A nano-aluminum-based adhesive system, a preparation method and application thereof

Abstract

The present application belongs to the technical field of energetic materials and nanocomposites, and particularly relates to a nano-aluminum-based bonding system, a preparation method and application thereof. A titanate catalyst is coordinated with a polydentate ligand to form a catalyst complex, which is then mixed with an end-functionalized binder to protect the active end groups of the binder. Through a catalytic decomposition reaction, nano-aluminum particles are generated in situ in the binder phase. The surface of the newly generated aluminum particles chemisorbs with the protected end groups of the binder, and a nano-aluminum-based bonding system is obtained after purification. The present application realizes in-situ synthesis and synchronous coating of nano-aluminum in the binder, effectively solves the problems of easy agglomeration, easy oxidation and difficult dispersion of nano-aluminum, and directly obtains a nano-aluminum-based bonding system with high active aluminum content and low viscosity.

Description

Technical Field

[0001] This invention relates to the field of energetic materials technology, specifically to a nano-aluminum-based adhesive system, its preparation method, and its application. Background Technology

[0002] Nano-aluminum powder, due to its extremely high energy density, reactivity, and combustion efficiency, has significant application value in fields such as solid propellants and composite energetic materials. Combining nano-aluminum powder with binders to form stable composite materials—nano-aluminum-based adhesive systems—can effectively improve its dispersibility, processability, and safety in use, representing a key technological approach to enhancing the overall performance of energetic materials.

[0003] Currently, the preparation of nano-aluminum-based adhesive systems mainly involves first preparing nano-aluminum powder separately through methods such as physical vapor deposition, high-energy ball milling, and chemical reduction, then performing surface coating modification or dispersion pretreatment on the nano-aluminum powder, and finally physically blending the modified nano-aluminum powder with adhesives and additives. However, the above methods have many insurmountable drawbacks: nano-aluminum powder has a large specific surface area and high surface energy, making it extremely prone to oxidation during preparation, storage, and post-processing, resulting in a significant decrease in active aluminum content; nano-aluminum powder particles are prone to spontaneous agglomeration, and even after surface coating modification, it is still difficult to achieve uniform dispersion when blended with adhesives, affecting the stability and combustion performance of the system; the addition of high-content nano-aluminum powder will cause a sharp increase in the viscosity of the adhesive system, resulting in poor fluidity and difficulty in meeting the requirements of casting, molding, and other processing techniques; and it is difficult to fundamentally solve the problems of agglomeration and secondary oxidation of nano-aluminum powder, so the dispersion uniformity and processing performance of the resulting composite material are still not ideal.

[0004] Therefore, developing a nano-aluminum-based adhesive system that combines low viscosity, high dispersion, high activity, and resistance to oxidation has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a nano-aluminum-based adhesive system, its preparation method, and its application. The nano-aluminum particles in the nano-aluminum-based adhesive system of this invention can be highly dispersed in the adhesive, and possess low viscosity, high activity, and are not easily oxidized.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a nano-aluminum-based adhesive system, comprising the following steps: S1. The titanate catalyst is mixed with the multidentate organic ligand to carry out the first coordination reaction, thereby obtaining the titanate multidentate organic ligand complex. S2. The catalyst complex is mixed with the end-functionalized binder to carry out a second coordination reaction to obtain an end-protected binder mixture; the end-functionalized binder contains hydroxyl and / or carboxyl groups. S3. The end-group protected adhesive mixture is mixed with an aluminum hydride amine complex solution and subjected to a catalytic decomposition reaction to obtain a nano-aluminum-based adhesive system.

[0007] Preferably, the titanate catalyst is tetraisopropyl titanate; and the multidentate organic ligand is a β-diketone compound.

[0008] Preferably, the molar ratio of the titanate catalyst to the multidentate organic ligand is 1:1~2; the temperature of the first coordination reaction is 10~30℃ and the time is 20~40min.

[0009] Preferably, the end-functionalized adhesive is hydroxyl-terminated polybutadiene and / or carboxyl-terminated polybutadiene; the molar ratio of the catalyst complex to all end groups in the end-functionalized adhesive is >1:1; The temperature of the second coordination reaction is 10~30℃ and the time is 80~120min.

[0010] Preferably, the concentration of the aluminum hydride amine complex solution is 0.01~0.1 mol / L; The method for preparing the aluminum hydride amine complex solution includes the following steps: Aluminum trichloride, tertiary amine compounds, lithium aluminum hydride, and organic solvents are mixed and subjected to a coordination reaction to obtain a solution of aluminum hydride amine complexes.

[0011] Preferably, the temperature of the catalytic decomposition reaction is 60~120℃ and the time is 3~5h.

[0012] Preferably, during or after the catalytic decomposition reaction, the reaction further includes adding small molecule compounds containing hydroxyl or carboxyl groups to the reaction system. Alternatively, after the catalytic decomposition reaction, a binder may be added to the reaction system.

[0013] The present invention provides a nano-aluminum-based adhesive system prepared by the above preparation method, comprising an end-functionalized adhesive and nano-aluminum particles dispersed in the end-functionalized adhesive; the viscosity range of the nano-aluminum-based adhesive system is 5000~10000 mPa·s, and the diameter of the nano-aluminum particles is 50~500 nm.

[0014] Preferably, the mass percentage of nano-aluminum particles in the nano-aluminum-based adhesive system is 5-50%; The particle size of the nano-aluminum particles is 50~500nm; This invention provides the application of the above-mentioned nano-aluminum-based adhesive system in energetic materials.

[0015] This invention provides a method for preparing a nano-aluminum-based adhesive system. First, a titanate catalyst is coordinated with a multidentate ligand to form a titanate multidentate organic ligand complex, which is then mixed with an end-functionalized adhesive to protect the active end groups of the adhesive. Next, the end-group-protected adhesive mixture is mixed with an aluminum hydride amine complex solution, and through a catalytic decomposition reaction, nano-aluminum particles are generated in situ within the adhesive phase. The surface of the newly formed aluminum particles undergoes chemical adsorption with the protected adhesive end groups, forming a coating structure, thus obtaining the nano-aluminum-based adhesive system. This invention, by coordinating and protecting the active end groups of the adhesive and catalytically decomposing the aluminum hydride amine complex in situ within the adhesive phase, intervenes in the nucleation and growth process of nano-aluminum particles. This allows for the direct synthesis of a low-viscosity nano-aluminum-based adhesive system with highly dispersed nano-aluminum particles in the continuous adhesive phase, achieving in-situ synthesis and simultaneous coating of nano-aluminum in the adhesive. This effectively solves the problems of easy agglomeration, easy oxidation, and difficulty in dispersion of nano-aluminum in the matrix. The results of the examples show that the mass content of nano-aluminum particles in the nano-aluminum-based adhesive system obtained by the present invention is 5-50%, the viscosity is 5000-10000 mPa·s, and the active aluminum content in the nano-aluminum particles is 75%-95%.

[0016] This invention provides a nano-aluminum-based adhesive system, comprising an end-functionalized adhesive and nano-aluminum particles dispersed in the end-functionalized adhesive. This invention utilizes the end groups of the adhesive to chemically adsorb and coat the surface of the nano-aluminum particles, thereby maintaining higher dispersion of the nano-aluminum particles, reducing their oxidation resistance, and simultaneously achieving higher activity and lower viscosity.

[0017] This invention provides the application of the aforementioned nano-aluminum-based binder system in energetic materials. The nano-aluminum-based binder system provided by this invention possesses high dispersibility, low viscosity, and high activity, making it suitable for the preparation of energetic materials. This system achieves high dispersion and coating of nano-aluminum particles within the continuous binder phase, balancing the high reactivity of aluminum particles with the system's low viscosity and good rheological properties. Compared to traditional nano-aluminum powder, this system significantly reduces particle agglomeration and surface deactivation, improves the uniform distribution of particles in the matrix, and enhances subsequent mixing, casting, and molding processes. In the preparation of energetic materials, this system helps improve component dispersion uniformity, reaction consistency, and processing adaptability, while mitigating the oxidative deactivation of nano-aluminum during storage and processing, demonstrating promising industrial application prospects. Attached Figure Description

[0018] Figure 1 Image of the crude product of the nano-aluminum-based adhesive system; Figure 2 This is a photograph of the nano-aluminum-based adhesive system after centrifugation of the crude product. Figure 3 This is a scanning electron microscope image of the hydroxyl-terminated polybutadiene-coated aluminum nanoparticles from Example 1. Figure 4 EDS spectra of the nano-aluminum-based adhesive system; Figure 5 This is a scanning electron microscope image of the hydroxyl-terminated polybutadiene-coated aluminum nanoparticles from Example 2. Detailed Implementation

[0019] This invention provides a method for preparing a nano-aluminum-based adhesive system, comprising the following steps: S1. The titanate catalyst is mixed with the multidentate organic ligand to carry out the first coordination reaction, thereby obtaining the titanate multidentate organic ligand complex. S2. The catalyst complex is mixed with the end-functionalized binder to carry out a second coordination reaction to obtain an end-protected binder mixture; the end-functionalized binder contains hydroxyl and / or carboxyl groups. S3. The end-group protected adhesive mixture is mixed with an aluminum hydride amine complex solution and subjected to a catalytic decomposition reaction to obtain a nano-aluminum-based adhesive system.

[0020] This invention involves mixing a titanate catalyst with a multidentate organic ligand to perform a first coordination reaction, yielding a titanate multidentate organic ligand complex. In this invention, the titanate catalyst is preferably tetraisopropyl titanate; the multidentate organic ligand is preferably a β-diketone compound, more preferably acetylacetone. In this invention, the molar ratio of the titanate catalyst to the multidentate organic ligand is preferably 1:1 to 2, more preferably 1:2. This invention does not have special requirements for the mixing method; any mixing method well-known in the art can be used, such as stirring. The temperature of the first coordination reaction is preferably 10 to 30°C, more preferably 20°C; the time is preferably 20 to 40 minutes, more preferably 30 minutes; the atmosphere of the first coordination reaction is preferably an inert atmosphere, more preferably an argon atmosphere.

[0021] After obtaining the catalyst complex, the present invention mixes the catalyst complex with an end-functionalized binder and performs a second coordination reaction to obtain an end-protected binder mixture. In the present invention, the end-functionalized binder preferably includes hydroxyl and / or carboxyl groups; the end-functionalized binder is preferably hydroxyl-terminated polybutadiene and / or carboxyl-terminated polybutadiene, more preferably hydroxyl-terminated polybutadiene; in the present invention, the molecular weight of the hydroxyl-terminated polybutadiene and carboxyl-terminated polybutadiene is preferably 2000-5000, more preferably 3000-4000.

[0022] In this invention, the mixing is preferably performed by first dissolving the end-functionalized binder in a solvent, and then adding the catalyst complex for mixing. In this invention, the solvent is preferably mesitylene, and the mesitylene is preferably subjected to dehydration and deoxygenation treatment, after which the water and oxygen content in the mesitylene is both below 1 ppm.

[0023] In this invention, the molar ratio of the catalyst complex to all end groups in the end-functionalized binder is preferably >1:1, more preferably 1.1~4:1. In this invention, the temperature of the second coordination reaction is preferably 10~30℃, more preferably 20℃; the time is preferably 80~120 min, more preferably 100~120 min; the atmosphere for the second coordination reaction is preferably an inert atmosphere, more preferably an argon atmosphere. This invention utilizes the coordination complexation reaction between titanium ions in the catalyst complex and active hydrogen atoms in the binder end groups to achieve protection of the binder end groups.

[0024] After obtaining the end-group protected adhesive mixture, the present invention mixes the end-group protected adhesive mixture with an aluminum hydride amine complex solution and performs a catalytic decomposition reaction to obtain a nano-aluminum-based adhesive system. In the present invention, the concentration of the aluminum hydride amine complex solution is preferably 0.01~0.1 mol / L, more preferably 0.03~0.05 mol / L; the volume ratio of the end-group protected adhesive mixture solution to the aluminum hydride amine complex solution is preferably 1~7:10, more preferably 2:3.

[0025] In this invention, the mass ratio of aluminum in the end-functionalized binder to the aluminum hydride amine complex solution is preferably greater than the theoretical grafting density of binder molecules on the surface of the aluminum nanoparticles. Specifically, the mass ratio of aluminum nanoparticles (Al) to the end-functionalized binder is greater than 2:10. In this invention, the mixing method is preferably stirring, with a stirring speed preferably of 500-2500 rpm, more preferably 1000-2000 rpm; the temperature of the catalytic decomposition reaction is preferably 60-120℃, more preferably 80-90℃, and further preferably 80℃; the time is preferably 3-5 h, more preferably 4 h; the atmosphere of the catalytic decomposition reaction is preferably an inert atmosphere, more preferably an argon atmosphere. This invention utilizes a catalyst complex to catalyze the decomposition of aluminum hydride amine complexes, generating active aluminum atoms in situ, which then nucleate and grow in the binder phase. Simultaneously, the nascent aluminum nanoparticles undergo chemical adsorption with the protected binder end groups, effectively avoiding the problems of easy agglomeration and oxidation of the aluminum nanoparticles.

[0026] In this invention, during or after the catalytic decomposition reaction, it is preferable to add a small molecule compound containing hydroxyl or carboxyl groups to the reaction system. In this invention, the small molecule compound is preferably methanol or formic acid, more preferably methanol. In this invention, the volume ratio of the titanate catalyst to the small molecule compound is preferably ≥3.7:1, more preferably 4:1. By adding a small molecule compound containing hydroxyl or carboxyl groups, the substituents of the small molecule compound can react with the catalyst complex to generate a low-boiling-point titanium compound, thereby desorbing the catalyst complex complexed with the binder end groups, facilitating subsequent purification and separation.

[0027] In this invention, after the catalytic decomposition reaction, a binder is preferably added to the resulting reaction system. The binder preferably includes hydroxyl-terminated polybutadiene and / or carboxyl-terminated polybutadiene. In this invention, the binder is preferably dissolved in a solvent beforehand, preferably mesitylene. The concentration of the binder solution is preferably 0.00125~0.007 g / mL, more preferably 0.00125 g / mL. In this invention, the mass of the binder is preferably 0~16 times the mass of aluminum trichloride in the aluminum hydride amine complex solution, more preferably 5~10 times. After adding the binder, the present invention preferably involves stirring for 4~20 h, more preferably 10~20 h.

[0028] In this invention, after the catalytic decomposition reaction is completed, a purification process is preferably included. The purification process typically involves concentration, washing, filtration, and drying performed sequentially. In this invention, the concentration is preferably centrifugal concentration, with a preferred centrifugal speed of 4000-8000 rpm, more preferably 6000 rpm; the preferred time is 3-10 min, more preferably 5 min; the washing process is preferably sequential washing with anhydrous acetone and methanol; the methanol washing temperature is preferably below 0°C; the drying process is preferably vacuum drying, with a preferred vacuum degree of -0.08 to -0.1 MPa, more preferably -0.1 MPa; the preferred temperature is 20-30°C, more preferably 30°C; and the preferred time is 8-24 h, more preferably 12-24 h. This invention does not have special requirements for the filtration method; any filtration method well-known to those skilled in the art can be used. This invention removes catalyst complexes from the system through purification, ensuring no catalyst residue in the system; the freed binder end groups firmly adsorb nano-aluminum particles, ensuring system stability.

[0029] In this invention, the method for preparing the aluminum hydride amine complex solution preferably includes the following steps: Aluminum trichloride, tertiary amine compounds, lithium aluminum hydride, and organic solvents are mixed and subjected to a coordination reaction to obtain a solution of aluminum hydride amine complexes.

[0030] In this invention, the aluminum trichloride is preferably anhydrous aluminum trichloride; the tertiary amine compound is preferably triethylamine; the solvent is preferably mesitylene, which is preferably treated to remove water and oxygen, and more preferably has a water and oxygen content of less than 1 ppm; the atmosphere for the coordination reaction is preferably an inert atmosphere, and more preferably an argon atmosphere. In this invention, the molar ratio of aluminum trichloride to lithium aluminum hydride is preferably 1:3~6, more preferably 1:5~6; the molar ratio of aluminum trichloride to the tertiary amine compound is selected as 1:4~8, more preferably 1:6~8; the mass-volume ratio of aluminum trichloride to mesitylene is preferably 0.05~0.5g:60mL, more preferably 0.1~0.3g:60mL. In this invention, the aluminum hydride amine complex is prepared by the following reaction equation: AlCl3 + 3LiAlH4 + 4NR3 → 4H3Al·NR3 + 3LiCl.

[0031] In this invention, the mixing is preferably performed by first dissolving aluminum trichloride and a tertiary amine compound in a solvent, and then adding lithium aluminum hydride for a heated reaction. In this invention, the mixing method is preferably stirring, with a stirring speed preferably of 1000-3000 rpm, more preferably 1500-2000 rpm; the dissolution temperature is preferably 10-70℃, more preferably 30-60℃; the heating reaction temperature is preferably 100-120℃, more preferably 120℃; and the heating reaction time is preferably 1.5-2.5 h, more preferably 2 h. In this invention, after the coordination reaction, the supernatant is preferably collected after standing to obtain an aluminum hydride amine complex solution.

[0032] This invention provides a nano-aluminum-based adhesive system, comprising an end-functionalized adhesive and nano-aluminum particles dispersed in the end-functionalized adhesive. In this invention, the mass fraction of the nano-aluminum particles is preferably 5-50%, more preferably 10-40%, and even more preferably 20-30%; the particle size of the nano-aluminum particles is preferably 50-500 nm, more preferably 100-300 nm; the viscosity range of the nano-aluminum-based adhesive system is preferably 5000-10000 mPa·s, more preferably 6000-8000 mPa·s. In this invention, the end-functionalized adhesive coats the surface of the nano-aluminum particles. This invention utilizes the end groups of the adhesive to coat the surface of the nano-aluminum particles through chemical adsorption, which allows the nano-aluminum particles to maintain higher dispersion, are less prone to oxidation, and simultaneously possess higher activity and lower viscosity.

[0033] This invention provides the application of the aforementioned nano-aluminum-based adhesive system in the preparation of energetic materials. The nano-aluminum-based adhesive system of this invention can be applied to the preparation of energetic materials such as HTPB composite solid propellants, nano-aluminothermic agents, and high-energy explosives, helping to improve the component dispersion uniformity, reaction consistency, and processing adaptability of these materials, while simultaneously mitigating the oxidative deactivation of nano-aluminum during storage and processing.

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0035] Example 1 In this embodiment, hydroxyl-terminated polybutadiene is used as a binder to synthesize a nano-aluminum-based adhesive system. The specific steps are as follows: 1. Reagent pretreatment and atmosphere control: All operations were carried out in the Schlenk line system after three cycles of vacuuming and argon purging. All solvents used were dehydrated and deoxygenated with trimethylbenzene, and the water and oxygen content of the reaction system was less than 1 ppm.

[0036] 2. Preparation of catalyst complex: 39 μL of tetraisopropyl titanate was pipetted into a micro-reaction flask, and 27 μL of acetylacetone (molar ratio of 1:2) was added dropwise to the reaction flask. The mixture was stirred to obtain a Ti(ACAC)2(Oi-Pr)2 catalyst complex solution.

[0037] 3. End-group protection: Add 0.052 g of hydroxyl-terminated polybutadiene (molecular weight 3500) to a beaker, add 10 mL of mesitylene to the beaker to dissolve the hydroxyl-terminated polybutadiene, and obtain a hydroxyl-terminated polybutadiene solution. Add the Ti(ACAC)2(Oi-Pr)2 catalyst complex solution obtained in step 2 to the above hydroxyl-terminated polybutadiene solution, and stir at 20 °C for 120 min until completely miscible to obtain an end-group protected binder mixture, and let it stand at room temperature for later use.

[0038] 4. Preparation of aluminum precursor solution: In a three-necked flask containing 60 mL of dried trimethylbenzene, under argon protection, add 0.05 g of anhydrous AlCl3 and heat to 60 °C with stirring. Slowly add 0.42 mL of triethylamine until the AlCl3 is completely dissolved; heat the solution to 120 °C and add 0.085 g of lithium aluminum hydride (AlCl3 to lithium aluminum hydride molar ratio 1:6, AlCl3 to triethylamine molar ratio 1:8), and maintain stirring for 2 hours. The byproduct LiCl precipitates at the bottom, and the supernatant is collected to obtain H3Al·NEt3 solution (0.03 mmol / L).

[0039] 5. In-situ synthesis reaction: Under argon gas protection, the end-group protected binder mixture obtained in step 3 was injected into the above H3Al·NEt3 solution using a syringe. The volume ratio of the end-group protected binder mixture to the H3Al·NEt3 solution was 2:3. The system temperature was maintained at 80℃, and stirring was carried out continuously at a stirring rate of 1000 rpm. It was observed that the system color gradually deepened, accompanied by the release of hydrogen gas. After stirring for 4 hours, a large amount of gray-black precipitate appeared in the system, and the color no longer changed. Heating was stopped, and after the temperature dropped to room temperature, hydroxyl-terminated polybutadiene was added to the system. The binder was dissolved in the solvent trimethylbenzene in advance. The mass of the added binder was 13 times the mass of aluminum chloride. Stirring was carried out for 4 hours to obtain the crude product.

[0040] 6. Purification and impurity removal: After the reaction is completed, the sample is concentrated by centrifugation at 8000 rpm for 10 minutes, then washed and filtered with anhydrous acetone and methanol (below 0℃) in sequence to remove impurities and unreacted raw materials. The sample is placed in a vacuum drying oven and dried for 8 hours at a vacuum of -0.1 MPa and a temperature of 30℃ until the sample reaches constant weight, thus obtaining the nano-aluminum-based adhesive system.

[0041] Figure 1 This is a mesitylene solution that produces a large amount of black precipitate after the in-situ synthesis reaction. Figure 2 To purify and remove impurities from the undried nano-aluminum-based adhesive system.

[0042] Figure 3 This is a scanning electron microscope (SEM) image of the hydroxyl-terminated polybutadiene-coated aluminum nanoparticles in the nano-aluminum-based adhesive system obtained in Example 1. Figure 3 It can be seen that the products are mainly spherical or near-spherical in appearance, with a particle size distribution of 50~400nm.

[0043] Figure 4 The image shows the EDS energy spectrum of aluminum nanoparticles in the aluminum nano-based adhesive system. Figure 4 It can be seen that the aluminum content of the nano-aluminum-based adhesive system is over 90%, while the oxygen content is extremely low. This indicates that most of the aluminum particles are successfully coated by HTPB, thus avoiding oxidation, and that the system has a high content of active aluminum.

[0044] Example 2 In this embodiment, hydroxyl-terminated polybutadiene is used as a binder to synthesize a nano-aluminum-based adhesive system. The specific steps are as follows: 1. Reagent pretreatment and atmosphere control: All operations were carried out in the Schlenk line system after three cycles of vacuuming and argon purging. All solvents used were dehydrated and deoxygenated with trimethylbenzene, and the water and oxygen content of the reaction system was less than 1 ppm.

[0045] 2. Preparation of catalyst complex: 39 μL of tetraisopropyl titanate was pipetted into a micro-reaction flask, and 27 μL of acetylacetone (molar ratio of 1:2) was added dropwise to the reaction flask. The mixture was stirred to obtain a Ti(ACAC)2(Oi-Pr)2 catalyst complex solution.

[0046] 3. End-group protection: Add 0.052 g of hydroxyl-terminated polybutadiene (molecular weight 3500) to a beaker, add 10 mL of mesitylene to the beaker to dissolve the hydroxyl-terminated polybutadiene, and obtain a hydroxyl-terminated polybutadiene solution. Add the Ti(ACAC)2(Oi-Pr)2 catalyst complex solution obtained in step 2 to the above hydroxyl-terminated polybutadiene solution, and stir at 20 °C for 120 min until miscible to obtain an end-group protected binder mixture, and let it stand at room temperature for later use.

[0047] 4. Preparation of aluminum precursor solution: In a three-necked flask containing 60 mL of dried trimethylbenzene, under argon protection, add 0.05 g of anhydrous AlCl3 and heat to 60 °C with stirring. Slowly add 0.42 mL of triethylamine until the AlCl3 is completely dissolved; heat the solution to 120 °C and add 0.043 g of lithium aluminum hydride (molar ratio of aluminum chloride to lithium aluminum hydride is 1:3), and maintain stirring for 2 hours. The byproduct LiCl precipitates at the bottom, and the supernatant is collected to obtain H3Al·NEt3 solution.

[0048] 5. In-situ synthesis reaction: Under argon gas protection, the end-group protected binder mixture obtained in step 3 was injected into H3Al·NEt3 solution through a syringe. The volume ratio of the end-group protected binder mixture to H3Al·NEt3 solution was 2:3. The system temperature was maintained at 80℃, and the mixture was stirred continuously at a stirring rate of 1000 rpm. It was observed that the color of the system gradually deepened, accompanied by the release of hydrogen gas. After stirring for 4 hours, a large amount of gray-black precipitate appeared in the system, and the color no longer changed. Heating was stopped, and the crude product was obtained.

[0049] 6. Purification and impurity removal: After the reaction is completed, the sample is concentrated by centrifugation at 8000 rpm for 10 minutes, then washed and filtered with anhydrous acetone and methanol (below 0℃) in sequence to remove impurities and unreacted raw materials. The sample is placed in a vacuum drying oven and dried for 8 hours at a vacuum of -0.1 MPa and a temperature of 30℃ until the sample reaches constant weight, thus obtaining the nano-aluminum-based adhesive system.

[0050] Figure 5 This is a scanning electron microscope (SEM) image of the hydroxyl-terminated polybutadiene-coated aluminum nanoparticles in the nano-aluminum-based adhesive system obtained in Example 2. Figure 5 It can be seen that the products are mainly spherical or near-spherical in appearance, with a particle size distribution of 50~400nm.

[0051] Performance testing The active aluminum content in the nano-aluminum-based binder system was determined using the gas volumetric method. The gas volumetric method works by calculating the active aluminum content based on the reaction of elemental Al in the sample with NaOH to release hydrogen gas, and then calculating the volume of hydrogen gas. The specific experimental principle follows the national standard GB / T 3169.1-1982, "Chemical Analysis Methods for Aluminum Powder: Determination of Active Aluminum by Gas Volumetric Method," with an allowable error of 0.8%. The test results are shown in Table 1.

[0052] The viscosity of the nano-aluminum-based adhesive system was determined using the rotation method. The rotation method calculates the dynamic viscosity of the fluid by measuring the viscous torque experienced by a rotor immersed in the fluid rotating at a constant speed. The specific principle is based on the national standard GB / T 10247-2008, "Viscosity Measurement Method". The test results are shown in Table 1.

[0053] Table 1 Performance Test Results

[0054] It can be seen that the mass content of nano-aluminum in the nano-aluminum-based adhesive system obtained by the present invention is 5.46~43.48%, the viscosity is 5.1~9.1 Pa·s, and the active aluminum content of the active nano-aluminum particles is 89~91.1%.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nano-aluminum-based adhesive system, characterized in that, Includes the following steps: S1. The titanate catalyst is mixed with the multidentate organic ligand to carry out the first coordination reaction, thereby obtaining the titanate multidentate organic ligand complex. S2. The catalyst complex is mixed with the end-functionalized binder to carry out a second coordination reaction to obtain an end-protected binder mixture; the end-functionalized binder contains hydroxyl and / or carboxyl groups. S3. The end-group protected adhesive mixture is mixed with an aluminum hydride amine complex solution and subjected to a catalytic decomposition reaction to obtain a nano-aluminum-based adhesive system.

2. The preparation method according to claim 1, characterized in that, The titanate catalyst is tetraisopropyl titanate; the multidentate organic ligand is a β-diketone compound.

3. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of the titanate catalyst to the multidentate organic ligand is 1:1~2; the temperature of the first coordination reaction is 10~30℃ and the time is 20~40min.

4. The preparation method according to claim 1, characterized in that, The end-functionalized binder is hydroxyl-terminated polybutadiene and / or carboxyl-terminated polybutadiene; the molar ratio of the catalyst complex to all end groups in the end-functionalized binder is >1:

1. The temperature of the second coordination reaction is 10~30℃ and the time is 80~120min.

5. The preparation method according to claim 1, characterized in that, The concentration of the aluminum hydride amine complex solution is 0.01~0.1 mol / L; The method for preparing the aluminum hydride amine complex solution includes the following steps: Aluminum trichloride, tertiary amine compounds, lithium aluminum hydride, and organic solvents are mixed and subjected to a coordination reaction to obtain a solution of aluminum hydride amine complexes.

6. The preparation method according to claim 1 or 5, characterized in that, The catalytic decomposition reaction is carried out at a temperature of 60~120℃ for 3~5 hours.

7. The preparation method according to claim 1, characterized in that, During or after the catalytic decomposition reaction, the process also includes adding small molecule compounds containing hydroxyl or carboxyl groups to the reaction system. Alternatively, after the catalytic decomposition reaction, a binder may be added to the reaction system.

8. The nano-aluminum-based adhesive system prepared by the preparation method according to any one of claims 1 to 7, characterized in that, It includes an end-functionalized adhesive and nano-aluminum particles dispersed in the end-functionalized adhesive; the viscosity range of the nano-aluminum-based adhesive system is 5000~10000 mPa·s, and the diameter of the nano-aluminum particles is 50~500 nm.

9. The nano-aluminum-based adhesive system according to claim 8, characterized in that, The mass percentage of nano-aluminum particles in the nano-aluminum-based adhesive system is 5-50%. The particle size of the nano-aluminum particles is 50~500nm.

10. The application of the nano-aluminum-based adhesive system according to claim 8 or 9 in energetic materials.

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