A method for reducing the susceptibility of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating

Abstract

The application discloses a method for reducing the sensitivity of ammonium perchlorate by adopting a polydopamine / fluorine-containing silane composite coating, and comprises the following steps: (1) dispersing ammonium perchlorate in an organic solvent, stirring to obtain a milky white suspension; (2) adding a catalyst dropwise into the suspension, stirring, uniformly mixing, then adding fluorine-containing silane and dopamine hydrochloride, and reacting at room temperature for 6-24 hours; the catalyst is an amine compound; (3) filtering, washing with the organic solvent until the color of the filtrate is clear, drying, and obtaining modified ammonium perchlorate particles. The application realizes uniform and complete coating of the polydopamine coating on the ammonium perchlorate by one-step method, meanwhile, the fluorine-containing silane is introduced to crosslink the polydopamine coating, effectively improves the interface coverage of the polydopamine on the ammonium perchlorate, reduces the sensitivity of the ammonium perchlorate, and reduces the hygroscopicity of the ammonium perchlorate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ammonium perchlorate modification, and particularly relates to a method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating. BACKGROUND

[0002] As a high-energy oxidizer, ammonium perchlorate has high oxygen content and large enthalpy of formation. It is an important component of energetic materials such as blasting explosives, fireworks, and solid propellants. Ultrafine ammonium perchlorate has a faster burning rate, but the decrease in size of ammonium perchlorate leads to increased moisture absorption and reduced safety performance. Researchers have used various methods to modify ammonium perchlorate. For example, insensitive explosives, inert organic substances or fluorides, and functional carbon materials are used as coating agents to coat ammonium perchlorate. When using these materials for coating, there is a common problem of weak interaction between the coating agent and ammonium perchlorate and poor interfacial compatibility. It has been found that dopamine can self-polymerize and adhere to various substrate materials through strong forces such as covalent bonds, π-π stacking, hydrogen bonds, and coordination. Traditional polydopamine coating processes need to be carried out in an alkaline aqueous medium, which is not suitable for water-soluble ammonium perchlorate. SUMMARY

[0003] In view of the defects of the prior art, the application provides a method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating. The method realizes uniform and complete coating of the polydopamine coating on ammonium perchlorate by one-step method, and the silane can cross-link the polydopamine coating, thereby effectively reducing the moisture absorption rate of ammonium perchlorate while reducing its sensitivity.

[0004] A method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating, comprising the following steps:

[0005] (1) dispersing ammonium perchlorate in an organic solvent, stirring to obtain a milky white suspension;

[0006] (2) adding a catalyst dropwise to the suspension, stirring, and then adding fluorine-containing silane and dopamine hydrochloride after mixing uniformly, and reacting at room temperature for 6-24 h; the catalyst is an amine compound;

[0007] (3) filtering, washing with an organic solvent until the filtrate is clear, drying, and obtaining modified ammonium perchlorate particles.

[0008] Preferably, the catalyst is at least one of diethylamine, ethylenediamine, and triethylamine.

[0009] Preferably, the organic solvent is at least one of ethyl acetate, anhydrous ethanol, toluene, paraffin oil, and white oil.

[0010] Preferably, the ratio of the ammonium perchlorate to the organic solvent is 1g:(6.625-26.5)mL.

[0011] Preferably, the ratio of the dopamine hydrochloride, the organic solvent, and the catalyst is 1mg:(0.1-1)mL:(3-20)μL.

[0012] Preferably, the ratio of the fluorine-containing silane to the organic solvent is (0.01-0.1)g:1mL.

[0013] Preferably, the fluorine-containing silane is a compound having the following structural formula:

[0014]

[0015] wherein R1, R2, and R3 are methyl or ethyl, and R4 is a chain alkane in which a part of hydrogen is replaced by fluorine or all hydrogen is replaced by fluorine.

[0016] Preferably, the fluorine-containing silane is trimethoxy(1H,1H,2H,2H-tridecafluoro-n-octyl)silane, trimethoxy(3,3,3-trifluoropropyl)silane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, or 3,3,3-trifluoropropyltriethoxysilane.

[0017] Preferably, the drying condition is drying at 40-80℃ for 4-6h.

[0018] Advantages of the present application:

[0019] The present application adopts a polydopamine biomimetic interface design strategy, realizes uniform and complete coating of polydopamine on ammonium perchlorate in a non-aqueous medium by a one-step method, and introduces fluorine-containing silane to crosslink the polydopamine coating, thereby solving the problems of weak interface interaction and poor uniformity in the desensitization process of ammonium perchlorate, effectively improving the interface coverage of polydopamine on ammonium perchlorate to reduce the sensitivity of ammonium perchlorate, and reducing the hygroscopicity of ammonium perchlorate. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 SEM images of raw ammonium perchlorate and modified ammonium perchlorate obtained by different methods;

[0021] Figure 2 XPS spectrum of modified ammonium perchlorate;

[0022] Figure 3 Figure 2 High-resolution XPS spectrum of C1s, N 1s, and O1s peaks. DETAILED DESCRIPTION

[0023] Example 1

[0024] ​A method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating, comprising the following steps:

[0025] (1) 4 g of ammonium perchlorate was dispersed in 53 mL of ethyl acetate, and magnetic stirring was performed for 60 min to fully disperse it, to obtain a milky white suspension;

[0026] (2) 530 μL of diethylamine was added dropwise to the suspension, and stirring was continued. After uniform mixing, 1.5 g of trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane and 159 mg of dopamine hydrochloride were added, and the reaction was performed at room temperature for 24 h to obtain a dark brown suspension;

[0027] (3) Filtration was performed, and washing with ethyl acetate was performed until the color of the filtrate was clear. Drying was performed at 60°C for 5 h to obtain modified ammonium perchlorate particles.

[0028] Example 2

[0029] 2 g of ammonium perchlorate was used, and the other conditions were the same as in Example 1.

[0030] Example 3

[0031] 8 g of ammonium perchlorate was used, and the other conditions were the same as in Example 1.

[0032] Example 4

[0033] A method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating, comprising the following steps:

[0034] (1) 4 g of ammonium perchlorate was dispersed in 53 mL of ethyl acetate, and magnetic stirring was performed for 30 min to fully disperse it, to obtain a milky white suspension;

[0035] (2) 530 μL of diethylamine was added dropwise to the suspension, and stirring was continued. After uniform mixing, 1 g of trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane and 53 mg of dopamine hydrochloride were added, and the reaction was performed at room temperature for 6 h to obtain a dark brown suspension;

[0036] (3) Filtration was performed, and washing with ethyl acetate was performed until the color of the filtrate was clear. Drying was performed at 60°C for 5 h to obtain modified ammonium perchlorate particles.

[0037] Example 5

[0038] A method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating, comprising the following steps:

[0039] (1) 4 g of ammonium perchlorate was dispersed in 53 mL of ethyl acetate, and magnetic stirring was performed for 30 min to fully disperse it, to obtain a milky white suspension;

[0040] (2) To the suspension, 795 μL of diethylamine was added dropwise, and stirring was continued. After the mixture was uniformly mixed, 5.3 g of trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane and 53 mg of dopamine hydrochloride were added, and the reaction was carried out at room temperature for 6 h to obtain a dark brown suspension;

[0041] (3) The suspension was suction-filtered, washed with anhydrous ethanol until the filtrate was colorless, and dried at 60°C for 5 h to obtain modified ammonium perchlorate particles.

[0042] Example 6

[0043] Trimethoxy(3,3,3-trifluoropropyl)silane was used instead of trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane, and the other steps were the same as in Example 1.

[0044] Example 7

[0045] 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane was used instead of trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane, and the other steps were the same as in Example 1.

[0046] Example 8

[0047] 3,3,3-trifluoropropyltriethoxysilane was used instead of trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane, and the other steps were the same as in Example 1.

[0048] Example 9

[0049] Anhydrous ethanol was used instead of ethyl acetate, and the other steps were the same as in Example 4.

[0050] Example 10

[0051] Paraffin oil was used instead of ethyl acetate, and the other steps were the same as in Example 4.

[0052] Example 11

[0053] White oil was used instead of ethyl acetate, and the other steps were the same as in Example 4.

[0054] Example 12

[0055] Toluene was used instead of ethyl acetate, and the other steps were the same as in Example 4.

[0056] Example 13

[0057] A method for reducing the susceptibility of ammonium perchlorate by using a polydopamine / fluorosilane composite coating, comprising the following steps:

[0058] (1) 4 g ammonium perchlorate was dispersed in 53 mL ethyl acetate, and stirred magnetically for 60 min to make it fully dispersed, to obtain a milky white suspension;

[0059] (2) 530 μL ethylenediamine was added dropwise to the suspension, and stirred continuously. After mixing evenly, 1 g trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane and 159 mg dopamine hydrochloride were added, and reacted at room temperature for 24 h to obtain a dark brown suspension;

[0060] (3) Filtration was performed, and washed with ethyl acetate until the filtrate was clear. Drying was performed at 60 °C for 5 h to obtain modified ammonium perchlorate particles.

[0061] Example 14

[0062] A method for reducing the sensitivity of ammonium perchlorate by using a polydopamine / fluorosilane composite coating, comprising the following steps:

[0063] (1) 4 g ammonium perchlorate was dispersed in 53 mL ethyl acetate, and stirred magnetically for 30 min to make it fully dispersed, to obtain a milky white suspension;

[0064] (2) 10.6 mL triethylamine was added dropwise to the suspension, and stirred continuously. After mixing evenly, 5.3 g trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane and 530 mg dopamine hydrochloride were added, and reacted at room temperature for 24 h to obtain a dark brown suspension;

[0065] (3) Filtration was performed, and washed with toluene until the filtrate was clear. Drying was performed at 100 °C for 5 h to obtain modified ammonium perchlorate particles.

[0066] Comparative Example 1

[0067] Without adding trimethoxy(1H, 1H, 2H, 2H-tridecafluoro-n-octyl)silane, the rest was the same as Example 1.

[0068] Comparative Example 2

[0069] Without adding dopamine hydrochloride, the rest was the same as Example 1.

[0070] Performance detection

[0071] I. Morphology characterization

[0072] The raw material ammonium perchlorate (AP), the ammonium perchlorate obtained in Example 1, Comparative Example 1 and Comparative Example 2 were subjected to scanning electron microscopy, and the results are shown in Figure 1 a, b, c, d in Table 1;

[0073] From Table 1, it can be seen that the ammonium perchlorate obtained in Example 1 has the best performance, and the ammonium perchlorate obtained in Comparative Example 2 has the worst performance. Figure 1It can be seen that the morphology of ammonium perchlorate particles in the raw material ammonium perchlorate (AP), Example 1 and Comparative Example 1 did not change significantly before and after modification. The reason is that the content of the coating agent is low (see Table 1), and the coating layer is thin, so the morphology change is not obvious, and the lower coating layer thickness and lower coating agent content are beneficial to maintain the high energy density of ammonium perchlorate. In Comparative Example 2, no small particle size ammonium perchlorate particles were observed in the electron micrograph, and the possible reason is that the by-product methanol generated by the silane reaction caused the dissolution of part of the ammonium perchlorate without polydopamine coating.

[0074] II. Chemical composition characterization

[0075] The chemical composition of the surface of the sample of Example 1 was analyzed using X-ray photoelectron spectroscopy (XPS), using the C1s peak (284.8 eV) for recording to calibrate the binding energy, respectively, Figure 2 and Figure 3 ;

[0076] It can be seen that in the XPS spectrum, there are characteristic peaks of ammonium perchlorate, such as N1s in N H4, O 1s in O -Cl, polydopamine (C1s in C -N, C =O, N 1s in C- N , C- N =C and O1s in C=- O ) and fluorine-containing silane (F 1s in C- F 2, C- F 3) characteristic peaks are also observed, which confirms that the polydopamine / fluorine-containing silane composite coating successfully coats the surface of ammonium perchlorate.

[0077] III. Coating agent content and ammonium perchlorate recovery rate test

[0078] The coating agent content and ammonium perchlorate recovery rate of the samples of Example 1, Comparative Examples 1-2 were tested, and the mass of the ammonium perchlorate raw material used was m0; after coating, the mass of the modified ammonium perchlorate sample obtained was m1; the modified ammonium perchlorate sample was washed with deionized water, and the ammonium perchlorate was washed off, and the mass of the coating composite coating was m2, all the masses were the mass after drying, then the coating agent content and the recovery rate of ammonium perchlorate were calculated as follows:

[0079]

[0080]

[0081] The calculation results are shown in Table 1;

[0082] Table 1 content of coating agent and ammonium perchlorate recovery rate

[0083] Sample Coating agent content (%) AP recovery rate (%) Example 1 0.76 86.7％ Comparative Example 1 0.68 81.3％ Comparative Example 2 0.66 32.4％ .

[0084] Four. Sensitivity test impact sensitivity: according to GJB-772A-97 standard method 601.1, the test conditions are that the weight of the drop hammer is 10.0 kg, the sample amount is 50 mg, each sample is tested 50 times, and the falling height of the drop hammer required for 50% explosion of the explosive sample in the test is recorded, that is, the characteristic drop height (H50);

[0085] Friction sensitivity: the friction sensitivity test is determined according to GJB-772A-97 standard method 601.2, the test conditions are that the weight of the pendulum is 1.5 kg, the swing angle is 90°, the sample amount is 20 mg, each sample is tested 50 times, and the explosion probability (P) is obtained;

[0086] The detection results are shown in Table 2, with the original ammonium perchlorate as a comparison.

[0087] Table 2 Sensitivity test results

[0088] Sample Impact sensitivity (H 50 , cm) Friction sensitivity (P, %) AP 69.6 76 Example 1 ≥125.9 8 Comparative Example 1 95 26 Comparative Example 2 86.5 28

[0089] As can be seen from Table 2, although the content of the coating agent and the coating layer of the example 1 of the present application are low and thin, the sensitivity of the ammonium perchlorate after coating is obviously reduced.

[0090] Five. Determination of moisture absorption rate

[0091] A saturated sodium chloride solution is prepared and placed in a desiccator to make the relative humidity reach 76%, the sample to be tested is dried and weighed as m0, and then placed in the desiccator with humidity of 76% to absorb moisture for 2 hours and 4 hours respectively, and the weights of the samples after absorbing moisture are recorded as m1 and m2 respectively, and the moisture absorption rate is: The detection results are shown in Table 3, with the original ammonium perchlorate as a comparison.

[0092] Table 3 Moisture absorption rate detection results

[0093] Sample 2h moisture absorption rate (%) 4h moisture absorption rate (%) AP 0.68％ 1.29％ Example 1 0.13％ 0.37％ Comparative Example 1 0.33％ 0.78％ Comparative Example 2 0.20％ 0.86％ .

Claims

1. A method for reducing the susceptibility of ammonium perchlorate by using a polydopamine / fluorine-containing silane composite coating, characterized by: Includes the following steps: (1) Disperse ammonium perchlorate in an organic solvent and stir to obtain a milky white suspension; (2) Add the catalyst dropwise to the suspension, stir, mix evenly, then add fluorosilane and dopamine hydrochloride, and react at room temperature for 6-24 hours; the catalyst is an amine compound; (3) Filter by suction, wash with organic solvent until the filtrate is clear, dry and obtain modified ammonium perchlorate particles; The fluorinated silane is trimethoxy(1H,1H,2H,2H-tridecylfluorooctyl)silane, trimethoxy(3,3,3-trifluoropropyl)silane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, or 3,3,3-trifluoropropyltriethoxysilane.

2. The method for reducing the sensitivity of ammonium perchlorate by using polydopamine / fluorine-containing silane composite coating according to claim 1, characterized in that: The catalyst is at least one of diethylamine, ethylenediamine, and triethylamine.

3. The method for modifying ammonium perchlorate to reduce sensitivity using a polydopamine / fluorinated silane composite coating as described in claim 2, characterized in that: The organic solvent is at least one of ethyl acetate, anhydrous ethanol, toluene, paraffin oil, and white oil.

4. The method for modifying ammonium perchlorate to reduce sensitivity using a polydopamine / fluorinated silane composite coating as described in claim 3, characterized in that: The ratio of ammonium perchlorate to organic solvent is 1 g: (6.625~26.5) mL.

5. The method for modifying ammonium perchlorate to reduce sensitivity using a polydopamine / fluorinated silane composite coating according to claim 4, characterized in that: The ratio of dopamine hydrochloride, organic solvent, and catalyst is 1 mg: (0.1~1) mL: (3~20) μL.

6. The method for modifying ammonium perchlorate to reduce sensitivity using a polydopamine / fluorinated silane composite coating as described in claim 5, characterized in that: The ratio of the fluorinated silane to the organic solvent is (0.01~0.1) g: 1 mL.

7. The method for modifying ammonium perchlorate to reduce sensitivity using a polydopamine / fluorinated silane composite coating according to claim 1, characterized in that: The drying conditions are as follows: drying at 40-80℃ for 4-6 hours.

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