阅读说明：本技术 一种具有交替多嵌段结构的3,3-双叠氮甲基氧杂环丁烷-四氢呋喃含能共聚醚及其合成方法 (3, 3-bis-azidomethyloxetane-tetrahydrofuran energetic copolyether with alternating multi-block structure and synthesis method thereof ) 是由 郑文芳 李雅楠 李文希 潘仁明 蔺向阳 于 2021-08-04 设计创作，主要内容包括：本发明公开了一种具有交替多嵌段结构的3,3-双叠氮甲基氧杂环丁烷-四氢呋喃含能共聚醚及其合成方法,交替多嵌段的含能粘合剂结构式如(I)所示：其中,m＝1～5,n＝1～4,k＝1～10,为整数。其合成过程包括以下步骤：以聚四氢呋喃(PTHF)和3,3-双叠氮甲基氧杂环丁烷均聚物(PBAMO)为原料,经过威廉姆森醚合成得到交替多嵌段的叠氮基类含能粘合剂。本合成方法简单,交替多嵌段的BAMO-THF含能粘合剂具有可调节的微观序列结构,能够赋予推进剂较好的力学性能。(The invention discloses a 3, 3-bis-azidomethyloxetane-tetrahydrofuran energetic copolyether with an alternate multi-block structure and a synthesis method thereof, wherein the structural formula of an alternate multi-block energetic adhesive is shown as (I):)

1. A3, 3-bis-azidomethyloxetane-tetrahydrofuran energetic copolyether with an alternate multi-block structure and a synthetic method thereof, wherein the structural formula of the alternate multi-block energetic adhesive is shown as (I)

Wherein m is 1 to 5, n is 1 to 4, and k is 1 to 10, and is an integer.

2. A3, 3-bis-azidomethyloxetane-tetrahydrofuran energetic copolyether with an alternate multi-block structure and a synthesis method thereof are characterized by comprising the following specific steps:

step 1, adding a 3, 3-bis-azidomethyloxetane oligomer with small molecular weight, tetrahydrofuran and a catalyst into a three-neck flask provided with a magnetic stirring device, a thermometer and a reflux device, and carrying out reflux stirring reaction to obtain a potassium/sodium terminal alkoxide 3, 3-bis-azidomethyloxetane oligomer;

step 2, dropwise adding a tetrahydrofuran solution containing p-toluenesulfonic acid polytetrahydrofuran (PTHF-OTS) into the potassium/sodium terminal alkoxide 3, 3-bis-azidomethyloxetane oligomer, carrying out reflux stirring reaction, and filtering to obtain a dark yellow liquid after the reaction is finished;

and 3, removing the tetrahydrofuran solvent in the yellow liquid by rotary evaporation, dissolving in dichloromethane, adjusting the pH value to be neutral by using a hydrochloric acid aqueous solution and a sodium chloride saturated aqueous solution, drying by using anhydrous sodium sulfate, filtering, and drying by rotary evaporation. Then petroleum ether and methanol are adopted for extraction to remove cyclic ether compounds and low molecular oligomers, and the BAMO-THF energy-containing copolyether with an alternate multi-block structure is obtained.

3. The method of claim 2, wherein in step 1, the molecular weight of the 3, 3-bis-azidomethyloxetane oligomer is Mn 186-930.

4. The method according to claim 2, wherein in step 1, the volume ratio of the 3, 3-bis-azidomethyloxetane oligomer to PTHF-OTS is 1: 1 to 3.

5. The method according to claim 2, wherein in step 1, the catalyst is potassium hydroxide, sodium hydride, sodium methoxide, or the like.

6. The method of claim 2, wherein in step 2, the molar ratio of the sodium/potassium 3, 3-diazacyclomethyloxetane terminated oligomer to the polytetrahydrofuran-terminated toluene sulfonic acid is 1-2: 1.

7. The preparation method according to claim 2, wherein in the step 2, the volume ratio of the polytetrahydrofuran p-toluenesulfonate to the tetrahydrofuran is 1: 1-3.

8. The preparation method according to claim 2, wherein in the step 2, the reflux reaction time is 12-72 hours.

9. The method according to claim 2, wherein in step 3, the concentration of the aqueous hydrochloric acid solution is not higher than 2 mol/L.

Technical Field

The invention relates to a 3, 3-bis-azidomethyloxetane-tetrahydrofuran copolymer with an alternate multi-block structure and a synthesis method thereof, and the compound can be used as an energetic adhesive of a solid propellant, belonging to the technical field of high polymer materials.

Background

3, 3-bis-azidomethyloxetane homopolymer (PBAMO) is taken as an energy-containing adhesive with high nitrogen content, has the advantages of high heat generation, high energy, good compatibility, low mechanical sensitivity and the like, and is one of the future development directions of research hotspots in the field of the energy-containing adhesive at present. The PBAMO improves energy by introducing azide groups into the side groups of the carbon chain, but the existence of the side groups can improve the glass transition temperature of the adhesive, so that the solid propellant is not resistant to low temperature and has poor toughness in a low-temperature environment.

In order to solve the problem of low-temperature embrittlement of PBAMO, researchers have introduced flexible chains into azide-based energetic binders to lower their glass transition temperatures. The 3, 3-bis-azidomethyloxetane-tetrahydrofuran (BAMO-THF) copolymer is one of the most promising energy-containing adhesives at present in China, and has wide application prospect and research value. The BAMO-THF copolymer is generally prepared by two synthetic routes, one is synthesized by direct ring-opening bulk copolymerization of BAMO and THF under the catalysis of Levvis acid, and the other is synthesized by polymerizing BCMO and THF, and then polymerizing the BCMO and THF with NaN₃Carrying out an azide reaction. However, the products of such cationic copolymerization are generally random copolymerization, and can only obtain a more ideal distribution state to a certain extent by the feed ratio, and the control of the sequence structure is difficult.

The result shows that the copolymer with the similar chain link ratio can be obtained by controlling the charge ratio, and the random distribution state of the two monomers is ideal and the random state is good from the viewpoints of the alternation degree, the average sequence length and the reactivity ratio. Jiahonghui et al found that when the charge ratio n (BAMO) to n (THF) was 50: 50, the BAMO segment length was mainly concentrated between 1-5 and the THF segment length was mainly concentrated between 1-2, i.e., theoretically, BAMO tended to form micro-blocks. Under the system of the charge ratio, the length of the BAMO number average sequence is 2.12, and the length of the THF number average sequence is 1.34. Therefore, the cation random copolymerization can not obtain controllable alternating multi-block copolymerization, and the microstructure of the micro-sequence needs to be further optimized.

Disclosure of Invention

The invention aims to provide a 3, 3-diazacyclomethyloxetane-tetrahydrofuran copolymer with an alternating multi-block structure and a synthesis method thereof.

The technical scheme for realizing the purpose of the invention is as follows:

polytetrahydrofuran (PTHF) and 3, 3-bis-azidomethyloxetane homopolymer (PBAMO) are used as raw materials, KOH is used as a catalyst, and nucleophilic substitution reaction is carried out to obtain the alternating segmented azide type energetic adhesive. The synthesis method is simple, the microstructure of the obtained alternating multi-block BAMO-THF energy-containing copolyether is adjustable, the propellant can be endowed with better mechanical property, and the structural formula is as follows:

the BAMO-THF energy-containing copolyether with an alternating multi-block structure comprises the following specific steps:

step 1, adding a 3, 3-bis-azidomethyloxetane oligomer with small molecular weight, tetrahydrofuran and excessive potassium hydroxide into a three-neck flask provided with a magnetic stirring device, a thermometer and a reflux device, and carrying out reflux stirring reaction to obtain a potassium/sodium terminal alkoxide 3, 3-bis-azidomethyloxetane oligomer;

step 2, dropwise adding a tetrahydrofuran solution of polytetrahydrofuran esterified with end-toluene sulfonic acid into the potassium/sodium end alkoxide 3, 3-bis-azidomethyloxetane oligomer, carrying out reflux stirring reaction, and filtering to obtain yellow liquid after the reaction is finished;

step 3, removing the tetrahydrofuran solvent in the yellow liquid by rotary evaporation, dissolving the tetrahydrofuran solvent in dichloromethane, adjusting the pH value to be neutral by using a hydrochloric acid aqueous solution and a sodium chloride saturated aqueous solution, drying the anhydrous sodium sulfate, and then, drying by rotary evaporation; then petroleum ether and methanol are used for extraction to remove cyclic ether and low molecular oligomer, and the BAMO-THF energy-containing copolyether with an alternate multi-block structure is obtained.

Preferably, in step 1, the molecular weight of the 3, 3-bis-azidomethyloxetane oligomer is Mn 186-930.

Preferably, in the step 1, the volume ratio of the 3, 3-bis-azidomethyloxetane oligomer to the tetrahydrofuran is 1: 1-3.

Preferably, in step 1, the catalyst may be potassium hydroxide, sodium hydride, sodium methoxide, etc.

Preferably, in the step 2, the molar ratio of the sodium/potassium terminal alkoxide 3, 3-diazacyclomethyloxetane to the polytetrahydrofuran p-toluenesulfonate is 1-2: 1.

Preferably, in the step 2, the volume ratio of the polytetrahydrofuran p-toluenesulfonate to the tetrahydrofuran is 1: 1-3.

Preferably, in the step 2, the reflux reaction time is 12-48 h.

Preferably, in the step 3, the concentration of the hydrochloric acid aqueous solution is not higher than 2 mol/L.

Compared with the prior art, the invention has the following advantages:

the invention gets rid of the common cationic polymerization copolymerization method in the prior art, realizes the polycondensation among the oligomers by a Wilson ether synthesis method, changes the micro-sequence structure of the BAMO-THF energy-containing copolyether by adjusting the molecular weight and the reaction time of the oligomers, effectively realizes the regulation and control of the mechanical property of the BAMO same-content random copolyether, and finally obtains the BAMO-THF energy-containing copolyether with different numbers of micro-block units.

Drawings

FIG. 1 is a schematic representation of a BAMO-THF alternating multiblock copolymer prepared in example 1; FIG. 2 is a plot of the Fourier infrared characteristic spectra of PBMO oligomer, PTHF-OTS, and BAMO-THF alternating multiblock copolymers prepared in example 1; FIG. 3 is the NMR spectrum of the BAMO-THF alternating multiblock copolymer of example 1; FIG. 4 is a schematic representation of a BAMO-THF alternating multiblock copolymer prepared in example 2; FIG. 5 is the NMR spectrum of the BAMO-THF alternating multiblock copolymer of example 2; FIG. 6 is a schematic representation of a BAMO-THF alternating multiblock copolymer prepared in example 3; (ii) a FIG. 7 is the NMR spectrum of the alternating BAMO-THF copolymer of example 3;

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.

Example 1

1.2g of PBAMO (Mn 322, 3.7mmol) was dissolved in 10mL of THF, 2.24g of KOH (40mmol) was added, and the system was transferred to a constant temperature oil bath at 65 ℃. A THF solution of 1.2g of a tosylate polytetrahydrofuran (Mn 542, 2.2mmol) was slowly added dropwise to the above reaction system, and after completion of the addition, the reaction was continued at 65 ℃ for 18 hours. The crude product was then filtered and rotary evaporated, dissolved in dichloromethane and washed to neutrality with distilled water. Drying with anhydrous magnesium sulfate, vacuum filtering, rotary steaming, sequentially adding petroleum ether with boiling point of 60-90 deg.C and methanol, washing, and rotary steaming to obtain yellow viscous substance (0.82g)

And (3) structural identification:

FT-IR Infrared: after the polytetrahydrofuran is subjected to p-toluenesulfonylation to obtain terminal tosylate polytetrahydrofuran, infrared hydroxyl 3000-3500cm^-1Disappearance, which proves that the end groups of PTHF have been completely modified. The hydroxyl peak of PBMO-THF prepared by PBMO and PTHF-OTS is obviously reduced compared with PBMO, and the p-toluenesulfonyl chloride is 1000-1500cm^-1The characteristic peak of (2) disappears.

Nuclear magnetism: BAMO content 22.7% by 1H-NMR, 1H-NMR (CDCl)₃500 MHz): delta.3.3-3.4 (CH in THF)₂-O)，δ3.23-3.28(CH₂-N₃) 3.18-3.23 (CH in BAMO)₂-O), 1.44-1.64 (C-CH in THF)₂-C)。

The above data indicate that the synthesized compound is a BAMO-THF copolyether energetic adhesive with an alternating multi-block structure

Example 2

1.5g of PBAMO (Mn 448, 3.3mmol) was dissolved in 20mL of THF, 2.57g of KOH (40mmol) was added, and the system was transferred to a constant temperature oil bath at 65 ℃. A THF solution of 1.2g of a tosylate polytetrahydrofuran (Mn 542, 2.2mmol) was slowly added dropwise to the above reaction system, and after completion of the addition, the reaction was continued at 65 ℃ for 24 hours. The crude product was then filtered and rotary evaporated, dissolved in dichloromethane and washed to neutrality with distilled water. Drying with anhydrous magnesium sulfate, vacuum filtering, rotary steaming, sequentially adding petroleum ether with boiling point of 60-90 deg.C and methanol, washing, and rotary steaming to obtain yellow viscous substance (0.74 g).

Example 3

1.28g of PBAMO (Mn 510, 2.5mmol) was dissolved in 20mL of THF, 2.01g of KOH (40mmol) was added, and the system was transferred to a constant temperature oil bath at 65 ℃. A solution of 0.8g of 1, 4-butanediol having a terminal tosylate group (Mn. 398, 2.0mmol) in THF was slowly added dropwise to the above reaction system, and after the addition was completed, the reaction system was allowed to continue at 65 ℃ for 24 hours. The crude product was then filtered and rotary evaporated, dissolved in dichloromethane and washed to neutrality with distilled water. Drying with anhydrous magnesium sulfate, vacuum filtering, rotary steaming, sequentially adding petroleum ether with boiling point of 60-90 deg.C and methanol, washing, and rotary steaming to obtain yellow viscous substance (0.52 g).