Novel high-energy oxidant eutectic and preparation method thereof

Abstract

The invention relates to the technical field of energetic materials and crystal engineering, in particular to a novel high-energy oxidant eutectic and a preparation method thereof. The co-crystal of the oxidizing agent is characterized in that the basic structure of the co-crystal of the oxidizing agent comprises an ammonium dinitramide molecule and a 3, 4-diamino furazan molecule; the moisture absorption resistance is excellent, the moisture absorption resistance is lower than 0.2% in the environment with the temperature of 25 DEG C and the relative humidity of 75.0%, the mechanical sensitivity is low, the impact sensitivity can reach 17 J, and the friction sensitivity can reach 288 N; the material has the characteristics of high specific impulse and high energy, meanwhile, the preparation method is simple and rapid, the material can be directly prepared by using water and ethanol as solvents and even can be directly obtained by a mechanical method without using any solvent, the preparation method is green and environment-friendly, different preparation, processing and application requirements can be met, and the material has great application potential in the field of energetic materials.

Description

Technical Field

[0001] The present invention relates to the technical fields of energetic materials and crystal engineering, and particularly relates to a novel high-energy oxidizer eutectic and a preparation method thereof. Background Art

[0002] As an important branch of energetic materials, solid propellants are important power sources for various solid motors in aerospace and weaponry. Among them, the oxidizer accounts for about 50-80% of the propellant mass, and its structure and properties directly affect the combustion, mechanical and stability properties of the propellant, thus determining the application effect of the propellant. Due to the absence of halogens in the molecule, ADN (ammonium dinitramide) is considered an environmentally friendly oxidizer, with low characteristic signal, high oxygen balance, high specific impulse, good thermal stability, etc., and is widely used in solid propellants. However, ADN has strong hygroscopic properties, which severely limit its engineering application and popularization.

[0003] Currently, there are mainly two methods used in production to improve the hygroscopicity of ADN, namely spheroidization technology and surface coating technology. However, the above methods cannot fundamentally solve the hygroscopicity problem of ADN. In recent years, the oxidizer eutectic technology has received extensive attention from researchers. Based on the supramolecular integration between the oxidizer and ligand molecules, it is expected to fundamentally improve the hygroscopicity of ADN and obtain a novel high-energy oxidizer with high energy and anti-hygroscopicity. Existing research has shown that the formation of ionic oxidizer eutectics requires changing the original Coulomb interaction between ions and coupling relatively weak intermolecular hydrogen bond interactions, making it difficult for the oxidizer to interact with neutral molecules to form multicomponent crystals. Therefore, the design and preparation of ionic oxidizer eutectics is a very challenging problem. So far, only five ADN ionic oxidizer eutectics with single crystal structures, namely ADN / pyrazine 1,4-dioxide (2019), ADN / urea (2022), ADN / DNBT (2024), and ADN / ICM-102 (2024, CN 118546384 A), have been reported. Generally speaking, these eutectic materials have problems such as difficult large-scale preparation and unsatisfactory anti-hygroscopicity, and are difficult to meet the requirements of engineering applications.

[0004] Based on this, the present invention has successfully prepared a novel ADN ionic oxidizer eutectic, whose anti-hygroscopicity is superior to all existing ADN eutectics, can fundamentally solve the hygroscopicity problem of ADN, and shows great application potential in fields such as solid propellant formulations. Summary of the Invention

[0005] The purpose of the present invention is to avoid the deficiencies of the prior art and provide a novel high-energy oxidizer eutectic and a preparation method thereof, which not only solve the problems of strong hygroscopicity and high sensitivity of ADN, but also can be rapidly prepared on a large scale, and the process is easy to scale up.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: The novel high-energy oxidizer eutectic has the following characteristics: The basic structure of the oxidizer eutectic includes an ammonium dinitramide molecule and a ligand molecule; The unit cell parameters of the oxidizer eutectic are a = 7.1278(4) Å, b = 12.5110(7) Å, c = 19.8995(11) Å, ɑ = 90°, β = 90°, γ = 90°, Z = 2, belonging to the orthorhombic system, Pbca space group.

[0007] Furthermore, the ligand is 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan.

[0008] Furthermore, the diffraction peaks of the oxidizer eutectic in the X-ray powder diffraction spectrum with Cu-kα radiation have the following characteristics: In the X-ray diffraction pattern, with the diffraction angle 2 θ expressed as: 15.007°, 15.496°, 16.939°, 18.043°, 19.805°, 23.143°, 26.262°, 26.798°, 27.705°, 28.391°, 29.494°, 29.890°, 30.333°, 30.825°, 31.047°, 37.144° each have characteristic diffraction peaks, and the error at each diffraction peak is ±0.2°.

[0009] Furthermore, the thermal analysis of the oxidizer eutectic has the following characteristics: When tested using differential scanning calorimetry (DSC), the peak decomposition temperature of the obtained eutectic is 202.7 °C, and the initial decomposition temperature is 165.0 °C.

[0010] The present invention provides a preparation method for the novel oxidizer eutectic, which is characterized by including the following steps: Step 1, dissolve two compounds of ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan in an organic solvent, or dissolve them in an aqueous solution of an organic solvent, and through magnetic force, mechanical stirring, or heating to 40 - 70 °C, fully dissolve the solution to obtain a eutectic solution; Step 2, after placing the eutectic solution obtained in Step 1 at room temperature for 2 - 10 minutes, white solid precipitates, or adding an antisolvent to the eutectic solution to precipitate white solid, or placing the eutectic solution in a sound field or magnetic field to precipitate white solid; filter out the mother liquor to obtain the oxidizer eutectic.

[0011] Further, in the first step, the molar ratio of ammonium dinitramide to 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan is 0.5:1 to 3:1.

[0012] Further, the organic solvent in the first step refers to methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, dimethyl sulfoxide.

[0013] Further, the aqueous solution of the organic solvent in the first step means that the proportion of the organic solvent in the solution is 30-90%, and the rest is water.

[0014] Further, the anti-solvent in the second step includes dichloromethane, petroleum ether, toluene, n-hexane, cyclohexane.

[0015] The present invention also provides a preparation method of the novel oxidizer eutectic, which is characterized by using melt crystallization to obtain the oxidizer eutectic. Specifically, it includes melting ammonium dinitramide molecules and 3,4-diaminofurazan molecules or isomers of 3,4-diaminofurazan at 90-120 °C and cooling to room temperature (15-35 °C) to obtain the oxidizer eutectic.

[0016] The present invention also provides a preparation method of a novel oxidizer eutectic, which is characterized by using a mechanical grinding method. Specifically, it includes grinding ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan with a molar ratio of 0.5:1 to 3:1 for more than 3 minutes until it becomes a uniform powder state, that is, obtaining the oxidizer eutectic.

[0017] Further, when preparing the oxidizer eutectic by the mechanical grinding method, first add 5-10 µl of an organic solvent or water, and then grind ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan with a molar ratio of 0.5:1 to 3:1 for more than 3 minutes until it becomes a uniform powder state and the solvent completely volatilizes, that is, obtaining the oxidizer eutectic.

[0018] Further, the organic solvent refers to methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, dimethyl sulfoxide, dichloromethane, petroleum ether, toluene, n-hexane, cyclohexane.

[0019] Compared with the prior art, the present invention has the following technical effects: A novel high-energy oxidizer eutectic and its preparation method. The novel oxidizer eutectic of the present invention has excellent moisture resistance, less than 0.2% in an environment of 25 °C and 75.0% relative humidity. DVS test shows that its critical relative humidity (CRH, the relative humidity value at which a substance begins to significantly absorb moisture at a certain temperature) is as high as 84%; the novel oxidizer eutectic has low mechanical sensitivity, with an impact sensitivity of up to 17 J and a friction sensitivity of up to 288 N; it has the characteristics of high specific impulse and high energy. Calculated by NASA software, its theoretical specific impulse is as high as 260 N*S / kg. At the same time, its preparation method is simple and rapid, can be directly prepared with water and ethanol as solvents, and even can be obtained by a direct mechanical method without using any solvents. The preparation method is green and environmentally friendly, can meet different preparation, processing and application requirements, and shows great application potential in the field of energetic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the polarized light microscope image of the eutectic of the specific example of the present invention; Figure 2 It is the PXRD pattern of the eutectic of the specific example of the present invention; Figure 3 It is the TGA / DSC pattern of the eutectic of the specific example of the present invention; Figure 4 It is the single crystal structure diagram of the eutectic of the specific example of the present invention; Figure 5 It is the dynamic vapor sorption result diagram of the eutectic of the specific example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The principles and features of the present invention will be described below with reference to the accompanying drawings; the examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0022] In order to achieve the above object, the present invention provides the following specific embodiments: Example 1: A novel high-energy oxidizer eutectic, characterized in that the basic structure of the oxidizer eutectic includes an ammonium dinitramide molecule and a ligand molecule; The unit cell parameters of the oxidizer eutectic are a = 7.1278(4) Å, b = 12.5110(7) Å, c = 19.8995(11) Å, ɑ = 90°, β = 90°, γ = 90°, Z = 2, belonging to the orthorhombic system, Pbca space group.

[0023] Among them, the ligand is 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan.

[0024] The diffraction peaks of the oxidizer eutectic in the Cu-Kα radiation X-ray powder diffraction spectrum have the following characteristics: In the X-ray diffraction pattern, with the diffraction angle 2 θ Expressed as: 15.007°, 15.496°, 16.939°, 18.043°, 19.805°, 23.143°, 26.262°, 26.798°, 27.705°, 28.391°, 29.494°, 29.890°, 30.333°, 30.825°, 31.047°, 37.144°, there are characteristic diffraction peaks at each position, and the error at each diffraction peak is ±0.2°.

[0025] The thermal analysis of the said oxidizer eutectic has the following characteristics: When tested using differential scanning calorimetry (DSC), the peak decomposition temperature of the obtained eutectic is 202.7 °C, and the onset decomposition temperature is 165.0 °C.

[0026] Example 2: The present invention also provides a preparation method of a novel oxidizer eutectic, which is characterized by including the following steps: Step 1, dissolve ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan in an organic solvent, or dissolve them in an aqueous solution of an organic solvent, and through magnetic force, mechanical stirring, or heating to 40 - 70 °C, fully dissolve the solution to obtain a eutectic solution; Among them, the molar ratio of the dosage of ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan is 0.5:1 to 3:1.

[0027] The organic solvent refers to methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, dimethyl sulfoxide.

[0028] The aqueous solution of the organic solvent means that the proportion of the organic solvent in the solution is 30 - 90%, and the rest is water.

[0029] Step 2, place the eutectic solution obtained in Step 1 at room temperature for 2 - 10 minutes to precipitate white solid, or add an anti-solvent to the eutectic solution to precipitate white solid, or place the eutectic solution in a sound field or magnetic field to precipitate white solid; filter out the mother liquor to obtain the oxidizer eutectic.

[0030] Among them, the anti-solvent includes dichloromethane, petroleum ether, toluene, n-hexane, cyclohexane.

[0031] Example 3: The present invention also provides a method for preparing a novel oxidizer eutectic, which is characterized by obtaining the oxidizer eutectic by melt crystallization. Specifically, ammonium dinitramide molecules and 3,4-diaminofurazan molecules or isomer molecules of 3,4-diaminofurazan are melted at 90 - 120 °C and then cooled to room temperature (15 - 35 °C) to obtain the oxidizer eutectic.

[0032] Example 4: The present invention also provides a method for preparing a novel oxidizer eutectic, which is characterized by using a mechanical grinding method. Specifically, ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan with a molar ratio of 0.5:1 to 3:1 are ground for more than 3 minutes until they become a uniform powder state, thereby obtaining the oxidizer eutectic.

[0033] When preparing the oxidizer eutectic by the mechanical grinding method, first add 5 - 10 μl of an organic solvent or water, and then grind ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan with a molar ratio of 0.5:1 to 3:1 for more than 3 minutes until they become a uniform powder state and the solvent completely volatilizes, thereby obtaining the oxidizer eutectic.

[0034] Among them, the organic solvents refer to methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, dimethyl sulfoxide, dichloromethane, petroleum ether, toluene, n-hexane, cyclohexane.

[0035] As Figures 1 - 5 shown, in order to further illustrate the technical solutions and effects of the present invention, the following specific examples are provided: Specific Example 1: As Figure 1 shown, in the process of preparing the novel oxidizer eutectic, under magnetic stirring at room temperature, 1.24 g (10 mmol) of ADN was added to 10 ml of acetonitrile, and then 1 g (10 mmol) of 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan was added.

[0036] After magnetic stirring for a period of time until the solid was almost completely dissolved, the mother liquor was collected and placed at room temperature. After volatilization for 48 h, filtration was carried out. Observation under a polarized light microscope showed transparent block crystals, as Figure 1 shown.

[0037] Specific Example 2: The process of preparing the novel oxidizer eutectic is as follows: Under magnetic stirring at room temperature, 1 g (10 mmol) of 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan was added to 10 ml of a 20% ADN acetonitrile solution, stirred for a period of time, and 2 g of white crystals were obtained by filtration.

[0038] Specific Example 3: The process for preparing the novel oxidizer eutectic is as follows: 1.24 g of ADN is mixed with 1 g of solid 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan, and then 5 μl of acetonitrile is added dropwise. After grinding for 3 minutes, a white powder is obtained.

[0039] The following analysis methods and equipment are used to characterize the novel high-energy oxidizer eutectic of the specific examples of the present invention: 1. As Figure 2 shown, X-ray powder diffraction (PXRD): The powder diffractometer used is the D / MAX2500 type produced by Rigaku Corporation of Japan. The test conditions are as follows: using a CuKα target for testing, with a voltage of 40 kV, a current of 100 mA, a scanning wavelength λ = 1.5418 Å, using continuous scanning for testing, and a scanning speed of 8° / min. After collecting the data, the Jade7.0 software is used for data analysis.

[0040] The oxidizer eutectic prepared in the specific example is tested. The diffraction peaks of the oxidizer eutectic in the X-ray powder diffraction spectrum under Cu-kα radiation have the following characteristics: At Figure 2 shown in the X-ray diffraction pattern, in terms of the diffraction angle 2 θ It is expressed as: 15.007°, 15.496°, 16.939°, 18.043°, 19.805°, 23.143°, 26.262°, 26.798°, 27.705°, 28.391°, 29.494°, 29.890°, 30.333°, 30.825°, 31.047°, 37.144° where there are characteristic diffraction peaks, and the error at each diffraction peak is ±0.2°.

[0041] Specific Examples 1 to 3 have consistent PXRD test results.

[0042] 2. As Figure 3 shown, thermogravimetry-differential scanning calorimetry (TG / DSC): Tested using a TGA / DSC instrument from Mettler Toledo. 0.2 - 0.5 mg of the sample is added to the crucible and placed in the furnace body. High-purity nitrogen is used as the protective gas (gas flow rate of 50.0 mL / min) and the reaction gas (gas flow rate of 200.0 mL / min) in the furnace body. The measurement temperature range is 50.0 - 400.0 °C, and the heating rate is 10.0 °C / min. The temperature, heat, and weight changes of the sample during heating are measured. The program control, data recording, and analysis are all completed by the STARe Software 18.0 developed by Mettler.

[0043] The oxidant eutectic prepared in Example 1 was subjected to TGA / DSC test. The results are as follows: Figure 3 As shown, within the test temperature range, the peak decomposition temperature of the oxidant eutectic is 202.7 ℃, and the initial decomposition temperature is 165.0 ℃. Compared with ADN, the thermal stability of the eutectic is significantly improved.

[0044] Specific Examples 1 to 3 have consistent TGA / DSC test results.

[0045] 3. If Figure 4 As shown, X-ray single crystal diffraction (SXRD): The present invention uses an X-ray single crystal diffractometer (RigakuR_AXISRapidII) produced by Rigaku Corporation of Japan, and the MoKα target generates rays with a wavelength of λ =0.71073 Å, test voltage 50 kV, current 90 mA, single crystal analysis and refinement using SHELXS-2013 software. Detailed single crystal structure determination data of oxidant eutectic is shown in Table 1. Figure 4 This is the crystal structure stacking diagram of the oxidant eutectic, which is formed by ADN molecules and 3,4-diaminofurazan molecules in a 1:1 (molar ratio) through intermolecular hydrogen bonding. The unit cell parameters are a=7.1278(4) Å, b=12.5110(7) Å, c=19.8995(11) Å, ɑ =90°, β =90°, γ =90°, Z =2, belongs to the orthorhombic system, Pbca Space group.

[0046] Table 1

[0047] 3. Mechanical sensitivity test The impact and friction sensitivity of the oxidizer eutectic were analyzed using equipment from the Federal Institute for Materials Testing (BAM). Its impact sensitivity is 8-17 J (due to certain differences in crystal morphology and particle size), and the optimal friction sensitivity can reach 288 N. Compared with ADN (impact sensitivity 5 J, friction sensitivity 96 N), its safety performance has been significantly improved.

[0048] 4. If Figure 5 As shown, the hygroscopicity test Dynamic vapor sorption (DVS) experiments were performed using a Q5000 SA dynamic vapor sorption analyzer. Sample mass was monitored at 5-90% relative humidity with a step size of 2%, an initial mass of 3-10 mg, and an equilibrium time of up to 120 minutes per step until the sample mass stabilized (<0.01% change in 2 minutes). The results are shown in Figure 2.Figure 5 As shown, the oxidizer eutectic hardly absorbs moisture at 84% humidity, indicating that this new type of high-energy oxidizer eutectic has excellent moisture absorption resistance.

[0049] The above are only the preferred embodiments of the present invention; they are not intended to limit the present invention; any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A novel high-energy oxidant eutectic, characterized in that: The basic structure of the oxidant eutectic includes an ammonium dinitramide molecule and a ligand molecule; The unit cell parameters of the oxidant eutectic are a=7.1278(4) Å, b=12.5110(7) Å, c=19.8995(11) Å, ɑ =90°, β =90°, γ =90°, Z =2, belongs to the orthorhombic system, Pbca Space group.

2. A novel high-energy oxidant eutectic according to claim 1, characterized in that: The ligand is 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan.

3. A novel high-energy oxidant eutectic according to claim 1, characterized in that: The diffraction peaks of the oxidant eutectic in the Cu-kα radiation X-ray powder diffraction spectrum have the following characteristics: The X-ray diffraction pattern is at a diffraction angle of 2 θ It is expressed as: there are characteristic diffraction peaks at 15.007°, 15.496°, 16.939°, 18.043°, 19.805°, 23.143°, 26.262°, 26.798°, 27.705°, 28.391°, 29.494°, 29.890°, 30.333°, 30.825°, 31.047°, and 37.144°, and the error of each diffraction peak is ±0.2°. The thermal analysis of the oxidant eutectic has the following characteristics: when tested using differential scanning calorimetry (DSC), the peak decomposition temperature of the obtained eutectic is 202.7°C and the onset decomposition temperature is 165.0°C.

4. A method for preparing a novel oxidant eutectic according to claims 1-3, characterized in that: The steps include: Step 1, dissolving ammonium dinitramide and 3,4-diaminofurazan in an organic solvent or in an aqueous solution of an organic solvent, and fully dissolving the solution by magnetic force, mechanical stirring, or heating to 40-70° C. to obtain a eutectic solution; Step 2: placing the eutectic solution obtained in step 1 at room temperature for 2-10 minutes to allow a white solid to precipitate, or adding an antisolvent to the eutectic solution to allow a white solid to precipitate, or placing the eutectic solution in an acoustic field or a magnetic field to allow a white solid to precipitate; filtering out the mother liquor to obtain the oxidant eutectic.

5. The method for preparing a novel oxidant eutectic according to claim 4, characterized in that: In the step 1, the molar ratio of ammonium dinitramide to 3,4-diaminofurazan or the isomer of 3,4-diaminofurazan is 0.5:1 to 3:

1.

6. The method for preparing a novel oxidant eutectic according to claim 4, characterized in that: The organic solvent in step 1 refers to methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, and dimethyl sulfoxide; the aqueous solution of the organic solvent refers to: the organic solvent accounts for 30-90% of the solution, and the rest is water.

7. The method for preparing a novel oxidant eutectic according to claim 4, characterized in that: The anti-solvent in step 2 includes dichloromethane, petroleum ether, toluene, n-hexane, and cyclohexane.

8. A method for preparing a novel oxidant eutectic according to claims 1-3, characterized in that: The oxidant eutectic is obtained by melt crystallization, specifically comprising melting the ammonium dinitramide molecule and the 3,4-diaminofurazan molecule or the isomer molecule of 3,4-diaminofurazan at 90-120°C, and cooling to room temperature (15-35°C) to obtain the oxidant eutectic.

9. A method for preparing a novel oxidant eutectic according to claims 1-3, characterized in that: The method using mechanical grinding specifically includes grinding ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan in a molar ratio of 0.5:1 to 3:1 for more than 3 minutes to make them into a uniform powder state, thereby obtaining an oxidant eutectic.

10. The method for preparing a novel oxidant eutectic according to claim 9, characterized in that: When preparing the oxidant eutectic by the mechanical grinding method, 5-10 μl of an organic solvent or water is first added, and then ammonium dinitramide and 3,4-diaminofurazan or an isomer of 3,4-diaminofurazan in a molar ratio of 0.5:1 to 3:1 are ground for more than 3 minutes to make it into a uniform powder state and the solvent is completely volatilized, thereby obtaining the oxidant eutectic; The organic solvent refers to methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, dimethyl sulfoxide, dichloromethane, petroleum ether, toluene, n-hexane, and cyclohexane.

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