Triblock energetic copolymer and preparation method thereof
A triblock energetic copolymer was prepared by cationic polymerization, combining 3-difluoroamino-3-methyloxetane with terminal hydroxyl polybutadiene, which solved the problem of insufficient low-temperature mechanical properties of PDFAMO, achieved a narrow molecular weight distribution, and met the low-temperature mechanical performance requirements of the adhesive system.
Patent Information
- Application Number
- CN202510698226.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-28
- Publication Date
- 2025-09-30
AI Technical Summary
The existing energetic material PDFAMO has a low Tg value, resulting in insufficient low-temperature mechanical properties, making it difficult to meet the requirements of the adhesive system.
A triblock energetic copolymer was prepared by cationic polymerization. By combining 3-difluoroamino-3-methyloxetane with terminal hydroxyl polybutadiene, a poly(3-difluoroamino-3-methyloxetane)-terminated hydroxyl polybutadiene-poly(3-difluoroamino-3-methyloxetane) triblock copolyether was formed. The molecular weight distribution was controlled and the low-temperature mechanical properties were improved.
The prepared triblock energetic copolymer has a narrow molecular weight distribution, which meets the low-temperature mechanical property requirements of the adhesive system.
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Figure CN120718261A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a triblock energetic copolymer and a preparation method thereof, belonging to the technical field of polymer materials. Background Art
[0002] Difluoroamino groups (-NF2) have a high heat of formation and can release a large amount of energy when decomposing, significantly increasing the energy level of the compound. During the decomposition, fluorinated products with oxidative properties are produced. These products continue to participate in the combustion reaction, thereby improving the oxygen balance of energetic materials and increasing the energy release efficiency. The combustion products are clean, making them one of the ideal energetic groups for improving the energy of binders used in solid propellants. As a promising candidate material, poly (3-difluoroamino-3-methyloxetane) (PDFAMO) containing -NF2 groups has shown great potential in improving the performance of solid propellants or PBX formulations. However, the T of PDFAMO recorded in the literature is g The value is -21.89℃, and the low-temperature mechanical properties are insufficient, which makes it difficult to meet the low-temperature mechanical properties requirements of the adhesive system.
[0003] Therefore, a triblock energetic copolymer and a preparation method thereof are needed to solve the above problems. Summary of the Invention
[0004] Purpose of the invention: To address the problems existing in the prior art, the present invention provides a triblock energetic copolymer.
[0005] A triblock energetic copolymer having the following structural formula:
[0006]
[0007] Where a, b, c, and n are real numbers.
[0008] Furthermore, its name is: poly 3-difluoroamino-3-methyloxetane-terminated hydroxyl polybutadiene-poly 3-difluoroamino-3-methyloxetane triblock copolyether.
[0009] Beneficial effects: The triblock energetic copolymer of the present invention has a narrow molecular weight distribution and can meet the low-temperature mechanical properties required by the adhesive system.
[0010] The present invention also discloses a method for preparing a triblock energetic copolymer, which comprises using 3-difluoroamino-3-methyloxetane as a polymerization monomer, boron trifluoride ethyl ether as a catalyst, hydroxyl-terminated polybutadiene as an initiator, and dichloromethane as a solvent to obtain a triblock copolyether through a cationic polymerization reaction, namely, a triblock energetic copolymer.
[0011] Furthermore, the following steps are included:
[0012] Step 1: stirring the initiator, catalyst and solvent at room temperature to obtain a complex system;
[0013] Step 2, adding the first mixed solution dropwise to the complex system obtained in step 1, stirring and polymerizing at room temperature after the addition is completed to obtain a polymerization solution, and adding a saturated sodium bicarbonate solution dropwise to the polymerization solution after the polymerization reaction is completed to terminate the reaction to obtain a reaction solution, wherein the first mixed solution is a mixed solution of 3-difluoroamino-3-methyloxetane and dichloromethane;
[0014] Step 3: dissolving the reaction solution obtained in step 2 in dichloromethane, adjusting the pH to neutral, extracting to obtain an organic phase, drying and filtering to remove dichloromethane, then extracting with a second mixed solution to remove low molecular weight oligomers, and vacuum drying to obtain a triblock copolyether, i.e., a triblock energetic copolymer, wherein the second mixed solution is a mixed solution of methanol and tetrahydrofuran.
[0015] Furthermore, the catalyst and solvent are both dehydrated with calcium hydride before use. The molecular weight of the hydroxy-terminated polybutadiene is 4600 and is dehydrated before use. The 3-difluoroaminomethyl-3-methyloxetane needs to be purified by reduced pressure distillation before use.
[0016] Furthermore, the molar ratio of the polymerization monomer, the initiator and the catalyst is 10-25:1:0.5-4.
[0017] Furthermore, in step 2, the volume ratio of the first mixed solution to the complexing system is 1:1, and the polymerization reaction time is 12 to 48 hours.
[0018] Furthermore, in step 1, the container for stirring and complexing the initiator, catalyst and solvent at room temperature is a three-necked flask, which is equipped with a magnetic stirring device and a PTFE three-way valve. The three-necked flask is vacuumed in a 140°C oil bath for at least 1 hour before use. After the three-necked flask is cooled, the gas in the flask is replaced with nitrogen at least 3 times.
[0019] Furthermore, in step three, the volume ratio of methanol to tetrahydrofuran in the second mixed solution is 0.5-0.8:1.
[0020] Furthermore, in step 2, the ratio of dichloromethane to 3-difluoroamino-3-methyloxetane in the first mixed solution is 1 to 8 mL / g.
[0021] Beneficial effects: The present invention adopts a cationic polymerization method to obtain a poly (3-difluoroamino-3-methyloxetane)-terminated hydroxyl polybutadiene-poly (3-difluoroamino-3-methyloxetane) triblock energetic copolyether with a narrow molecular weight distribution. Since the terminal hydroxyl polybutadiene is introduced into the 3-difluoroamino-3-methyloxetane, the prepared triblock copolyether can meet the low-temperature mechanical properties required by the adhesive system. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 is the Fourier transform infrared spectrum of the triblock energetic copolymer in Example 1;
[0023] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the triblock energetic copolymer in Example 1;
[0024] Figure 3 is the carbon NMR spectrum of the triblock energetic copolymer in Example 1;
[0025] Figure 4 is the nuclear magnetic resonance fluorine spectrum of the triblock energetic copolymer in Example 1;
[0026] Figure 5 is the gel chromatogram of the triblock energetic copolymer in Example 1;
[0027] Figure 6 is the gel chromatogram of the triblock energetic copolymer in Example 2;
[0028] Figure 7 This is the gel chromatogram of the triblock energetic copolymer in Example 3. DETAILED DESCRIPTION
[0029] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings to more clearly and completely illustrate the technical solutions of the present invention.
[0030] Example 1
[0031] See also Figure 1-Figure 5As shown, a three-necked flask was vacuum-treated at 140°C for 1 hour. After cooling, the atmosphere was replaced with nitrogen three times. 1 mmol of the initiator, hydroxy-terminated polybutadiene, which had been vacuum-treated, was dissolved in 2.8 mL of dehydrated dichloromethane. This was added to the treated three-necked flask and mixed thoroughly. Then, 1 mmol of the catalyst, boron trifluoride etherate, was added and stirred at 25°C for 1 hour. After the complexation was complete, a mixture of 20 mmol of DFAMO and 2.8 mL of dichloromethane was added dropwise using a constant pressure dropping funnel for 1 hour. After the addition was complete, the reaction was stirred at 0°C for 24 hours. After the reaction was complete, a small amount of saturated sodium carbonate solution was added to the flask to terminate the reaction and proceed with post-processing. The reaction solution was dissolved in dichloromethane, and the organic phase was washed several times with water and saturated sodium chloride solution in sequence until the pH reached neutral. After the organic phase was extracted, anhydrous sodium sulfate was added thereto for drying. After filtration, the solvent was removed by vacuum rotary evaporation to obtain a yellow viscous liquid. The obtained liquid was washed several times with isopropanol / tetrahydrofuran. The precipitate was collected and dried in a vacuum drying oven at 70°C to finally obtain a yellow viscous triblock copolyether with a yield of 92%. The molecular weight of the sample was measured by gel permeation chromatography, and the results were: number average molecular weight Mn = 6741, and polydispersity PDI = 1.48.
[0032] Example 2
[0033] See also Figure 6 As shown, a three-necked flask was vacuum-treated at 140°C for 1 hour. After cooling, the atmosphere was replaced with nitrogen three times. 1 mmol of the initiator, hydroxy-terminated polybutadiene, which had been vacuum-treated, was dissolved in 5.6 mL of dehydrated dichloromethane. This was added to the treated three-necked flask and mixed thoroughly. Then, 1 mmol of the catalyst, boron trifluoride etherate, was added and stirred at 25°C for 1 hour. After the complexation was complete, a mixture of 20 mmol of DFAMO and 5.6 mL of dichloromethane was added dropwise using a constant pressure dropping funnel for 1 hour. After the addition was complete, the reaction was stirred at 25°C for 24 hours. After the reaction was complete, a small amount of saturated sodium carbonate solution was added to the flask to terminate the reaction and perform post-processing. The reaction solution was dissolved in dichloromethane, and the organic phase was washed several times with water and saturated sodium chloride solution in sequence until the pH reached neutral. After the organic phase was extracted, anhydrous sodium sulfate was added thereto for drying. After filtration, the solvent was removed by vacuum rotary evaporation to obtain a yellow viscous liquid. The obtained liquid was washed several times with isopropanol / tetrahydrofuran. The precipitate was collected and dried in a vacuum drying oven at 70°C to finally obtain a yellow viscous triblock copolyether with a yield of 78%. The molecular weight of the sample was measured by gel permeation chromatography, and the results were: number average molecular weight Mn = 6703, polydispersity PDI = 1.84.
[0034] Example 3
[0035] See also Figure 7As shown, a three-necked flask was vacuum-treated at 140°C for 1 hour. After cooling, the atmosphere was replaced with nitrogen three times. 1 mmol of the initiator, hydroxy-terminated polybutadiene, which had been vacuum-treated, was dissolved in 2.8 mL of dehydrated dichloromethane. This was added to the treated three-necked flask. After mixing, 1 mmol of the catalyst, boron trifluoride etherate, was added and stirred at 25°C for 1 hour. After the complexation was complete, a mixture of 15 mmol of DFAMO and 2.8 mL of dichloromethane was added dropwise using a constant pressure dropping funnel for 1 hour. After the addition was complete, the reaction was stirred at 25°C for 24 hours. After the reaction was complete, a small amount of saturated sodium carbonate solution was added to the flask to terminate the reaction and perform post-processing. The reaction solution was dissolved in dichloromethane, and the organic phase was washed several times with water and saturated sodium chloride solution in sequence until the pH reached neutral. After the organic phase was extracted, anhydrous sodium sulfate was added thereto for drying. After filtration, the solvent was removed by vacuum rotary evaporation to obtain a yellow viscous liquid. The obtained liquid was washed several times with isopropanol / tetrahydrofuran. The precipitate was collected and dried in a vacuum drying oven at 70°C to finally obtain a yellow viscous triblock copolyether with a yield of 64%. The molecular weight of the sample was measured by gel permeation chromatography, and the results were: number average molecular weight Mn = 5907, and polydispersity PDI = 2.45.
[0036] Structural Verification
[0037] FT-IR: 3700~3600cm -1 (-OH), 3000~2800cm -1 (-CH2-, -CH3), 1733cm -1 (-NF2), 1646cm -1 (C=C), 1436, 966cm -1 (CH), 1105cm -1 (COC), 1052, 896cm -1 (NF), 798cm -1 (CN);
[0038] 1 H-NMR (500MHz, CDCl3): 5.34~5.46ppm (5H, -CH=CH-in HTPB), 4.90~5.03ppm (2H, CH2=CH-C in HTPB), 3.40~3.60ppm (4H, -CH2-NF2 in PDFAMO), 3.25~3.38ppm (8H, CO-CH2 in PDFAMO), 1.06~1.12ppm(6H,-CH3 in PDFAMO);
[0039] 13C-NMR(125MHz,CDCl3):118~142ppm(-CH=CH-C-in HTPB),76.23ppm(-CH-O-Cin PDFAMO),69.38ppm(O-CH2-NF2 in PDFAMO),39.87ppm(CH3-C-CH2NF2in PDFAMO),27.23~42.61ppm(-C-H in HTPB),18.78ppm(-CH3 in PDFAMO)。
[0040] 19 F-NMR(470MHz,CDCl3):65.2ppm(-NF2 in PDFAMO)。
Claims
1. A triblock energetic copolymer, characterized in that: Its structural formula is as follows: Where a, b, c, and n are real numbers.
2. The triblock energetic copolymer according to claim 1, wherein Its name is: poly 3-difluoroamino-3-methyloxetane-terminated hydroxyl polybutadiene-poly 3-difluoroamino-3-methyloxetane triblock copolyether.
3. A method for preparing a triblock energetic copolymer, characterized in that: The triblock copolyether is obtained by cationic polymerization using 3-difluoroamino-3-methyloxetane as a polymerization monomer, boron trifluoride ethyl ether as a catalyst, hydroxyl-terminated polybutadiene as an initiator, and dichloromethane as a solvent. The triblock copolyether is a triblock energetic copolymer.
4. The method for preparing the triblock energetic copolymer according to claim 3, wherein: The following steps are involved: Step 1: stirring the initiator, catalyst and solvent at room temperature to obtain a complex system; Step 2, adding the first mixed solution dropwise to the complex system obtained in step 1, stirring and polymerizing at room temperature after the addition is completed to obtain a polymerization solution, and adding a saturated sodium bicarbonate solution dropwise to the polymerization solution after the polymerization reaction is completed to terminate the reaction to obtain a reaction solution, wherein the first mixed solution is a mixed solution of 3-difluoroamino-3-methyloxetane and dichloromethane; Step 3: dissolving the reaction solution obtained in step 2 in dichloromethane, adjusting the pH to neutral, extracting to obtain an organic phase, drying and filtering to remove dichloromethane, then extracting with a second mixed solution to remove low molecular weight oligomers, and vacuum drying to obtain a triblock copolyether, i.e., a triblock energetic copolymer, wherein the second mixed solution is a mixed solution of methanol and tetrahydrofuran.
5. The method for preparing the triblock energetic copolymer according to claim 3, wherein: The catalyst and solvent are both dehydrated with calcium hydride before use. The molecular weight of the hydroxy-terminated polybutadiene is 4600 and is dehydrated before use. The 3-difluoroaminomethyl-3-methyloxetane is purified by reduced pressure distillation before use.
6. The method for preparing a triblock energetic copolymer according to claim 3, wherein: The molar ratio of the polymerization monomer, the initiator and the catalyst is 10-25:1:0.5-4.
7. The method for preparing a triblock energetic copolymer according to claim 4, wherein: In step 2, the volume ratio of the first mixed solution to the complexing system is 1:1, and the polymerization reaction time is 12 to 48 hours.
8. The method for preparing a triblock energetic copolymer according to claim 4, wherein: In step 1, the container for stirring and complexing the initiator, catalyst and solvent at room temperature is a three-necked flask, which is equipped with a magnetic stirring device and a PTFE three-way valve. The three-necked flask is vacuumed in a 140°C oil bath for at least 1 hour before use. After the three-necked flask is cooled, the gas in the flask is replaced with nitrogen at least 3 times.
9. The method for preparing a triblock energetic copolymer according to claim 4, wherein: In step 3, the volume ratio of methanol to tetrahydrofuran in the second mixed solution is 0.5-0.8:
1.
10. The method for preparing a triblock energetic copolymer according to claim 4, wherein: In step 2, the ratio of dichloromethane to 3-difluoroamino-3-methyloxetane in the first mixed solution is 1 to 8 mL / g.