KR102386460B1 - An energetic prepolymer for solid propellant binder and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a high-energy prepolymer used in a binder for a solid propellant and a preparation method thereof. Specifically, a prepolymer in which a nitramine functional group is introduced into a triazole skeleton structure is used as a binder for a solid propellant so that the performance of the binder can be improved, toxicity can be reduced, and the manufacturing cost can also be lowered.

Description

An energetic prepolymer for solid propellant binder and manufacturing method thereof

The present invention relates to a prepolymer used in a binder for a solid propellant and a method for preparing the same.

The field of rocket propellants developed during the world war and space race in the 1900s has been continuously studied for the development of the aerospace industry and the development of long-range missiles until recently. These propellants are divided into liquid propellants and solid propellants according to their shape. In the case of liquid fuel engines using liquid propellants, they have a disadvantage in that they receive a lot of size restrictions during manufacturing due to their complex structure. Solid propellants that can be designed into fuel engines are widely used.

Among various types of solid propellants, especially, in the case of a mixed solid propellant manufactured using polysulfide as a binder by Thiokol Company in the United States in the 1950s, it has the advantage of easy storage and high thrust for a short time. A lot of research is still in progress.

Mixed-type solid propellant consists of an oxidizer, a solid component that supplies oxygen required for combustion, metallic fuel powder that releases high energy during propellant combustion (energetic materials), and a binder that physically binds the oxidizer and fuel. is done Among them, the binder maintains the mechanical properties of the propellant grains to withstand external and internal thermal and mechanical stress. In addition, as an adhesive that helps the motor case and propellant combine and a combustible material necessary for generating propulsion during combustion, a rubbery viscoelastic material obtained by reacting a low molecular weight polymer with a curing agent is often used as a binder material.

In general, a prepolymer used in a binder for a solid propellant is a low-molecular-weight polymer in a liquid form with no crystallinity and flowability, and forms a large network structure through cross-linking. Recently, research on the development of binders for high-energy propellants to further increase the energy (specific thrust) of the propellants is being actively conducted. there is a bar

However, while glycidyl azide polymer has the advantage of releasing a large amount of gas and thermal energy during combustion, it is expensive, uses toxic and explosive monomers during synthesis, and releases gas during processing or storage. do.

In addition, the triazole cross-linked polymer is environmentally friendly because it is not sensitive to moisture and does not generate by-products during synthesis, but has a disadvantage in that price competitiveness is lowered by using expensive raw materials.

J. Macromol. Sci. C Polym. Rev. 2003, 43, 505-545.

The present invention has been devised to solve the problems of the prior art as described above, and an object of the present invention is to improve the performance of the existing solid propellant binder, reduce toxicity, and lower the manufacturing cost. To provide a high-energy prepolymer used for and a method for preparing the same.

The prepolymer according to the present invention for achieving the above object is characterized in that it comprises the following formula (1).

[Formula 1]

In Formula 1,

T ₁ and each T ₂ is independently hydroxy or azide;

R ₁ to R ₇ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and —CH ₂ — of the alkylene of R ₁ to R ₇ is —O—, —S -, -NH-, -C(=O)- or a combination thereof may be substituted, and =CH- of alkenylene of R ₁ to R ₇ may be substituted with N;

n is an integer selected from 1 to 100.

According to an aspect of the present invention, in Formula 1, R ₁ to R ₇ are each independently (C1-C10)alkylene, and —CH ₂ — of the alkylene of R ₁ to R ₇ is —O—, —C (=O)- or a combination thereof.

According to an aspect of the present invention, the prepolymer of the present invention may be represented by the following Chemical Formula 2 or Chemical Formula 3.

[Formula 2]

[Formula 3]

In Formula 2 and Formula 3,

R ₂ to R ₆ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and —CH ₂ — of the alkylene of R ₂ to R ₆ is —O—, —S -, -NH-, -C(=O)- or a combination thereof may be substituted, and =CH- of alkenylene of R ₂ to R ₆ may be substituted with N;

n is an integer selected from 1 to 100.

According to an aspect of the present invention, in Formulas 2 and 3, R ₂ to R ₆ are each independently (C1-C10)alkylene, and —CH ₂ — of the alkylene of R ₂ to R ₆ is —O -, -C(=O)-, or a combination thereof may be substituted.

According to an aspect of the present invention, the number average molecular weight of the prepolymer may be 2000 g/mol to 4000 g/mol.

According to an aspect of the present invention, the glass transition temperature (T _g ) of the prepolymer may be -20 °C to 20 °C.

According to an aspect of the present invention, the prepolymer may be amorphous.

According to an aspect of the present invention, it is possible to provide a binder for a high energy solid propellant comprising the prepolymer.

According to an aspect of the present invention, the step of preparing the prepolymer includes preparing a prepolymer represented by the following formula (1) by a triazole formation reaction of a compound represented by the following formula (4) and a compound represented by the following formula (5) can do.

[Formula 1]

[Formula 4]

[Formula 5]

In Formula 1 and Formula 4 to Formula 5,

T ₁ , T ₂ , T ₁₀ and each T ₁₁ is independently hydroxy or azide;

R ₁ to R ₆ , R ₁₁ and R ₂₁ to R ₂₃ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and R ₁ to R ₆ , R ₁₁ and R ₂₁ -CH ₂ - of alkylene of to R ₂₃ may be substituted with -O-, -S-, -NH-, -C(=O)-, or a combination thereof, and alkenylene of R ₁ to R ₇ =CH- of may be substituted with N,

n is an integer selected from 1 to 100.

According to an aspect of the present invention, the compound represented by Formula 4 and the compound represented by Formula 5 may be reacted in a molar ratio of 1:0.1 to 1:10.

According to the present invention, it is possible to provide a prepolymer applicable as a binder for a high energy propellant and a method for manufacturing the same. Specifically, the prepolymer of the present invention can improve the mechanical properties and thermal properties of the binder by introducing a nitramine functional group into the triazole skeleton structure. Since the nitramine group has low toxicity and is relatively inexpensive, the toxicity and manufacturing cost of the binder can be lowered, and the decomposition of the nitramine group enables the release of high energy even at a relatively low temperature. In addition, by having a triazole skeleton structure, it is possible to provide a binder that is strong against moisture and has excellent physical properties.

1 is a ¹ H-NMR measurement result of the compound AEE-PGDNH synthesized in Example 1.
2 is a ¹ H-NMR measurement result of prepolymer 1 (PGDNH-AEE-OH) synthesized in Example 1.
3 is an FT-IR measurement result of prepolymer 1 (PGDNH-AEE-OH) synthesized in Example 1.
4 is a ¹ H-NMR measurement result of the prepolymer 2 (PGDNH-AEE-N ₃ ) synthesized in Example 2.
5 is an FT-IR measurement result of prepolymer 2 (PGDNH-AEE-N ₃ ) synthesized in Example 2.
6 is a differential scanning calorimeter thermal analysis diagram (DSC Thermogram) of Comparative Example 1.
7 is a differential scanning calorimetry thermogram (DSC Thermogram) of prepolymer 1 (PGDNH-AEE-OH) synthesized in Example 1. FIG.
8 is a differential scanning calorimetry thermogram (DSC Thermogram) of prepolymer 2 (PGDNH-AEE-N ₃ ) synthesized in Example 2.

Hereinafter, the prepolymer according to the present invention and a method for preparing the same will be described in more detail through Preparation Examples and Examples. However, the following preparation examples and examples are provided only as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art, and the present invention is not limited thereto, and may be implemented in various forms. In addition, all technical and scientific terms, unless otherwise defined, have the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs, and may unnecessarily obscure the subject matter of the present invention in the following description. A description of possible known functions and configurations will be omitted.

As used in this specification and the appended claims, the singular form is intended to include the plural form as well, unless the context specifically dictates otherwise.

In this specification and the appended claims, terms such as first, second, etc. are used for the purpose of distinguishing one element from another, not in a limiting sense.

As used herein, the term “comprises” is an open-ended description having an equivalent meaning to expressions such as “comprises”, “contains”, “has” or “characterizes”, and is an element not listed in addition; Materials or processes are not excluded.

As used herein, the term “alkylene” refers to a divalent linear or branched saturated hydrocarbon radical composed of only carbon and hydrogen atoms, and includes methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, and the like. It is not limited.

As used herein, the term “alkenylene” refers to a divalent linear or branched unsaturated hydrocarbon radical having a carbon atom and containing one or more double bonds, and includes ethenylene, 2-propenylene, butenylene, pentenylene, and the like. However, it is not limited thereto.

As used herein, the term “single bond” refers to a case in which an atom does not exist in the corresponding site. For example, when Y is a single bond in the structure of X-Y-Z, X and Z are directly connected to form the structure of X-Z.

Hereinafter, the binder for a solid propellant of the present invention and a manufacturing method thereof will be described in detail with reference to Examples and drawings.

The prepolymer of the present invention is characterized in that it comprises a compound represented by the following formula (1).

[Formula 1]

(In Formula 1,

T ₁ and each T ₂ is independently hydroxy or azide;

R ₁ to R ₇ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and —CH ₂ — of the alkylene of R ₁ to R ₇ is —O—, —S -, -NH-, -C(=O)- or a combination thereof may be substituted, and =CH- of alkenylene of R ₁ to R ₇ may be substituted with N;

n is an integer selected from 1 to 100.)

According to an embodiment of the present invention, R ₁ to R ₇ in Formula 1 are each independently (C1-C10)alkylene, and —CH ₂ - of the alkylene of R ₁ to R ₇ is —O—, -C(=O)- or a combination thereof may be substituted.

According to an embodiment of the present invention, n in Formula 1 may be an integer selected from 1 to 50, preferably an integer selected from 1 to 20, and more preferably an integer selected from 1 to 10. there is.

According to an embodiment of the present invention, the prepolymer may be represented by the following Chemical Formula 2 or Chemical Formula 3.

[Formula 2]

[Formula 3]

(In Formula 2 and Formula 3,

R ₂ to R ₆ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and —CH ₂ — of the alkylene of R ₂ to R ₆ is —O—, —S -, -NH-, -C(=O)- or a combination thereof may be substituted, and =CH- of alkenylene of R ₂ to R ₆ may be substituted with N;

n is an integer selected from 1 to 100.)

According to an embodiment of the present invention, in Formulas 2 and 3, R ₂ to R ₆ are each independently (C1-C10)alkylene, and —CH ₂ — of the alkylene of R ₂ to R ₆ — It may be substituted with O-, -C(=O)-, or a combination thereof.

According to an embodiment of the present invention, n in Formulas 2 and 3 may be an integer selected from 1 to 50, preferably an integer selected from 1 to 20, and more preferably selected from 1 to 10 may be an integer.

The prepolymer of the present invention can be applied as a binder for a high-energy solid propellant by introducing an energetic nitramine functional group into the triazole back bone as shown in Formula 1, Formula 2 or Formula 3, and has mechanical properties and thermal properties. A binder having improved properties and the like may be provided. Specifically, the nitramine group has low toxicity and is relatively inexpensive, so the toxicity and manufacturing cost of the binder can be lowered, and the decomposition of the nitramine group enables the release of high energy even at a relatively low temperature. In addition, since the prepolymer has a triazole skeleton structure, it can be applied as a binder that is strong in moisture and has excellent physical properties.

According to an embodiment of the present invention, the number average molecular weight of the prepolymer may be 2000 g/mol to 4000 g/mol. As a prepolymer having a relatively narrow number average molecular weight, it may be particularly suitable for manufacturing a binder for a high energy solid propellant because it may exhibit high energy and may have a low viscosity even at high filling.

According to an embodiment of the present invention, the glass transition temperature (T _g ) of the prepolymer may be -20°C to 20°C, and more preferably, by having a glass transition temperature of -20°C to 15°C, storage and easy processing, and easy to control content and temperature during binder manufacture.

According to an embodiment of the present invention, the prepolymer is amorphous, has no crystallinity and is a low molecular weight polymer having flowability, and may form a macro network structure through cross-linking. In particular, since it can be amorphous even at 50 to 60 ° C, which is a temperature condition when manufacturing a binder, it does not show a change in heat flow due to melting. have

According to an embodiment of the present invention, it is possible to provide a binder for a solid propellant comprising the prepolymer. The binder for the solid propellant may include the prepolymer and the crosslinking agent, and the mechanical properties of the binder are different depending on the ratio. As the crosslinking agent, any compound including a reactive functional group having reactivity with a hydroxyl group or an azide group may be used without limitation. As a non-limiting example, the reactive functional group may be an alkyne group or an isocyanate group, and the number of reactive functional groups in one compound may be 2 to 6, but is not limited thereto. The crosslinking agent may be 1 to 100 parts by weight, specifically 5 to 50 parts by weight, based on 100 parts by weight of the prepolymer, but is not limited thereto.

According to an embodiment of the present invention, the method for preparing the prepolymer includes preparing a prepolymer represented by the following formula (1) by a triazole formation reaction of a compound represented by the following formula (4) and a compound represented by the following formula (5) characterized in that

[Formula 1]

[Formula 4]

[Formula 5]

(In Formula 1 and Formula 4 to Formula 5,

T ₁ , T ₂ , T ₁₀ and each T ₁₁ is independently hydroxy or azide;

R ₁ to R ₆ , R ₁₁ and R ₂₁ to R ₂₃ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and R ₁ to R ₆ , R ₁₁ and R ₂₁ -CH ₂ - of alkylene of to R ₂₃ may be substituted with -O-, -S-, -NH-, -C(=O)-, or a combination thereof, and alkenylene of R ₁ to R ₇ =CH- of may be substituted with N,

n is an integer selected from 1 to 100.)

According to an embodiment of the present invention, in Formulas 1 and 4 to 5, R ₁ to R ₆ , R ₁₁ and R ₂₁ to R ₂₃ are each independently (C1-C10)alkylene, and R ₁ -CH ₂ - of alkylene of to R ₆ , R ₁₁ and R ₂₁ to R ₂₃ may be substituted with -O-, -C(=O)-, or a combination thereof.

According to an embodiment of the present invention, n in Formula 1 may be an integer selected from 1 to 50, preferably an integer selected from 1 to 20, and more preferably an integer selected from 1 to 10. there is.

According to an embodiment of the present invention, the compound represented by Formula 4 and the compound represented by Formula 5 may be reacted in a molar ratio of 1:0.1 to 1:10, more preferably 1:0.3 to 1: It may be reacted in a 3 molar ratio.

According to an embodiment of the present invention, a triazole ring bond is formed by reacting an azide present at the terminal of the compound represented by Formula 4 and an ethynyl group present at both terminals of the compound represented by Formula 5.

According to an embodiment of the present invention, the catalyst is any catalyst based on copper metal, but as a specific example, it may be CuI, and the amount of the catalyst used is 0.01 to 0.1 moles per 1 mole in Chemical Formula 5, 1 mole can

According to an embodiment of the present invention, the solvent used in the preparation method is not particularly limited as long as it can dissolve the components of the present invention, but 1,4-dioxane, dichloromethane (DCM) ), dichloroethane (DCE), toluene (Toluene), acetonitrile (MeCN), nitromethan (nitromethan), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N,N -It is preferable to use dimethylacetamide (DMA) and chlorobenzene (CB), and it is preferable to use N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) as a solvent. more preferably. The reaction time may vary depending on the reactant, the type of the solvent, and the amount of the solvent.

According to an embodiment of the present invention, the reaction temperature is preferably 25 °C to 150 °C, more preferably 50 °C to 120 °C.

Hereinafter, the prepolymer for a solid propellant binder of the present invention and a manufacturing method thereof will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are merely references for describing the present invention in detail, and the present invention is not limited thereto and may be implemented in various forms.

[Preparation Example 1] Preparation of monomer A having ethynyl groups at both terminals

97% nitric acid (64.26g, 1.02mol) and 98% sulfuric acid (7.32g, 0.07mol) were put in a 2-neck flask and cooled under 0℃ stirring. Imidazolidinone (20.90g, 0.25 mol) in acid is maintained at 0°C and portion wise. After stirring at 0° C. for 1 hour, the mixture was stirred at room temperature for 2 hours. After completion of the reaction with cold distilled water, it was filtered under reduced pressure to obtain 1,3-dinitroimidazolidin-2-one as a white solid (10.50 g, 58%). The obtained white solid is added to boiling distilled water (1 L). After boiling until no gas is generated, the flask is brought to room temperature to cool, and then recrystallized at 0℃. The recrystallized solid was filtered under reduced pressure once more to obtain N,N'-(ethane-1,2-diyl)dinitramide (21 g, 60%) as a white solid. N,N'-(ethane-1,2-diyl)dinitramide (10.00 g, 0.06 mol) and paraformaldehyde (4 g, 0.13 mol) were added to dioxane (150 mL) and stirred. Then, dry HCl gas was injected through the glass tube while bubbling into the dioxane solution with the reactant. When the color in the solution became transparent after 2 hours, the change in the peak was confirmed through ¹ H NMR at 1 hour intervals (produdct ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ5.89(s, 4H), 4.15(s) , 4H), ¹³ C-NMR (100 MHz, DMSO-d ₆ ) δ 60.3, 48.1).

When the position of the peak is completely changed to the peak of the product, dioxane is distilled under reduced pressure to terminate the reaction. When the remaining reactant becomes an opaque colored oil, it is dissolved in CHCl ₃ , recrystallized at 0° C., and filtered under reduced pressure to obtain 1,6-dichloro-2,5-dinitrazahexane (9.41 g, 63.5%) as a white solid.

After that, 1,6-dichloro-2,5-dinitrazahexane (26.00 g, 0.11 mol) and propargyl alcohol (53.46 g, 0.95 mol) were added and stirred at room temperature for 7 hours under Ar gas. The reaction product was stored at 5° C. or lower for 14 hours and recrystallized, followed by filtration under reduced pressure to obtain a white solid monomer A (20 g, 68%) (product ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ5.21(s) ,4H), 4.27(d,J=4.0Hz,4H), 4.08(s,4H), 3.53(t,=4.0Hz,2H), ¹³ C-NMR (100MHz, DMSO-d ₆ ) δ79.2, 78.5, 77.3, 56.3, 47.8).

[Preparation Example 2] Preparation of monomer B having azide groups at both ends

Bis(2-bromoethyl)ether (46.38g, 0.20mol) and sodium azide (39.00g, 0.60mol) were dissolved in DMF (500mL) and reacted at 60℃ for 28 hours. After the reaction was terminated by adding distilled water, the organic layer was extracted three times using diethyl ether. The organic layer was dried using MgSO ₄ and distilled under reduced pressure. The remaining reactant was separated by a silica gel column (hexane/EtOAc=5/1) to obtain a colorless liquid, monomer B (32.05 g, 99%) (product ¹ H-NMR (400 MHz, CDCl ₃ ) δ3.70 (t, J=8.0Hz,4H), 3.42(d,J=4.0Hz,4H), 4.08(s,4H), 3.53(t,=4.0Hz,2H), ¹³ C-NMR (100MHz, CDCl ₃ ) δ69. 9, 50.6).

[Preparation Example 3] Preparation of monomer C having an azide group and a hydroxyl group at both ends

(2-Chloroethyloxy)ethanol (10.00g, 0.08mol) and sodium azide (10.44g, 0.16mol) are dissolved in distilled water (80mL) and reacted at 90℃ for 18 hours. After the reaction was terminated by adding distilled water, the organic layer was extracted three times using CH ₂ Cl ₂ . The organic layer was dried using MgSO ₄ and distilled under reduced pressure to obtain a colorless liquid, monomer C (10 g, 99%) (product ¹ H-NMR (400 MHz, CDCl ₃ ) δ3.69-3.60 (m, 4H) , 3.56-3.51(m,2H), 3.35(t,J=4.0Hz,2H), 2.89(t,J=4.0Hz,2H), ¹³ C-NMR(100MHz, CDCl ₃ ) δ72.7, 69.6, 61.3, 50.4).

[Example 1] Preparation of prepolymer 1 having hydroxyl groups at both ends

The above triazole-based prepolymer synthesis reaction is a reaction for synthesizing a prepolymer having ethynyl functional groups at both ends and a reaction for changing an ethynyl functional group at the terminal to a hydroxyl group (-OH). progressed through steps. The 1st step of synthesizing a prepolymer (AEE-PGDNH) having ethynyl functional groups at both ends is at 50 °C using the monomer A synthesized in Preparation Example 1 and CuI as a catalyst together with the monomer B synthesized in Preparation Example 2 It was carried out for 12 hours under DMF solvent. After that, in the 2nd step of changing the terminal ethynyl functional group to a hydroxyl group (-OH), an excess of the monomer C synthesized in Preparation Example 3 was added to the reactant synthesized in the 1st step, and at 50° C. under a DMF solvent for 6 hours. proceeded The reaction product proceeded to the 2nd step was purified by precipitation in methanol, and dried at 60° C. for 12 hours using a vacuum oven to synthesize prepolymer 1 (PGDNH-AEE-OH) having a hydroxyl group at the end.

The molecular weight of the synthesized prepolymer was controlled by varying the ratio of the monomer A and the monomer B during the synthesis, and the molecular weight and molecular weight distribution results of the prepolymer according to the ratio of the monomer A and the monomer B used for the synthesis are shown in Table 1.

prepolymer
[A] : [B] : [Cat.] M _n PDI
PGDNH-AEE-OH-1
1: 0.55: 0.06 2300 1.2
PGDNH-AEE-OH-2
1: 0.70: 0.06 3000 1.2
PGDNH-AEE-OH-3
1: 0.78: 0.06 4000 1.5

1 is a ¹ H-NMR measurement result of AEE-PGDNH having ethynyl groups at both ends of Example 1, and FIG. 2 is a prepolymer 1 (PGDNH-AEE-OH) having hydroxyl groups at both ends of Example 1. ¹ This is the result of H-NMR measurement.

Referring to FIG. 1, the ethynyl group (-C≡C), which is the terminal of AEE_PGDNH synthesized through the 1st step of Example 1, shows a peak at 3.55 ppm, and a nitramine group (-N through the peaks at 5.26 and 4.67 ppm). -NO ₂ ) can be confirmed to exist. In addition, it can be confirmed that the triazole ring formed through the click reaction exists through the peak at 7.99 ppm, and the polymer backbone polymerized in the form of polyether can be confirmed through the peak at 4.14 ppm. As a result of ¹ H-NMR measurement, it can be seen that a low molecular weight prepolymer (AEE-PGDNH) having a triazole ring composed of ethynyl groups at both ends and a polymer backbone in the form of polyether was synthesized.

AEE_PGDNH: ¹ H-NMR (500 MHz, DMSO-d ₆ ); δ7.99, 5.26, 4.67, 4.53, 4.30, 4.14, 3.82, 3.55.

Referring to Figure 2, the 2nd of Example 1 The hydroxyl group (-OH) at the end of the prepolymer 1 (PGDNH_AEE-OH) synthesized through the step shows a peak at 4.53 ppm, and a nitramine group (-N-NO ₂ ) exists through the peaks at 5.26 and 4.67 ppm. can confirm. In addition, it can be confirmed that the triazole ring formed through the click reaction is present through the peak at 7.99 ppm, and the polymer skeleton polymerized in the form of polyether can be confirmed through the peak at 4.11 ppm. As a result of ¹ H-NMR measurement, it can be seen that a low molecular weight prepolymer having a triazole ring composed of ethynyl groups at both ends and a polymer backbone in the form of polyether was synthesized.

Prepolymer 1 (PGDNH-AEE-OH): ¹ H-NMR (500 MHz, DMSO-d ₆ ); δ7.99, 5.26, 4.67, 4.53, 4.11, 3.85, 3.82, 3.47, 3.43.

3 is an FT-IR measurement result of prepolymer 1 (PGDNH-AEE-OH) having hydroxyl groups at both ends of Example 1.

Referring to FIG. 3, a broad peak appears at 3200-3500 cm ^-1 due to the hydroxyl group (-OH) at the end of the prepolymer, and the main functional groups of the triazole ring are 1350 cm ^-1 , 1600-1650 cm ^-1 , 3100-3200 cm -1 , respectively ^. In the vicinity of ¹ , it can be seen that the nitrogen dioxide group (-NO ₂ ) peaks at 1290 to 1360 cm ^-1 and 1475 to 1550 cm ^-1 . Through this, it can be seen that a nitramine group exists in the polymer chain and prepolymer 1 having a hydroxyl group (-OH) at the end was synthesized.

[Example 2] Preparation of prepolymer 2 having azide groups at both ends

Synthesis of prepolymer 2 (PGDNH-AEE-N ₃ ) having azide group (-N ₃ ) ends at both ends is a monomer A having ethynyl functional groups at both ends, and an azide functional group at both ends Eggplant was run for 12 hours under a DMF solvent at 50°C using CuI as a catalyst together with monomer B. The reaction product was purified by precipitation in acetonitrile, and dried at 60° C. for 12 hours using a vacuum oven to synthesize a prepolymer 2 (PGDNH-AEE-N ₃ ) having an azide (-N ₃ ) group at the end.

The molecular weight of the synthesized prepolymer 2 was adjusted by varying the ratio of the monomer A and the monomer B during the synthesis, and the molecular weight and molecular weight distribution results of the prepolymer 2 according to the ratio of the monomer A and the monomer B used for the synthesis are shown in Table 2.

prepolymer
[A] : [B] : [Cat.] M _n PDI
PGDNH-AEE-N ₃ -1
1:1.50: 0.06 1900 1.2
PGDNH-AEE-N ₃ -2
1:1.33: 0.06 2950 1.2
PGDNH-AEE-N ₃ -3
1:1.22:0.06 3900 1.5

4 is a ¹ H-NMR measurement result of the prepolymer 2 (PGDNH-AEE-N ₃ ) having azide groups at both ends prepared in Example 2.

4, the carbon linked to the azide group at the end of the synthesized prepolymer 2 (PGDNH-AEE-N ₃ ) shows a peak at 3.36 ppm and a nitramine group (-N-NO ₂ through the peaks at 5.26 and 4.67 ppm) ) can be verified. In addition, it can be confirmed that the triazole ring formed through the click reaction is present through the peak at 7.99 ppm, and the polymer skeleton polymerized in the form of polyether can be confirmed through the peak at 4.11 ppm. As a result of ¹ H-NMR measurement, it can be seen that low molecular weight prepolymer 2 having a triazole ring composed of azide groups at both ends and a polymer backbone in the form of polyether was synthesized.

Prepolymer 2 (PGDNH-AEE-N ₃ ): ¹ HNMR (500 MHz, DMSO-d ₆ ); δ7.99, 5.26, 4.67, 4.53, 4.11, 3.85, 3.56, 3.36.

5 is an FT-IR measurement result of the prepolymer 2 (PGDNH-AEE-N ₃ ) having azide groups at both ends prepared in Example 2.

5, the peak appears at 2200-2300 cm ^-1 by the azide group (-N ₃ ), which is the terminal of prepolymer 2, and the main functional groups of the triazole ring are 1350 cm ^-1 , 1600-1650 cm ^-1 , 3100- In the vicinity of 3200 cm ^-1 , it can be seen that the nitrogen dioxide group (-NO ₂ ) peaks at 1290 to 1360 cm ^-1 and 1475 to 1550 cm ^-1 . Through this, it can be seen that a nitramine group exists in the polymer chain, and prepolymer 2 having an azide group (-N ₃ ) at the end was synthesized.

[Experimental Example 1] Measurement of thermal properties

The thermal properties of prepolymers 1 and 2 were measured with a differential scanning calorimeter (Instrumnet DSC Q20 V24.11 Build 124) at a temperature range of -80°C to 100°C under nitrogen gas at 10°C/min.

In addition, for comparative evaluation with Examples 1 (prepolymer 1) and 2 (prepolymer 2), a polyester-based prepolymer (number average molecular weight: 2,000) synthesized from commercially available adipic acid and diethylene glycol was prepared. It was named Comparative Example 1, and thermal properties were measured in the same manner as in Experimental Example 1.

6 is a differential scanning calorimeter thermal analysis diagram (DSC Thermogram) of Comparative Example 1.

7 is a differential scanning calorimetry thermogram (DSC Thermogram) of prepolymer 1 (PGDNH-AEE-OH) having a hydroxyl group terminal of Example 1 synthesized according to an embodiment of the present invention.

8 is a differential scanning calorimetry thermogram (DSC Thermogram) of prepolymer 2 (PGDNH-AEE-N ₃ ) having an azide group terminal of Example 2 synthesized according to an embodiment of the present invention.

6, 7 and 8 , the prepolymer 1 (PGDNH-AEE-OH) having a hydroxyl group terminal of Example 1 and the prepolymer 2 (PGDNH-AEE-N ₃ ) of Example 2 are Comparative Example 1 It can be confirmed that it has a higher glass transition temperature (T _g ) (T _g of Comparative Example 1 is -40°C, T _g of prepolymer 1 is -16°C, and T _g of prepolymer 2 is 9°C).

Here, Comparative Example 1 is a polyester-based prepolymer synthesized with adipic acid and diethylene glycol. Through comparison with Experimental Example 1, the difference in physical properties according to the structure of the prepolymer having a nitramine functional group in the triazole skeleton structure can be compared. there is.

Considering this, the reason that the glass transition temperature (T _g ) of Experimental Example 1 is higher than the glass transition temperature (T _g ) of Comparative Example 1 is due to the skeletal structure of the energetic nitramine group and triazole series of the prepolymer. It is considered that this is because the cohesive energy density indicating the cohesive properties of the chain is high.

In addition, it can be confirmed that Experimental Example 1 is an amorphous polymer that does not form crystals because there is no change in heat flow due to polymer melting at 60° C., which is a binder manufacturing condition.

As described above, the present invention has been described by specific matters and limited examples, but these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and the field to which the present invention belongs Various modifications and variations are possible from these descriptions by those of ordinary skill in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the claims described below, but also all of the claims and all equivalents or equivalent modifications to the claims will be said to belong to the scope of the spirit of the present invention. .

Claims (10)

A prepolymer comprising a compound represented by the following formula (1).
[Formula 1]

In Formula 1,
T ₁ and each T ₂ is independently hydroxy or azide;
R ₁ to R ₇ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and —CH ₂ — of the alkylene of R ₁ to R ₇ is —O—, —S -, -NH-, -C(=O)- or a combination thereof may be substituted, and =CH- of alkenylene of R ₁ to R ₇ may be substituted with N;
n is an integer selected from 1 to 100. The method of claim 1,
In Formula 1, R ₁ to R ₇ are each independently (C1-C10)alkylene, and -CH ₂ - of the alkylene of R ₁ to R ₇ is -O-, -C(=O)-, or these A prepolymer that may be substituted with a combination of The method of claim 1,
A prepolymer represented by Formula 2 or Formula 3 below.
[Formula 2]

[Formula 3]

In Formula 2 and Formula 3,
R ₂ to R ₆ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and —CH ₂ — of the alkylene of R ₂ to R ₆ is —O—, —S -, -NH-, -C(=O)- or a combination thereof may be substituted, and =CH- of alkenylene of R ₂ to R ₆ may be substituted with N;
n is an integer selected from 1 to 100. 4. The method of claim 3,
In Formulas 2 and 3, R ₂ to R ₆ are each independently (C1-C10)alkylene, and -CH ₂ - of the alkylene of R ₂ to R ₆ is -O-, -C(=O) - or a prepolymer, which may be substituted with a combination thereof. According to any one of claims 1 to 4 selected from,
The number average molecular weight of the prepolymer will be 2000g/mol to 4000g/mol, the prepolymer. According to any one of claims 1 to 4 selected from,
The glass transition temperature (T _g ) of the prepolymer is -20 ℃ to 20 ℃, the prepolymer. According to any one of claims 1 to 4 selected from,
The prepolymer is amorphous, the prepolymer. A binder for a high energy solid propellant comprising the prepolymer according to any one of claims 1 to 4. A method for preparing a prepolymer represented by the following formula (1), comprising the step of preparing a prepolymer represented by the following formula (1) by a triazole-forming reaction of a compound represented by the following formula (4) and a compound represented by the following formula (5).
[Formula 1]

[Formula 4]

[Formula 5]

In Formula 1 and Formula 4 to Formula 5,
T ₁ , T ₂ , T ₁₀ and each T ₁₁ is independently hydroxy or azide;
R ₁ to R ₆ , R ₁₁ and R ₂₁ to R ₂₃ are each independently a single bond, (C1-C20)alkylene or (C2-C20)alkenylene, and R ₁ to R ₆ , R ₁₁ and R ₂₁ -CH ₂ - of alkylene of to R ₂₃ may be substituted with -O-, -S-, -NH-, -C(=O)-, or a combination thereof, and alkenylene of R ₁ to R ₇ =CH- of may be substituted with N,
n is an integer selected from 1 to 100. 10. The method of claim 9,
The method for preparing a prepolymer, wherein the compound represented by Formula 4 and the compound represented by Formula 5 are reacted in a molar ratio of 1:0.1 to 1:10.

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