FR3013712A1 - POLYMERS WITH TERMINAL AZIDE FUNCTIONS, THEIR OBTAINING; SOLID PROPERGOLS OBTAINED FROM SAID POLYMERS - Google Patents

Abstract

The subject of the present invention is: - polymers with an azide terminal function of formula (IV) - obtaining such polymers from + a hydroxytelechelic polymer of formula (I): OH-P-OH; + an azidoalcohol of formula (II): HO-R1-N3, and + of a diisocyanate of formula (III): O = C = N-R2-N = C = O - solid propellants, capable of be obtained from said polymers. Said propellants may contain any type of energy charges, including energy charges with intrinsic acidity.

Description

The present invention is in the technical field of solid propellants. It proposes new polymers (crosslinkable polymers = functionalized "prepolymers", binder precursors) which make it possible to confer on the new solid propellants obtained from these properties interesting properties, quite similar to those of high performance solid propellants used for this purpose. day, and which, moreover, are perfectly adapted to the formulation of energy charges having an intrinsic acidity.

The present invention more specifically relates to: polymers with azide terminal functions ("functionalized prepolymers", suitable as precursors for solid propellant binder), the production of said polymers, and solid propellants, obtainable from said polymers. To date, it is perfectly mastered, for obtaining high performance solid propellants, processes of type A or B below, the main stages (successive) are recalled below: - type A: mixing of a pasty composition comprising a polymer (functionalized "prepolymer") and energetic charges, addition to said composition of (at least) one (generally a) crosslinking agent, casting the resulting mixture in at least one mold and heat treatment ( crosslinking); type B: kneading of a pasty composition comprising a polymer (functionalized "prepolymer") and energetic charges, addition to said composition of (at least) one (generally a) crosslinking agent, extrusion of the resulting mixture, cutting said extruded mixture and heat treatment (crosslinking) "pieces" obtained. In particular, as the polymer (crosslinkable polymer = functionalized "prepolymer"), hydroxytelechelic polymers (especially hydroxytelechelic polybuta-1,3-dienes (PBHT)) and as crosslinking agent, isocyanates at least bi-functional (usually di- or triisocyanates). Polyurethane-bonded propellants are thus obtained. Propellants of this type, containing "conventional" fillers, for example octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine (HMX or octogen), hexahydro-1, 3,5-trinitro-1,3,5-triazine (RDX or hexogen or cyclonite), or 2, 4, 6, 8, 10, 12-hexanitrohexaazaisowurtzitane (CL20 or HNIW) have, in particular, mechanical properties as well as aging resistance, interesting.

In recent years, it has been proposed new energy charges including energy charges (such as ammonium dinitroamide (DNA) and nitropyrazoles, including trinitropyrazole) which have intrinsic acidity and may have at least one labile hydrogen. The formulation of this type of filler with hydroxytelechelic polymers is problematic. Indeed, because of their intrinsic acidity, said charges are, during the crosslinking mentioned above, consuming isocyanate. They develop in fact a parasitic reaction which consumes in part the crosslinking agent present in the reaction medium. This parasitic reaction (on an isocyanate function of the crosslinking agent) is schematized below.

O R-N = C = O + B-H Isocyanate Charge with H labile Such reactivity of the energetic charges with respect to the crosslinking agent limits the formation of polyurethane (the binder of the desired propellant); it prevents a perfect mastery of this training. With reference to this technical problem of the formulation of charges which present an intrinsic acidity, the inventors propose an original solution (which it is easy to understand that its field of application is in no way limited to this or that type of energy charge) . The inventors propose functionalized "prepolymers" (crosslinkable) of the type of those of the prior art (insofar as they aim to obtain, for the solid propellants obtained from said functionalized "prepolymers", properties, especially mechanical and aging, interesting, similar to those of propellants of the prior art) but modified however compared to said "prepolymers" of the prior art, so that their crosslinking can be implemented without crosslinking agent capable of reacting with fillers energy having intrinsic acidity. With reference to the technical problem identified above, they have resorted to the concept of "Click chemistry", more specifically to its application in the Huisgen cycloaddition reaction (1,3-cycloaddition, dipolar) between an azide and an alkyne; said reaction giving a triazole. Said concept and its application mentioned above have been described in numerous publications, in particular by Rostovtsev, Vsevolod V.; Green, Luke G.; Fokin Valery V.; and Sharpless K. Barry in 3 H 2002 in Angewandte Chemie International Edition 41 (14), pages 2596-2599 (publication titled: "A Stepwise Huisgen Cycloaddition Process: Copper (I) -Catalyzed Regloselective" Ligation "of Azides and Terminal Alkynes" ). This approach of the inventors is quite original and the good results obtained were not acquired in advance, especially since isocyanates are used during the modification of the prepolymers recommended. All this is explained in detail below. It is now proposed to describe the invention in its different aspects.

According to its first object, the present invention therefore relates to a functionalized "prepolymer" (crosslinkable polymer) of the type of "pre-polymers" hydroxytelechelic of the prior art but modified (so that it can be crosslinked without a crosslinking agent capable of reacting with energy charges with intrinsic acidity) (see above and below). According to its first subject, the present invention relates in fact to an azide terminal functional polymer which corresponds to the following formula (V): ## STR1 ## in which P represents the hydrocarbon chain of a homopolymer containing: n1 alkylene units (especially ethylene, isobutylene, butadiene (more particularly buta-1,3-diene)), n1 being between 5 and 300, or 3013 712 5 n2 ether units (especially alkylene glycol (more particularly ethylene glycol)), n2 being between 5 and and 300, or n, ether ester units (especially di (ethylene glycol) adipate), n3 being between 5 and 100; R 1 represents a linear, branched or cyclic, saturated or unsaturated (conjugated or non-conjugated) hydrocarbon difunctional radical containing from 2 to 15 carbon atoms and optionally at least one heteroatom chosen from nitrogen and oxygen, the group N3-R1-0- containing a number of carbon atoms (NC) and a number of nitrogen atoms (NN) such that said number of nitrogen atoms (NN) does not exceed said number of carbon atoms (NC) (NC NN); R2 represents the difunctional radical of an aliphatic or aromatic diisocyanate of formula (III): O = C = N-R2-N = C = O. In consideration of the above, it is understood that the polymer of formula (V) of the invention is in fact a polymer of formula (I): HO-P-OH ("prepolymer" functionalized with hydroxyl functions , suitable as a solid propellant binder precursor, such as a modified PBHT), so that it has azide terminal functions. By means of said azide terminal functions, said polymer may be crosslinked with a crosslinking agent having propargyl functions (according to the application of the "Click chemistry" mentioned above). According to a very advantageous variant, in the formula (V) of the polymer of the invention, P represents the hydrocarbon chain of a n-butadiene-1,3-diene homopolymer (the hydrocarbon chain of a polybuta-1, 3-diene hydroxytelechelic), n1 being between 5 and 300, advantageously between 25 and 85. According to this advantageous variant, the polymer P of the invention is therefore a polybuta-1,3-diene hydroxytelechelic modified in the direction specified below. above. P may also, inter alia, represent the hydrocarbon chain of a homopolymer with n 2 ethylene glycol units: 5 n2 300 or n3 di (ethylene glycol adipate) units: 5 n 100 100. The polymer of formula (V) of the The invention thus proposed as functionalized "prepolymer", solid propellant binder precursor - can quite well be described as polymer P (for example polybutadiene) diazidotelechelic tetra-urethane.

It has of course been understood that the numbers n1, n2 and n3 are integers and that the presence of branches in the hydrocarbon chain P of the homopolymer (branches which may have been generated during the polymerization carried out for the first time). obtaining said homopolymer) can not be ruled out.

The radical R 1 may therefore be almost arbitrary, aliphatic or aromatic (it however has a limited carbon number so that the new functionalized "prepolymer" of formula (V) is not substantially different from the functionalized "prepolymer" of formula (I) HO-P-OH, so that the solid propellants obtained from said functionalized "prepolymers" of formula (V) and (I) have properties, including mechanical, neighboring). The condition NC NN ensures the non-explosive nature of the compound of formula (II): HO-R1-N3, necessary to obtain the polymer of formula (V) (see below). Those skilled in the art are also aware that compounds with azide group (s) directly attached to aromatic rings, carboxyl functions or double bonds are more dangerous than aliphatic azides.

According to an advantageous variant, in the formula (V) of the polymer of the invention, the group -O-R1-N3 corresponds to one or other of the following groups: OR With reference to the definition of R2, it is understood that the diisocyanate in question (of formula (III)) was used for the grafting of terminal azide functions. According to advantageous variants, in the formula (V) of the polymer of the invention: R2 represents the difunctional radical of an aliphatic diisocyanate of formula (III) chosen from hexamethylene diisocyanate (HMDI), 1-methyl-2 , 4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), methylene diisocyanate, 1,6-hexane diisocyanate, 2, 2,4-trimethyl-1,6-hexane diisocyanate, most preferably hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI); or R2 represents the difunctional radical of an aromatic diisocyanate of formula (III) chosen from 2,4-toluene diisocyanate (TDI), 2,6-toluene diisocyanate (TDI) and 4,4-diphenylmethane diisocyanate (MDI) .

According to one particularly advantageous variant, the azide terminal functional polymer of the invention corresponds to formula (V) in which: P represents the hydrocarbon chain of a n-butadiene-1,3-diene homopolymer (the hydrocarbon chain a polybuta-1,3-diene hydroxytelechelic), n1 being between 5 and 300, advantageously between 25 and 85; the group -O-R1-N3 corresponds to one or the other of the 3 groups whose formula is given above; and R2 represents one of the difonctinal radicals of an aliphatic or aromatic diisocyanate as specified above. The azide terminal functional polymer of the invention, as described above, corresponding to the formula (V) specified above, is therefore perfectly suitable as functionalized "prepolymer" (with azide functional groups: -N3), precursor of a binder (triazole ball joint (see below)) solid propellant. It is crosslinkable with a crosslinking agent having propargyl functions. It is thus quite capable of being loaded with energetic charges (with or without labile hydrogen) and then crosslinked, via its azide functions, to generate a propellant bearing properties similar to those of the propellant obtained under "analogous" conditions from corresponding polymer of formula HO-P-OH (crosslinked via its hydroxyl functions with an isocyanate crosslinking agent).

The skilled person has already grasped the full interest of the invention. It is now proposed to specify the process for obtaining the polymer of the invention of formula (V). Said method constitutes the second object of the invention. It is therefore a question of modifying a suitable hydroxy-elechelic polymer of formula HO-P-OH (see definition of P given above with reference to formula (V))) to convert it to a terminal azide polymer of formula (V). Typically, said method comprises: providing a hydroxytelechelic homopolymer of formula (I): HO-P-OH, wherein P is as defined above; the provision of an azidoalcohol of formula (II): HO-R1-N3, wherein R1 is as defined above; providing an aliphatic or aromatic diisocyanate of formula (III): ## STR5 ## the reaction of said azidoalcohol of formula (II) with said diisocyanate of formula (III), said azidoalcohol of formula (II) being added, in parts, to said diisocyanate of formula (III) present in a quantity not exceeding 99 ° / ( ), generally in an amount of 95 to 99 ° h, of the stoichiometric amount, to obtain a monoisocyanate of formula (IV): - the reaction of said monoisocyanate of formula (IV) with said hydroxytelechelic homopolymer of formula (I) for obtaining said azide terminal functional polymer of formula (V). The hydroxytelechelic homopolymer of formula (I) advantageously consists of a polymer of this type already known as prepolymer, functionalized (with hydroxyl functions), propellant precursor (see above); it thus advantageously consists of a polybutadiene (polybuta-1,3-diene) hydroxytelechelic to n1 butadiene units: 5 n1 5 .. 300, preferably 25 n1 85, a polyethylene 3013 712 glycol n2 ethylene glycol units: 5 n2 300 or a polydi (ethylene glycol adipate) n3 units di (ethylene glycol adipate: 5 n 100. It is very advantageously a polybutadiene (polybuta-1,3-diene) hydroxytelechelic as specified above. the hydrocarbon chain of said HO-P-OH homopolymer is capable of containing ramifications (branches which may have been generated during the polymerization used to obtain said homopolymer) As regards the azidoalcohol of formula (II) ), it may be a commercial product, said azidoalcohol of formula (II) may also be prepared by direct azidation of an epoxy (such a synthesis has been described in particular by Biswanath D. and Vturkuri S.R. in Synthesis, 2007, 5, pp. 666-668) or a haloalcohol. On said epoxy or haloalcohol, sodium nitride is generally used in a solvent such as polyethylene glycol. Said azidoalcohol of formula (II) advantageously consists of: 2-azido-1-phenyl-ethan-1-ol, 1-hydroxy-2-azido-cyclohexane, or 2-hydroxy-3-azido-n-hexane (See the 3 formulas indicated above for the group -O-R1-N3). The aliphatic and aromatic diisocyanates of formula (III), conventional crosslinking agents, especially used according to the prior art for crosslinking the prepolymers of formula HO-P-OH are known per se. These are commercial products. The method of the invention therefore uses the homopolymer of formula (I) as well as the compounds of formula (II) and (III) and consists, for converting said homopolymer of formula (I) into the polymer of formula (V) to involve said compounds of formulas (II) and (III). The compound of formula (II) (azidoalcohol) provides the desired azide functions. It reacts, initially, via its hydroxy function, with an isocyanate function of the diisocyanate of formula (III) to obtain the carbamate derivative of formula (IV). For such a reaction, leading to the desired monoisocyanate of formula (IV), are reacted successively portions (only) of the compound of formula (II). Said diisocyanate also intervenes in a sub-stoichiometric amount so that it is entirely consumed. The carbamate derivative of formula (IV) therefore contains, in its formula, an azide function and an isocyanate function (the second of the diisocyanate of formula (III)). This isocyanate function is then used to graft said carbamate derivative, with its azide function, onto the polymer of formula (I) via its hydroxyl functions. It is understood that the desired azide terminal functions are fed to said polymer of formula (I) by said compound of formula (II) via said compound of formula (III).

The two successive steps of the process of the invention: (II) + (III) - (IV) and (IV) + (I) - (V) can, schematically, be illustrated as follows, in the hypothesis where: (I) = PBHT (II) = 2-azido-1-phenylethan-1-ol, and (III) = IPDI.

For reasons of simplification, the second reaction is shown only on a hydroxyl function of the PBHT. It obviously takes place on both hydroxyl functions.

With reference to the first of said reactions ((II) + (III) -> (IV)), it is recalled that it is conducted in the presence of an amount of diisocyanate less than the stoichiometric amount. It is appropriate that, at the end of the reaction, the reaction medium is free of diisocyanate (unreacted), capable of reacting with energy charges with intrinsic acidity (see above). The first of said reactions ((II) + (III) -> (IV)) is generally carried out, without a solvent, at room temperature or at a temperature above room temperature. It is the same for the second of said reactions ((I) + (IV) -> (V)).

The use at room temperature, without solvent, assumes liquid reagents. With reference to the viscosity of the reaction medium, it may therefore be appropriate to carry out said reactions at a temperature above room temperature. The inventors have in particular operated at 60 ° C. We now come to the third object of the present invention: the solid propellants, obtainable from the functional azide terminated functional terminated polymers ("prepolymers") of the invention, as described above (per se or This third object can be analyzed as a use of said polymers, an outlet thereof, it is with reference to this use that said polymers have been designed, have been prepared, According to its third object, the present invention therefore relates to solid propellants containing energetic charges in a crosslinked binder, said propellants being, typically, capable of being obtained by crosslinking a paste comprising: azide terminal functional polymer of formula (V) as described above and / or as obtained after the implementation of the method described above essus, - energy charges, and - at least one crosslinking agent, of di- or tri-propargyl type. Said at least one crosslinking agent is present in an effective amount, generally suitable to provide a bridging ratio of between 0.5 and 1.5. It is understood that the properties, especially mechanical properties of the propellant depend on this bridging ratio. The propellant of the invention is thus obtained without isocyanate in the dough to be crosslinked, i.e. without contact: energy charges / isocyanate. The technical problem of the prior art explained in the introduction of this text is therefore not likely to arise. Said at least one intervening crosslinking agent, generally the intervening crosslinking agent, is therefore of di- or tri-propargyl type. The triple bonds of said at least one crosslinking agent are ideally suited to react with the azide terminal functions of the polymer (see the "Click chemistry" reaction mentioned in the introduction to this text). Crosslinking is thus provided via triazole patellae of the formula: ## STR1 ## Said at least one crosslinking agent is advantageously tripropargyl tricarbalylate (TCATP). It is proposed to illustrate schematically below the crosslinking reaction generating a propellant of the invention, crosslinking the polymer of formula (V) shown above with tripropargyl tricarbolylate (TCATP). For the sake of simplicity, only a single azide function of the polymer and thus the crosslinking is shown at the level of said single azide function: The energy charges present in the propellant of the invention may consist of any type of energetic charge , those conventional (HMX, RDX, CL 20 ...) and therefore also those with intrinsic acidity, such as DNA (dinitroamidure ammonium) and nitropyrazoles, including trinitropyrazole. It is recalled that the invention has been developed with reference to the technical problem of the formulation of this type of charge.

In consideration of the above remarks, it is understood that the interest of the invention which opens the field of application of the "pre-polymers" hydroxytelechelic of the prior art to the new types of charges, not modifying said " pre-polymers "only insubstantially so that the final properties of the propellants in question are not substantially modified. It can further be made clear with reference to the propellants of the invention that the dough to be crosslinked is advantageously obtained as follows. by kneading a pasty composition comprising said azide terminal functional polymer of formula (V) and said energetic charges; adding to said pasty composition of said at least one crosslinking agent; and then extruding said pasty composition with crosslinking agent (s) and cutting said pasty composition with extruded or cast crosslinking agent (s) of said pasty composition with crosslinking agent (s) in minus one mold; and that the crosslinking comprises (conventionally) a heat treatment. Said heat treatment is generally carried out at a temperature between 20 ° C and 100 ° C for a period of 6 h to 48 h.

It is quite possible within the scope of the invention to prepare the azide terminal functional polymer of formula (V) and the corresponding propellant directly in a "one pot" operation. In this, the present invention is also particularly interesting. It is now proposed to illustrate the invention, in its various aspects, by the examples below. Example 1 a) Synthesis of the azidoalcohol: 2-azido-1-phenylethan-1-ol HO NaN3 PEG 400 This synthesis was carried out in accordance with the teaching of Biswanath D. and Vturkuri SR, in Synthesis, 2007, 5, 25 p. 666-668.

In a 250 mL three-neck solvent (PEG-400 (100 g)), styrene oxide (10 g, 0.08 mol) was added with stirring. At 20 ° C, the sodium azide (0.11 moles, 7.5 g) was added portionwise to the reaction medium. The temperature of the reaction medium rose slightly from 20 ° C to 25 ° C. The reaction medium was stirred at 70 ° C. for 3 hours. The reaction was monitored by thin layer chromatography (TLC). At the end of the reaction, the medium was hydrolysed in water (500 ml) to solubilize the salts formed and the PEG was extracted with ethyl acetate (2 times 500 ml). The organic phase was dried over magnesium sulfate and then evaporated to dryness. The product (azidoalcohol of formula II) was obtained with 80% yield. The infra-red spectrum of this product has been obtained. The characteristic bands of it are indicated below.

IR: 3381 cm-1 OH, 3032 cm-1 aromatic CH, 2916 cm-1 aliphatic CH, 2102 cm-1 N3, 1493 cm-1 aromatic CC, 1453 cm-1 N = N, 1251 cm-1 C- 0H, 1070 cm -1 CN, 700-759 cm -1 aromatic. B) Synthesis of the corresponding azido derivative of PBHT Said synthesis is shown schematically as follows: IPDI IPDI PBHT 3013 712 18 b1) In a small kneader, isophorone diisocyanate (IPDI) (6.78 g, 0.0307 mole) and a few drops of di-n-dibutyltin (DBTL) were introduced. While stirring at 60 ° C, 2-azido-1-phenyl-ethan-1-ol (0.307 moles, 5 g) was then added portionwise. The reaction was monitored by monitoring the disappearance of the hydroxyl function and the appearance of the carbamoyl function by IR (for about 2 hours). The characteristic bands of the intermediate product obtained (IV = II + III) are indicated below.

IR: 3000 cm-1 aromatic CH, 2956 cm-1 aliphatic CH, 2263 cm-1 urethane, 2104 cm-1 N3, 1733 cm-1 N = C = O, 1454 cm-1 N = N, 1251 cm -1 1 aromatic CC, 1065 cm-1 CN, 700-759 cm -1 aromatic CH. B2) PBTH (9. 10-3 mol, 19.9 g), R45M marketed by the company 3M (n1 = 40, Mw = 2002) was then added in one go. At a temperature of 60 ° C, the formulation was stirred for 2 hours while the disappearance of the isocyanate functions was followed by IR (complete disappearance of the isocyanate bands was observed). The "dicarbamoyl azido" derivative of PBHT (a yellow polymer that was fairly viscous when cold but hot-pourable (60 ° C.)) was obtained in a yield of 70 ° h (8.5 g). The characteristic bands of its infra-red spectrum are indicated below.

IR: 3500 cm-1 aromatic CH, 2916 cm-1CH aliphatic, 2283 cm-1 urethane, 2099 cm-1 N3, 1639 cm-1 C = C, 866-739 cm-1 H-C = C-H.

Example 2 a) Synthesis of the azidoalcohol: 1-hydroxy-2-azido-cyclohexane OH NaN 3 PEG 400 OEN 3 This synthesis was carried out in accordance with the teaching of Biswanath D. and Vturkuri SR, in Synthesis, 2007, 5, p. 666-668.

In a 25 mL three-neck solvent (PEG-400 (10 g)), cyclohexane oxide (1 g, 0.01 mol) was added with stirring. At 20 ° C, the sodium azide (0.011 mole, 0.75 g) was added portionwise to the reaction medium. The temperature of the reaction medium rose slightly from 20 ° C to 25 ° C. The reaction medium was stirred at 70 ° C. for 3 hours. The reaction was monitored by TLC. At the end of the reaction, the medium was hydrolysed in water (50 ml) and the PEG was extracted with ethyl acetate (twice 50 ml). The organic phase was dried over magnesium sulfate and evaporated to dryness. The product was obtained with 75% yield. The infra-red spectrum of this product has been obtained. The characteristic bands of it are indicated below. IR: 3375 cm -1 OH, 2936 cm -1 CH 2 aliphatic, 2114 cm -1 N 3, 1451 cm -1 N = N, 1074 cm -1 C-N, 1080 cm -1 C-OH. In a small kneader, isophorone diisocyanate (IPDI) (6.78 g, 0.0307 moles) and a few drops of di-n-dibutyltin (DBTL) were introduced. While stirring at 60 ° C, 1-hydroxy-2-azido cyclohexane (0.307 moles, 4.3 g) was then added portionwise. The reaction was monitored by IR by monitoring the disappearance of the hydroxyl function and the appearance of the carbamoyl function (for about 2h).

IR: 2950 cm -1 CH 2 aliphatic, 2260 cm -1 urethane, 2104 cm -1 N 3, 1730 cm -1 N = C = 0, 1450 cm -1 N = N, 1065 cm -1 C-N. b2) PBHT (9. 10-3 mol, 19.9 g), R45M sold by the company 3M (n1 = 40, Mw = 2002) was then added at once.

The formulation was stirred at 60 ° C for 2 hours while the disappearance of the isocyanate functions was followed by IR. The "dicarbamoyl azido" derivative of PBHT was obtained with a yield of 72% (8.7 g). b) Synthesis of the Corresponding Azido Derivative of PBHT Said synthesis is schematized as follows: IDPK IPDI IPDI IPDI IPDI 25 IR: 2940 cm-1CH aliphatic, 2280 cm-1 urethane, 2110 cm-1 N3, Example 3 Crosslinking An azido derivative of PBHT In a kneader, the azido derivative of PBHT (5 g) prepared in Example 1 was stirred at 60 ° C to lower its viscosity. Tripropargyl tricarbalylate (TCATP) (0.37 g (adequate amount for a bridging ratio of 1)) was then introduced. The mixture was stirred for a few minutes to homogenize, then poured into a mold and baked for 1 week at 60 ° C. The crosslinked object obtained was then demolded. Small blocks of 2 to 3 cm in diameter for 2 to 3 cm in height have been obtained in this way. Tensile specimens (H2 specimens), also obtained in this manner, were tested to determine the mechanical properties of the material. The results of these tests (tensile characterization tests, carried out according to the standard (mechanical properties of energetic materials): NFT 70-315) are given below: Elongation: 850 Maximum tensile strength at break: 0, 85 MPa. These values can be compared with those obtained under the same conditions, for the reference binder: PBHT (R45M marketed by the company 3M (n1 = 40, Mw = 2002)), crosslinked, with a bridging ratio of 0.9 , with IPDI: Elongation: 1000% Maximum tensile strength: 1 MPa.

Claims (15)

REVENDICATIONS1. Azide terminal functional polymer, corresponding to the following formula (V): ## STR2 ## in which P represents the hydrocarbon chain of a homopolymer containing: ## STR2 ## , n1 being between 5 and 300, OR n2 ether units, n2 being between 5 and 300, 15 or n3 ether-ester units, n3 being between 5 and 100; R 1 represents a linear, branched or cyclic, saturated or unsaturated, hydrocarbon difunctional radical containing from 2 to 15 carbon atoms and optionally at least one heteroatom chosen from nitrogen and oxygen, or a cyclic hydrocarbon difunctional radical; aliphatic or aromatic, having from 4 to 6 carbon atoms and optionally at least one heteroatom selected from nitrogen and oxygen; the group N3-R1-0- containing a number of carbon atoms (n1) and a number of nitrogen atoms (n2) such that said number of nitrogen atoms (n2) does not exceed said number of carbon atoms (n1) (n1? _n2); R2 represents the difunctional radical of an aliphatic or aromatic diisocyanate of formula (III): O = C = N-R2-N = C = O. 2. Polymer according to claim 1, of formula (V) wherein P represents the hydrocarbon chain of a homopolymer with buta-1,3-diene units, n1 being between 5 and 300, advantageously between 25 and 85. 3. Polymer according to claim 1 or 2, of formula (V) in which the group -O-R1-N3 corresponds to: OR 4. Polymer according to claim 1, wherein R2 represents the difunctional radical of an aliphatic diisocyanate of formula (III) chosen from hexamethylene diisocyanate 2,2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), methylene diisocyanate, 1,6-hexane diisocyanate, 2,2,4-trimethyl-1,6-hexane diisocyanate, advantageously chosen from hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI). 5. The polymer according to claim 1, wherein R2 represents the difunctional radical of an aromatic diisocyanate of formula (III) chosen from 2,4-toluene diisocyanate 2 6-toluene diisocyanate (TDI) and 4,4-diphenylmethane diisocyanate (MDI) .6. Polymer according to any one of claims 1 to 5, of formula (V) wherein: P is as defined in claim 2, -O-R1-N3 is as defined in claim 3, R2 is as defined in claim 4 or 5. 7. Process for obtaining a polymer with azide terminal functions, corresponding to the formula (V) according to any one of claims 1 to 6, characterized in that it comprises: - the provision of a polymer hydroxytelechelic compound of formula (I): HO-P-OH, wherein P is as defined in claim 1 or 2; - providing an azidoalcohol of formula (II): HO-R1-N3, wherein R1 and the group N3-R1-0- are as defined in claim 1 or 3; the provision of an aliphatic or aromatic diisocyanate of formula (III): ## STR2 ## according to claim 1, 4 or 5; the reaction of said azidoalcohol of formula (II) with said diisocyanate of formula (III), said azidoalcohol of formula (II) being added, in parts, to said diisocyanate of formula (III) present in an amount not exceeding 99%, generally in an amount of 95 to 99%, of the stoichiometric amount, for obtaining a monoisocyanate of formula (IV): ## STR2 ## the reaction of said monoisocyanate of formula (IV) with said hydroxytelechelic polymer of formula (I) for obtaining said azide terminal functional polymer of formula (V). 8. Method according to claim 7, characterized in that said azidoalcohol of formula (II) is obtained by direct azidation of an epoxy or a haloalcohol. 9. A method according to claim 7 or 8, characterized in that the reaction of said azidoalcohol of formula (II) with said diisocyanate of formula (III) is carried out, without solvent, at room temperature or at a temperature above ambient temperature. 10. Process according to any one of claims 7 to 9, characterized in that the reaction of said monoisocyanate of formula (IV) with said hydroxytelechelic polymer of formula (I) is carried out, without solvent, at room temperature or at room temperature. a temperature higher than the ambient temperature. 11. Solid propellant containing energy charges in a crosslinked binder, obtainable by crosslinking a paste comprising: an azide terminal functional polymer of formula (V) according to any one of claims 1 to 6 and or as obtained at the end of the implementation of the process according to any one of claims 7 to 10, - energetic charges, and - at least one crosslinking agent, of di- or tri-propargyl type. 301 3 7 1 2 26 12. Propellant according to claim 11, characterized in that said crosslinking agent consists of tripropargyl tricarbalylate (TCATP). 5 13. Propellant according to claim 11 or 12, characterized in that said energy charges have an intrinsic acidity and advantageously consist of ammonium dinitroamide (DNA) or a nitropyrazole. 10 14. Propellant according to any one of claims 11 to 13, characterized in that said paste is obtained by: - mixing a pasty composition comprising said azide terminal functional polymer of formula (V) and said energy charges; Adding to said pasty composition of said at least one crosslinking agent; then - extruding said pasty composition with crosslinking agent (s) and cutting said pasty composition with extruded crosslinking agent (s) or casting said pasty composition with crosslinking agent (s) in at least one mold; and in that said crosslinking comprises a heat treatment.