Polyimide resin with characteristics of low curing temperature and high heat resistance and preparation method thereof

Abstract

The invention belongs to the field of advanced materials, and particularly relates to polyimide resin with low curing temperature and high heat resistance and a preparation method thereof. According to the invention, pararosaniline is introduced into the molecular chain structure of the phenylacetylene-terminated polyimide resin, and the curing temperature of the phenylacetylene-terminated polyimide resin is reduced by changing the spatial distortion degree of the polyimide molecular chain and introducing free radicals to catalyze the curing process. The polyimide resin can be cured and molded at a relatively low temperature, and keeps excellent heat resistance and mechanical properties. The forming temperature of the high-performance polyimide and the composite material thereof is effectively reduced, so that the manufacturing difficulty and cost are reduced, and the preparation method has important application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of advanced materials, and in particular relates to a polyimide resin with low curing temperature and high heat resistance and a preparation method thereof. Background Art

[0002] Polyimides are a class of aromatic heterocyclic polymers containing imide groups on their backbones. They possess outstanding thermal and mechanical properties and are widely used. Thermosetting polyimides are formed by curing and crosslinking polyimide prepolymers terminated with reactive groups at high temperatures. They have a high temperature resistance rating, with long-term operating temperatures exceeding 300°C and short-term operating temperatures exceeding 500°C. Among them, thermosetting polyimides terminated with phenylethynyl end-capping agents exhibit superior thermal and oxidative stability. Furthermore, the chain extension reaction of the acetylene bond allows prepolymers with lower designed molecular weights to be converted to higher molecular weights, thereby improving the mechanical properties of the material. Precisely because of these properties, phenylethynyl end-capped polyimides have become a hot topic and focus of research in high-temperature resistant matrix resins, with widespread applications in aerospace, electronics, electrical engineering, and other high-temperature environments, including structural materials, coatings, and adhesives.

[0003] However, the thermal polymerization of phenylethynyl groups in phenylethynyl-terminated polyimide resins requires high temperatures to activate the breakage and rearrangement of triple bonds, resulting in excessively high processing temperatures and specific process conditions. This leads to the following technical drawbacks: 1) Phenylacetylene groups are susceptible to thermal decomposition or side reactions at high temperatures, causing material performance degradation and internal microporous defects; 2) High-temperature molding processes place stringent demands on processing equipment, significantly increasing energy costs; 3) High-temperature melt fluidity is poor, making it difficult to control and resulting in a narrow curing reaction window, which can easily lead to internal stress accumulation, poor interfacial bonding, and dimensional deviations in the finished product; 4) Co-molding compatibility with heat-sensitive materials is limited, restricting the expansion of application scenarios and increasing manufacturing costs and difficulty. Therefore, there is an urgent need to develop a more environmentally friendly and economical processing technology that can lower its curing temperature, reduce manufacturing costs, and improve production efficiency.

[0004] Currently, research on low-temperature curing of phenylethynyl polyimide resins mainly focuses on catalytic curing, which promotes the curing process of phenylethynyl groups by introducing catalysts. Professor Zhang Chunhua's team at Harbin Institute of Technology used a composite catalyst of isopropyl peroxide and cobalt naphthenate to catalyze the cross-linking reaction of phenylethynyl-terminated polyimide resins, reducing the curing temperature of phenylethynyl polyimide to 300°C. In subsequent research, a thiocarbonyl disulfide compound was introduced to achieve catalytic curing of phenylethynyl-terminated polyimide, reducing the curing temperature to 260.4°C. [1]However, the organic / inorganic composite catalytic curing strategy requires that the PI resin and the catalyst be dissolved in a common good solvent, thus placing stringent requirements on the matching selection of the solvent. In the present invention, the molecular spatial structure of the phenylethynyl polyimide resin is designed and regulated through molecular design to achieve low-temperature curing molding of the phenylethynyl-terminated polyimide, providing a new solution for the low-temperature curing strategy of polyimide resin.

[0005] [1] Qian, Y., Yang, J., & Zhang, C. (2021). Phenylethynyl terminated polyimideresin / carbon fiber composite catalytic cured at 300℃ and its performance. Journal of Adhesion Science and Technology, 35(23), 2652–2663. Summary of the Invention

[0006] In view of the problems of the prior art, the present invention provides a polyimide resin with low curing temperature and high heat resistance and a preparation method thereof.

[0007] The invention discloses an application of a benzene ring-containing triamine monomer in the preparation of a phenylethynyl-terminated polyimide resin.

[0008] Preferably, the benzene ring-containing triamine monomer is selected from at least one of melamine, 1,3,5-triaminobenzene, rosaniline, 4,4'4"-triaminotriphenylamine, 4,4'4"-(benzene-1,3,5-triyltri(oxy))triphenylamine, and 1,3,5-tris(4-aminophenyl)benzene.

[0009] The present invention also provides a functionally modified phenylethynyl-terminated polyimide resin, which is prepared from the following raw materials in parts by weight:

[0010] 10-50 parts of triamine monomer containing benzene ring,

[0011] 10-50 parts of anhydride monomer,

[0012] 10-50 parts of dianhydride monomer,

[0013] 10-50 parts of end-capping agent,

[0014] 5-100 parts of dehydrating agent,

[0015] 5-100 parts of organic base catalyst.

[0016] Preferably, it is made from the following raw materials in parts by weight:

[0017] 24.23 parts of benzene ring-containing triamine monomer,

[0018] 11.85 parts of anhydride monomer,

[0019] 11.77 parts of dianhydride monomer,

[0020] 19.86 parts of end-capping agent,

[0021] 98.01 parts of dehydrating agent,

[0022] 75.84 parts of organic base catalyst

[0023] Preferably, the benzene ring-containing triamine monomer is selected from at least one of melamine, 1,3,5-triaminobenzene, rosaniline, 4,4'4"-triaminotriphenylamine, 4,4'4"-(benzene-1,3,5-triyltri(oxy))triphenylamine, and 1,3,5-tris(4-aminophenyl)benzene.

[0024] Preferably, the acid anhydride monomer is a monofunctional acid anhydride monomer or a difunctional acid anhydride monomer; the monofunctional acid anhydride monomer or the difunctional acid anhydride monomer is selected from at least one of phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, trimellitic anhydride, 2,3-naphthalene dicarboxylic anhydride, 1,2-naphthalene dicarboxylic anhydride, 4,7-dimethylisobenzofuran-1,3-dione, 2,3-anthracene dicarboxylic anhydride, and 5-hydroxyisobenzofuran-1,3-dione;

[0025] And / or, the dianhydride monomer is selected from 2,3,3',4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3,4,4-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, hexafluorodianhydride, bisphenol A diether dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 1 , at least one of 2,4,5-cyclohexanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, (4-phthalic anhydride) formyloxy-4-phthalate, bis[(3,4-dianhydride)phenyl]terephthalate, p-phenylene-diphthalic acid trimellitic dianhydride, and 4,4'-phenylenedioxydiphthalic anhydride;

[0026] and / or, the end-capping agent is selected from 4-phenylethynylphthalic anhydride;

[0027] And / or, the dehydrating agent is selected from at least one of acetic anhydride, propionic anhydride, and trifluoroacetic anhydride;

[0028] And / or, the organic base catalyst is at least one selected from pyridine, triethylamine, dimethylethanolamine, and picoline.

[0029] Preferably, the monofunctional acid anhydride monomer or difunctional acid anhydride monomer is selected from phthalic anhydride;

[0030] And / or, the dianhydride monomer is selected from 2,3,3',4'-biphenyltetracarboxylic dianhydride.

[0031] Preferably, the degree of polymerization n of the functionally modified phenylethynyl-terminated polyimide resin is selected from 1, 3, 5, 7, and 9.

[0032] The present invention also provides a method for preparing the functionally modified phenylethynyl-terminated polyimide resin, comprising the following steps:

[0033] Step 1, reacting a benzene ring-containing triamine monomer with the acid anhydride monomer to obtain compound 1;

[0034] Step 2, polymerizing Compound 1 with the dianhydride monomer, and then adding a capping agent to react to obtain Compound 2;

[0035] Step 3, reacting compound 2 with a dehydrating agent and an organic base catalyst, and vacuum drying to obtain a functionally modified phenylethynyl-terminated polyimide resin prepolymer;

[0036] Step 4: hot-pressing the functionally modified phenylethynyl-terminated polyimide resin prepolymer to obtain the functionally modified phenylethynyl-terminated polyimide resin.

[0037] Preferably, in step 1, the solvent of the reaction is N-methylpyrrolidone;

[0038] And / or, in step 1, the reaction temperature is 20-30° C., and the reaction time is 1-3 h;

[0039] And / or, in step 2, the polymerization reaction time is 1-3 hours; the temperature for adding the end-capping agent to carry out the reaction is 20-30° C., and the reaction time is 1-3 hours;

[0040] And / or, in step 3, the reaction temperature is 70-90° C. and the reaction time is 22-26 h;

[0041] And / or, in step 3, the vacuum drying procedure is 140-160° C. for 10-14 h, and 170-190° C. for 5-7 h.

[0042] The present invention also provides the use of the functionally modified phenylethynyl-terminated polyimide resin in the preparation of structural materials, coatings, and adhesives for aerospace, electronics, electrical and high-temperature environments.

[0043] For prepolymers, the degree of polymerization (DP) refers to the average number of monomer units in the molecule. In other words, it indicates how many monomers are chemically linked together in a prepolymer chain. A higher DP indicates more monomers in the chain and a correspondingly higher molecular weight.

[0044] The present invention functionally modifies a phenylethynyl-terminated polyimide resin by introducing rosaniline as a triamine monomer into the molecular chain structure of the phenylethynyl-terminated polyimide resin to synthesize phenylethynyl-terminated polyimide resins with different degrees of polymerization. This reduces the curing temperature of the phenylethynyl-terminated polyimide resins while maintaining good heat resistance and thermomechanical properties. Therefore, the rosaniline-containing phenylethynyl-terminated polyimide resins provided by the present invention have advantages such as reduced manufacturing costs, lowered energy consumption, and environmental friendliness, and have promising application prospects.

[0045] Obviously, based on the above contents of the present invention, according to common technical knowledge and customary means in this field, without departing from the above basic technical ideas of the present invention, other various forms of modifications, replacements or changes can be made.

[0046] The following further describes the above content of the present invention in detail through specific embodiments in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a diagram of the preparation process of phenylethynyl-terminated polyimide resin containing rose aniline.

[0048] Figure 2 The infrared spectra of phenylethynyl-terminated polyimide resins containing rosaniline with different degrees of polymerization.

[0049] Figure 3 (a) DSC curves of PEPA monomer and 4-phenylethynylphthalic anhydride physically blended with 5% mass fraction of rosaniline (PEPA-5% PA); (b) DSC curves of phenylethynyl-terminated polyimide resins containing rosaniline at different polymerization degrees (n=1, 3, 5, 7, 9).

[0050] Figure 4 This is a graph showing the thermogravimetric loss results of a phenylethynyl-terminated polyimide resin containing rosaniline with a degree of polymerization of n=3.

[0051] Figure 5 This is a graph showing the thermomechanical properties of a phenylethynyl-terminated imide resin containing rosaniline with a degree of polymerization of n=3.

[0052] Figure 6 The compressive strength of the phenylethynyl polyimide resin containing rosaniline with a polymerization degree of n=3. DETAILED DESCRIPTION

[0053] In the following examples and experimental examples, reagents and raw materials not specifically described are all commercially available.

[0054] The structure of the repeating unit of the phenylethynyl-terminated polyimide resin prepolymer of the present invention is as follows:

[0055]

[0056] Example 1 Preparation of a phenylethynyl-terminated polyimide resin containing rosaniline having a degree of polymerization n=1

[0057] 1. Preparation of phenylethynyl-terminated polyimide resin prepolymer containing rose aniline with a degree of polymerization of n=1

[0058] Preparation process as Figure 1 As shown, first, 24.23 g (0.08 mol) of rosaniline (PA) and 11.85 g (0.08 mol) of phthalic anhydride (PTA) were reacted with N-methylpyrrolidone (NMP) as solvent at 25° C. under nitrogen protection for 2 h to obtain a phenyl-grafted diamine. Subsequently, 11.77 g (0.06 mol) of 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA) was added to the reaction system and polymerized for 2 h. 19.86 g (0.08 mol) of 4-phenylethynylphthalic anhydride (4-PEPA) was then added for end-capping. The reaction was carried out at 25° C. for 2 h under nitrogen protection to obtain an intermediate product. Acetic anhydride (98.01 g) and pyridine (75.84 g) were then added to the reaction system. The reaction time was 24 h at a reaction temperature of 80° C. to complete chemical imidization. The mixture was poured into 1 L of deionized water to precipitate a large amount of precipitate. The precipitate was washed 3-5 times with 500 ml of deionized water and then vacuum dried at 150° C. for 12 h and 180° C. for 6 h to obtain a phenylethynyl-terminated polyimide resin prepolymer containing rosaniline with a degree of polymerization n=1. The formula is shown in Table 1.

[0059] Table 1 Formulation of phenylethynyl-terminated polyimide resin prepolymer containing rosaniline with degree of polymerization n=1

[0060]

[0061] 2. Preparation of phenylethynyl-terminated polyimide resin containing rosaniline with a degree of polymerization of n=1

[0062] The obtained rosaniline-containing phenylethynyl-terminated polyimide resin prepolymer was placed in a mold and hot-pressed at 300° C. (30 min, 0 MPa) and 320° C. (90 min, 5 MPa) under vacuum assistance to obtain a rosaniline-containing phenylethynyl-terminated polyimide resin with a degree of polymerization of n=1.

[0063] Example 2 Preparation of Phenylacetylene-Terminated Polyimide Resins Containing Rosaniline When the Degree of Polymerization n is 3, 5, 7, and 9

[0064] The preparation method of the phenylethynyl-terminated polyimide resin containing rosaniline with a degree of polymerization of n=1 is the same as that in Example 1, except that the amounts of raw materials used are different; specifically, phenylethynyl-terminated polyimide resins containing rosaniline with different degrees of polymerization (n=3, 5, 7, 9) were prepared according to Table 2.

[0065] Table 2 Formulations of phenylethynyl-terminated polyimide resins containing rosaniline with different degrees of polymerization (n=3, 5, 7, 9)

[0066]

[0067] The technical solution of the present invention is further illustrated by experiments below.

[0068] The phenylethynyl-terminated polyimide resins containing rosaniline and having different polymerization degrees (n=1, 3, 5, 7, 9) used in this experimental example were prepared according to the method of Example 1-2.

[0069] Experimental Example 1: Characterization of phenylethynyl-terminated polyimide resins containing rosaniline with different degrees of polymerization

[0070] 1. Experimental Methods

[0071] Infrared spectroscopy

[0072] Instrument model: American Nicoletis50

[0073] Wavelength range: 4000~400cm -1

[0074] Resolution: better than 0.09cm –1

[0075] Scan speed: 65(at 16cm -1 ), 95(at 32cm -1 )

[0076] 2. Experimental Results

[0077] like Figure 2As shown in the figure, the infrared spectra of different polymerized phenylethynyl-terminated polyimide resins containing rose aniline are slightly different, at 2210 cm -1 The peak at 1778cm is the alkynyl peak, corresponding to the alkynyl in the 4-PEPA structure. -1 , 1721cm -1 , 1380cm -1 and 778cm -1 The characteristic peaks corresponding to the imide rings indicated the successful synthesis of the polyimide structure.

[0078] Experimental Example 2: Curing Temperature of Phenylacetylene-Terminated Polyimide Resin Containing Rosaniline

[0079] 1. Experimental Methods

[0080] Differential scanning calorimetry (DSC) was used with a heating rate of 10°C / min and a temperature range of 120-450°C.

[0081] Physical blending of 5% mass fraction of rosaniline with 4-phenylethynylphthalic anhydride (PEPA-5% PA): 9.5g of 4-phenylethynylphthalic anhydride (PEPA) was weighed and blended with 0.5g of rosaniline (PA). The curing temperature of the blend was then tested by DSC.

[0082] 2. Experimental Results

[0083] like Figure 3 As shown in (a), the curing temperature of PEPA is 365℃, and the curing temperature of PEPA-5% PA has only a weak curing peak at 280℃, and the main curing peak is still at 365℃, indicating that the PA added in the blend has a certain catalytic effect on its curing; Figure 3 As shown in (b), after the introduction of rosaniline into the molecular structure of phenylethynyl-terminated polyimide, its curing temperature is significantly reduced. The degree of reduction of the curing temperature is different at different polymerization degrees. When the polymerization degree (n=1) is reached, the curing temperature is greatly reduced and can reach 321.9°C.

[0084] Experimental Example 3: Thermogravimetric Behavior of Phenylacetylene-Terminated Polyimide Resin Containing Rosaniline I. Experimental Method

[0085] Thermogravimetric analyzer (TGA) was used with a heating rate of 10°C / min and a temperature range of 200-800°C.

[0086] The phenylethynyl-terminated polyimide resin containing rosaniline having a degree of polymerization of n=3 was tested after being cured at its peak curing temperature.

[0087] 2. Experimental Results

[0088] like Figure 4The 5% thermal weight loss temperature under N2 atmosphere is 537.50℃, and the 5% thermal weight loss temperature under Air atmosphere is 499.66℃, indicating that the phenylethynyl-terminated polyimide resin containing rosaniline still has good heat stability on the basis of low curing temperature and has great application potential.

[0089] Experimental Example 4: Dynamic Thermomechanical Behavior of Phenylacetylene-Terminated Polyimide Resin Containing Rosaniline

[0090] 1. Experimental Methods

[0091] A dynamic thermomechanical analyzer (TGA) was used with a heating rate of 5°C / min, a temperature range of 250-450°C, and a bending mode.

[0092] The phenylethynyl-terminated imide resin containing rosaniline with a degree of polymerization of n=3 was cured at its peak curing temperature (327° C.) and tested.

[0093] 2. Experimental Results

[0094] like Figure 5 The glass transition temperature of the cured resin is 380.4℃, indicating that it still maintains good thermomechanical properties at a low curing temperature.

[0095] Experimental Example 5: Compressive Strength of Phenylacetylene-Terminated Polyimide Resin Containing Rosaniline

[0096] 1. Experimental Methods

[0097] The test was carried out using a universal material testing machine and reference standard GB / T 2567-2021 "Test method for properties of resin castings". The sample size was 10*10*25mm cube.

[0098] The formula for calculating compressive strength is:

[0099] Where, σ: represents the compressive strength, the unit is Pascal (Pa);

[0100] F: represents the compressive force acting on the object, the unit is Newton (N);

[0101] S: represents the cross-sectional area of ​​the object under force, the unit is square meter (m 2 ).

[0102] 2. Experimental Results

[0103] The force-displacement curve of the phenylethynyl polyimide resin containing rose aniline with a polymerization degree of n=3 was tested after being cured at its peak curing temperature (327°C) for 2 hours. Figure 6As shown, the maximum force during compression was greater than 5084.74 N. According to the compressive strength calculation formula, the compressive strength was >50 MPa. After multiple measurements, the compressive strength was 52.35 ± 14.88 MPa. These results demonstrate that the phenylethynylene-based polyimide resin containing rosaniline prepared by the present invention exhibits excellent mechanical properties (compressive strength greater than 50 MPa) despite low curing temperature.

[0104] Therefore, the present invention introduces rosaniline into the molecular structure of phenylethynyl-terminated polyimide, which can significantly reduce the curing temperature of the phenylethynyl-terminated polyimide resin. The phenylethynyl-terminated polyimide resin still maintains good heat stability, thermomechanical properties and mechanical properties at a low curing temperature. At the same time, the phenylethynyl-terminated polyimide resin containing rosaniline provided by the present invention has the advantages of low manufacturing cost and high production efficiency.

Claims

1. Use of a benzene ring-containing triamine monomer in the preparation of a phenylethynyl-terminated polyimide resin.

2. The use according to claim 1, characterized in that: The benzene ring-containing triamine monomer is selected from at least one of melamine, 1,3,5-triaminobenzene, rosaniline, 4,4'4"-triaminotriphenylamine, 4,4'4"-(benzene-1,3,5-triyltri(oxy))triphenylamine, and 1,3,5-tris(4-aminophenyl)benzene.

3. A functionally modified phenylethynyl-terminated polyimide resin, characterized in that: It is made from the following raw materials in parts by weight: 10-50 parts of triamine monomer containing benzene ring, 10-50 parts of anhydride monomer, 10-50 parts of dianhydride monomer, 10-50 parts of end-capping agent, 5-100 parts of dehydrating agent, 5-100 parts of organic base catalyst.

4. The functionally modified phenylethynyl-terminated polyimide resin according to claim 3, characterized in that: It is made from the following raw materials in parts by weight: 24.23 parts of benzene ring-containing triamine monomer, 11.85 parts of anhydride monomer, 11.77 parts of dianhydride monomer, 19.86 parts of end-capping agent, 98.01 parts of dehydrating agent, 75.84 parts of organic base catalyst 5. The functionally modified phenylethynyl-terminated polyimide resin according to claim 3 or 4, characterized in that: The benzene ring-containing triamine monomer is selected from at least one of melamine, 1,3,5-triaminobenzene, rosaniline, 4,4'4"-triaminotriphenylamine, 4,4'4"-(benzene-1,3,5-triyltri(oxy))triphenylamine, and 1,3,5-tris(4-aminophenyl)benzene.

6. The functionally modified phenylethynyl-terminated polyimide resin according to claim 3 or 4, characterized in that: The acid anhydride monomer is a monofunctional acid anhydride monomer or a difunctional acid anhydride monomer; the monofunctional acid anhydride monomer or the difunctional acid anhydride monomer is selected from at least one of phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, trimellitic anhydride, 2,3-naphthalene dicarboxylic anhydride, 1,2-naphthalene dicarboxylic anhydride, 4,7-dimethylisobenzofuran-1,3-dione, 2,3-anthracene dicarboxylic anhydride, and 5-hydroxyisobenzofuran-1,3-dione; And / or, the dianhydride monomer is selected from 2,3,3',4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3,4,4-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, hexafluorodianhydride, bisphenol A diether dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 1 , at least one of 2,4,5-cyclohexanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, (4-phthalic anhydride) formyloxy-4-phthalate, bis[(3,4-dianhydride)phenyl]terephthalate, p-phenylene-diphthalic acid trimellitic dianhydride, and 4,4'-phenylenedioxydiphthalic anhydride; and / or, the end-capping agent is selected from 4-phenylethynylphthalic anhydride; And / or, the dehydrating agent is selected from at least one of acetic anhydride, propionic anhydride, and trifluoroacetic anhydride; And / or, the organic base catalyst is at least one selected from pyridine, triethylamine, dimethylethanolamine, and picoline.

7. The functionally modified phenylethynyl-terminated polyimide resin according to claim 6, characterized in that: The monofunctional acid anhydride monomer or difunctional acid anhydride monomer is selected from phthalic anhydride; And / or, the dianhydride monomer is selected from 2,3,3',4'-biphenyltetracarboxylic dianhydride.

8. The functionally modified phenylethynyl-terminated polyimide resin according to any one of claims 3 to 7, characterized in that: The polymerization degree n of the functionally modified phenylethynyl-terminated polyimide resin is selected from 1, 3, 5, 7, and 9.

9. The method for preparing the functionally modified phenylethynyl-terminated polyimide resin according to any one of claims 3 to 8, characterized in that: The steps include: Step 1, reacting a benzene ring-containing triamine monomer with the acid anhydride monomer to obtain compound 1; Step 2, polymerizing Compound 1 with the dianhydride monomer, and then adding a capping agent to react to obtain Compound 2; Step 3, reacting compound 2 with a dehydrating agent and an organic base catalyst, and vacuum drying to obtain a functionally modified phenylethynyl-terminated polyimide resin prepolymer; Step 4: hot-pressing the functionally modified phenylethynyl-terminated polyimide resin prepolymer to obtain the functionally modified phenylethynyl-terminated polyimide resin.

10. Use of the functionally modified phenylethynyl-terminated polyimide resin according to any one of claims 3 to 8 in the preparation of structural materials, coatings, and adhesives for aerospace, electronics, electrical applications, and high-temperature environments.

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