A ferrocenyl diamine monomer, a polyimide and a preparation method and application thereof

Abstract

The application discloses a ferrocenyl diamine monomer, a polyimide and a preparation method and application thereof, the ferrocenyl diamine monomer is prepared by reacting a ferrocene carbonyl compound with aniline, so as to introduce a ferrocene structural unit into the diamine monomer, and form a novel ferrocenyl diamine monomer for preparing the polyimide; the ferrocenyl diamine monomer is polymerized with a tetracarboxylic dianhydride and is subjected to an imidization reaction to prepare the polyimide, and the polyimide is used as a burning rate catalyst; the polyimide can not only effectively ensure the ferrocene content, has good thermal stability, greatly reduce the high-temperature decomposition temperature of an oxidant, has a smaller influence on the low-temperature decomposition temperature, and can significantly reduce the migration rate, effectively improve the performance of the ferrocene polymer burning rate catalyst, and is beneficial to the use safety.

Description

Technical Field

[0001] This invention relates to the field of materials science and technology, and in particular to a ferrocene-based diamine monomer, a polyimide, its preparation method, and its application. Background Technology

[0002] Solid propellants are the energy source and working fluid of solid rocket engines, playing a decisive role in the performance of rockets and missiles. Burning rate catalysts are the core functional components of solid propellants; even a small amount can increase the oxidation rate of the propellant, regulate its calorific value, and control its pressure index. Ferrocene and its derivatives are widely used as burning rate catalysts due to their excellent catalytic activity and compatibility. Currently, commercially available ferrocene burning rate catalysts are mainly alkyl-substituted ferrocene, such as catoxine (Cat), n-butylferrocene (NBF), tert-butylferrocene (TBF), and octylferrocene (NOF). However, these ferrocene derivatives, due to their small molecular weight, are prone to migration during long-term storage. Using them as burning rate catalysts can lead to ballistic instability and even deflagration during ignition, causing safety accidents.

[0003] To address the issues of volatility, sublimation, and migration inherent in ferrocene combustion rate catalysts, researchers have designed and synthesized numerous ferrocene combustion rate catalytic systems with high catalytic efficiency and low migration, including the modification of ferrocene through various reactions to obtain derivative compounds. Publicly available patent CN109438526B proposes a benzoate combustion rate catalyst with a binuclear ferrocene group, which exhibits low migration and volatility under natural conditions, with a weight loss onset temperature above 200℃, demonstrating a certain degree of thermal stability compared to conventional catalysts. However, hydrogen bonding alone is insufficient to completely resolve the issues of thermal stability, anti-migration, and volatility of ferrocene compounds. The published patent CN115739185B proposes a method for encapsulating ferrocene in a zeolite-like material. By encapsulating the ferrocene combustion rate catalyst in a zeolite-like imidazole ester framework material (ZIF-8) prepared from metal and methylimidazolium, the exothermic reaction of the prepared combustion rate catalyst (AP) is more concentrated, and the anti-migration property is greatly improved. However, the problems of ferrocene migration and volatility are not completely solved. In addition, the published patent CN118546043A proposes a composite combustion rate catalyst Bi2O3-Fc / β-CD / CNT-Fc (CN118546043A) prepared based on the supramolecular bonding principle, using ferrocene-modified bismuth oxide, ferrocene-grafted carbon nanotubes, and β-cyclodextrin. Although this catalyst has a certain degree of anti-migration property and significantly reduces the thermal decomposition temperature of AP, which is beneficial to the combustion of solid propellants, its thermal stability is slightly poor, and it begins to decompose above 180°C.

[0004] Therefore, it is necessary to further improve the structure of ferrocene polymer combustion rate catalysts based on the existing problems, in order to obtain a ferrocene polymer combustion rate catalyst that has high thermal stability, thermally accelerated catalytic decomposition and anti-migration properties. Summary of the Invention

[0005] The purpose of this invention is to provide a ferrocene-based diamine monomer, a polyimide, and their preparation method and application, which solve the problems of easy volatility and migration in commercial ferrocene combustion rate catalysts.

[0006] Therefore, the technical solution of the present invention is as follows:

[0007] A ferrocene-based diamine monomer has the following chemical structural formula:

[0008] ,

[0009] In the formula, R is selected from H or alkyl groups having 1 to 10 carbon atoms.

[0010] Preferably, a ferrocene-based diamine monomer has the following preferred chemical structural formula:

[0011] .

[0012] A method for preparing the above-mentioned ferrocene-based diamine monomer, the specific preparation steps of which are as follows:

[0013] The ferrocene carbonyl compound was dissolved in aniline and an acidic reagent was added to form a reaction system. The reaction system was then heated to 80℃~140℃ under nitrogen protection and reacted for 8h~24h. The reaction endpoint was determined by TLC. After removing impurities from the reaction product system, the ferrocene diamine monomer was obtained.

[0014] Preferably, in the above preparation method, the molar ratio of ferrocene carbonyl compound to aniline is 1:(9-15), so that it can simultaneously serve as both a reactant and a solvent.

[0015] Preferably, in the above preparation method, the acidic reagent is trifluoroacetic acid, trifluoromethanesulfonic acid, or concentrated hydrochloric acid; wherein, the concentrated hydrochloric acid is generally a 36wt% hydrochloric acid aqueous solution.

[0016] Preferably, in the above preparation method, the acidic reagent is used as an activating agent for the carbonyl group, and the molar ratio of the ferrocene carbonyl compound to the acidic reagent is 1:(0.08-0.6).

[0017] Preferably, in the above method for preparing ferrocene-based diamine monomer, the specific steps for removing impurities from the reaction system are as follows: 1) After the temperature of the reaction system drops to room temperature, a mixture of a good solvent and a bad solvent is added and slurryed to remove most of the aniline; 2) A 1:1 volume mixture of organic solvent A and H2O is added, and the pH is adjusted to 1-2 with hydrochloric acid. After stirring for at least 30 minutes, the organic solvent A phase is removed, and the aqueous phase is washed with organic solvent A 1-3 times; 3) The pH of the aqueous phase is adjusted to 7-9 with an alkaline reagent, and then extracted with organic solvent A. After evaporation, the crude product is obtained; the crude product is purified by slurrying with organic solvent B to obtain the target product.

[0018] In step 1) above, the good solvent is selected from ethyl acetate, dichloromethane, methyl tert-butyl ether or diethyl ether, more preferably ethyl acetate; the bad solvent is selected from alkane solvents with C5 to C9 carbon atoms or petroleum ether, more preferably petroleum ether; the volume ratio of good solvent to bad solvent is 1:(8 to 10), and the amount of mixed solvent added is 1 to 5 times the volume of aniline.

[0019] In step 2) above, organic solvent A is selected from ethyl acetate, dichloromethane, methyl tert-butyl ether or diethyl ether, more preferably ethyl acetate; alkaline reagent is selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate or ammonia, more preferably sodium carbonate; the amount of the mixture of organic solvent A and H2O added is 1 to 5 times the volume of aniline.

[0020] In step 2) above, the weight ratio of crude product to organic solvent B is 1:(2~5), and organic solvent B is selected from ethyl acetate or methyl tert-butyl ether.

[0021] A polyimide is prepared by polymerizing a ferrocene-based diamine monomer with a tetracarboxylic dianhydride and then performing an imidization reaction; wherein the tetracarboxylic dianhydride is pyromellitic dianhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, 4,4'-oxobisphthalic anhydride, or biphenyl dianhydride; wherein the imidization reaction is preferably performed by a chemical imidization method.

[0022] The chemical structural formula of this polyimide is:

[0023] ,

[0024] In the formula, A represents the residues of a tetracarboxylic dianhydride containing an aromatic or alicyclic ring after removing four carboxyl groups.

[0025] A method for preparing the above-mentioned polyimide, comprising the following specific steps:

[0026] S1. Dissolve ferrocene-based diamine monomer in an aprotic polar solvent, add tetracarboxylic dianhydride, and stir the reaction at room temperature for at least 24 hours to prepare a polyamic acid solution; wherein the molar ratio of ferrocene-based diamine monomer to tetracarboxylic dianhydride is 1:(1.02-1.04).

[0027] S2. Add aprotic polar solvent to the polyamic acid solution to dilute the polyamic acid solution to a mass fraction of 12wt%~40wt%; then add pyridine and acetic anhydride, and heat to 160℃-200℃ and stir for 15h~18h to obtain the reaction product; wherein, the molar ratio of ferrocene diamine monomer, acetic anhydride and pyridine is 1:(5.5~6.5):(5~6);

[0028] S3. The reaction-generated droplets are added to an organic solvent to precipitate and obtain a crude polymer product. After filtration, the product is washed repeatedly with an organic solvent at least three times and then placed in a vacuum dryer at 50°C for 12 hours to prepare polyimide.

[0029] Preferably, in step S1, the aprotic polar solvent is dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, sulfolane, or diethylene glycol dimethyl ether; more preferably, it is N,N-dimethylformamide or N,N-dimethylacetamide.

[0030] Preferably, in step S3, the organic solvent is ethyl acetate, methanol, ethanol, isopropanol, tetrahydrofuran, or more preferably methanol or ethanol.

[0031] One application of the above-mentioned polyimide, which combines high thermal stability, thermally accelerated catalytic decomposition and anti-migration properties, can be used as a ferrocene polymer combustion rate catalyst in combination with oxidants (such as, but not limited to, rocket propellant oxidants).

[0032] Preferably, the polyimide is added to the oxidant (e.g., but not limited to rocket propellant) at an amount of 2 wt% to 6 wt%.

[0033] Compared with existing technologies, this invention designs a novel ferrocene-based diamine monomer. The polyimide prepared based on this ferrocene-based diamine monomer not only has higher thermal stability and can significantly reduce the high-temperature decomposition temperature of oxidants while having little impact on the low-temperature decomposition temperature, but also has anti-migration properties and catalytic effects. Therefore, when used as a ferrocene polymer combustion rate catalyst, it not only benefits the combustion rate of solid propellants and improves their combustion efficiency, but also improves safety. Attached Figure Description

[0034] Figure 1 The proton NMR spectrum of 1-ferrocenyl-1,1'-bis(4-aminophenyl)methane prepared in Example 1 of the present invention;

[0035] Figure 2 The proton NMR spectrum of 1-ferrocene-1,1'-bis(4-aminophenyl)ethane prepared in Example 2 of the present invention;

[0036] Figure 3 The DSC curves are for rocket propellant perchloric acid with polyimide prepared in Examples 11 and 12 of this invention, and for rocket propellant perchloric acid alone. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention.

[0038] Example 1

[0039] In a reactor equipped with a stirrer and reflux device, 8.1 g (37.84 mmol) of ferrocene formaldehyde, 0.27 mL (3.63 mmol) of trifluoroacetic acid, and 32 mL (0.35 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 100 °C for 12 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 32 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to slurry the mixture to remove most of the aniline. Then, 32 mL of a 1:1 mixture of ethyl acetate and H2O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was slurried with twice its weight of ethyl acetate to obtain 8.39 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane with a purity of 97.8%, which was a pale yellow solid.

[0040] Example 2

[0041] In a reactor equipped with a stirrer and reflux device, 10.87 g (47.65 mmol) of acetylferrocene, 0.3 mL (4.03 mmol) of trifluoromethanesulfonic acid, and 40 mL (0.44 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 100 °C for 12 h. TLC was used to detect the complete conversion of acetylferrocene. After cooling to room temperature, 45 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 50 mL of a 1:1 mixture of ethyl acetate and H2O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. Then, the pH was adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and dried by rotary evaporation. The crude product was then slurried with 3 times its weight of ethyl acetate to obtain 11.33 g of 1-ferrocene-1,1'-di(4-aminophenyl)ethane with a purity of 98.9%, which was a pale yellow solid.

[0042] Example 3

[0043] In a reactor equipped with a stirrer and reflux device, 10.2 g (47.65 mmol) of ferrocene formaldehyde, 0.3 mL (4.03 mmol) of trifluoromethanesulfonic acid, and 40 mL (0.44 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 80 °C for 8 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 45 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 50 mL of a 1:1 mixture of ethyl acetate and H2O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was then slurried with 2.5 times its weight of ethyl acetate to obtain 10.2 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane with a purity of 98.5%, which was a pale yellow solid.

[0044] Example 4

[0045] In a reactor equipped with a stirrer and reflux device, 7.6 g (35.5 mmol) of ferrocene formaldehyde, 0.88 mL (10.24 mmol) of 36% concentrated hydrochloric acid, and 30 mL (0.33 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 140 °C for 24 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 150 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 60 mL of a 1:1 mixture of ethyl acetate and H2O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The resulting product was then slurried with 4 times its weight of ethyl acetate to obtain 7.59 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane with a purity of 98.5%, which was a pale yellow solid.

[0046] Example 5

[0047] In a reactor equipped with a stirrer and reflux device, 9.4 g (43.91 mmol) of ferrocene formaldehyde, 2.2 mL (25.6 mmol) of 36% concentrated hydrochloric acid, and 40 mL (0.44 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 100 °C for 12 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 120 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 200 mL of a 1:1 mixture of ethyl acetate and H₂O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was then removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide, and ethyl acetate was used as the aqueous phase. After extraction and evaporation, the crude product was obtained. The crude product was then slurried with 5 times its weight of ethyl acetate to obtain 10.4 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane. g, purity 98.8%, beige solid.

[0048] Example 6

[0049] In a reactor equipped with a stirrer and reflux device, 11 g (51.38 mmol) of ferrocene formaldehyde, 2.61 mL (30.31 mmol) of 36% concentrated hydrochloric acid, and 45 mL (0.495 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 120 °C for 16 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 120 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 90 mL of a 1:1 mixture of ethyl acetate and H₂O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was then removed, and the aqueous phase was washed with ethyl acetate, repeating the process 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was then slurried with three times its weight of ethyl acetate to obtain 11.9 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane. g, purity 98.4%, beige solid.

[0050] Example 7

[0051] In a reactor equipped with a stirrer and reflux device, 10.5 g (49.04 mmol) of ferrocene formaldehyde, 1.22 mL (HCl 14.2 mmol) of 36% concentrated hydrochloric acid, and 42 mL (0.46 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 100 °C for 20 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 200 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 200 mL of a 1:1 mixture of ethyl acetate and H₂O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was then removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was then slurried with 3 times its weight of ethyl acetate to obtain 10.9 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane. g, purity 98.7%, beige solid.

[0052] Example 8

[0053] In a reactor equipped with a stirrer and reflux device, 9.8 g (45.77 mmol) of ferrocene formaldehyde, 1.14 mL (13.27 mmol) of 36% concentrated hydrochloric acid, and 50 mL (0.55 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 130 °C for 20 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 200 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 250 mL of a 1:1 mixture of ethyl acetate and H₂O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was then removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was then slurried with three times its weight of ethyl acetate to obtain 10.5 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane. g, purity 98.9%, beige solid.

[0054] Example 9

[0055] In a reactor equipped with a stirrer and reflux device, 12 g (56.04 mmol) of ferrocene formaldehyde, 1.4 mL (16.3 mmol) of 36% concentrated hydrochloric acid, and 60 mL (0.66 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 120 °C for 24 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 240 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 300 mL of a 1:1 mixture of ethyl acetate and H₂O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was then removed, and ethyl acetate was added again. The aqueous phase was washed 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was then slurried with twice its weight of methyl tert-butyl ether to obtain 13.5 g of 1-ferrocene-1,1'-di(4-aminophenyl)methane. g, purity 98.8%, beige solid.

[0056] Example 10

[0057] In a reactor equipped with a stirrer and reflux device, 11.5 g (53.71 mmol) of ferrocene formaldehyde, 1.34 mL (15.6 mmol) of 36% concentrated hydrochloric acid, and 58 mL (0.64 mol) of aniline were added. Nitrogen gas was introduced, and the reaction was carried out at 120 °C for 24 h. TLC was used to detect the complete conversion of ferrocene formaldehyde. After cooling to room temperature, 250 mL of a 1:10 mixture of ethyl acetate and petroleum ether was added to remove most of the aniline. Then, 120 mL of a 1:1 mixture of ethyl acetate and H₂O was added to dilute the reaction solution. The pH was adjusted to 1-2 with hydrochloric acid, and the mixture was stirred for 30 min. The ethyl acetate phase was then removed, and the aqueous phase was washed with ethyl acetate. This process was repeated 1-3 times. The pH was then adjusted to 7-9 with sodium hydroxide. The aqueous phase was extracted with ethyl acetate and evaporated to dryness. The crude product was then slurried with twice its weight of methyl tert-butyl ether to obtain 1-ferrocene-1,1'-di(4-aminophenyl)methane 12.1. g, purity 98.6%, beige solid.

[0058] Example 11

[0059] In a dry three-necked flask equipped with a nitrogen inlet and a mechanical stirrer, 1.91 g (4.95 mmol) of 1-ferrocene-1,1'-di(4-aminophenyl)methane prepared in Example 1 and 8.0 mL (7.584 g) of N,N-dimethylformamide were added. After dissolving the diamine monomer with stirring, 1.11 g (5.10 mmol) of pyromellitic dianhydride was added, and the solution was stirred at room temperature for 24 h. Then, 10 mL of N,N-dimethylformamide was added for dilution, followed by 2.2 mL (27.37 mmol) of pyridine and 2.8 mL (29.84 mmol) of acetic anhydride. The mixture was heated to 180 °C and reacted for 16 h. Subsequently, the reaction product was precipitated in 1000 mL of methanol. The resulting polymer was filtered, washed three times with methanol, and dried under vacuum at 50 °C for 12 h to obtain 2.82 g of a grayish-white solid.

[0060] Example 12

[0061] In a dry three-necked flask equipped with a nitrogen inlet and a mechanical stirrer, 1.98 g (5.00 mmol) of 1-ferrocene-1,1'-di(4-aminophenyl)ethane prepared in Example 2 and 8.0 mL of N,N-dimethylacetamide were added. After the diamine monomer was dissolved by stirring, 1.12 g (5.15 mmol) of pyromellitic dianhydride was added, and the solution was stirred at room temperature for 24 h. Then, 10 mL of N,N-dimethylformamide was added for dilution, followed by 2.2 mL (27.37 mmol) of pyridine and 2.8 mL (29.84 mmol) of acetic anhydride, and the mixture was heated to 180 °C and reacted for 18 h. Subsequently, the reaction product was added droplets to 1000 mL of methanol to precipitate the polymer. The resulting polymer was filtered, washed three times with methanol, and dried under vacuum at 50 °C for 12 h to obtain 2.88 g of polymer, a grayish-white solid.

[0062] Example 13

[0063] In a dry three-necked flask equipped with a nitrogen inlet and a mechanical stirrer, 1.91 g (4.95 mmol) of 1-ferrocene-1,1'-di(4-aminophenyl)methane prepared in Example 3 and 8.0 mL of N,N-dimethylacetamide were added. After the diamine monomer was dissolved by stirring, 2.26 g (5.10 mmol) of 4,4'-(hexafluoroisopropene)phthalic anhydride was added, and the solution was stirred at room temperature for 24 h. Then, 10 mL of N,N-dimethylformamide was added for dilution, followed by 2.2 mL (27.37 mmol) of pyridine and 2.8 mL (29.84 mmol) of acetic anhydride, and the mixture was heated to 180 °C and reacted for 16 h. Subsequently, the reaction product was added droplets to 1000 mL of methanol to precipitate the polymer. The resulting polymer was filtered, washed three times with methanol, and dried under vacuum at 50 °C for 12 h to obtain 3.77 g of polymer, an off-white solid.

[0064] Example 14

[0065] In a dry three-necked flask equipped with a nitrogen inlet and a mechanical stirrer, 1.92 g (4.98 mmol) of 1-ferrocene-1,1'-di(4-aminophenyl)methane prepared in Example 4 and 8.0 mL of N,N-dimethylacetamide were added. After the diamine monomer was dissolved by stirring, 1.58 g (5.10 mmol) of 4,4'-oxophthalic anhydride was added, and the solution was stirred at room temperature for 24 h. Then, 10 mL of N,N-dimethylformamide was added for dilution, followed by 2.2 mL (27.37 mmol) of pyridine and 2.8 mL (29.84 mmol) of acetic anhydride, and the mixture was heated to 180 °C and reacted for 16 h. Subsequently, the reaction product was added droplets to 1000 mL of methanol to precipitate the polymer. The resulting polymer was filtered, washed three times with methanol, and dried under vacuum at 50 °C for 12 h to obtain 3.29 g of polymer as a grayish-white solid.

[0066] Example 15

[0067] In a dry three-necked flask equipped with a nitrogen inlet and a mechanical stirrer, 1.90 g (4.92 mmol) of 1-ferrocene-1,1'-di(4-aminophenyl)methane prepared in Example 5 and 8.0 mL of N,N-dimethylacetamide were added. After the diamine monomer was dissolved by stirring, 1.50 g (5.10 mmol) of biphenyltetracarboxylic dianhydride was added, and the solution was stirred at room temperature for 24 h. Then, 10 mL of N,N-dimethylformamide was added for dilution, followed by 2.2 mL (27.37 mmol) of pyridine and 2.8 mL (29.84 mmol) of acetic anhydride, and the mixture was heated to 180 °C and reacted for 15 h. Subsequently, the reaction product was added droplets to 1000 mL of methanol to precipitate the polymer. The resulting polymer was filtered, washed three times with methanol, and dried under vacuum at 50 °C for 12 h to obtain 3.15 g of polymer as a grayish-white solid.

[0068] Performance testing:

[0069] (a) Chemical structure characterization:

[0070] The synthetic routes for the ferrocene diamine compounds prepared in Examples 1 to 10 are shown below:

[0071] ,

[0072] In Examples 1 and 3-10, R is H, and in Example 2, R is CH3.

[0073] Based on this, the compounds prepared in Examples 1 to 10 were characterized by proton NMR spectra.

[0074] like Figure 1The figure shows the 1H NMR spectrum of 1-ferrocenyl-1,1'-bis(4-aminophenyl)methane prepared in Example 1. In the spectrum, chemical shifts 6.76-6.79 and 6.39-6.42 represent the eight hydrogen atoms on the aminobenzene ring; 4.83 represents the four hydrogen atoms of the amino group; 4.76 represents the one hydrogen atom of the methyl group; and 3.82-4.17 represents the nine hydrogen atoms on the ferrocenyl group. This 1H NMR spectrum confirms the successful synthesis of 1-ferrocenyl-1,1'-bis(4-aminophenyl)methane.

[0075] like Figure 2 The figure shows the 1H NMR spectrum of 1-ferrocenyl-1,1'-bis(4-aminophenyl)ethane prepared in Example 2. In the spectrum, positions 6.73-6.76 and 6.42-6.45 represent the eight hydrogen atoms on the aminobenzene ring; position 4.81 represents the four hydrogen atoms of the amino group; position 4.76 represents the one hydrogen atom of the methyl group; positions 3.82-4.21 represent the nine hydrogen atoms on the ferrocenyl group; and position 2.26 represents the three hydrogen atoms of the methyl group. This 1H NMR spectrum confirms the successful synthesis of 1-ferrocenyl-1,1'-bis(4-aminophenyl)ethane.

[0076] Similarly, the compounds prepared in Examples 3 to 10, after being characterized by 1H NMR spectra, also reached the same conclusions as in Example 1, which fully demonstrates that the newly designed diamine monomer of this invention was successfully synthesized.

[0077] (II) Polyimide performance testing:

[0078] The polyimide films prepared in Examples 11-15 were subjected to glass transition temperature testing, catalytic thermal decomposition performance testing, and migration performance testing in sequence.

[0079] The glass transition temperature (Tg) of the polyimides prepared in Examples 11-15 was determined using DSC thermal analysis. The method involved using a differential scanning calorimeter (DSC) under a nitrogen atmosphere with a heating rate of 10 °C / min to calculate the glass transition temperature. The specific test results are shown in Table 1 below.

[0080] Table 1:

[0081] Test case Glass transition temperature Tg Example 11 315 ℃ Example 12 295 ℃ Example 13 306 ℃ Example 14 302 ℃ Example 15 312 ℃

[0082] As can be seen from the test results in Table 1, the glass transition temperature (Tg) of the polyimides prepared in Examples 11-15 is higher than 290℃, indicating good thermal stability.

[0083] Furthermore, the polyimides prepared in Examples 11-15 were added to perchloric acid (AP), a commonly used rocket propellant, to investigate their catalytic thermal decomposition performance. The tests were also performed using a differential scanning calorimeter (DSC); argon gas was used for protection during the tests, the heating rate was 5 °C / min, the data acquisition temperature range was 40 °C to 680 °C, the sample mass was 5.00 mg to 10.00 mg, and the amount of polyimide added to the AP was 5 wt%.

[0084] like Figure 3 The diagram shows the DSC curves of perchloric acid as a rocket propellant oxidizer with polyimide prepared in Examples 11 and 12 of this invention, and perchloric acid as a rocket propellant oxidizer alone. Figure 3 In the diagram, AP represents the DSC curve of perchloric acid alone as a rocket propellant oxidizer, Group A represents the DSC curve of perchloric acid, a commonly used rocket propellant oxidizer, with the addition of polyimide prepared in Example 11, and Group B represents the DSC curve of perchloric acid, a commonly used rocket propellant oxidizer, with the addition of polyimide prepared in Example 12.

[0085] from Figure 3 The comparative test results show that the low-temperature decomposition temperature of the AP group is 308℃, and the high-temperature thermal decomposition temperature is 432℃. The high-temperature decomposition temperature of the A group is advanced to 356℃, which is 76℃ earlier than that of the AP group, and its low-temperature decomposition temperature is 288℃, which is 20℃ earlier than that of the AP group. The high-temperature decomposition temperature of the B group is advanced to 378℃, which is 54℃ earlier than that of the AP group, and its low-temperature decomposition temperature is 302℃, which is 6℃ earlier than that of the AP group. It can be seen that the addition of polyimide in this invention has little effect on the low-temperature decomposition temperature of AP, but only significantly reduces the high-temperature decomposition temperature of AP. This is not only beneficial to the burning rate of solid propellants and improves their combustion efficiency, but also to their safety in use.

[0086] The polyimides prepared in Examples 13-15 exhibited the same catalytic thermal decomposition effect after the addition of 5% of the rocket propellant perchloric acid; specifically, the high-temperature decomposition temperature of the polyimides prepared in Examples 13-15 was 349℃~381℃, and the low-temperature decomposition temperature was 298℃~311℃.

[0087] Furthermore, the migration properties of the polyimides prepared in Examples 11-15 were tested. Specifically, the test samples containing the components of the embodiments of the present invention consisted of: 700 mg of rocket propellant perchloric acid (AP), 230 mg of hydroxyl-terminated polybutadiene (HTPB), 26 mg of isophorone diisocyanate (IPDI), and 170 mg of the polyimide prepared in this embodiment (as a burn rate catalyst). The blank test sample consisted of: 730 mg of commonly used rocket propellant perchloric acid (AP), 243 mg of hydroxyl-terminated polybutadiene (HTPB), and 27 mg of isophorone diisocyanate.

[0088] The test method is as follows: After mixing the test sample thoroughly, fill it into a glass tube and push it to the center. Press both ends of the sample as flat as possible, wipe the glass walls at both ends clean with a cotton swab, and place it in a 50℃ oven for constant temperature curing for four days. Fill both ends of the sample with blank test sample to the vicinity of the glass port to obtain the migration test sample. Place the glass tube in a 50℃ oven again for constant temperature for six weeks, and take it out every week to measure the distance between the two ends of the test sample.

[0089] Tests showed that the polyimide samples prepared in Examples 11-15 did not exhibit significant migration after six weeks, demonstrating that the polyimide of the present invention has excellent anti-migration properties as a thermal decomposition catalyst. This prevents it from easily moving or leaking from its initial position under long-term storage and heating conditions, while also avoiding uneven combustion rates caused by movement, which could lead to localized combustion rate differences and explosion hazards.

[0090] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A ferrocene-based diamine monomer, characterized in that, Its chemical structural formula is: ， In the formula, R is selected from H or alkyl groups having 1 to 10 carbon atoms.

2. A method for preparing the ferrocene-based diamine monomer as described in claim 1, characterized in that, The steps are as follows: dissolve the ferrocene carbonyl compound in aniline, add an acidic reagent, then replace with nitrogen for protection, heat the reaction system to 80℃~140℃, and react for 8h~24h to prepare the ferrocene diamine monomer.

3. The method for preparing the ferrocene-based diamine monomer according to claim 2, characterized in that, The molar ratio of ferrocene carbonyl compound to aniline is 1:(9-15); the acidic reagent is trifluoroacetic acid, trifluoromethanesulfonic acid or concentrated hydrochloric acid; the molar ratio of ferrocene carbonyl compound to acidic reagent is 1:(0.08-0.6).

4. The method for preparing the ferrocene-based diamine monomer according to claim 2, characterized in that, After the reaction is complete, the ferrocene-based diamine monomer is subjected to impurity removal treatment. The steps are as follows: 1) After the temperature of the reaction system drops to room temperature, a mixture of a good solvent and a bad solvent is added and slurryed to remove aniline; 2) A 1:1 volume mixture of organic solvent A and H2O is added, and the pH is adjusted to 1-2 with hydrochloric acid. After stirring for at least 30 minutes, the organic solvent A phase is removed, and the aqueous phase is washed with organic solvent A 1-3 times; 3) The pH of the aqueous phase is adjusted to 7-9 with an alkaline reagent, and then extracted with organic solvent A. After evaporation, the crude product is obtained; the crude product is purified by slurrying with organic solvent B to obtain the target product.

5. The method for preparing the ferrocene diamine compound according to claim 4, characterized in that, In step 1), the good solvent is selected from ethyl acetate, dichloromethane, methyl tert-butyl ether, or diethyl ether; the bad solvent is selected from alkane solvents with C5 to C9 carbon atoms or petroleum ether; the volume ratio of the good solvent to the bad solvent is 1:(8~10), and the amount of mixed solvent added is 1 to 5 times the volume of aniline; in step 2), organic solvent A is selected from ethyl acetate, dichloromethane, methyl tert-butyl ether, or diethyl ether; the alkaline reagent is selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, or ammonia; the amount of the mixture of organic solvent A and H2O added is 1 to 5 times the volume of aniline; the weight ratio of the crude product to organic solvent B is 1:(2~5), and organic solvent B is selected from ethyl acetate or methyl tert-butyl ether.

6. A polyimide, characterized in that, The product is prepared by polymerizing the ferrocene-based diamine monomer of claim 1 with tetracarboxylic dianhydride and then performing an imidization reaction; wherein the tetracarboxylic dianhydride is pyromellitic dianhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, 4,4'-oxobisphthalic anhydride or biphenyl dianhydride.

7. A method for preparing polyimide as described in claim 6, characterized in that, The steps are as follows: S1. Dissolve the ferrocene-based diamine monomer in an aprotic polar solvent, add tetracarboxylic dianhydride, and stir the reaction at room temperature for at least 24 hours to prepare a polyamic acid solution; the molar ratio of ferrocene-based diamine monomer to tetracarboxylic dianhydride is 1:(1.02-1.04). S2. Add aprotic polar solvent to the polyamic acid solution to dilute the polyamic acid solution to a mass fraction of 12wt%~40wt%; then add pyridine and acetic anhydride, and heat to 160℃-200℃ and stir for 15h~18h to obtain the reaction product; the molar ratio of ferrocene diamine monomer, acetic anhydride and pyridine is 1:(5.5~6.5):(5~6); S3. The reaction-generated droplets are added to an organic solvent to precipitate and obtain a crude polymer product. After filtration, the product is repeatedly washed with an organic solvent and then dried under vacuum to prepare polyimide.

8. The method for preparing polyimide according to claim 7, characterized in that, In step S1, the aprotic polar solvent is dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, sulfolane, or diethylene glycol dimethyl ether; in step S3, the organic solvent is ethyl acetate, methanol, ethanol, isopropanol, or tetrahydrofuran.

9. An application of the polyimide as described in claim 6, characterized in that, It is used in conjunction with an oxidant as a combustion rate catalyst.

10. The application of the polyimide according to claim 9, characterized in that, The amount of polyimide added to the oxidant is 2wt%~6wt%.

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