Preparation method and application of a physical and chemical synergistically modified polyether sulfone composite dielectric film
By introducing polycarbonate and benzoyl into polyethersulfone films and combining them with ultraviolet irradiation, a stable three-dimensional molecular network was constructed, which solved the problems of aggregation and interfacial compatibility of inorganic nanofilled phases, improved the breakdown field strength and energy storage density of polyethersulfone films, and achieved stability and high-efficiency energy storage at high temperatures.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN UNIV OF SCI & TECH
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-02
AI Technical Summary
In existing technologies, inorganic nanofillers are prone to agglomeration, have poor compatibility with polymer matrices, and the pure blended matrix has a loose structure and insufficient high-temperature performance. This leads to increased leakage current and thermal breakdown failure of polyethersulfone films under strong electric field and high-temperature coupling environments, making it difficult to improve breakdown field strength and energy storage density.
Using polycarbonate and polyethersulfone resin as the matrix, benzoyl is added as a functional dopant phase. The modification is carried out by ultraviolet irradiation process to induce cross-linking of organic molecular chains, form a stable three-dimensional molecular network, eliminate interface defects, and enhance the uniform dispersion and structural stability of molecules.
It significantly improves the breakdown field strength and energy storage performance of composite films, reduces leakage current density, improves energy storage efficiency and mechanical properties at high temperatures, and extends the service life of dielectric films.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials and energy storage, specifically to a method for preparing and applying a polyethersulfone composite dielectric thin film modified by physical and chemical synergistic methods. Background Technology
[0002] As power electronic systems continue to evolve towards higher frequencies, higher power densities, and greater integration, polymeric thin-film capacitors, with their outstanding advantages such as high power density, fast charge and discharge response, and excellent self-healing properties, play a crucial role in pulse power storage, new energy vehicles, and power equipment. Polyethersulfone (PESU), as a high-performance engineering plastic, possesses both excellent thermal stability and superior mechanical properties, making it an ideal matrix material for preparing high-temperature dielectric energy storage materials. However, pure PESU films are highly susceptible to thermally assisted electron injection and carrier migration under strong electric fields and high-temperature coupling environments, leading to a sharp increase in leakage current. This not only significantly reduces energy storage efficiency but also easily triggers thermal breakdown failure. To improve dielectric energy storage performance, traditional modification strategies often employ inorganic nanoparticles as the filler phase. Although inorganic fillers can improve the dielectric constant and thermal conductivity to some extent, they are prone to aggregation in the polymer matrix. This non-uniform multiphase structure induces electric field distortion and physical defects at the interface, making it difficult to effectively suppress leakage current and instead becoming a weak point in electrical breakdown, thus limiting further improvement of the breakdown field strength. Therefore, how to overcome the interface defects introduced by traditional inorganic fillers while maintaining the excellent processing performance of polyethersulfone, effectively suppress charge transport, and simultaneously improve the breakdown field strength and energy storage density of the material has become a key scientific and technological problem that urgently needs to be solved in the field of high-performance high-temperature dielectrics. Summary of the Invention
[0003] The purpose of this invention is to solve the problems of easy agglomeration of inorganic nanofillers, poor interfacial compatibility with polymer matrix, loose structure of pure blend matrix, and insufficient high-temperature performance in the prior art, and to provide a method for preparing and applying a polyethersulfone composite dielectric film modified by physical and chemical synergy.
[0004] This invention uses polyethersulfone resin (PESU) as the matrix, polycarbonate (PC) as the blending modification phase, and benzoyl (Benzil) as the functional dopant phase to construct a Benzil-PC-PESU composite dielectric film. The composite film is then post-treated by ultraviolet irradiation with specific parameters to optimize the film's microstructure, enhance the stability and trapping ability of deep trap energy levels, significantly suppress the directional transport and migration of charge carriers, and significantly improve the breakdown field strength and energy storage performance of the composite film. Compared to traditional inorganic-organic composite systems, this invention employs a combination of all organic components. By utilizing the compatibility between organic molecules, it eliminates interfacial defects caused by inorganic fillers, ensuring that each component is uniformly dispersed at the molecular level within the PESU matrix. Crucially, the ultraviolet irradiation process can precisely control the surface and internal microstructure of the composite film, inducing appropriate cross-linking and orientation regularization of organic molecular chains. This further tightens the gaps between molecular chains, reduces the internal free volume, and enhances the internal density and structural stability of the matrix, avoiding performance degradation caused by excessive molecular chain movement at high temperatures. After ultraviolet irradiation modification, the composite film not only retains the excellent thermal stability, mechanical strength, and temperature resistance of polyethersulfone (PESU), but also possesses the flexibility of PC and the functional carrier regulation function of benzoyl, achieving a comprehensive improvement in energy storage density, charge-discharge efficiency, high-temperature stability, and mechanical properties.
[0005] A method for preparing a synergistically modified polyethersulfone composite dielectric film using physical and chemical methods involves using polycarbonate, polyethersulfone resin, and benzoyl as raw materials. By introducing an ultraviolet irradiation process, the photoinitiating properties of benzoyl are utilized to induce a photocrosslinking reaction between polycarbonate and polyethersulfone resin. Benzoyl molecules undergo α-cleavage, and the characteristic ketone bonds in the molecule gradually break, generating highly active benzoyl free radicals, providing sufficient active sites for subsequent crosslinking reactions. These free radicals further act on the benzene ring CH bonds adjacent to the sulfone group in the PESU molecular chain and the alkyl CH bonds adjacent to the carbonyl group in the PC molecular chain, causing homolytic cleavage of the CH bonds in both polymer chains to generate active free radicals. This leads to the formation of stable CC covalent crosslinking bonds between the PESU and PC molecular chains, constructing a stable three-dimensional molecular network.
[0006] This invention significantly improves the energy storage characteristics of PESU dielectric films by combining ultraviolet irradiation treatment with benzoyl and polycarbonate doping. Under ultraviolet irradiation, benzoyl enhances the mechanical strength and structural stability of the film through a "photolysis-active initiation-crosslinking" reaction, and improves the dispersion and interfacial bonding of PC in the matrix. It has applications in capacitors, converter valves, and inverters.
[0007] A method for preparing a polyethersulfone composite dielectric thin film with synergistic physical and chemical modification is specifically carried out according to the following steps:
[0008] 1. Dry the benzoyl, polycarbonate and polyethersulfone resins;
[0009] 2. Dissolve dried benzoyl in an organic solvent, then add dried polycarbonate and polyethersulfone resin, heat and stir to obtain a homogeneous precursor solution.
[0010] 3. Place the homogeneous precursor solution into a vacuum drying oven and let it stand to remove bubbles;
[0011] IV. A solution-coated precursor solution to remove air bubbles is applied to the surface of the substrate, followed by gradient drying, peeling, and drying to obtain a dense and smooth dielectric film.
[0012] 5. The dense and flat dielectric film is placed under a UV lamp for UV irradiation to obtain a polyethersulfone composite dielectric film with synergistic physical and chemical modification.
[0013] The beneficial effects of this invention are:
[0014] I. This invention employs a ternary organic component combination, utilizing the compatibility between organic molecules to eliminate interfacial defects caused by inorganic fillers, ensuring that each component achieves molecular-level uniform dispersion within the PESU matrix. By introducing ultraviolet (UV) irradiation, the photoinitiation properties of Benzil are fully utilized to induce photocrosslinking reactions between PC and PESU, enhancing interfacial constraints and overcoming the technical bottlenecks of easy aggregation and poor interfacial compatibility of traditional inorganic fillers, significantly improving the breakdown field strength of the composite film. Simultaneously, the UV irradiation process can precisely control the surface and internal microstructure of the composite film, inducing appropriate crosslinking and orientation regularization of organic molecular chains, further tightening the molecular chain gaps, reducing internal free volume, strengthening the internal compactness and structural stability of the matrix, and avoiding performance degradation caused by excessive molecular chain movement at high temperatures, thereby significantly improving the energy storage density and energy storage efficiency of the film. Compared with pure PESU dielectric films, UV-irradiated PESU ternary composite dielectric films exhibit higher energy storage and polarization performance and lower leakage current density at medium and high temperatures, providing key technical support and theoretical basis for the development of a new generation of high-performance, long-life high-temperature dielectric energy storage devices.
[0015] II. The PESU film prepared by this invention breaks down at a temperature of 150°C and an electric field of 300~370kV / mm, with the energy density dropping to 3.6J / cm². 3 The charge / discharge efficiency is approximately 34.75%, while the energy storage density of the 5-7B-10P-P thin film prepared in this invention is approximately 12.1 J / cm² at 680 kV / mm. 3The charge-discharge efficiency is 55.3%, which is 80% higher than that of pure PESU film. The breakdown field strength of pure PESU film at 150°C is about 354 kV / mm, while that of 5-7B-10P-P film prepared in this invention is about 688 kV / mm, which is 1.9 times higher than that of pure PESU film. The leakage current density of both pure PESU and xB-10P-P film at 150°C increases with the increase of electric field strength. Among them, PESU has the highest leakage current density, while the leakage current density of 5-7B-10P-P film prepared in this invention is the lowest and is always significantly lower than that of PESU throughout the entire electric field range.
[0016] Third, the preparation process and required equipment of this invention are inexpensive, and the experiment is simple and easy to implement; the physical and chemical synergistic modification of polyethersulfone composite dielectric film can effectively improve the energy storage performance of polymer at medium and high temperatures, and has broad application prospects. Attached Figure Description
[0017] Figure 1 FTIR spectra of Benzil, PC, PESU and xB-10P-P composite dielectric films;
[0018] Figure 2 Dielectric properties of PESU and xB-10P-P composite dielectric films;
[0019] Figure 3 Leakage current density of PESU and xB-10P-P composite dielectric film;
[0020] Figure 4 The breakdown field strength of the PESU and xB-10P-P composite dielectric film;
[0021] Figure 5 The energy storage performance of PESU and xB-10P-P composite dielectric films. Detailed Implementation
[0022] Specific Implementation Method 1: This implementation method is a physical and chemical synergistic modification method for preparing polyethersulfone composite dielectric films. It uses polycarbonate, polyethersulfone resin, and benzoyl as raw materials. By introducing an ultraviolet irradiation process, the photoinitiation properties of benzoyl are used to induce a photocrosslinking reaction between polycarbonate and polyethersulfone resin. Benzoyl molecules undergo α-cleavage reaction, and the characteristic ketone bonds in the molecules gradually break, generating highly active benzoyl free radicals, providing sufficient active sites for subsequent crosslinking reactions. These free radicals further act on the benzene ring CH bonds adjacent to the sulfone group in the PESU molecular chain and the alkyl CH bonds adjacent to the carbonyl group in the PC molecular chain, causing homolytic cleavage of the CH bonds in the two polymer molecular chains to generate active free radicals. This leads to the formation of stable CC covalent crosslinking bonds between the PESU and PC molecular chains, constructing a stable three-dimensional molecular network.
[0023] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that it involves a method for preparing a polyethersulfone composite dielectric film with synergistic physical and chemical modification, specifically completed according to the following steps:
[0024] 1. Dry the benzoyl, polycarbonate and polyethersulfone resins;
[0025] 2. Dissolve the dried benzoyl in an organic solvent, then add the dried polycarbonate and polyethersulfone resin, heat and stir to obtain a homogeneous precursor solution.
[0026] 3. Place the homogeneous precursor solution into a vacuum drying oven and let it stand to remove bubbles;
[0027] IV. A solution-coated precursor solution to remove air bubbles is applied to the surface of the substrate, followed by gradient drying, peeling, and drying to obtain a dense and smooth dielectric film.
[0028] 5. Place the dense and flat dielectric film under a UV lamp for UV irradiation to obtain a physically and chemically modified polyethersulfone composite dielectric film. Other steps are the same as in Specific Implementation Method 1.
[0029] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the molecular weight of the polycarbonate mentioned in step one is 26000 g / mol to 100000 g / mol; the molecular weight of the polyethersulfone resin is 10000 g / mol to 400000 g / mol; the drying in step one is vacuum drying, the vacuum drying temperature is 60℃ to 80℃, and the vacuum drying time is 8h to 10h. Other steps are the same as in Specific Implementation Method One or Two.
[0030] Specific Embodiment Four: This embodiment differs from Specific Embodiments One to Three in that: the organic solvent mentioned in step one is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; the method for dissolving the dried benzoyl in the organic solvent in step one is as follows: add the dried benzoyl to the organic solvent, stir magnetically at 40°C to 60°C for 1 to 2 hours, and then sonicate for 15 to 30 minutes. Other steps are the same as in Specific Embodiments One to Three.
[0031] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the heating and stirring temperature in step two is 60℃~80℃, and the time is 10h~12h; the concentration of the precursor solution in step two is 0.1g / mL~0.5g / mL. Other steps are the same as in Specific Implementation Methods One to Four.
[0032] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the mass ratio of polycarbonate to polyethersulfone resin in the precursor solution described in step two is (0~30):100; the mass of benzoyl in step two accounts for 0%~20% of the total mass of benzoyl, polycarbonate, and polyethersulfone resin. Other steps are the same as in Specific Implementation Methods One to Five.
[0033] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the vacuum degree of the vacuum drying oven mentioned in step three is -80 kPa, and the time for standing and defoaming is 2 to 4 hours; the substrate mentioned in step four is a clean glass plate. Other steps are the same as in Specific Implementation Methods One to Six.
[0034] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the gradient drying method described in step four is as follows: first, place the sample in a constant temperature oven and pre-dry it at 60℃~80℃ for 8h~12h, then transfer it to a vacuum drying oven and vacuum dry it at 80℃~120℃ for 4h~12h; the peeling method described in step four is as follows: immerse the glass plate in deionized water to peel the film off the glass plate. Other steps are the same as in Specific Implementation Methods One to Seven.
[0035] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the ultraviolet irradiation conditions described in step five are: ultraviolet wavelength of 220nm~380nm; ultraviolet irradiation time of 5min~30min; and the thickness of the physically and chemically synergistically modified polyethersulfone composite dielectric film described in step five is 5μm~30μm. Other steps are the same as in Specific Implementation Methods One to Eight.
[0036] Specific Implementation Method 10: This implementation method is an application of a physically and chemically synergistically modified polyethersulfone composite dielectric film in capacitors, converter valves, and inverters.
[0037] The beneficial effects of the present invention are verified using the following embodiments:
[0038] Example 1: A method for preparing a 5-5B-10P-P composite dielectric thin film, characterized in that the preparation method is specifically carried out according to the following steps:
[0039] 1. Dry benzoyl (Benzil), polycarbonate (PC) and polyethersulfone resin (PESU) at 60°C for 6 hours;
[0040] The polycarbonate mentioned in step one has a molecular weight of 45000 g / mol;
[0041] The polyethersulfone resin mentioned in step one has a molecular weight of 20000 g / mol;
[0042] 2. Add dried benzoyl to N-methyl-2-pyrrolidone (NMP), stir at 40°C for 1 h, then sonicate for 15 min to dissolve benzoyl in N-methyl-2-pyrrolidone. Then add dried polycarbonate and polyethersulfone resin, heat and stir at 60°C for 12 h to obtain a homogeneous precursor solution.
[0043] The mass ratio of polycarbonate to polyethersulfone resin in the precursor solution described in step two is 10:100.
[0044] The benzoin mentioned in step two accounts for 5% of the total mass of benzoin, polycarbonate, and polyethersulfone resin;
[0045] The concentration of the precursor solution mentioned in step two is 0.2 g / mL;
[0046] 3. Place the homogeneous precursor solution in a vacuum drying oven with a vacuum degree of -80kPa and let it stand for 2 hours to remove bubbles;
[0047] IV. A solution coating method is used to coat the surface of a clean glass plate with a precursor solution that removes air bubbles. Then, the plate is subjected to gradient drying. The glass plate is then placed in deionized water to peel the film off the glass plate. After drying, a dense and flat dielectric film is obtained.
[0048] The gradient drying process described in step four is as follows: first, place it in a constant temperature oven and pre-dry it at 60°C for 12 hours, then transfer it to a vacuum drying oven and vacuum dry it at 80°C for 4 hours, at 100°C for 4 hours, and at 120°C for 4 hours.
[0049] 5. Place the dense and flat dielectric film under a UV lamp for UV irradiation to obtain the xB-10P-P composite dielectric film (denoted as 5-5B-10P-P).
[0050] The conditions for ultraviolet irradiation in step five are: energy intensity of 100%, ultraviolet wavelength of 254nm, and ultraviolet irradiation time of 5min.
[0051] The thickness of the physically and chemically modified polyethersulfone composite dielectric film described in step five is 11 μm.
[0052] Example 2: The difference between this example and Example 1 is that the ultraviolet irradiation time in step five is 10 minutes; the xB-10P-P composite dielectric film obtained in step five is denoted as 10-5B-10P-P. Other steps and parameters are the same as in Example 1.
[0053] Example 3: The difference between this example and Example 1 is that the ultraviolet irradiation time in step five is 15 minutes; the xB-10P-P composite dielectric film obtained in step five is denoted as 15-5B-10P-P. Other steps and parameters are the same as in Example 1.
[0054] Example 4: The difference between this example and Example 1 is that the mass of benzoyl in step two accounts for 7% of the total mass of benzoyl, polycarbonate and polyethersulfone resin; the xB-10P-P composite dielectric film obtained in step five is designated as 5-7B-10P-P. Other steps and parameters are the same as in Example 1.
[0055] Example 5: The difference between this example and Example 4 is that the ultraviolet irradiation time in step five is 10 min; the xB-10P-P composite dielectric film obtained in step five is denoted as 10-7B-10P-P. Other steps and parameters are the same as in Example 4.
[0056] Example 6: The difference between this example and Example 4 is that the ultraviolet irradiation time in step five is 15 minutes; the xB-10P-P composite dielectric film obtained in step five is denoted as 15-7B-10P-P. Other steps and parameters are the same as in Example 4.
[0057] Comparative Example 1: A method for preparing a PESU dielectric thin film, characterized in that the preparation method is specifically carried out according to the following steps:
[0058] 1. Dry the polyethersulfone resin (PESU) at 60°C for 6 hours;
[0059] The polyethersulfone resin mentioned in step one has a molecular weight of 20000 g / mol;
[0060] 2. Add the dried polyethersulfone resin (PESU) to N-methyl-2-pyrrolidone and heat and stir at 60°C for 12 hours to obtain a homogeneous precursor solution.
[0061] The concentration of the precursor solution mentioned in step two is 0.2 g / mL;
[0062] 3. Place the homogeneous precursor solution in a vacuum drying oven with a vacuum degree of -80kPa and let it stand for 2 hours to remove bubbles;
[0063] IV. A solution-coated precursor solution for removing air bubbles is coated onto the surface of a clean glass plate using a solution coating method. The plate is then subjected to gradient drying. The glass plate is then immersed in deionized water to allow the film to peel off from the glass plate. After drying, a PESU dielectric film (denoted as PESU) is obtained.
[0064] The gradient drying process described in step four is as follows: first, place it in a constant temperature oven and pre-dry it at 60°C for 12 hours, then transfer it to a vacuum drying oven and vacuum dry it at 80°C for 4 hours, at 100°C for 4 hours, and at 120°C for 4 hours.
[0065] The thickness of the PESU dielectric film mentioned in step four is 11 μm.
[0066] Figure 1 FTIR spectra of Benzil, PC, PESU and xB-10P-P composite dielectric films;
[0067] The two sets of FTIR spectra shown in Figure a and b characterize the chemical structure evolution of benzoyl (Benzil) doping in the Benzoyl-PC-PESU composite dielectric films under different UV irradiation times when the doping concentration is 7 wt.% and 5 wt.%. All composite films completely retain PESU (1582 cm⁻¹). -1 1485cm -1 The peak of the benzene ring stretching vibration is at 1150 cm⁻¹. -1 1322cm -1 sulfone characteristic peak), PC (1777 cm⁻¹) -1 carbonyl stretching vibration peak), Benzil (1670 cm⁻¹) -1 The intrinsic characteristic peak of the ketone group (without significant shift in position) was observed; as the UV irradiation time increased from 5 min to 15 min, the peak position at 1670 cm⁻¹ remained unchanged. -1 The intensity of the ketone characteristic peak of Benzil showed a continuous decreasing trend, confirming that Benzil, as a photoinitiator, underwent α-cleavage and was gradually consumed during irradiation; at the same irradiation time, the 1670 cm⁻¹ intensity of the 7 wt.% series was also observed. -1The peak intensity was significantly higher than that of the 5wt.% series, verifying the effectiveness of this peak position in characterizing changes in physical irradiation and chemical composition, and providing a chemical structural basis for optimizing the ultraviolet irradiation modification process of this composite dielectric film.
[0068] Figure 2 Dielectric properties of PESU and xB-10P-P composite dielectric films;
[0069] like Figure 2 As shown, at 150℃, 50-10 6 Within the Hz frequency range, pure PESU and PESU composite dielectrics with different irradiation times and filler contents all exhibited relatively stable frequency response characteristics. Pure PESU showed more significant fluctuations at high temperatures, while the composite system showed relatively gentler changes. Dielectric loss increased significantly in the low-frequency region but remained at a low level in the mid-to-high-frequency region. The 7wt.%Benzil system performed better, especially the 5-7B-10P-P sample, whose loss remained at approximately 0.01.
[0070] Figure 3 Leakage current density of PESU and xB-10P-P composite dielectric film;
[0071] like Figure 3 As shown, under 150℃ conditions, the leakage current density of each sample increases with increasing electric field strength, and the overall value is around 10. -11 -10 -7 A / cm 2 Within the specified range, typical field-induced conductivity behavior was observed. Compared to pure PESU, the leakage current of the multi-component composite system was significantly reduced, indicating that the introduction of Benzil and PC, along with UV irradiation modification, effectively suppressed carrier migration. Under the same UV irradiation time, the leakage current of the 7wt.% Benzil system was generally lower than that of the 5wt.% system; furthermore, within the 7wt.% Benzil system, the sample irradiated for 5 minutes exhibited the lowest leakage current, demonstrating superior insulation performance. This suggests that appropriately increasing the Benzil content and optimizing the irradiation time enhances the degree of cross-linking and interfacial bonding, thereby reducing charge transport channels and suppressing conductivity.
[0072] Figure 4 The breakdown field strength of the PESU and xB-10P-P composite dielectric film;
[0073] As shown in the figure, under 150℃ conditions, the E of 5-7B-10P-P bThe breakdown strength is 688 kV / mm, approximately 1.9 times that of pure PESU (354 kV / mm), and the β value (16.81) is far superior to that of the pure matrix. This significant performance improvement is mainly attributed to the deep optimization of the microstructure: on the one hand, 7 wt.% Benzil doping in the system constructs a high-density deep-trap network, effectively capturing thermally excited charge carriers at high temperatures using its strongly electronegative functional groups, thereby suppressing conductivity loss and thermal breakdown; on the other hand, 5 min of ultraviolet irradiation induces a full photochemical reaction in Benzil, promoting the formation of a dense three-dimensional cross-linked network between PC and PESU chains. This cross-linked structure not only significantly reduces the internal free volume but also locks the long-range thermal motion of polymer molecular chains, effectively suppressing the occurrence of electron avalanche effects. The 5-7B-10P-P system, through the synergistic effect of deep-trap trapping and photoinduced cross-linking, ensures that the material has high breakdown strength and reliability over a wide temperature range.
[0074] Figure 5 Energy storage performance of PESU and xB-10P-P composite dielectric films;
[0075] like Figure 5 As shown, at 150℃, the U of each sample e The polarization response gradually increases with increasing electric field strength, exhibiting good polarization response characteristics. Pure PESU breaks down under electric fields of 200-340 kV / mm. e Reduced to 3.6 J / cm 3 In contrast, the composite system modified by ultraviolet irradiation can still withstand higher electric fields. In the 7wt.%Benzil system, 5-7B-10P-P can still maintain stable output above 600kV / mm, and its U e It can reach 12.1 J / cm 3 η remains above 55.3%, an 80% increase compared to pure PESU. Compared to pure PESU, its U at high temperatures... e The improvement is approximately 1.5-3 times. This indicates that the UV-induced cross-linking structure can enhance interfacial bonding and restrict segment thermal motion, thereby improving the material's breakdown strength and energy storage stability under high-temperature electric fields.
Claims
1. A method for preparing a polyethersulfone composite dielectric thin film with synergistic physical and chemical modification, characterized in that... The preparation method uses polycarbonate, polyethersulfone resin, and benzoyl as raw materials. By introducing ultraviolet irradiation, the photoinitiating properties of benzoyl are used to induce a photocrosslinking reaction between polycarbonate and polyethersulfone resin. Benzil molecules undergo α-cleavage, and the characteristic ketone bonds in the molecule gradually break, generating highly active benzoyl free radicals, providing sufficient active sites for subsequent crosslinking reactions. These free radicals further act on the benzene ring CH bonds adjacent to the sulfone group in the PESU molecular chain and the alkyl CH bonds adjacent to the carbonyl group in the PC molecular chain, causing homolytic cleavage of the CH bonds in both polymer chains to generate active free radicals. This leads to the formation of stable CC covalent crosslinking bonds between the PESU and PC molecular chains, constructing a stable three-dimensional molecular network.
2. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The preparation method is specifically carried out according to the following steps:
1. Dry the benzoyl, polycarbonate and polyethersulfone resins; 2. Dissolve dried benzoyl in an organic solvent, then add dried polycarbonate and polyethersulfone resin, heat and stir to obtain a homogeneous precursor solution.
3. Place the homogeneous precursor solution into a vacuum drying oven and let it stand to remove bubbles; IV. A solution-coated precursor solution to remove air bubbles is applied to the surface of the substrate, followed by gradient drying, peeling, and drying to obtain a dense and smooth dielectric film.
5. The dense and flat dielectric film is placed under a UV lamp for UV irradiation to obtain a polyethersulfone composite dielectric film with synergistic physical and chemical modification.
3. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The polycarbonate mentioned in step one has a molecular weight of 26,000 g / mol to 100,000 g / mol; the polyethersulfone resin has a molecular weight of 10,000 g / mol to 400,000 g / mol; the drying mentioned in step one is vacuum drying, the vacuum drying temperature is 60℃ to 80℃, and the vacuum drying time is 8h to 10h.
4. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The organic solvent mentioned in step one is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; the method for dissolving the dried benzoyl in the organic solvent in step one is as follows: add the dried benzoyl to the organic solvent, stir magnetically at 40°C to 60°C for 1 to 2 hours, and then sonicate for 15 to 30 minutes.
5. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The heating and stirring temperature in step two is 60℃~80℃, and the time is 10h~12h; the concentration of the precursor solution in step two is 0.1g / mL~0.5g / mL.
6. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... In step two, the mass ratio of polycarbonate to polyethersulfone resin in the precursor solution is (0~30):100; the mass of benzoyl in step two accounts for 0%~20% of the total mass of benzoyl, polycarbonate and polyethersulfone resin.
7. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The vacuum degree of the vacuum drying oven mentioned in step three is -80kPa, and the time for standing and defoaming is 2h~4h; the substrate mentioned in step four is a clean glass plate.
8. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The gradient drying process described in step four is as follows: first, place the glass plate in a constant temperature oven and pre-dry it at 60℃~80℃ for 8h~12h, then transfer it to a vacuum drying oven and vacuum dry it at 80℃~120℃ for 4h~12h; the peeling process described in step four is as follows: place the glass plate in deionized water to peel the film off the glass plate.
9. The method for preparing a physically and chemically synergistically modified polyethersulfone composite dielectric thin film according to claim 1, characterized in that... The conditions for ultraviolet irradiation in step five are: ultraviolet wavelength of 220nm~380nm; ultraviolet irradiation time of 5min~30min; and the thickness of the polyethersulfone composite dielectric film modified by physical and chemical synergy in step five is 5μm~30μm.
10. The application of the physically and chemically synergistically modified polyethersulfone composite dielectric film as described in claim 1, characterized in that... A physically and chemically synergistically modified polyethersulfone composite dielectric film is used in capacitors, converter valves, and inverters.