Aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material and method of making

Abstract

The application discloses an aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material and a preparation method thereof. The aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material is prepared by modifying aluminum powder with perfluoropolyether (PFPE), coating a polymer shell layer, and finally preparing the aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material through a cooling crystallization method. The polymer layer can prevent the PFPE from falling off, improve the combustion efficiency, and prevent the oxidant AP from directly contacting the reducing agent Al powder, thereby improving the use safety, and the preparation cost is low and the toxicity is small. Meanwhile, the particle size and the morphology of the Al / PFPE / polymer / AP composite particles prepared by the cooling crystallization method can be adjusted within a certain range.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, specifically relating to an aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material and its preparation method. Background Technology

[0002] Aluminum is widely used as a fuel additive component in solid propellants and explosives due to its high energy density. It has a melting point of 660.32℃ and a density of 2.7 g / cm³. 3 Al is widely distributed in nature and is an easily obtainable raw material. Ammonium perchlorate (AP), as an oxidant, is widely used in solid propellant applications due to its high oxygen content, strong oxidizing power, and good chemical stability. In solid propellants, Al powder, as a reducing agent, is often combined with the oxidant AP to prepare Al / AP composite energetic materials.

[0003] Patent CN105665718A discloses a method for preparing nano-Al / AP energetic composite particles, using a solvent evaporation method. The advantage is that it increases the contact area between Al powder and AP, while simultaneously solving the problem of easy agglomeration of nano-aluminum powder. Patent CN106365934A discloses a method for preparing AP / Ni / Al composite materials, utilizing the cooling and deposition of a supersaturated AP solution to prepare AP / Ni / Al composite materials, thus improving the material's exothermic performance. The drawback is that the direct coating of Al / Ni with AP makes safety difficult to guarantee.

[0004] In practical applications of aluminum powder, the high surface energy of the aluminum powder surface easily leads to the formation of a dense alumina shell, which reduces the activity of the aluminum powder and requires higher energy to burn the prepared Al / AP composite particles. Related literature indicates that adding fluorides to aluminum powder can effectively disrupt the alumina shell and improve combustion performance.

[0005] Patents CN115141071A, CN115947640A, CN116655441A, and CN115180997A utilize different types of fluorides to coat and modify aluminum powder. During combustion, the fluorine in the fluoride preferentially reacts with alumina, causing the alumina shell to dissolve and releasing the active aluminum from the aluminum powder, thus improving the combustion efficiency of the composite particles. However, a drawback is that the fluoride is prone to peeling off during subsequent use. Summary of the Invention

[0006] To address the shortcomings of existing technologies in the subsequent use of Al powder coated with perfluoropolyether (PFPE), this invention provides an aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material and its preparation method. The aluminum powder is modified with perfluoropolyether (PFPE), then coated with a polymer shell, and finally the aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material is obtained by a cooling crystallization method.

[0007] The present invention adopts the following technical solution:

[0008] An energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate is prepared by the following steps:

[0009] (1) Preparation of Al / PFPE composite particles: Dissolve perfluoropolyether in an organic solvent, add aluminum powder, and evaporate the solvent to obtain Al / PFPE composite particles;

[0010] The ratio of perfluoropolyether, organic solvent, and aluminum powder is 0.1g:10mL:1g;

[0011] (2) Preparation of Al / PFPE / polymer composite particles: pH adjuster is added to water, solvent is added under heating and stirring conditions, then organic polymer monomer and Al / PFPE composite particles are added, and the reaction is continued to be heated and stirred. After the reaction is completed, Al / PFPE / polymer composite particles are obtained by centrifugation, washing and drying.

[0012] The ratio of pH adjuster, water, solvent, organic polymer monomer, and Al / PFPE composite particles is 0.5 mL: 29.5 mL: 6 mL: 0.2 g: 0.5 g;

[0013] (3) Preparation of Al / PFPE / polymer / ammonium perchlorate composite particles: Al / PFPE / polymer composite particles are completely dispersed in a low-temperature saturated ammonium perchlorate solution, and then a high-temperature saturated ammonium perchlorate solution is added dropwise. After the addition is completed, the mixture is aged, filtered and dried to obtain an aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material.

[0014] The ratio of Al / PFPE / polymer composite particles, low-temperature saturated ammonium perchlorate solution, and high-temperature saturated ammonium perchlorate solution is 0.5g:50mL:20mL.

[0015] Further, in step (1), the organic solvent is selected from toluene, diethyl ether, hydrofluoroether, ethanol, cyclohexane, acetone and dichloromethane.

[0016] Further, in step (2), the pH adjuster is selected from hydrochloric acid, sodium hydroxide, tris(hydroxymethyl)aminomethane hydrochloride, azobisisobutyronitrile, isophorone diisocyanate, diethylenetriamine, tetrabutylammonium bromide, pyridine acetate and sodium dihydrogen phosphate.

[0017] Further, in step (2), the solvent is selected from water, toluene, acetone, ethanol, cyclohexanone, isopropanol and propylene oxide.

[0018] Further, in step (2), the organic polymer monomer is selected from dopamine hydrochloride, methyl methacrylate, hydroxyl-terminated polybutadiene, dicyclohexylmethane diisocyanate and epoxy resin.

[0019] Furthermore, in step (2), the heating temperature is 20~70℃, the stirring speed is 100r / min~1500r / min, and the reaction time is 10min~16h.

[0020] Furthermore, in step (3), the temperature of the low-temperature saturated ammonium perchlorate solution is 0~50℃, and the temperature of the high-temperature saturated ammonium perchlorate solution is 40~90℃.

[0021] This invention utilizes perfluoropolyether (PFPE) to modify aluminum powder. PFPE is a synthetic polymer that is a colorless, odorless, and transparent liquid at room temperature. It is a high-molecular-weight compound composed of fluorine, carbon, and oxygen atoms, possessing a unique chemical structure. This structure endows PFPE with many unique properties. Due to its high fluorine content and chemical stability, this property is utilized to coat aluminum powder, and a polymer layer is then coated onto the surface of the modified aluminum powder. The polymer not only prevents the PFPE layer from peeling off during subsequent use, but also effectively maintains the stability of the composite energetic material.

[0022] The organic polymer monomers selected are dopamine, methyl methacrylate, hydroxyl-terminated polybutadiene, dicyclohexylmethane diisocyanate, or epoxy resin. Dopamine is a sticky biomaterial that can self-polymerize on the surface of other materials under certain conditions to form a polydopamine shell, exhibiting strong adhesion and high chemical reactivity. Methyl methacrylate, through polymerization to form polymethyl methacrylate, also possesses stickiness and relatively stable properties. Hydroxyl-terminated polybutadiene, dicyclohexylmethane diisocyanate, and epoxy resin are also inherently sticky, making them compatible with the polymer shell. Therefore, one of the above materials was selected as the polymer layer to develop a multilayer core-shell Al / PFPE / polymer / AP composite particle. PFPE can remove the Al2O3 shell, improving the combustion performance of Al powder. Simultaneously, the presence of the polymer layer prevents the PFPE layer from being damaged, further enhancing the combustion performance of the composite particle. This is of great significance for the development of high-performance propellants.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] ① By using in-situ polymerization to coat the surface of PFPE-modified aluminum powder with an organic polymer, the PFPE layer can be effectively prevented from falling off, improving combustion efficiency. At the same time, the presence of the organic polymer can avoid direct contact with oxidants and prevent reactions during the application of aluminum powder, thus providing a safety guarantee for the application of aluminum powder.

[0025] ② Experimental data show that adding polymer-coated Al / PFPE composite particles has the function of protecting the PFPE layer, and the addition of polymer forms an organic polymer layer on the surface of modified aluminum powder, which can increase the specific surface area of ​​modified aluminum powder and is beneficial to subsequent applications.

[0026] ③ By using a cooling crystallization method, a high-temperature AP saturated solution and a low-temperature solution are set up. Al / PFPE / polymer / AP composite particles are prepared by controlling the temperature gradient and the droplet method. The advantage is that the particle size and morphology of the prepared composite particles can be adjusted within a certain range. Attached Figure Description

[0027] Figure 1 SEM image of the Al / PFPE / polymer composite particles prepared in Example 1.

[0028] Figure 2 EDS image of the Al / PFPE / polymer composite particles prepared in Example 1.

[0029] Figure 3 The image shows the FTIR spectrum of the Al / PFPE / polymer composite particles prepared in Example 1.

[0030] Figure 4 The image shows the XRD pattern of the Al / PFPE / polymer composite particles prepared in Example 1.

[0031] Figure 5 The image shows a SEM image of the Al / PFPE / polymer / AP composite energetic material prepared in Example 1. Implementation

[0032] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0034] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1

[0035] A method for preparing an energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate includes the following steps:

[0036] (1) Preparation method of Al / PFPE composite particles: Dissolve 0.1g PFPE in 10 mL hydrofluoroether, add 1g Al powder, and evaporate the solvent to obtain Al / PFPE composite particles.

[0037] (2) Preparation method of Al / PFPE / polymer composite particles: Take a 100mL single-necked flask, add 0.5mL of tris(hydroxymethyl)aminomethane hydrochloride buffer (concentration of 1 mol / L), then add 29.5mL of distilled water, and stir for 10min (850r / min) under a 40℃ water bath until it is completely dispersed. Then add 6mL of isopropanol and stir for another 30min to mix evenly. Then add 0.2g of dopamine hydrochloride and 0.5g of Al / PFPE composite particles. Under a 40℃ water bath, the reaction solution changes from colorless and transparent to light pink, and then to black. The reaction time is 16h. After the reaction is completed, centrifuge (rpm=9000, t=10min), wash with water 3 times, then wash with anhydrous ethanol 3 times, and dry after treatment to obtain Al / PFPE / polymer composite particles.

[0038] (3) Preparation method of Al / PFPE / polymer / ammonium perchlorate composite energetic material: Al / PFPE / polymer / AP composite particles with adjustable particle size and morphology were prepared based on Al / PFPE / polymer composite particles by cooling crystallization method. By setting up a set of 50 mL 85℃ saturated AP solution and a set of 50 mL 5℃ saturated AP solution, 0.5 g Al / PFPE / polymer composite particles were completely dispersed in 50 mL 5℃ saturated AP solution. Then, 20 mL 5℃ saturated AP solution was slowly added to 50 mL low temperature saturated AP solution at a dropping rate of 5 mL / min. After the dropping was completed, the mixture was aged for 5 min, filtered and dried to obtain Al / PFPE / polymer / AP composite energetic material.

[0039] Figure 1 The image shows an SEM image of Al / PFPE / polymer composite particles. The image contains many spherical particles with rough surfaces. The surface of pure Al powder is relatively smooth. The rough surface may be due to polydopamine molecules polymerized in situ.

[0040] Figure 2The image shows the EDS diagram of the Al / PFPE / polymer composite particles. Elemental analysis of the surface revealed that C, O, and F elements are uniformly distributed on the Al particle surface. The C element originates solely from polydopamine, indicating that polydopamine was successfully coated onto the Al / PFPE surface, consistent with the SEM analysis results.

[0041] Figure 3 Curves (a) and (b) are the FTIR spectra of Al / PFPE / polymer composite particles and polydopamine monomer particles, respectively. Figure 3 It can be known that 3411 cm -1 and 1607 cm -1 The absorption peak at 652 cm⁻¹ corresponds to the stretching vibration of -OH groups on the Al powder surface and in polydopamine, indicating that the composite particles contain polydopamine. -1 The broad, strong absorption peak at this point corresponds to the stretching vibration of the Al-O bond in amorphous Al₂O₃. The peak at 1123 cm⁻¹ in curve a... -1 1242 cm -1 1340 cm -1 The absorption peaks appearing at the positions correspond to the stretching vibrations of -CF-, -CF2-, and -CF3, respectively. The substances corresponding to these absorption peaks are perfluorinated polyethers, further proving that the Al / PFPE / polymer composite particles were successfully prepared.

[0042] Figure 4 Curves (a) and (b) are the XRD patterns of Al / PFPE / polymer composite particles and Al / PFPE composite particles, respectively. Figure 4 The diffraction peaks of the Al / PFPE / polymer composite particles at 38.36 °, 44.63 °, 65.06 °, 78.16 °, and 82.34 ° correspond well to the crystal planes of Al / PFPE at (111), (200), (220), (311), and (222), respectively. The positions of the diffraction peaks in curve (a) are consistent with those in curve (b), and no new peaks appear, indicating that the addition of the polymer did not change the crystal structure of Al / PFPE.

[0043] Figure 5 The image shows an SEM image of the Al / PFPE / polymer / AP composite energetic material. The prepared particles have a relatively smooth surface, are irregularly polyhedral in shape, and have a particle size of about 10-15 μm. A small number of uncoated Al / PFPE / polymer composite particles are distributed on the surface. Example 2

[0044] A method for preparing an energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate includes the following steps:

[0045] (1) Preparation method of Al / PFPE composite particles: Dissolve 0.1g PFPE in 10 mL hydrofluoroether, add 1g Al powder, and evaporate the solvent to obtain Al / PFPE composite particles.

[0046] (2) Preparation method of Al / PFPE / polymer composite particles: Take a 100mL single-necked flask, add 0.5mL of azobisisobutyronitrile aqueous solution (concentration of 0.4 mol / L), then add 29.5mL of distilled water, and stir for 10min (850r / min) under a 40℃ water bath until completely dissolved. Then add 6mL of isopropanol and stir for another 30min to mix evenly. Then add 0.2g of methyl methacrylate and 0.5g of Al / PFPE composite particles, and react under a 40℃ water bath for 16h. After the reaction, the solution color changed from black to gray, indicating that methyl methacrylate was successfully polymerized and coated on the surface of Al / PFPE composite particles, resulting in a lighter color of the composite particles. Centrifuge (rpm=9000, t=10min), wash with water 3 times, then wash with anhydrous ethanol 3 times, and dry after treatment to obtain Al / PFPE / polymer composite particles.

[0047] (3) Preparation method of Al / PFPE / polymer / ammonium perchlorate composite energetic material: Al / PFPE / polymer / AP composite particles with adjustable particle size and morphology were prepared based on Al / PFPE / polymer composite particles by cooling crystallization method. By setting up a set of 50 mL 85℃ saturated AP solution and a set of 50 mL 5℃ saturated AP solution, 0.5 g Al / PFPE / polymer composite particles were completely dispersed in 50 mL 5℃ saturated AP solution. Then, 20 mL 5℃ saturated AP solution was slowly added to 50 mL low temperature saturated AP solution at a dropping rate of 5 mL / min. After the dropping was completed, the mixture was aged for 5 min, filtered and dried to obtain Al / PFPE / polymer / AP composite energetic material. Example 3

[0048] A method for preparing an energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate includes the following steps:

[0049] (1) Preparation method of Al / PFPE composite particles: Dissolve 0.1g PFPE in 10 mL hydrofluoroether, add 1g Al powder, and evaporate the solvent to obtain Al / PFPE composite particles.

[0050] (2) Preparation method of Al / PFPE / polymer composite particles: Take a 100mL single-necked flask, add 0.5mL of isophorone diisocyanate and then add 29.5mL of distilled water. Stir for 10min (850r / min) under a 40℃ water bath until completely dissolved. Then add 6mL of isopropanol and stir for 30min until uniformly mixed. Then add 0.2g of hydroxyl-terminated polybutadiene and 0.5g of Al / PFPE composite particles. React under a 40℃ water bath for 16h. After the reaction, observe whether the Al / PFPE composite particles are deposited at the bottom of the flask. If most of them are deposited, it indicates that the hydroxyl-terminated polybutadiene has successfully polymerized and coated the surface of the Al / PFPE composite particles, resulting in an increase in their weight and deposition. Centrifuge (rpm=9000, t=10min), wash with water 3 times, then wash with anhydrous ethanol 3 times, and dry after treatment to obtain Al / PFPE / polymer composite particles.

[0051] (3) Preparation method of Al / PFPE / polymer / ammonium perchlorate composite energetic material: Al / PFPE / polymer / AP composite particles with adjustable particle size and morphology were prepared based on Al / PFPE / polymer composite particles by cooling crystallization method. By setting up a set of 50 mL 85℃ saturated AP solution and a set of 50 mL 5℃ saturated AP solution, 0.5 g Al / PFPE / polymer composite particles were completely dispersed in 50 mL 5℃ saturated AP solution. Then, 20 mL 5℃ saturated AP solution was slowly added to 50 mL low temperature saturated AP solution at a dropping rate of 5 mL / min. After the dropping was completed, the mixture was aged for 5 min, filtered and dried to obtain Al / PFPE / polymer / AP composite energetic material. Example 4

[0052] A method for preparing an energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate includes the following steps:

[0053] (1) Preparation method of Al / PFPE composite particles: Dissolve 0.1g PFPE in 10 mL hydrofluoroether, add 1g Al powder, and evaporate the solvent to obtain Al / PFPE composite particles.

[0054] (2) Preparation method of Al / PFPE / polymer composite particles: Take a 100mL single-necked flask, add 0.5mL of diethylenetriamine and then 29.5mL of distilled water. Stir for 10min (850r / min) in a 40℃ water bath until completely dissolved. Then add 6mL of isopropanol and stir for 30min until uniformly mixed. Add 0.2g of dicyclohexylmethane diisocyanate and 0.5g of Al / PFPE composite particles. React in a 40℃ water bath for 16h. After the reaction, the solution color changes from light yellow to black mixed with polymer monomers to gray. This is because the reaction of dicyclohexylmethane diisocyanate causes the solution color to lighten. At the same time, the graying of the composite particles indicates that the polymer monomers have successfully polymerized and coated the surface of the Al / PFPE composite particles. Centrifuge (rpm=9000, t=10min), wash with water 3 times, then wash with anhydrous ethanol 3 times, and dry after treatment to obtain Al / PFPE / polymer composite particles.

[0055] (3) Preparation method of Al / PFPE / polymer / ammonium perchlorate composite energetic material: Al / PFPE / polymer / AP composite particles with adjustable particle size and morphology were prepared based on Al / PFPE / polymer composite particles by cooling crystallization method. By setting up a set of 50 mL 85℃ saturated AP solution and a set of 50 mL 5℃ saturated AP solution, 0.5 g Al / PFPE / polymer composite particles were completely dispersed in 50 mL 5℃ saturated AP solution. Then, 20 mL 5℃ saturated AP solution was slowly added to 50 mL low temperature saturated AP solution at a dropping rate of 5 mL / min. After the dropping was completed, the mixture was aged for 5 min, filtered and dried to obtain Al / PFPE / polymer / AP composite energetic material. Example

[0056] A method for preparing an energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate includes the following steps:

[0057] (1) Preparation method of Al / PFPE composite particles: Dissolve 0.1g PFPE in 10 mL hydrofluoroether, add 1g Al powder, and evaporate the solvent to obtain Al / PFPE composite particles.

[0058] (2) Preparation method of Al / PFPE / polymer composite particles: Take a 100mL single-necked flask, add 0.5mL of sodium dihydrogen phosphate aqueous solution (concentration of 0.83 mol / L), then add 29.5mL of distilled water, and stir for 10min (850r / min) under a 40℃ water bath until completely dissolved. Then add 6mL of isopropanol and stir for another 30min to mix evenly. Then add 0.2g of epoxy resin and 0.5g of Al / PFPE composite particles, and react under a 40℃ water bath for 16h. After the reaction, observe whether the Al / PFPE composite particles are deposited at the bottom of the flask. If most of them are deposited, it indicates that the epoxy resin has successfully polymerized and coated the surface of the Al / PFPE composite particles, resulting in an increase in their weight and deposition. Centrifuge (rpm=9000, t=10min), wash with water 3 times, then wash with anhydrous ethanol 3 times, and dry after treatment to obtain Al / PFPE / polymer composite particles.

[0059] (3) Preparation method of Al / PFPE / polymer / ammonium perchlorate composite energetic material: Al / PFPE / polymer / AP composite particles with adjustable particle size and morphology were prepared based on Al / PFPE / polymer composite particles by cooling crystallization method. By setting up a set of 50 mL 85℃ saturated AP solution and a set of 50 mL 5℃ saturated AP solution, 0.5 g Al / PFPE / polymer composite particles were completely dispersed in 50 mL 5℃ saturated AP solution. Then, 20 mL 5℃ saturated AP solution was slowly added to 50 mL low temperature saturated AP solution at a dropping rate of 5 mL / min. After the dropping was completed, the mixture was aged for 5 min, filtered and dried to obtain Al / PFPE / polymer / AP composite energetic material.

Claims

1. An energetic composite material of aluminum powder, perfluoropolyether, polymer, and ammonium perchlorate, characterized in that, It is prepared by the following steps: (1) Preparation of Al / PFPE composite particles: Dissolve perfluoropolyether in an organic solvent, add aluminum powder, and evaporate the solvent to obtain Al / PFPE composite particles; The ratio of perfluoropolyether, organic solvent, and aluminum powder is 0.1g:10mL:1g; (2) Preparation of Al / PFPE / polymer composite particles: pH adjuster is added to water, solvent is added under heating and stirring conditions, then organic polymer monomer and Al / PFPE composite particles are added, and the reaction is continued to be heated and stirred. After the reaction is completed, Al / PFPE / polymer composite particles are obtained by centrifugation, washing and drying. The ratio of pH adjuster, water, solvent, organic polymer monomer, and Al / PFPE composite particles is 0.5 mL: 29.5 mL: 6 mL: 0.2 g: 0.5 g; The pH adjuster is tris(hydroxymethyl)aminomethane hydrochloride; the solvent is isopropanol; and the organic polymer monomer is dopamine hydrochloride. The heating temperature is 20~70℃, the stirring speed is 100r / min~1500r / min, and the reaction time is 10min~16h; (3) Preparation of Al / PFPE / polymer / ammonium perchlorate composite particles: Al / PFPE / polymer composite particles are completely dispersed in a low-temperature saturated ammonium perchlorate solution, and then a high-temperature saturated ammonium perchlorate solution is added dropwise. After the addition is completed, the particles are aged, filtered, and dried to obtain an aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material. The ratio of Al / PFPE / polymer composite particles, low-temperature saturated ammonium perchlorate solution, and high-temperature saturated ammonium perchlorate solution is 0.5g:50mL:20mL.

2. The aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material according to claim 1, characterized in that, In step (1), the organic solvent is selected from toluene, diethyl ether, hydrofluoroether, ethanol, cyclohexane, acetone and dichloromethane.

3. The aluminum powder / perfluoropolyether / polymer / ammonium perchlorate composite energetic material according to claim 1, characterized in that, In step (3), the temperature of the low-temperature saturated ammonium perchlorate solution is 0~50℃, and the temperature of the high-temperature saturated ammonium perchlorate solution is 40~90℃.

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