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CN-121991345-A - Polyimide dielectric film containing carboxyl betaine and preparation method thereof

CN121991345ACN 121991345 ACN121991345 ACN 121991345ACN-121991345-A

Abstract

The invention discloses a polyimide dielectric film containing carboxyl betaine and a preparation method thereof. The dielectric film of the polyimide containing the carboxyl betaine is prepared from polyimide containing the carboxyl betaine, and the polyimide containing the carboxyl betaine is prepared by taking a precursor of the carboxyl betaine, m-phenylenediamine and bisphenol a type diether dianhydride as monomers, performing polycondensation reaction to obtain polyamic acid, completely imidizing the polyamic acid under the action of isoquinoline catalyst to obtain polyimide containing the precursor, and reacting the polyimide containing the precursor with sodium bromoacetate to obtain the polyimide containing the carboxyl betaine. The invention improves the dielectric and energy storage properties of the polyimide dielectric film by introducing the zwitterion into the polyimide structure, and simultaneously has the advantages of low cost, simple process, controllable and adjustable properties, suitability for large-scale application and the like.

Inventors

  • YE HUIJIAN
  • REN BAILIN
  • XU LIXIN

Assignees

  • 浙江工业大学
  • 平湖市浙江工业大学新材料研究院

Dates

Publication Date
20260508
Application Date
20260121

Claims (10)

  1. 1. A polyimide dielectric film containing carboxyl betaine is characterized in that the polyimide dielectric film containing carboxyl betaine is prepared from a polyimide containing carboxyl betaine, and the polyimide containing carboxyl betaine is prepared by taking a precursor of carboxyl betaine, metaphenylene diamine and bisphenol a type diether dianhydride as monomers, wherein the ratio of the total molar quantity of the precursor of carboxyl betaine to the molar quantity of the metaphenylene diamine to the molar quantity of bisphenol a type diether dianhydride is 1:1, the molar quantity of the precursor of carboxyl betaine accounts for 1-10 percent of the total molar quantity of the precursor of carboxyl betaine and metaphenylene diamine, a reaction solution with the solid content of 10-12 percent is prepared, and polyamide acid is obtained through polycondensation reaction; The precursor of the carboxyl betaine is 2- (4-aminophenyl) -5-aminobenzimidazole, and the structure is shown as follows: the structure of the bisphenol a type diether dianhydride is shown as follows: 。
  2. 2. the polyimide dielectric film containing carboxybetaine according to claim 1, wherein the molar amount of the precursor of carboxybetaine is 2 to 5%, preferably 5%, based on the total molar amount of the precursor of carboxybetaine and m-phenylenediamine.
  3. 3. The polyimide dielectric film containing carboxybetaine according to claim 1 or 2, wherein the solvent of the reaction liquid of the polycondensation reaction is anhydrous NMP, and the polycondensation reaction is carried out at a reaction temperature of 0 to 10 ℃ for 18 to 30 hours, preferably 24 hours.
  4. 4. The polyimide dielectric film containing carboxybetaine according to claim 1 or 2, wherein the feed ratio of the precursor-containing polyimide to sodium bromoacetate is 1:4 to 6, preferably 1:4, based on the molar ratio of the precursor unit to sodium bromoacetate.
  5. 5. A process for the preparation of a polyimide dielectric film containing carboxybetaine as defined in any one of claims 1 to 4, comprising the steps of: Taking a precursor of carboxyl betaine, m-phenylenediamine and bisphenol a type diether dianhydride as monomers, wherein the ratio of the total molar quantity of the precursor of carboxyl betaine to the m-phenylenediamine to the molar quantity of bisphenol a type diether dianhydride is 1:1, the molar quantity of the precursor of carboxyl betaine accounts for 1-10% of the total molar quantity of the precursor of carboxyl betaine and the m-phenylenediamine, preparing a reaction solution with the solid content of 10-12%, and carrying out polycondensation reaction to obtain polyamide acid; step 2, the polyamide acid obtained in the step 1 is fully imidized under the action of isoquinoline catalyst to obtain polyimide containing a precursor; Step 3, reacting polyimide containing a precursor with sodium bromoacetate to obtain polyimide containing carboxyl betaine, wherein the added molar quantity of the sodium bromoacetate is 3-6 times of the molar quantity of a precursor unit contained in the polyimide containing the precursor; and 4, preparing the polyimide dielectric film containing the carboxyl betaine by using the polyimide containing the carboxyl betaine obtained in the step 3 through a solution film forming method.
  6. 6. The method of claim 5, wherein the step 2 is performed as follows: And (3) dropwise adding isoquinoline serving as a catalyst into the reaction solution containing polyamide acid obtained in the step (1) of polycondensation reaction, fully and uniformly stirring, controlling the temperature to be 160-200 ℃ for reaction for 6-24 hours, and separating and purifying after the reaction is finished to obtain polyimide powder containing a precursor.
  7. 7. The method of claim 5, wherein the step 3 is performed as follows: Adding a water-free solvent and polyimide containing a precursor into a reaction container under the protection of nitrogen atmosphere, fully stirring to completely dissolve the polyimide to obtain a polyimide solution containing the precursor, then dropwise adding a sodium bromoacetate solution, controlling the temperature to be 80-90 ℃ for reaction for 24-72h, and separating and purifying after the reaction is finished to obtain polyimide powder containing carboxyl betaine.
  8. 8. The method according to claim 7, wherein in step 3, the anhydrous solvent is anhydrous NMP or anhydrous DMSO so that the solid content of the polyimide solution containing the precursor is 5 to 8wt%.
  9. 9. The method according to claim 7, wherein in the step3, the solvent of the sodium bromoacetate solution is anhydrous DMSO having a solid content of 1-2wt%.
  10. 10. The method according to claim 9, wherein in the step 3, the reaction temperature is 85 ℃ and the reaction time is 24-72 hours.

Description

Polyimide dielectric film containing carboxyl betaine and preparation method thereof Technical Field The invention relates to a polyimide dielectric film containing carboxyl betaine and a preparation method thereof. Background Dielectric capacitors are one of the most widely used components in electrical and electronic systems, and their body is spread over many fields such as energy storage, pulse power systems, power conditioning devices, and even power factor correction devices. Polymeric capacitors are widely used in capacitor applications due to their low cost, high breakdown strength, and unique self-healing capabilities. Achieving both high energy density and low dielectric loss is a great challenge for polymer films. Among the existing polymer dielectrics, either non-ferroelectric dielectric polymers have low energy densities or ferroelectric dielectric polymers have high dielectric losses, thus severely limiting their applications. It is well known that the maximum electrostatic energy stored in a dielectric can be estimated simply using the following equation: Ue= (1) Where ε 0 represents the vacuum permittivity, ε r and E b are the permittivity and the electrical breakdown strength, respectively. Equation (1) means that a high energy density requires a polymer with both high ε r and E b. Biaxially oriented polypropylene (BOPP) film capacitors widely applied to the market at present cannot meet the requirement of stable operation in complex environments such as high temperature, high pressure and the like because of the lower T g of the biaxially oriented polypropylene (BOPP) film capacitors, which cause the service temperature of less than 105 ℃. On the other hand, the low dielectric constant limits the energy density, and the requirements of miniaturization and light weight cannot be met. And the polyimide main chain is composed of an imine ring and a benzene ring, and has excellent high temperature resistance (T g >250 ℃) and dielectric properties. In addition, the high-strength plastic has the characteristics of good flexibility, easiness in processing, good thermal stability, free structural design and the like, and is widely paid attention to researchers. However, due to the pi-pi conjugation effect between polyimide chain segments, the band gap is lower, and the energy storage performance is poorer. Whereas in terms of dielectric energy storage, ionic groups are generally considered detrimental, as they lead to a large increase in dielectric loss and conductivity. Furthermore, ionic groups tend to aggregate into large ion domains, which cannot follow the high frequency alternating electric field, resulting in a much lower increase in dielectric constant than expected. Disclosure of Invention The technical problem to be solved by the invention is to provide the polyimide dielectric film containing the carboxyl betaine and the preparation method thereof, and the dielectric property and the energy storage property of the polyimide dielectric film are improved by introducing the zwitterion into a polyimide structure, and meanwhile, the polyimide dielectric film has the advantages of low cost, simple process, controllable and adjustable property, suitability for large-scale application and the like in preparation. The technical scheme adopted by the invention is specifically described below. In a first aspect, the invention provides a carboxyl betaine-containing polyimide dielectric film, which is prepared from carboxyl betaine-containing polyimide, wherein the carboxyl betaine-containing polyimide is prepared by taking a precursor of carboxyl betaine, m-phenylenediamine (MPD) and bisphenol a type diether dianhydride (BPADA) as monomers, the ratio of the total molar weight of the precursor of carboxyl betaine to the total molar weight of the bisphenol a type diether dianhydride (BPADA) is 1:1, the molar weight of the precursor of carboxyl betaine is 1-10% of the total molar weight of the precursor of carboxyl betaine and m-phenylenediamine, and a reaction solution with the solid content of 10-12% is prepared, and polyamide acid is obtained through polycondensation reaction; The precursor of the carboxybetaine is 2- (4-aminophenyl) -5-aminobenzimidazole (APBIA), and the structure is shown as follows: the structure of the bisphenol a type diether dianhydride is shown as follows: 。 Preferably, the polycondensation reaction conditions are a reaction temperature of from 0 to 10℃and a reaction time of from 18 to 30 hours, preferably 24 hours. Preferably, the molar amount of the precursor of carboxybetaine is 2-5%, more preferably 5%, based on the total molar amount of the precursor of carboxybetaine and m-phenylenediamine. By preference, higher breakdown field strength and energy storage efficiency and lower leakage current density of the dielectric film can be achieved. Preferably, the solvent of the reaction liquid of the polycondensation reaction is anhydrous NMP. Preferably, the feed ratio of the