1.01:1. The mixture is stirred at 0℃~5℃ for 10 h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then at 220°C for 3 hours, and finally at 290°C for 1.5 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0054] Comparative Example 4 This comparative example provides a sulfonated polyetherimide-polyetheramine copolymer dielectric film, which differs from Example 4 only in that the diamino-terminated D-2000 type polyetheramine is replaced with D-230 type polyetheramine. The specific preparation method includes the following steps: S1, 4,4'-bis(4-aminophenoxy)diphenyl sulfone and D-230 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 100:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 12 mL. The mixture is stirred at 0℃~5℃ for 10 h to obtain a mixed solution. 4,4'-oxybisphthalic anhydride is added to the mixed solution, with the molar ratio of 4,4'-oxybisphthalic anhydride to 4,4'-bis(4-aminophenoxy)diphenyl sulfone being 1.01:1. The mixture is stirred at 0℃~5℃ for 12 h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then at 220°C for 3 hours, and finally at 290°C for 1.5 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0055] Comparative Example 5 This comparative example provides a polyimide dielectric film, the preparation method of which includes the following steps: S1, p-phenylenediamine and pyromellitic dianhydride were added to N-methylpyrrolidone at a molar ratio of 1:1.01, with the total mass of solute to N-methylpyrrolidone being 0.7 g: 10 mL. The mixture was stirred at 0 °C to 5 °C for 10 h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then at 220°C for 3 hours, and finally at 290°C for 1.5 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0056] Comparative Example 6 This comparative example provides a dielectric thin film, the preparation method of which includes the following steps: S1, p-phenylenediamine and diamino-terminated D-2000 type polyetheramine are added to N-methylpyrrolidone at a molar ratio of 100:1, with the total mass of solute to N-methylpyrrolidone ratio being 0.7 g: 10 mL. The mixture is stirred at 0℃~5℃ for 10 h to obtain a mixed solution. Pyromellitic dianhydride is added to the mixed solution, with a molar ratio of pyromellitic dianhydride to p-phenylenediamine of 1.01:1. The mixture is stirred at 0℃~5℃ for 10 h to obtain a polyamic acid solution. S2, after casting the polyamic acid into a film on the substrate, the film is then subjected to high-temperature imidization by heat treatment: reacting at 70°C for 3 hours, then at 110°C for 3 hours, continuing to heat to 160°C for 3 hours, then at 220°C for 3 hours, and finally at 290°C for 1.5 hours. After cooling, the film is peeled off from the substrate to obtain a dielectric film.

[0057] Performance testing The films prepared in Examples 1-6 and Comparative Examples 1-6 were tested for breakdown field strength and high-temperature energy storage density at 150°C.

[0058] 1. Breakdown Field Strength Test The breakdown field strength of each group of thin film samples was characterized using a breakdown voltage tester. The testing equipment was a DDJ-50KV breakdown voltage tester from Beijing Guancheng Precision Instrument Equipment Co., Ltd. The test conditions were: DC electric field boost rate of 200V / s, using cylindrical electrodes with a diameter of 8mm, and the samples were immersed in silicone oil. The test samples were cut into 1cm×1cm square pieces, and 15 effective breakdown voltage values ​​were collected for each group of samples. The cumulative density function of a two-parameter Weibull distribution was used to statistically analyze the breakdown field strength data. The results are as follows: Figures 1-2 As shown in Table 1.

[0059] Experimental results show that, compared with Comparative Example 1, Examples 1-3, and Examples 4-6, compared with Comparative Example 2, all exhibited significantly improved characteristic breakdown field strengths after the introduction of diamino-terminated D-2000 polyetheramine. This is because the ether oxygen atoms in the diamino-terminated D-2000 polyetheramine segments can form a rich intermolecular hydrogen bond network with the sulfone groups (-SO2-) and imide ring carbonyl groups (C=O) on the sulfonated polyetherimide backbone. Due to the non-uniform spatial distribution of hydrogen bonds and the kinetic differences between the flexible polyetheramine segments and the rigid imide backbone, numerous deep-level charge traps can be formed at the two-phase interface and hydrogen bond network nodes. These traps effectively capture charge carriers excited under high temperature and high electric field, suppressing the migration and hopping conduction processes of charge carriers, thereby improving the breakdown strength of the film.

[0060] The test results of Comparative Examples 3 and 4 show that, compared with the introduction of low molecular weight and low flexibility D-230 type polyetheramine, the copolymer film with D-2000 type polyetheramine has higher breakdown strength. This indicates that long-chain flexible polyetheramine is more conducive to constructing effective microscopic heterostructures and deep-level trap systems in the system, and has a more significant effect on suppressing carrier transport.

[0061] The test results of Comparative Examples 5 and 6 show that the sulfonated polyetherimide matrix has a higher breakdown strength than the ordinary polyetherimide matrix. This is because the sulfonated polyetherimide molecule has higher polarity and better spatial structure characteristics. The ether bridging groups in the main chain and the sulfone itself can generate a steric hindrance effect, initially inhibiting the continuous migration of charges within the chain. Simultaneously, it can form a large number of deep-level charge traps within the system that can capture charge carriers, further improving the breakdown field strength of the material.

[0062] In summary, the synergistic effect of constructing a special polyetherimide structure and introducing D-2000 type polyetheramine through this invention significantly improves the breakdown strength.

[0063] 2. Thermal stability test Thermogravimetric analysis (TGA) figures of the dielectric thin films prepared in Examples 1-3 and Comparative Example 1 are shown below. Figure 3As shown, the test results indicate that the mass retention rate of all samples below 400℃ is close to 100%, demonstrating the good initial thermal stability of each material within this temperature range. The rapid thermal weight loss initiation temperatures of the sulfonated polyetherimide-polyetheramine copolymer films prepared in Examples 1 to 3 are similar to those of the pure sulfonated polyetherimide film prepared in Comparative Example 1. At the same temperature, the residual mass of each sample shows only slight differences, indicating that the introduction of polyetheramine segments does not significantly degrade the bulk thermal stability of the material and can maintain the original high-temperature resistance characteristics of the matrix material, meeting the heat resistance requirements of high-temperature service scenarios.

[0064] Differential scanning calorimetry (DSC) plots of the dielectric thin films prepared in Examples 1-3 and Comparative Example 1 are shown below. Figure 3 As shown, the test results indicate that the glass transition temperature of all film samples is above 200℃, demonstrating that the copolymer retains the inherent heat resistance of the sulfonated polyetherimide matrix after polyetheramine copolymerization modification. In summary, the introduction of flexible polyetheramine segments optimizes the film's flexibility and enhances its dielectric energy storage characteristics without compromising its thermal stability, enabling the resulting copolymer dielectric film to meet the application requirements of high-temperature capacitor dielectric materials.

[0065] 3. Energy storage density and charge / discharge efficiency Figure 5 , Figure 6 The results show the discharge energy density and charge / discharge efficiency of the dielectric thin film samples prepared in each embodiment and comparative example.

[0066] Energy storage performance testing employed a ferroelectric analyzer to obtain the hysteresis loop (DE curve) of the dielectric thin film. The testing equipment was a Huace FE-2000 ferroelectric analyzer. Samples were prepared as 1cm square pieces with a 6mm diameter conductive silver paste coated at the center as an electrode. Testing conditions included: the maximum test voltage was set to the breakdown field voltage corresponding to each sample, and the electric field boost rate was 200V / s. Cyclic performance testing was conducted at an electric field strength of 100kV / mm and a test frequency of 100Hz. Testing was performed at 150℃, with the samples immersed in silicone oil during the test. Charge-discharge response testing utilized an energy storage dielectric charge-discharge testing system, model Huace-DCS10KV. Sample specifications and electrode preparation were the same as above, the test electric field strength was set to 100kV / mm, and the test loop resistance was 10kΩ.

[0067] Test results show that the energy storage performance of sulfonated polyetherimide matrix films is superior to that of ordinary polyetherimide films; the copolymer films incorporating D-2000 type polyetherimide exhibit significantly higher discharge energy density and charge-discharge efficiency than the pure matrix films without polyetherimide. The mechanism of performance improvement lies in the fact that after the flexible D-2000 type polyetherimide segments are introduced into the polymer backbone, the system forms a nanoscale microphase separation structure, simultaneously constructing an intermolecular hydrogen bond network. On the one hand, the D-2000 type polyetherimide segments effectively expand the intermolecular distance of the rigid backbone through the space-filling effect, suppressing the π-π stacking of aromatic rings and the formation of charge transfer complexes, thus reducing polarization losses at high temperatures; on the other hand, the ether oxygen atoms on the polyetherimide chain interact with the sulfone groups and imide carbonyl groups of the sulfonated polyetherimide backbone to form a hydrogen bond network, introducing a large number of deep-level charge traps at the microphase interface, which can efficiently capture excited charge carriers under high temperature and high electric field conditions and suppress charge carrier jumping and conduction. The breakdown field strength of the thin film is significantly improved by the synergistic effect of steric hindrance suppression loss and hydrogen bond trap enhancement, and the dielectric loss over a wide temperature range is effectively suppressed, ultimately enhancing the energy storage performance of the material under both room temperature and high temperature conditions.

[0068] 4. Dielectric loss The dielectric loss of the dielectric thin film samples prepared in each embodiment and comparative example was tested using an impedance analyzer. The equipment used was a UCE Electronics UC710S. The sample requirements and test parameters were as follows: the sample was a square sample with a side length of 1 cm, and a conductive silver paste with a diameter of 6 mm was coated in the center of the sample as a sample electrode. The test was conducted at room temperature, and the test frequency range was 100 Hz to 1 MHz.

[0069] Test results show that the dielectric losses of Examples 1-6 are significantly lower than those of the corresponding comparative examples. Analysis suggests that the introduction of flexible polyetheramine segments effectively increases the inter-chain spacing, suppresses the formation of charge transfer complexes, and reduces dipole polarization loss. Simultaneously, the nano-heterojunction formed between the polyetheramine segments and the rigid matrix introduces deep-level traps, effectively suppressing the jumping conduction of charge carriers under high temperature and high electric field, thereby significantly reducing leakage conduction loss.

[0070] Table 1 The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sulfonated polyetherimide-polyetheramine copolymer, characterized in that, Its structure is shown in equation (Ⅰ): Equation (I) Ar1 is selected from or ; n≥30; m=50~100.

2. A method for preparing the sulfonated polyetherimide-polyetheramine copolymer according to claim 1, characterized in that, Includes the following steps: S1, the sulfone-containing aromatic diamine monomer shown in formula (a), the ether-containing aromatic dianhydride monomer shown in formula (b), and the diamino-terminated polyetheramine shown in formula (c) are subjected to a condensation reaction to obtain polyamic acid; S2, the polyamic acid is subjected to an imidization reaction to obtain the sulfonated polyetherimide-polyetheramine copolymer shown in formula (Ⅰ); (a) (b) (c) Ar1 is selected from or ; for or ; n≥30。 3. The method for preparing the sulfonated polyetherimide-polyetheramine copolymer as described in claim 2, characterized in that, Specifically, the steps include the following: S1, add the sulfone-containing aromatic diamine monomer shown in formula (a) and the diamino-terminated polyetheramine shown in formula (c) to an organic solvent to obtain a mixed solution; add the ether-containing aromatic dianhydride monomer shown in formula (b) to the mixed solution to carry out a condensation reaction to obtain a polyamic acid solution; S2, the polyamic acid is subjected to an imidization reaction to obtain the sulfonated polyetherimide-polyetheramine copolymer shown in formula (Ⅰ).

4. The method for preparing the sulfonated polyetherimide-polyetheramine copolymer as described in claim 2 or 3, characterized in that, In S1, the molar ratio of the sulfone-containing aromatic diamine monomer to the ether-containing aromatic dianhydride monomer is 1:1 to 1:1.

02.

5. The method for preparing the sulfonated polyetherimide-polyetheramine copolymer as described in claim 2 or 3, characterized in that, In S1, the molar ratio of the diamino-terminated polyetheramine to the sulfone-containing aromatic diamine monomer is 1:50 to 1:

100.

6. The method for preparing the sulfonated polyetherimide-polyetheramine copolymer as described in claim 3, characterized in that, In S1, the organic solvent is N-methylpyrrolidone; and / or In S1, the mass-to-volume ratio of the total solute to the solvent in the mixed solution is 0.7 g: (6~15) mL; and / or In S1, the condensation reaction is carried out at a temperature of 0°C to 5°C for a reaction time of 8 hours to 12 hours; and / or In S2, the specific steps of the imidization reaction are as follows: first, react at 60℃~80℃ for 2h~5h, then at 100℃~120℃ for 2h~5h, continue to heat to 150℃~180℃ for 2h~5h, then heat to 200℃~240℃ for 2h~5h, and finally heat to 280℃~300℃ for 1h~2h.

7. A dielectric thin film, characterized in that, Includes the sulfonated polyetherimide-polyetheramine copolymer of claim 1 or the sulfonated polyetherimide-polyetheramine copolymer prepared by the preparation method of any one of claims 2 to 6.

8. A method for preparing a dielectric thin film, characterized in that, Includes the following steps: S1, add the sulfone-containing aromatic diamine monomer shown in formula (a) and the diamino-terminated polyetheramine shown in formula (c) to an organic solvent to obtain a mixed solution; add the ether-containing aromatic dianhydride monomer shown in formula (b) to the mixed solution to carry out a condensation reaction to obtain a polyamic acid solution; (a) (b) (c) Ar1 is selected from or ; for or ; n≥30； S2, after casting the polyamic acid into a film on the substrate, an imidization reaction is carried out, and the film is peeled off from the substrate to obtain a dielectric film.

9. The method for preparing a dielectric thin film as described in claim 8, characterized in that, In S2, the thickness of the dielectric film is 10μm~20μm.

10. An energy storage capacitor, characterized in that, Includes the dielectric thin film as described in claim 7.

Images