Monomer of super-crosslinked polyamide-imide and preparation method thereof

Abstract

The invention discloses a super-crosslinked polyamide-imide monomer and a preparation method thereof, and relates to an organic polymer and a preparation method thereof. The monomer for preparing super-crosslinked poly (amide-imide) is 2, 2 ', 2', 2 ', 2', 2 ', 2', 2 ', 2', 2 ', 2', 2 ', 2', 2 ', 2', 2 ', 2', 2 ', 2 The 2, 2 ''-(nitrile tri (phenyl-4, 1-diyl) tri (1, 3-dioxoisoindoline-5-carboxylic acid) is used as an organic hybrid monomer and has different functional groups and structures such as carboxyl (-COOH), amide (-CONH), an aromatic (phenyl) ring and an imide ring, so that the 2, 2 ''-(nitrile tri (phenyl-4, 1-diyl) tri (1, 3-dioxoisoindoline-5-carboxylic acid) can be used as a construction unit to construct a novel super-crosslinked polymer, and the problems that an existing super-crosslinked polymer is few in active sites, low in cost and the like are solved. The heteroatom content is low, and the adsorption selectivity is poor. The synthesis route is simpler, the triacid monomer can be obtained only through simple reaction steps, and the cost is reduced.

Description

Technical Field

[0001] The invention relates to an organic polymer and a preparation method thereof, in particular to a monomer of a hyper-crosslinked polyamide-imide and a preparation method thereof. Background Art

[0002] In recent years, due to the characteristics of hyper-crosslinked polymers such as diverse building blocks, easy functionalization, and unique structure, more and more research has been devoted to the preparation of new hyper-crosslinked polymers as adsorbents. However, most hyper-crosslinked polymers have few active sites, low heteroatom content, and poor adsorption selectivity. Therefore, it is crucial to develop new monomers to manufacture hyper-crosslinked polymers with high bromine, iodine and dye adsorption rates and good selectivity by selecting reasonable monomers, appropriate length of crosslinkers, and optimizing reaction conditions.

[0003] Aromatic polyimide materials have attracted the attention of researchers in industry and academia due to their high porosity, multiple active sites, excellent thermal stability and chemical stability, and their high adsorption capacity for bromine, iodine and dyes. As a type of aromatic polyimide, hypercrosslinked poly(amide-imide) not only has the unique advantages of polyamide, but also has the advantages of polyimide with a five-membered ring structure. At the same time, the hypercrosslinked structure enhances the porosity and specific surface area of ​​the material, showing unique advantages in the field of adsorption, providing more active sites for adsorption and improving adsorption capacity. In addition, the chemical resistance and corrosion resistance of polyamide-imide enable it to maintain its performance in harsh environments, which is particularly important for the adsorption of harmful chemicals.

[0004] The tridentate building unit has a stable three-dimensional structure and plays an important role in the formation of complexes or organic skeletons. The tridentate imidic acid monomer, as an organic hybrid monomer in the tridentate building unit, has different functional groups and structures such as carboxyl (-COOH), amide (-CONH), aromatic (phenyl) ring and imide ring. It can be used as a building unit to construct a new type of hyper-cross-linked polymer. The high rigidity of the polymer network produced by chemical cross-linking can effectively prevent the polymer chain from collapsing into a dense and non-porous state. In addition, it has a high content of heteroatoms and good adsorption selectivity, and has potential application value in the field of adsorption.

[0005] In the prior art, the material agent prepared by using the diacid monomer polymer 4,4′-bis[4″-(trimethylbenzene imidazolyl)phenylisopropylidene-4″′-phenoxy]diphenyl sulfone or the diacid monomer polymer 4,4′-bis[4″-(trimethylbenzene imidazolyl)phenylisopropylidene-4″′-phenoxy] has insufficient active sites and low heteroatom content, and is difficult to maintain performance in applications that require high temperature resistance, corrosion resistance and various harsh environments. Summary of the invention

[0006] The object of the present invention is to provide a monomer of a hyper-crosslinked polyamide-imide and a preparation method thereof. The monomer contains a carboxyl group (-COOH), an amide (-CONH), an aromatic (phenyl) ring and an imide ring rigid structure. If it is used to prepare a hyper-crosslinked poly (amide-imide), the polymer will have more active sites, a higher heteroatom content and better structural stability.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The first object of the present invention is to provide a monomer for preparing a hyper-crosslinked poly(amide-imide), wherein the monomer for preparing the hyper-crosslinked poly(amide-imide) has a structural formula of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid) of formula (I):

[0009]

[0010] The second object of the present invention is a method for preparing a monomer for preparing a hyper-crosslinked poly(amide-imide), the technical point of which is that it comprises the following steps:

[0011] Step 1, reduction reaction: under nitrogen atmosphere, tri(4-nitrophenyl)amine and catalyst are dispersed in ethanol in a three-necked round-bottom flask in turn, placed in an oil bath and stirred, the sample is mixed evenly and then heated, when the reaction temperature is balanced and stable, hydrazine hydrate is added dropwise to the reaction system using a constant pressure funnel, and the drop rate is controlled to be 4-5s per drop to obtain a mixture A, and reacted under reflux for 1 to 3 days, and the plate is pressed at regular intervals to observe the reduction of the sample. After the reaction is completed, a sand core funnel is used to filter and remove the catalyst in the solution, and the filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate to obtain a mixture B. Under stirring conditions, the mixture B is added to an ice-water mixture to obtain a light yellow precipitate, and the light yellow precipitate is thoroughly washed with distilled water to remove the unevaporated solvent and reducing agent, and after vacuum drying, dichloromethane column chromatography is performed to obtain a white solid powder, namely tri(4-aminophenyl)amine. The specific reaction is as follows:

[0012]

[0013] Step 2, buckling reaction: in a three-necked round-bottom flask under a nitrogen atmosphere, tris(4-aminophenyl)amine and trimellitic anhydride are dispersed in 20-60 mL of glacial acetic acid, and mechanically stirred at room temperature for 1-5 hours. After the sample in the flask is evenly mixed, the reaction is heated for 12-60 hours. The product is filtered and washed with methanol for 3-5 times, and then dried in a vacuum drying oven at 60° C. for 24 hours to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid). The specific reaction equation is as follows:

[0014]

[0015] In order to better realize the above technical scheme, in step 1 of the preparation method of the monomer for preparing hyper-crosslinked poly(amide-imide) of the present invention, the mass volume ratio of tri(4-nitrophenyl)amine, catalyst and ethanol is (1.9-18) g: (0.1-2) g: (25-250) mL.

[0016] In order to better realize the above technical scheme, the preparation method of the monomer for preparing hyper-crosslinked poly(amide-imide) of the present invention is characterized in that the catalyst is palladium carbon.

[0017] In order to better realize the above technical scheme, in step 1 of the preparation method of the monomer for preparing hyper-crosslinked poly(amide-imide) of the present invention, the temperature is slowly raised to 75-100°C, the reflux time is 1-2h, hydrazine hydrate is added dropwise, the reaction is carried out at 75-100°C for 15-30h, and the temperature is lowered to 20-40°C after the reaction is completed.

[0018] In order to better realize the above technical scheme, in step 2 of the preparation method of the monomer for preparing hyper-crosslinked poly(amide-imide) of the present invention, the mass volume ratio of tri(4-aminophenyl)amine, trimellitic anhydride and glacial acetic acid is (1-7.5) g: (3-22) g: (20-100) mL.

[0019] The advantages and positive effects of the present invention are:

[0020] 1. The monomer used to prepare the hyper-crosslinked poly(amide-imide) of the present invention is 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), which has different functional groups and structures such as carboxyl (-COOH), amide (-CONH), aromatic (phenyl) ring and imide ring. It has high porosity, multiple active sites, high heteroatom content and excellent thermal stability and chemical stability. Therefore, it can be used as a building block to construct a new hyper-crosslinked polymer for application in the field of adsorption, solving the problems of existing hyper-crosslinked polymers with few active sites, low heteroatom content and poor adsorption selectivity.

[0021] 2. The preparation method of the monomer for preparing a super-crosslinked poly(amide-imide) of the present invention is to use tri(4-nitrophenyl)amine as a raw material, prepare a triamino monomer tri(4-aminophenyl)amine by a reduction reaction, and then use the triamino monomer and trimellitic anhydride to prepare a tridentate imidic acid monomer 2,2',2"-(nitrile tri(phenyl-4,1-diyl)tri(1,3-dioxoisoindoline-5-carboxylic acid) by a thermal buckling reaction. The synthetic route of the present invention is simpler, and the triacid monomer can be obtained through simple reaction steps, thereby reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The H NMR spectrum of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid) of Example 1 of the present invention;

[0023] Figure 2 This is the infrared spectrum of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid) of Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] A monomer for preparing a hyper-crosslinked poly(amide-imide) has the structural formula (I), 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid):

[0026]

[0027] The tridentate imide acid monomer of formula (I) used for preparing the super cross-linked poly (amide-imide) as an organic hybrid monomer in the tridentate building unit has different functional groups and structures such as carboxyl (-COOH), amide (-CONH), aromatic (phenyl) ring and imide ring, so that the super cross-linked poly (amide-imide) prepared by using the monomer has high porosity, multiple active sites, excellent thermal stability and chemical stability. The high rigidity of the polymer network generated by the rigid structure such as the aromatic (phenyl) ring and the imide ring and the chemical cross-linking can effectively prevent the polymer chain from collapsing into a dense and non-porous state, and it has a high content of self-contained heteroatoms and good adsorption selectivity, and has potential application value in the field of adsorption.

[0028] The method for preparing the monomer for preparing the hyper-crosslinked poly(amide-imide) comprises the following steps:

[0029] Step 1, reduction reaction: under a nitrogen atmosphere, tri(4-nitrophenyl)amine and a catalyst are dispersed in ethanol in a three-necked round-bottom flask in turn, placed in an oil bath and stirred, the sample is mixed evenly and then heated, and when the reaction temperature is balanced and stable, hydrazine hydrate is added dropwise to the reaction system using a constant pressure funnel, and the dripping rate is controlled to be 4-5s per drop to obtain a mixture A, wherein the mass volume ratio of tri(4-nitrophenyl)amine, catalyst, and ethanol is (1.9-18) g: (0.1-2) g: (25-250) mL. Preferably, the mass volume ratio of tri(4-nitrophenyl)amine, catalyst, and ethanol of the present invention is The reaction mixture is (1.9-16.2) g: (0.1-1.9) g: (25-85) mL, and the mixture is reacted under reflux for 1-3 days. The plate is pressed at regular intervals to observe the reduction of the sample. After the reaction is completed, a sand core funnel is used to filter and remove the catalyst in the solution. The filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate to obtain a mixture B. Under stirring conditions, the mixture B is added to an ice-water mixture to obtain a light yellow precipitate. The light yellow precipitate is thoroughly washed with distilled water to remove the undistilled solvent and reducing agent. After vacuum drying, the mixture is eluted by dichloromethane column chromatography to obtain a white solid powder, namely tris(4-aminophenyl)amine. The specific reaction is as follows:

[0030]

[0031] Step 2, buckling reaction: tris(4-aminophenyl)amine and trimellitic anhydride are dispersed in 20-60 mL of glacial acetic acid in a three-necked round-bottom flask under a nitrogen atmosphere, and mechanically stirred for 1-5 h at room temperature. After the sample in the flask is evenly mixed, the reaction is heated for 12-60 h, wherein the mass volume ratio of tris(4-aminophenyl)amine, trimellitic anhydride and glacial acetic acid is (1-7.5) g: (3-22) g: (20-100) mL, as a preferred , the mass volume ratio of tri(4-aminophenyl)amine, trimellitic anhydride and glacial acetic acid is (1-7.3) g: (3-21.8) g: (20-85) mL, the product is filtered and washed with methanol 3-5 times, and then placed in a vacuum drying oven at 60°C for 24 hours to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), the specific reaction equation is as follows:

[0032]

[0033] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0034] Example 1

[0035] 1. Synthesis of tris(4-aminophenyl)amine

[0036] Tris(4-nitrophenyl)amine (3.8g, 10mmol) and palladium / carbon (10%, 0.21g) were dispersed in ethanol (55mL), and the sample was mixed evenly and heated to 75°C. When the reaction temperature was balanced and stable, hydrazine hydrate was slowly dripped under nitrogen protection. After that, the mixture was refluxed for 1 day, and the plate was tapped at regular intervals to observe the reduction of the sample. After the reflux was completed, the palladium carbon was removed by a sand core funnel, and the filtrate was concentrated by a rotary evaporator to remove excess hydrazine hydrate. Under stirring, the mixture was added to an ice-water mixture to obtain a light yellow precipitate. The formed product was collected by filtration, thoroughly washed with distilled water, vacuum dried, and eluted with dichloromethane column chromatography to obtain a white solid powder, i.e., tris(4-aminophenyl)amine, 2.47g.

[0037] 2. Synthesis of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid)

[0038] Tris(4-aminophenyl)amine (2.4 g, 8.27 mmol) and trimellitic anhydride (15.23 g, 79.26 mmol) were dispersed in 60 mL of glacial acetic acid under a nitrogen atmosphere and mechanically stirred for 3 h at room temperature. After the sample in the flask was evenly mixed, the reaction was heated for 24 h. The product was filtered and washed with methanol for 3-5 times, and then dried in a vacuum drying oven at 60°C for 24 h to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), 12.138 g.

[0039] Example 2

[0040] 1. Synthesis of tris(4-aminophenyl)amine

[0041] The method is the same as in Example 1, except that tri(4-nitrophenyl)amine is changed to (11.76g, 30.9mmol), palladium / carbon is changed to (10%, 0.517g) and dispersed in ethanol (150mL). After the sample is mixed evenly, it is heated to 75°C. When the reaction temperature is balanced and stable, hydrazine hydrate is slowly dripped under nitrogen protection. After that, the mixture is refluxed for 1 day, and the plate is tapped at regular intervals to observe the reduction of the sample. After the reflux is completed, palladium carbon is removed by a sand core funnel, and the filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate. Under stirring, the mixture is added to an ice-water mixture to obtain a light yellow precipitate. The formed product is filtered and collected, thoroughly washed with distilled water, vacuum dried, and eluted with dichloromethane column chromatography to obtain a white solid powder, i.e., tri(4-aminophenyl)amine, 8.82g.

[0042] 2. Synthesis of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid)

[0043] The method is the same as that of Example 1. Under a nitrogen atmosphere, tri(4-aminophenyl)amine is replaced with (6.32 g, 21.76 mmol) and trimellitic anhydride is replaced with (19.28 g, 100 mmol) and dispersed in 75 mL of glacial acetic acid. The mixture is mechanically stirred for 3 h at room temperature. After the sample in the flask is evenly mixed, the mixture is heated for reaction for 32 h. The product is filtered and washed with methanol for 3-5 times. The product is then dried in a vacuum drying oven at 60° C. for 24 h to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), 17.88 g.

[0044] Example 3

[0045] 1. Synthesis of tris(4-aminophenyl)amine

[0046] The method is the same as in Example 1, except that tri(4-nitrophenyl)amine is changed to (18.79 g, 49 mmol) and palladium / carbon is changed to (10%, 1 g) and dispersed in ethanol (250 mL). After the sample is mixed evenly, it is heated to 75°C. When the reaction temperature is balanced and stable, hydrazine hydrate is slowly dripped under nitrogen protection. After that, the mixture is refluxed for 1 day, and the plate is tapped at regular intervals to observe the reduction of the sample. After the reflux is completed, palladium carbon is removed by a sand core funnel, and the filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate. Under stirring, the mixture is added to an ice-water mixture to obtain a light yellow precipitate. The formed product is filtered and collected, thoroughly washed with distilled water, vacuum dried, and eluted with dichloromethane column chromatography to obtain a white solid powder, i.e., tri(4-aminophenyl)amine, 14.09 g.

[0047] 2. Synthesis of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid)

[0048] The method is the same as that of Example 1. Under a nitrogen atmosphere, tri(4-aminophenyl)amine is replaced with (7.5 g, 25.83 mmol) and trimellitic anhydride is replaced with (22.5 g, 117 mmol) and dispersed in 90 mL of glacial acetic acid. The mixture is mechanically stirred for 3 h at room temperature. After the sample in the flask is evenly mixed, the mixture is heated for reaction for 32 h. The product is filtered and washed with methanol for 3-5 times. The product is then dried in a vacuum drying oven at 60° C. for 24 h to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), 18.03 g.

[0049] Example 4

[0050] 1. Synthesis of tris(4-aminophenyl)amine

[0051] The method is the same as Example 1, except that tri(4-nitrophenyl)amine is changed to (22.36 g, 58.8 mmol), palladium / carbon is changed to (10%, 1.2 g) and dispersed in ethanol (290 mL). After the sample is mixed evenly, it is heated to 75°C. When the reaction temperature is balanced and stable, hydrazine hydrate is slowly dripped under nitrogen protection. After that, the mixture is refluxed for 2 days, and the plate is tapped at regular intervals to observe the reduction of the sample. After the reflux is completed, the palladium carbon is removed by a sand core funnel, and the filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate. Under stirring conditions, the mixture is added to an ice-water mixture to obtain a light yellow precipitate. The formed product is collected by filtration, thoroughly washed with distilled water, dried in vacuo, and eluted by dichloromethane column chromatography to obtain a white solid powder, i.e., tri(4-aminophenyl)amine, 16.77 g.

[0052] 2. Synthesis of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid)

[0053] The method is the same as that of Example 1. In a nitrogen atmosphere, tri(4-aminophenyl)amine is replaced with (8.3 g, 28.5 mmol) and trimellitic anhydride is replaced with (23.7 g, 123 mmol) and dispersed in 80 mL of glacial acetic acid. The mixture is mechanically stirred for 3 h at room temperature. After the sample in the flask is evenly mixed, the mixture is heated for reaction for 54 h. The product is filtered and washed with methanol for 3-5 times. The product is then dried in a vacuum drying oven at 60° C. for 24 h to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), 19.2 g.

[0054] Example 5

[0055] 1. Synthesis of tris(4-aminophenyl)amine

[0056] The method is the same as in Example 1, except that tri(4-nitrophenyl)amine is changed to (24.32g, 64mmol) and palladium / carbon is changed to (10%, 2g) and dispersed in ethanol (320mL). After the sample is mixed evenly, it is heated to 75°C. When the reaction temperature is balanced and stable, hydrazine hydrate is slowly dripped under nitrogen protection. After that, the mixture is refluxed for 2 days, and the plate is tapped at regular intervals to observe the reduction of the sample. After the reflux is completed, the palladium carbon is removed by a sand core funnel, and the filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate. Under stirring conditions, the mixture is added to an ice-water mixture to obtain a light yellow precipitate. The formed product is collected by filtration, thoroughly washed with distilled water, dried in vacuo, and eluted by dichloromethane column chromatography to obtain a white solid powder, i.e., tri(4-aminophenyl)amine, 18.19g.

[0057] 2. Synthesis of 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid)

[0058] The method is the same as that of Example 1. In a nitrogen atmosphere, tri(4-aminophenyl)amine is replaced with (10.15 g, 35 mmol) and trimellitic anhydride is replaced with (26.88 g, 140 mmol) and dispersed in 100 mL of glacial acetic acid. The mixture is mechanically stirred for 3 h at room temperature. After the sample in the flask is evenly mixed, the mixture is heated for reaction for 54 h. The product is filtered and washed with methanol for 3-5 times, and then dried in a vacuum drying oven at 60° C. for 24 h to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), 23.6 g.

[0059] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A monomer of a hyper-crosslinked polyamide-imide, characterized in that: The monomer structure of the hyper-crosslinked polyamide-imide is 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid) of formula (I):

2. A method for preparing a monomer of a hyper-crosslinked polyamide-imide, characterized in that: The method comprises the following steps: Step 1, reduction reaction: under nitrogen atmosphere, tri(4-nitrophenyl)amine and catalyst are dispersed in ethanol in a three-necked round-bottom flask in turn, placed in an oil bath and stirred, the sample is mixed evenly and then heated, when the reaction temperature is balanced and stable, hydrazine hydrate is added dropwise to the reaction system using a constant pressure funnel, and the drop rate is controlled to be 4-5s per drop to obtain a mixture A, and reacted under reflux for 1 to 3 days, and the plate is pressed at regular intervals to observe the reduction of the sample. After the reaction is completed, a sand core funnel is used to filter and remove the catalyst in the solution, and the filtrate is concentrated by a rotary evaporator to remove excess hydrazine hydrate to obtain a mixture B. Under stirring conditions, the mixture B is added to an ice-water mixture to obtain a light yellow precipitate, and the light yellow precipitate is thoroughly washed with distilled water to remove the unevaporated solvent and reducing agent, and after vacuum drying, dichloromethane column chromatography is performed to obtain a white solid powder, namely tri(4-aminophenyl)amine. The specific reaction is as follows: Step 2, buckling reaction: tris(4-aminophenyl)amine and trimellitic anhydride are dispersed in 20-60 mL of glacial acetic acid in a three-necked round-bottom flask under a nitrogen atmosphere, and mechanically stirred for 1-5 hours at room temperature. After the sample in the flask is evenly mixed, the reaction is heated for 12-60 hours, the product is filtered, washed with methanol 3-5 times, and then dried in a vacuum drying oven at 60° C. for 24 hours to obtain the 2,2',2"-(nitrile tris(phenyl-4,1-diyl)tris(1,3-dioxoisoindoline-5-carboxylic acid), and the specific reaction equation is as follows:

3. The method for preparing a monomer of a hyper-crosslinked polyamide-imide according to claim 2, characterized in that: In the step 1, the mass volume ratio of tri(4-nitrophenyl)amine, catalyst and ethanol is (1.9-18) g: (0.1-2) g: (25-250) mL.

4. The method for preparing a monomer of a hyper-crosslinked polyamide-imide according to claim 3, characterized in that: The catalyst is palladium on carbon.

5. The method for preparing a monomer of a hyper-crosslinked polyamide-imide according to claim 2, characterized in that: In the step 1, the temperature is slowly raised to 75-100° C., the reflux time is 1-2 hours, hydrazine hydrate is added dropwise, and the reaction is carried out at 75-100° C. for 15-30 hours. After the reaction is completed, the temperature is lowered to 20-40° C.

6. The method for preparing a monomer of a hyper-crosslinked polyamide-imide according to claim 2, characterized in that: In the step 2, the mass volume ratio of tri(4-aminophenyl)amine, trimellitic anhydride and glacial acetic acid is (1-7.5) g: (3-22) g: (20-100) mL.

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