Star-shaped four-arm glycidyl azide polymer with hyperbranched characteristic and synthesis method of star-shaped four-arm glycidyl azide polymer

Abstract

The invention discloses star-shaped four-arm glycidyl azide polymer (GAP) with a hyperbranched characteristic and a synthesis method of the star-shaped four-arm glycidyl azide polymer (GAP). The preparation method comprises the following steps: under the catalysis of a boron trifluoride complex, carrying out cationic ring-opening polymerization by taking bis (trihydroxymethyl) propane (DiTMP) as a multifunctional core initiator and taking epichlorohydrin (ECH) as a monomer to construct a star-shaped four-arm polyepichlorohydrin (DiTMP-PECH) precursor; and then performing efficient substitution on chlorine atoms in the molecular structure through sodium azide (NaN3) to obtain the hyperbranched star-shaped four-arm glycidyl azide polymer (DiTMP-GAP). The star-shaped polymer has relatively high end group functionalization degree and good structural uniformity, has the characteristics of a star-shaped topological structure and high azide group content, and provides a new way for molecular design of energetic polymers. The synthesis method is simple and convenient in process and controllable in condition, has good expandability, and is expected to show application potential in the fields of high-energy solid propellants and explosive adhesives.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties and its synthesis method. Background Technology

[0002] Energetic binders are key components in modern high-energy propellant and explosive systems, and their performance directly affects the mechanical stability, cryogenic adaptability, and energy release efficiency of the explosive charge. Traditional linear glycidyl azidopolyether (GAP) is widely used due to its high energy density, but its glass transition temperature is relatively high (…). T g At approximately -45°C, it is prone to brittleness under low-temperature conditions, making it difficult to meet the mechanical requirements under harsh environments.

[0003] To improve the viscoelastic properties of GAPs, researchers have attempted to introduce flexible, inert polymers (such as hydroxyl-terminated polybutadiene HTPB, polycaprolactone PCL, and polyethylene glycol PEG) into GAPs for copolymerization, and optimized the performance by adjusting the crosslinking density and the average molecular weight between crosslinking points. However, the introduction of these inert polymers significantly dilutes the energy density of the system, leading to a negative feedback loop of "mechanical enhancement – ​​energy decay." Furthermore, the differences in reactivity among different monomers make the copolymerization process difficult to control precisely. To address these issues, researchers have proposed transforming the topology of GAPs from linear to hyperbranched configurations, which is expected to solve these problems. For example, in 2018, Zhang et al. synthesized a hyperbranched star copolymer POG-n (where n is the number of arms) using hydroxyl-terminated hyperbranched poly(3-ethyl-3-(hydroxymethyl)oxybutane) as the core initiator, followed by ECH cationic ring-opening polymerization and azide substitution. Compared to linear GAPs, this type of polymer exhibits a lower glass transition temperature (e.g., POG-8). T g The temperature was approximately -51℃, indicating that branched structures have advantages in improving low-temperature performance. However, this method requires the pre-preparation of hyperbranched cores followed by stepwise grafting and chain extension, making the synthesis process cumbersome. Therefore, there is an urgent need for an energetic binder with simple synthesis steps, precisely controllable topology, and the ability to balance high energy density with excellent low-temperature mechanical properties, in order to overcome the above shortcomings and improve the overall performance of propellant and explosive systems. Summary of the Invention

[0004] To address the aforementioned existing problems and shortcomings, this invention provides a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties and its synthesis method, wherein DiTMP-GAP homopolymer ether is obtained through cationic ring-opening polymerization and azidation reaction.

[0005] Technical solution: To achieve the above-mentioned objectives, the present invention adopts the following technical solution: Using four-armed DiTMP as an initiator and boron trifluoride complex as a catalyst, cationic ring-opening polymerization of cyclic ECH was initiated to prepare DiTMP-PECH; subsequently, it reacted with NaN3 to obtain a star-shaped four-armed energetic binder DiTMP-GAP with hyperbranched properties, the structural formula of which is as follows: Where x+y+m+n = 18~34, and x, y, m, and n are all integers.

[0006] The specific steps are as follows: Step 1: Mix bis(trimethylol)propane (DiTMP), boron trifluoride complex, and organic solvent and stir. Add epichlorohydrin (ECH) dropwise to react. After the reaction is complete, quench, extract, wash, dry, and vacuum rotary evaporate to obtain colorless and transparent DiTMP-PECH.

[0007] In some preferred embodiments, after the reaction is complete, a saturated sodium carbonate solution is added to the reaction solution for quenching. The reaction solution is then extracted with an appropriate amount of organic solvent, the organic phase is washed with saturated brine, dried, and then rotary evaporated under vacuum to obtain colorless and transparent DiTMP-PECH.

[0008] Step 2: Dissolve the DiTMP-PECH obtained in Step 1 in a solvent, add excess NaN3, and stir continuously under reflux to obtain a pale yellow viscous liquid. Remove the solvent by rotary evaporation and then dissolve it in dichloromethane. After washing, drying and filtering, star-shaped four-armed polyazidoglycidyl ether DiTMP-GAP with hyperbranched properties is obtained.

[0009] In some preferred embodiments, after the reaction is complete, the solvent in the above pale yellow viscous liquid is removed by rotary evaporation, the residue is dissolved in CH2Cl2, washed with saturated brine, dried with anhydrous sodium sulfate, filtered, and then subjected to rotary evaporation and vacuum drying in sequence to obtain DiTMP-GAP.

[0010] Preferably, the solvent in step 1 is dichloromethane or toluene.

[0011] Preferably, in step 1, the catalyst is a boron trifluoride diethyl ether complex or a boron trifluoride tetrahydrofuran complex, and the molar ratio of DiTMP to the boron trifluoride complex is 1:1 to 4.

[0012] Preferably, in step 1, the activation time of the DiTMP is 0.5 to 1 hour, and the activation temperature is 0 to 35°C.

[0013] Preferably, in step 1, the ECH is added over a period of 2 to 8 hours, the reaction temperature is controlled at 0 to 35°C, and the polymerization reaction time is 18 to 36 hours.

[0014] Preferably, in step 2, the solvent used for the azidation reaction is N,N-dimethylformamide, dimethyl sulfoxide, or a mixed solution of acetonitrile and water.

[0015] Preferably, in step 2, the molar ratio of DiTMP-PECH to NaN3 is 1:23~30.

[0016] Preferably, in step 2, the reflux reaction temperature is 70–110°C and the reaction time is 24–48 h.

[0017] Technical advantages: This invention discloses a star-shaped four-armed polyazide glycidyl ether with hyperbranching properties and its synthesis method. Specifically, it involves a technical solution for synthesizing DiTMP-GAP energetic homopolymer ether through a two-step reaction using DiTMP as a four-armed star initiator, boron trifluoride complex as a catalyst, ECH as a monomer, and NaN3 as an azide reagent.

[0018] The energetic adhesive prepared by this invention has the number of arms precisely controlled by the number of hydroxyl groups in the DiTMP molecule, and the arm length can be adjusted by the ratio of monomer to initiator, thereby achieving directional design of product structure and properties. Attached Figure Description

[0019] Figure 1 The present invention is a star-shaped four-armed polyazidoglycidyl ether prepared in Example 1 of this invention.

[0020] Figure 2 This is the Fourier transform infrared characteristic spectrum of the star-shaped four-armed polyepoxychloropropylene precursor in Embodiment 1 of the present invention.

[0021] Figure 3 This is the Fourier transform infrared characteristic spectrum of the star-shaped four-armed polyazidoglycidyl ether with hyperbranching characteristics in Example 1 of the present invention.

[0022] Figure 4 This is the 1H NMR spectrum of the star-shaped four-armed polyazidoglycidyl ether with hyperbranching characteristics in Example 1 of the present invention.

[0023] Figure 5 This is a gel chromatogram of a star-shaped four-armed polyazidoglycidyl ether with hyperbranching characteristics in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0025] Using four-armed DiTMP as an initiator and boron trifluoride complex as a catalyst, cationic ring-opening polymerization of cyclic ECH was initiated to prepare DiTMP-PECH; subsequently, it reacted with NaN3 to obtain a star-shaped four-armed energetic binder DiTMP-GAP with hyperbranched properties, the structural formula of which is as follows: Where x+y+m+n = 18~34, are integers.

[0026] Step 1: In a three-necked flask equipped with a magnetic stirrer and thermometer, add appropriate amounts of solvent, DiTMP, and boron trifluoride complex as a catalyst in sequence. After stirring for a certain period of time, slowly add ECH dropwise. After the reaction is complete, quench the reaction solution with saturated sodium carbonate solution. Extract the reaction solution with an appropriate amount of organic solvent, wash the organic phase with saturated brine, dry it, and then rotary evaporate it under vacuum to obtain colorless and transparent DiTMP-PECH.

[0027] Step 2: Dissolve the DiTMP-PECH obtained in Step 1 in a suitable solvent, transfer it to a three-necked flask equipped with a magnetic stirrer, thermometer and reflux device, add NaN3 in batches, and stir continuously under reflux conditions to obtain a pale yellow viscous liquid.

[0028] Step 3: Remove the solvent from the above pale yellow viscous liquid by rotary evaporation, dissolve the residue in CH2Cl2, wash with saturated brine, dry with anhydrous sodium sulfate, filter, and then perform rotary evaporation and vacuum drying in sequence to obtain DiTMP-GAP.

[0029] Example 1 1.25g DiTMP (Mn=250 g mol) -1 Dissolve 5 mmol) in 20 mL of CH2Cl2, add 0.71 g of BF3·Et2O (Mn = 142 g mol) -1 The system was activated in an ice-water bath for 1 h with 27.75 g of ECH (Mn = 92.5 g mol). -1 Add 300 mmol of sodium carbonate solution dropwise to the above reaction system over 8 hours. After the addition is complete, continue the reaction at 0–10 °C for 24 hours. When the reaction reaches the termination stage, saturated sodium carbonate solution is added to quench the reaction. Then, dissolve the crude product in CH2Cl2 and wash with saturated brine and deionized water until neutral. Dry with anhydrous magnesium sulfate, filter, and rotary evaporate to obtain 25.70 g of a colorless, transparent, viscous liquid, with a yield of 88.62%.

[0030] 2.5g of PECH (Mn=22217.5 g mol) -1Dissolve 1.12 mmol of NaN3 in 25 mL of LDM, and transfer the system to a 75°C constant temperature oil bath. Add 1.75 g of NaN3 (Mn = 65 g mol) to a solution of 1.12 mmol of NaN3. -1 Add 27 mmol (27 mmol) in batches to the above reaction system, ensuring exothermic reaction. After the addition is complete, continue the reaction at 75 °C for 36 h. After the reaction is complete, evaporate the solvent, extract the product in CH2Cl2, and wash repeatedly with saturated brine and deionized water until the extract layer is distinct and the solution is clear. Then dry with anhydrous magnesium sulfate, filter, and rotary evaporate to obtain 2.70 g of a yellow, transparent, viscous liquid, with a yield of 63.53%. The structural formula of the obtained product is: Where x+y+m+n = 18~34, are integers.

[0031] Structural identification FT-IR infrared spectroscopy: After cyclic ECH undergoes cationic ring-opening polymerization to obtain the DiTMP-PECH precursor, 1108 cm⁻¹ -1 ether bond peak and 746 cm -1 The appearance of the carbon-chlorine bond peak indicates the presence of polyetherification and chlorination in the tested substance. After DiTMP-PECH undergoes an azide reaction to form DiTMP-GAP, the peak at 1108 cm⁻¹... -1 The ether bond peak did not disappear, thus preserving the ether bond structure. Simultaneously, the 746 cm⁻¹ peak of the carbon-chlorine bond disappeared, while the 2097 cm⁻¹ peak of the azide group... -1 The appearance of the peak indicates that the chlorine groups in the chlorinated polyether have been completely replaced by azide groups. Simultaneously, due to the high molecular weight of the two tested substances and the extremely low content of hydroxyl groups, the hydroxyl group peaks at 3000-3500 cm⁻¹. -1 The characteristic peaks were not observed.

[0032] NMR: 1H-NMR (CDCl 3500MHz): δ4.00-3.91 (HO-C), δ3.80-3.69 (CH2-O), δ0.87-0.83 (-CH3), δ1.40-1.36 (CH2-N3), δ1.72 (CH3-CH2) The above data indicate that the synthesized compounds are DiTMP-PECH (the former) and DiTMP-GAP (the latter).

[0033] Example 2 2.5g DiTMP (Mn=250 g mol) -1 Dissolve 10 mmol) in 40 mL of CH2Cl2, add 3.0 g of BF3·Et2O (Mn = 142 g mol) -1The system was activated in an ice-water bath for 0.5 h with 21.13 mmol of ECH. Subsequently, 55.5 g of ECH (Mn = 92.5 g mol) was added. -1 Add 600 mmol of sodium carbonate solution dropwise to the above reaction system over 4 hours. After the addition is complete, continue the reaction at 10–20 °C for 36 hours. When the reaction reaches the termination stage, saturated sodium carbonate solution is added to quench the reaction. Then, dissolve the crude product in toluene and wash with saturated brine and deionized water until neutral. Dry with anhydrous magnesium sulfate, filter, and rotary evaporate to obtain 52.6 g of a colorless, transparent, viscous liquid, with a yield of 90.69%.

[0034] 1.2g of PECH (Mn=2217.5 g mol) was added. -1 Dissolve 0.54 mmol of NaN3 in 20 mL of a mixed solution of acetonitrile and water, and transfer the system to a constant temperature oil bath at 100 °C. Add 1.0 g of NaN3 (Mn = 65 g mol) to a solution of acetonitrile and water. -1 15.38 mmol was added in batches to the above reaction system, and the reaction was carried out exothermically. After the addition was complete, the system was reacted at 100 °C for 24 h. After the reaction was complete, the solvent was evaporated, the product was extracted in CH2Cl2, and repeatedly washed with saturated brine and deionized water until the extract layer was clear and the solution was clear. Then, it was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain 1.54 g of a yellow transparent viscous liquid, with a yield of 70%. The structural formula of the obtained product is: Where x+y+m+n = 18~34, are integers.

[0035] The application performance of the star-shaped four-armed polyazolidone glycidyl ether adhesive of the present invention.

[0036] (1) Reactivity of star-shaped four-armed polyazide glycidyl ether The star-shaped four-armed poly(diTMP-GAP) adhesive system obtained in Examples 1 and 2 of this invention, at a weight of 49 wt%, was further modified by adding 2 wt% toluene diisocyanate (TDI) as a curing agent, 49 wt% Bu-NENA as a plasticizer, and triphenylbismuth (TPB) as a catalyst (0.5 wt% of the total amount of DiTMP-GAP, TDI, and Bu-NENA). This mixture forms a clear and transparent homogeneous mixed system. The mixture can achieve a stable and controllable curing reaction within a temperature range of 60-70°C. The resulting polyurethane elastomers are named DiTMP-GAP-1 and DiTMP-GAP-2, respectively.

[0037] (2) Mechanical properties of elastomers The key mechanical properties of the polyurethane elastomer generated by reacting the DiTMP-GAP-based adhesive described in this invention with TDI, Bu-NENA and TPB are detailed in Table 1.

[0038] Table 1 Mechanical properties of DiTMP-GAP-based elastomers (20℃) .

Claims

1. A star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties, characterized in that: The structural formula of the energetic adhesive is as follows: Where x+y+m+n = 18~34, and x, y, m, and n are all integers.

2. The method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 1, characterized in that, Includes the following steps: Step 1: Mix bis(trimethylol)propaneDiTMP, boron trifluoride complex and organic solvent and stir. Add epichlorohydrin ECH dropwise to react. After the reaction is completed, quench, extract, wash, dry and vacuum rotary evaporate to obtain colorless and transparent DiTMP-PECH. Step 2: Dissolve the DiTMP-PECH obtained in Step 1 in a solvent, add excess NaN3, and stir continuously under reflux to obtain a pale yellow viscous liquid. Remove the solvent by rotary evaporation and then dissolve it in dichloromethane. After washing, drying and filtering, star-shaped four-armed polyazidoglycidyl ether DiTMP-GAP with hyperbranched properties is obtained.

3. The method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 2, characterized in that: The boron trifluoride complex mentioned in step 1 is either boron trifluoride diethyl ether complex BF3·Et2O or boron trifluoride tetrahydrofuran complex BF3·THF.

4. A method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 3, characterized in that: The molar ratio of DiTMP to the boron trifluoride complex is 1:1 to 4.

5. The method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 2, characterized in that: The organic solvent in step 1 is dichloromethane or toluene; the ECH is added over a period of 2 to 8 hours, and the reaction continues for 18 to 36 hours after the addition is complete; the temperature during the addition and reaction processes is 0 to 35°C.

6. The method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 2, characterized in that: In step 2, the solvent is N,N-dimethylformamide, dimethyl sulfoxide, or a mixture of acetonitrile and water.

7. The method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 2, characterized in that: The molar ratio of DiTMP-PECH to NaN3 is 1:23-30.

8. The method for synthesizing a star-shaped four-armed polyazidoglycidyl ether with hyperbranched properties according to claim 2, characterized in that: The reflux reaction is carried out at a temperature of 70–110°C for 24–48 hours.

9. A solid propellant, characterized in that, Includes the star-shaped four-armed polyazidoglycidyl ether with hyperbranching properties as described in claim 1, or the star-shaped four-armed polyazidoglycidyl ether with hyperbranching properties prepared by the method described in any one of claims 2-8.

10. An explosive adhesive, characterized in that, Includes the star-shaped four-armed polyazidoglycidyl ether with hyperbranching properties as described in claim 1, or the star-shaped four-armed polyazidoglycidyl ether with hyperbranching properties prepared by the method described in any one of claims 2-8.

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