A neutral polymeric bonding agent, its preparation method and uses

Abstract

The present invention discloses a neutral polymer bonding agent and a method for preparing the same. The bonding agent has a structure as shown in Formula I or Formula II. Furthermore, when the neutral polymer bonding agent has a structure as shown in Formula I, the resulting solid propellant exhibits significantly improved elongation at break. The neutral polymer bonding agent provided herein can be used in an ATPET-GAP curing system, significantly improving the mechanical properties of the solid propellant. #imgabs0#

Description

Technical Field

[0001] The present invention belongs to the technical field of propellant bonding agents, and specifically relates to a neutral polymer bonding agent (NPBA) for propellant and a preparation method thereof, and tests the mechanical properties of the NPBA bonding agent in propellant. Background Art

[0002] Bonding agents are functional additives in composite solid propellants. First discovered and applied to polyurethane systems by Oberth in 1969, his interfacial bonding theory garnered significant attention from propellant researchers. These agents offer advantages such as low dosage and improved interface performance between oxidizers and adhesives. As an auxiliary component in propellants, bonding agents can significantly enhance mechanical properties, improving aging and low-temperature performance.

[0003] Bonding agents are physically or chemically compatible with all components of the solid propellant, have no adverse effects on the properties of other propellant components, and possess a strong affinity for oxidants and binders. Bonding agents often contain highly polar groups such as -CN, -OH, -NR, and -CO- to prevent desiccation and enhance mechanical properties. Bonding agent molecules contain at least two different types of active groups: one type typically readily bonds with inorganic materials; the other type reacts with organic compounds, thereby strengthening the bond with the oxidant.

[0004] Bonding agents are primarily categorized into small molecule bonding agents and neutral bonding agents. Small molecule bonding agents primarily include polyamines, hydantoins, aziridine polyesters, polyols, alcoholamines, and silane compounds. Neutral bonding agents, designed by Kim CS, are designed to improve the interfacial adhesion between the binder and nitramine particles in NEPE propellants. They reduce manufacturing costs, enhance process safety, and significantly improve the mechanical properties of NEPE propellants.

[0005] The curing system of acetylene-terminated poly(ethylene oxide) tetrahydrofuran copolyether (ATPET) and glycidyl polyazide (GAP) is a typical example of click chemistry in the propellant field. This curing method can address the incompatibility issue between isocyanates and inorganic fillers such as ammonium dinitramide and boron in polyurethane adhesive curing systems. It also exhibits excellent thermal stability and a low glass transition temperature, making it valuable for applications in composite propellants.

[0006] To further enhance the interfacial interaction between the binder and solid oxidant in a curing system of acetylenically terminated polyethylene oxide copolyether (ATPET) and glycidyl azide (GAP), a bonding agent for this binder-curing system is urgently needed to further improve the mechanical properties of the solid propellant and mitigate dewetting. Therefore, the development of a neutral bonding agent for use in the ATPET-GAP curing system is highly desirable, as it would be of great significance and application value in improving the performance of solid propellants. Summary of the Invention

[0007] One object of the present invention is to provide a neutral polymer bonding agent and a method for preparing the same. Another object of the present invention is to provide the use of the neutral polymer bonding agent in an ATPET-GAP curing system. This invention addresses the existing ATPET and GAP adhesive curing system used in solid propellants by synthesizing a polymer material primarily composed of acrylonitrile. This polymer material serves as a neutral bonding agent and is used in solid propellants. This has significant implications for improving the mechanical properties of composite propellants and expanding their applications.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] In a first aspect, the present invention provides a neutral polymer bonding agent, characterized in that the bonding agent structure is as shown in Formula I or Formula II:

[0010]

[0011] x, y and z represent the proportions of the three polymer monomers respectively, x is selected from 70-75%, y is selected from 10-15%, and z is selected from 10-15%.

[0012] L is -OCO- or -COO-, R1 is selected from C 1-5 Straight chain / branched alkyl, the C 1-5 The alkyl group is a C1 alkyl group, a C2 alkyl group, a C3 alkyl group, a C4 alkyl group, or a C5 alkyl group.

[0013] Preferably, the R1 is selected from -CH3, -C2H5, propyl, isopropyl, butyl, and tert-butyl.

[0014] In the most preferred embodiment of the present invention, said R1 is -CH3.

[0015] Specifically, the neutral polymer bonding agent provided by the present invention has the following structure:

[0016]

[0017] In a second aspect, the present invention provides a method for preparing a neutral polymer bonding agent, characterized in that the method comprises the following steps:

[0018] In an organic solvent, acrylonitrile as the first monomer is mixed with the second monomer and the third monomer, an initiator and a chain transfer agent are added, and the mixture is reacted at 50-70° C. for 4-24 hours under inert gas protection, and a sedimentation agent is added for sedimentation, filtered, and dried to obtain a neutral polymer bonding agent or a neutral polymer bonding agent intermediate.

[0019] The second monomer is selected from methyl acrylate or vinyl acetate, and the third monomer is selected from maleic anhydride or propynyl acrylate.

[0020] When the third monomer is maleic anhydride, the above method produces a neutral polymer bonding agent intermediate, and the preparation method further comprises: dissolving the intermediate in DMF, adding propargylamine, reacting at 50-70°C under inert gas for 4-24 hours, adding a precipitant for precipitation, filtering, and drying to obtain the neutral polymer bonding agent. The molar mass ratio of the propargylamine to the maleic anhydride is (1-2):1.

[0021] The initiator is selected from azo initiators, organic peroxide initiators, and diacyl peroxides, and those skilled in the art can select the initiator according to actual conditions.

[0022] The chain transfer agent is selected from aliphatic mercaptan or dodecyl mercaptan.

[0023] The method for preparing the neutral polymer bonding agent provided by the present invention has no special limitation on the amount of the initiator and the chain transfer agent added, and those skilled in the art can add them according to conventional experience.

[0024] The sedimentation agent of the present invention is selected from alcohols, preferably methanol, ethanol, and dichloromethane. In a specific embodiment of the present invention, the sedimentation agent is ethanol.

[0025] In the preparation method provided by the present invention, the molar mass ratio of the first monomer, the second monomer and the third monomer is (7.5-8):1:(1-1.5).

[0026] In a third aspect, the present invention provides a solid propellant, comprising the following components in parts by mass: 15-20 parts of RDX, 30-35 parts of ammonium perchlorate, 18-20 parts of aluminum powder, 8-9 parts of 2,2-dinitropropanol formal, 8-9 parts of 2,2-dinitropropanol acetal, 10-12 parts of terminal alkynyl oxirane-tetrahydrofuran, 0.5-0.8 parts of glycidyl azide, 0.5-1 parts of cuprous bromide, and 0.5-1 parts of a neutral polymer bonding agent prepared by the present invention.

[0027] In a fourth aspect, the present invention provides an application of a neutral polymer bonding agent in an ATPET-GAP curing system.

[0028] The neutral polymer bonding agent provided by the present invention has the following beneficial technical effects:

[0029] (1) The neutral polymer bonding agent prepared by the present invention can be applied to azide-terminated alkynyl-terminated polytriazole polyether adhesive system solid propellant to improve the mechanical properties, interfacial effects and bonding effects of the solid propellant;

[0030] (2) The present invention can prepare polymer bonding agents with different molecular weights by adjusting different feed ratios and feed masses, thereby achieving different mechanical properties in the propellant;

[0031] (3) The preparation method provided by the present invention can be synthesized in a materials laboratory and has the advantages of mild reaction conditions, high preparation efficiency, and no pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Infrared analysis detection diagram of NPBA-1 intermediate.

[0033] Figure 2 TG curve of NPBA-1 intermediate.

[0034] Figure 3 GPC characterization analysis of NPBA-1 intermediate.

[0035] Figure 4 Infrared analysis of NPBA-1.

[0036] Figure 5 TG curves of NPBA-1 intermediate and bonding agent.

[0037] Figure 6 Infrared analysis detection diagram of NPBA-2 bonding agent.

[0038] Figure 7 TG curve of NPBA-2 intermediate.

[0039] Figure 8 NPBA-2 bonding agent 1 H-NMR spectrum.

[0040] Figure 9 Infrared spectrum of NPBA-3 intermediate.

[0041] Figure 10 TG curve of NPBA-3 intermediate.

[0042] Figure 11 NPBA-3 intermediate bonding agent 1 H-NMR spectrum.

[0043] Figure 12 IR curve of NPBA-3 bonding agent.

[0044] Figure 13 GPC curve of NPBA-3 bonding agent.

[0045] Figure 14 TG curve of NPBA-3 bonding agent.

[0046] Figure 15 NPBA-3 bonding agent 1 H-NMR curve. DETAILED DESCRIPTION

[0047] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0048] Preparation of bonding agent

[0049] Example 1

[0050] The synthetic route is as follows:

[0051]

[0052] 8g acrylonitrile (0.15mol), 2.85g maleic anhydride (0.03mol), and 2g vinyl acetate (0.02mol) were added to a nitrogen-protected three-necked flask, 30mL acetone was added as the reaction solvent, 0.5g azobisisobutyronitrile was added as the initiator, and 2-mercaptoethanol was used as the chain transfer agent. The reaction temperature was 60°C and the reaction time was 6h. After the reaction was completed, the ethanol was precipitated to obtain a pure product. The solid product obtained by filtration was the NPBA-1 intermediate. The product was spread on a petri dish and placed in a vacuum drying oven at 50°C for 4h to obtain a light yellow powdery solid product.

[0053] The infrared spectrum of NPBA-1 intermediate is as follows Figure 1 As shown, the infrared spectrum shows 2929cm -1 The stretching vibration absorption peak of -CH2 is 2970cm -1 The stretching vibration absorption peak of -CH3 is at 2240cm -1 The stretching vibration peak of -CN is at 1782cm -1 The antisymmetric stretching vibration absorption peak of carbonyl group is 1722cm -1 The symmetrical stretching vibration absorption peak of carbonyl is 1667 cm -1 The peak at 1452 cm is the stretching vibration peak of C=O on the ester group in vinyl acetate. -1 The peak of maleic anhydride, 1371 cm -1 The peak of vinyl acetate. 1230cm -1The stretching vibration absorption peak of -CN is at 1029cm -1 The peak is the stretching vibration absorption peak of the COC ether bond.

[0054] The thermal properties of NPBA-1 intermediate were analyzed using a NETZSCH TGA analyzer at a test temperature of 10 / min. The thermal analysis properties of NPBA are as follows: Figure 2 The thermal decomposition starting temperature of NPBA-1 intermediate is T 95％ =178.68℃, and the residual carbon content at 800℃ is 41.92%.

[0055] Waters GPC was used to analyze the molecular weight of the polymer, with PS as the standard. The results are as follows: Figure 3 The molecular weight of the NPBA-1 intermediate obtained by GPC test is M n =3542,M w =6991, PDI=1.97.

[0056] The molecular weight and elements of the NPBA-1 intermediate sample were analyzed based on the molecular weight calculated by GPC. The propargylamine dosage was calculated based on the mass of maleic anhydride. 1g of the NPBA-1 intermediate was used as the raw material, DMF was used as the solvent, and 0.3g of propargylamine (0.005mol) was added. The mixture was placed in a three-necked flask and, under high-purity nitrogen, the reaction temperature was set at 60°C for 6 hours. After the reaction was complete, the product was filtered and washed with ethanol after settling. The product was dried in a vacuum drying oven to obtain a gray-brown powdery solid product, NPBA-1.

[0057]

[0058] The product was analyzed and determined by Fourier transform infrared spectrometer. Figure 4 As shown, the wave number is 4000~400cm -1 , with a resolution of 4cm -1 3279cm -1 The stretching vibration peak of alkyne ≡CH is at 2929cm -1 The stretching vibration absorption peak of -CH2 is 2970cm -1 The stretching vibration absorption peak of -CH3 is 2242cm -1 The stretching vibration peak of -CN is at 1782cm -1 The antisymmetric stretching vibration absorption peak of carbonyl group is 1722cm -1 The symmetrical stretching vibration absorption peak of carbonyl is 1452 cm -1 The peak of maleic anhydride, 1371 cm -1 The peak of vinyl acetate is 1236 cm -1The stretching vibration absorption peak of -CN is 1029cm -1 The peak is the stretching vibration absorption peak of the COC ether bond.

[0059] The thermal performance of the prepared NPBA-1 was analyzed using a NETZSCH TGA analyzer at a test temperature of 10°C / min. The thermal analysis performance of NPBA is as follows: Figure 5 As shown. The thermal decomposition starting temperature of NPBA-1 is T 95％ =192.27℃, the residual carbon content at 800℃ is 44.38%.

[0060] Example 2

[0061] The synthetic route is as follows:

[0062]

[0063] A neutral bonding agent, NPBA-2, was prepared by reacting 8g (0.15 mol) of acrylonitrile, 2g (0.02 mol) of methyl acrylate, and 2.85g (0.03 mol) of propargyl acrylate using AIBN as the initiator and acetone as the solvent. 0.45g of 2-mercaptoethanol was added as a chain transfer agent. The reaction was carried out in a three-necked flask under high-purity nitrogen protection at 60°C for 8 hours. After completion, the product was precipitated with ethanol and dried to obtain a pale yellow powdery solid.

[0064] The products were analyzed by Fourier transform infrared spectrometer. Figure 6 As shown, the wave number is 4000~400cm -1 , with a resolution of 4cm -1 3294cm -1 The stretching vibration peak of the alkynyl group is at 660 cm -1 Bend vibration peak of alkynyl at 2934 cm -1 , 2865cm -1 The stretching vibration absorption peak of -CH2 and -CH is 1450cm -1 The bending vibration absorption peak of -CH in -CH2 is at 2970cm -1 The stretching vibration absorption peak of -CH3 is at 2240cm -1 The stretching vibration peak of -CN is at 1734cm -1 The stretching vibration peak of C=O on the ester group of propargyl acrylate is at 1667 cm -1 The stretching vibration peak of C=O on the ester group of methyl acrylate is at 1163 cm -1 The peak at is the stretching vibration peak of the CO bond in propargyl acrylate.

[0065] The thermal performance of the prepared NPBA-2 was analyzed by NETZSCH TGA analyzer at a test rate of 10℃ / min. The thermal analysis performance of NPBA-2 is as follows: Figure 7 As shown. The thermal decomposition starting temperature of NPBA-2 is T 95％ =271.25℃, and the residual carbon content at 800℃ is 29.97%.

[0066] The monomers were measured by Bruker NMR using DMSO as solvent. Figure 8 This is the H NMR spectrum of NPBA-2. The peak at δ = 2.50 is the residual DMSO-d6 solvent peak, and the peak at δ = 3.33 is the water peak. The absorption peak at δ = 4.74 is assigned to the hydrogen atom of the methylene group connected to the alkyne (g); the peak at δ = 3.67 is assigned to the hydrogen atom of the methyl group in the repeating unit methyl acrylate (i); the absorption peak at δ = 3.53 is assigned to the hydrogen atom of the alkynyl group in propargyl acrylate (h); the absorption peak at δ = 3.12 is assigned to the hydrogen atom of the -CH group in the polymer carbon chain (b, d, f); and the absorption peak at δ = 2.09 is assigned to the hydrogen atom of the -CH2 group in the polymer carbon chain (a, c, e).

[0067] Example 3

[0068] The synthetic route is as follows:

[0069]

[0070] The raw materials were: 0.38g of initiator AIBN, acetone as solvent, 2.14g (0.02mol) of maleic anhydride, 6g (0.11mol) of acrylonitrile, and 1.5g (0.02mol) of methyl acrylate as raw materials to prepare the neutral bonding agent NPBA-3 intermediate, with 2-mercaptoethanol as the chain transfer agent. The mixture was placed in a three-necked flask under high-purity nitrogen protection. The reaction temperature was 65°C and the reaction time was 9.5h. After the reaction was completed, the product was precipitated with ethanol to obtain a pure product. The solid product was filtered and dried in a vacuum drying oven at 50°C for 4h to obtain a light yellow powdery solid product.

[0071] The product was analyzed and determined by Fourier transform infrared spectrometer. Figure 9 As shown, the wave number is 4000~400cm -1 , with a resolution of 4cm -1 .2934cm -1 , 2865cm -1 The stretching vibration absorption peak of -CH2 and -CH is 2970cm -1 The stretching vibration absorption peaks of -CH3 are at 1450, 1375 cm -1 The stretching vibration peak of -C-CH3 is at 2240cm -1The stretching vibration peak of -CN is at 1782cm -1 The antisymmetric stretching vibration absorption peak of carbonyl group is 1722cm -1 、1667cm -1 The symmetrical stretching vibration absorption peak of carbonyl is 1667 cm -1 The stretching vibration peak of C=O on the ester group in methyl acrylate is at 1100 cm -1 The peak at is the stretching vibration peak of the CO bond in propargyl acrylate.

[0072] The thermal performance of the prepared NPBA-3 intermediate was analyzed by TGA analyzer at a test temperature of 10 / min. The thermal analysis performance is as follows: Figure 10 The thermal decomposition starting temperature of NPBA-3 intermediate is T 95％ =235℃, the residual carbon content at 800℃ is 33.68%.

[0073] Using DMSO as solvent, the NPBA-3 intermediate sample was measured by nuclear magnetic resonance hydrogen spectrum and carbon spectrum at room temperature using Bruker's nuclear magnetic resonance. 1 The H-NMR spectrum is shown in Figure 11: δ = 2.50 is the solvent peak of DMSO; the absorption peaks at δ = 3.0 to 3.3 are attributed to the hydrogen atoms in -CH on the polymer carbon chain segment (a, c); the absorption peaks at δ = 1.90 to 2.30 are attributed to the hydrogen atoms in -CH2 on the polymer carbon chain segment (b, d, g, e, f); δ = 3.69 ppm is the chemical shift with the methyl group (g) on the methyl acrylate component in NPBA-3.

[0074] The molecular weight and elements of the NPBA-3 intermediate sample were analyzed based on the molecular weight calculated by GPC. The propargylamine dosage was calculated based on the mass of maleic anhydride. Using 1g of the NPBA-3 intermediate as the raw material and DMF as the solvent, 0.22g of propargylamine (0.004mol) was added to a three-necked flask. Under high-purity nitrogen, the reaction temperature was set at 60°C for 6 hours. After the reaction was complete, the product was filtered and washed with ethanol to allow it to settle. The product was dried in a vacuum drying oven to obtain a gray-brown powdery solid product, NPBA-3.

[0075]

[0076] The infrared analysis of NPBA-3 is as follows Figure 12 As shown, 3286cm -1 The stretching vibration peak of C≡CH is at 2114 cm -1 The stretching vibration peak of C≡C was found, which confirmed that NPBA-3 was successfully synthesized.

[0077] Using DMF as the mobile phase, the molecular weight and molecular weight distribution of the polymer were calculated. The results are shown in Table 1. Figure 13 As shown. The number average molecular weight M of NPBA-3-M was analyzed by gel permeation chromatography. n =3800, molecular weight distribution PDI = 1.46, number average molecular weight M of NPBA-3 n =4010, molecular weight distribution PDI=1.61.

[0078] Table 1 GPC molecular weight data of NPBA-3

[0079] name <![CDATA[M n ]]> <![CDATA[M w ]]> <![CDATA[M p ]]> PDI NPBA-3-M 3805 5544 7660 1.46 NPBA-3 4011 6461 5819 1.61

[0080] Elemental analysis of NPBA-3 revealed that the sample contained 19.13% nitrogen, 62.5% carbon, 5.763% hydrogen, and 11.736% oxygen. Based on this, the weight content of each monomer was calculated to be: 63.63% AN, 12.00% methyl acrylate, and 22.71% maleic anhydride.

[0081] Table 2 Data of elements in NPBA-3

[0082]

[0083] Thermogravimetric curves such as Figure 14 As shown, the thermal decomposition starting temperature of NPBA-3 is T 95％ =268℃, the residual carbon content at 800℃ is 40.93%.

[0084] The prepared NPBA-3 was analyzed by nuclear magnetic resonance hydrogen and carbon spectra at room temperature using DMSO containing internal standard TMS. 1 H-NMR spectrum Figure 15 As shown: δ = 3.28 ppm is the hydrogen on the terminal alkynyl group (i), and 4.12 ppm is the hydrogen on the methylene group (h).

[0085] Preparation of solid propellants

[0086] The solid propellant is composed of the following raw materials by mass fraction: 20% RDX, 34% ammonium perchlorate, 18% aluminum powder, 8.25% 2,2-dinitropropanol formal, 8.25% 2,2-dinitropropanol acetal, 10% terminal alkynyl oxirane-tetrahydrofuran, 0.5% azide glycidyl ether, 0.5% cuprous bromide, and 0.5% bonding agent.

[0087] The above-mentioned bonding agents are the neutral polymer bonding agents NPBA-1, NPBA-2, NPBA-3 and NPBA-4 prepared in Examples 1-3, respectively. A blank control group is also set up, in which no bonding agent is added.

[0088] The above components were mixed and thickly cast into a PTFE mold. The mixture was then placed in a 50°C constant temperature water oven and cured for 7 days to prepare a solid propellant sample. The prepared propellant sample was cut into dumbbell shapes according to the national standard GB / T 528 and mechanical properties were analyzed using a universal material testing machine. The results are shown in the following table:

[0089] Table 3 Test results of mechanical properties of solid propellants

[0090] Elongation at break (%) Elastic modulus (MPa) Tensile strength (MPa) Blank control 32.76 4.32 0.44 NPBA-1 76.79 5.73 0.42 NPBA-2 39.49 5.85 0.42 NPBA-3 77.61 4.86 0.59

[0091] As can be seen from the data in the table above, the propellant strips without the addition of a bonding agent exhibited an elongation at break of 32.76%, an elastic modulus of 4.32 MPa, and a tensile strength of 0.44 MPa. Compared to propellant strips without the addition of a bonding agent, the addition of the bonding agent prepared in this invention significantly improved the mechanical properties of the propellant strips. For example, when NPBA-3 was used in solid propellant, the elongation at break was 77.61%, a 137% increase compared to the blank control; the elastic modulus was 4.86 MPa, a 12.5% increase compared to the blank control; and the tensile strength was 0.59 MPa, a 34% increase compared to the blank control.

[0092] In addition, the present invention technicians unexpectedly discovered that when the third monomer is maleic anhydride, the prepared bonding agent has a significant improvement in the elongation at break of the solid propellant. The technicians analyzed that, compared with the polymer monomer being propargyl acrylate, when the polymer monomer is maleic anhydride, the bonding agent molecular chain formed has a five-membered ring structure, and the cross-linkable alkynyl site is located on the five-membered ring structure. Compared with the chain monomer, the cross-linked structure is more stable, resulting in a propellant grain designed with this bonding agent having a higher elongation at break.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A neutral polymer bonding agent, characterized in that The bonding agent structure is shown in Formula I: x, y and z represent the proportions of the three polymer monomers, respectively, x is selected from 70-75%, y is selected from 10-15%, and z is selected from 10-15%; L is -OCO- or -COO-, R1 is selected from C 1-5 Straight chain / branched alkyl, the C 1-5 The alkyl group is a C1 alkyl group, a C2 alkyl group, a C3 alkyl group, a C4 alkyl group, or a C5 alkyl group.

2. The neutral polymer bonding agent according to claim 1, characterized in that The R1 is selected from -CH3, -C2H5, propyl, isopropyl, butyl, and tert-butyl.

3. The neutral polymer bonding agent according to claim 2, characterized in that The R1 is -CH3.

4. The neutral polymer bonding agent according to claim 3, characterized in that The structure of the neutral polymer bonding agent is as follows:

5. The method for preparing the neutral polymer bonding agent according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: In an organic solvent, acrylonitrile is used as a first monomer, mixed with a second monomer and a third monomer, an initiator and a chain transfer agent are added, and the mixture is reacted at 50-70° C. for 4-24 hours under inert gas protection, a precipitant is added for sedimentation, suction filtering, and drying to obtain a neutral polymer bonding agent intermediate; the neutral polymer bonding intermediate is dissolved in DMF, propargylamine is added, and the mixture is reacted at 50-70° C. for 4-24 hours under inert gas protection, a precipitant is added for sedimentation, suction filtering, and drying to obtain a neutral polymer bonding agent; the molar mass ratio of the propargylamine to maleic anhydride is (1-2):1; The second monomer is selected from methyl acrylate or vinyl acetate, and the third monomer is maleic anhydride.

6. The preparation method according to claim 5, characterized in that The molar mass ratio of the first monomer, the second monomer and the third monomer is (7.5-8):1:(1-1.5).

7. The preparation method according to claim 5, characterized in that The initiator is selected from azo initiators, organic peroxide initiators or diacyl peroxides; the chain transfer agent is selected from aliphatic mercaptan or dodecyl mercaptan.

8. The preparation method according to claim 5, characterized in that The sedimentation agent is selected from alcohols.

9. The preparation method according to claim 5, characterized in that The sedimentation agent is methanol or ethanol.

10. A solid propellant comprising the following components in parts by weight: 15-20 parts of RDX, 30-35 parts of ammonium perchlorate, 18-20 parts of aluminum powder, 8-9 parts of 2,2-dinitropropanol formal, 8-9 parts of 2,2-dinitropropanol acetal, 10-12 parts of terminal alkynyl oxirane-tetrahydrofuran, 0.5-0.8 parts of glycidyl azide, 0.5-1 parts of cuprous bromide, and 0.5-1 parts of the neutral polymer bonding agent according to any one of claims 1 to 4.

11. Use of the neutral polymer bonding agent according to any one of claims 1 to 4 in an ATPET-GAP curing system.

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