FR2743807A1 - Energetic hydrocarbon polymers used as charge or binder in composite fuels - Google Patents

Abstract

A novel energetic hydrocarbon polymer of formula(I) and its preparation are claimed. {CR=CR(CH2)x-A-(CH2)x-CR=CR-(CH2)y-CR=CR2z} (I) where A is a cage pattern and R are identical or different substituents of H or a hydrocarbyl residue, x and y = 0 - 3.

Description

The object of the present invention is a new family of hydrocarbon polymers having chain units in their chain, such as cubane or homocubane, separated by unsaturated acyclic chain members.

The invention also relates to the method for obtaining these polymers by polymerization and carbene copolymerization of dienes a-o in the presence of an olefin metathesis catalyst.

Obtaining hydrocarbon polymers of high density and containing highly stretched cycles, that is to say very energetic, is particularly sought for the preparation of composite fuels used as propellants and semi-propellants. These polymers can be used as fillers or as binders and must have suitable mechanical properties.

 There are few examples of hydrocarbon polymers containing a pattern, consisting of several tense cycles, the latter being an integral part of the chain. This is polybenzvalene, obtained by ring-opening carbene polymerization of benzvalene (R.H. Grubbs et al J. Am., Chem.

1989, 111, 4413) and poly [1.1.1] propellan obtained by anionic polymerization (A.D. Schlüter, Macromolecules 1988, 21, 1208). Chains of cubane units directly connected to each other ("oligocubanes") have been described by P. E. Eaton (Angew Chem Int, Ed., 1992, 31, 1421). This author has also described the sequence of two Cubane units by homocoupling of two cubylacetylenes (J. Am., Chem., Soc.

1994, 116, 7588). Because of their rigidity these molecules are solids of high melting point and very sparingly soluble. Cage molecules such as cubane are nevertheless potentially interesting because of their high density and the very high voltage of their cycles which make them compounds whose volumic energy is very important. Thus the cubane itself has the following characteristics - density: 1.29 g / ml - heat of formation: 601.9 kJ / mole - voltage energy: 693.9 kJ / mole.

These molecules are thermodynamically unstable but kinetically stable (up to 200 ° C in the case of cubane), but in the presence of certain salts or metal complexes, these molecules are isomerized into more stable molecules with release of energy. cubane can thus be isomerized to cyclooctatetraene in the presence of rhodium complexes.

It has now been found, and this is the object of the present invention, that the polymers which comprise in their sequence cage patterns separated by alkenyl acyclic chains possess both a high cycle voltage energy and physicomechanical properties which allow them to be used as filler or as precursors of binders for propellants and semi-propellants. The repeating unit of these polymers can be represented according to:
- (CR = CR (CH2) xA- (CH2) xC R = CR [- (CH2) yC R = CR] zi - in which A is a cage unit such as cubane diyl and / or homocubane diyl, and / or syn-tricyclooctane diyl and / or secocubane diyl and / or 1,8bishomocuban diyl and substituted thereof The cage unit may be substituted by the macromolecular chain of the product in various positions, for example in positions 1-2 , 1-3 or 1-4 for the cubane unit and the cage unit A is then respectively -1,2-diol cubane or -1,3-dian cubane or 1,4-cuban-1,4-cubane or their substituted. The corresponding hydrocarbons (cubane, homocubane, 1,8-bishomocubane, secocubane, syn-tricyclooctane) are defined, for example, in an article by LA Paquette (J. Am., Chem., Soc.

1975, 97, 1084). The substituents R which may be identical or different represent a hydrogen atom, a methyl or any other substituent such as a hydrocarbyl residue, generally having from 1 to 6 carbon atoms optionally comprising a heteroatom, for example oxygen or nitrogen.

The physicomechanical properties of the polymer will naturally depend on the position and nature of the substituents.

In this formula x, y and z can take all integer values 0, 1, 2, 3 and preferably x is 1, 2 or 3.

Another object of the invention is the preparation of such polymers by catalytic metathesis reaction of dienes ao of general formula:
RHC = CR- (CH2) xA- (CH2) x-CR = CHR (I)
A, R being defined as above. It is also possible to copolymerize two different dienes of formula (I), and in particular those comprising different cage molecules.

The dienes of formula (I) are new products also object of the invention.

The polymers according to the invention can also be obtained by catalytic cometathesis reaction of monomer I with aH 2 dienes of general formula:
CHR = CR (CH2) yCR = CHR (II) not having a cage motif, R being defined as above.

dans laquelle X représente les restes (CH2)x-A-(CH2)x et (CH2)y des monomères I et Il. The catalytic reaction of polymerization and / or copolymerization by metathesis is done with release of a light olefin and corresponds to the following equation:

wherein X represents the (CH2) xA- (CH2) x and (CH2) y residues of monomers I and II.

The metathesis polymerization may be preferably carried out in an aprotic solvent such as toluene, benzene, hexane, cyclohexane, pentane, chlorobenzene, dichloromethane, dimethoxyethane. But it can be done without solvent.

The polymerization reaction preferably takes place at room temperature but can take place at -50 ° C to + 200 ° C and preferably at 0 ° to 80 ° C. The polymerization is carried out under vacuum or under an inert gas, advantageously with sweeping, at a pressure of between 10-5 torr (ie 1, 333x10-3 Pa) and 106 Pa and preferably between 0.5x105 and 2 x 10 5 Pa.

The reaction time is generally between a quarter of an hour and 48 hours, preferably between 2 and 16 hours.

The molar monomer ratio (diene of formula (I)) on catalyst is between 25: 1 and 5000: 1 and preferably between 50: 1 and 500: 1.

dans laquelle R1, R2, R3, R4, peuvent être identiques ou différents et représentent des groupes alkyl, aryl, aralkyl, haloaryl ou haloaralkyl et M est le molybdène ou le tungstène. Les synthèses de ces catalyseurs ont été décrites par R.R. Schrock et al. (J. Am. Chem. Soc. 1990, 112, 3875 pour le molybdène, et Organometallics 1990, 9, 2262. pour le tungstène).The catalyst used to carry out the metathesis polymerization according to the invention may be any catalyst known to those skilled in the art and in particular a carbene of molybdenum or tungsten of general formula:

wherein R1, R2, R3, R4 may be the same or different and represent alkyl, aryl, aralkyl, haloaryl or haloalkyl groups and M is molybdenum or tungsten. The syntheses of these catalysts have been described by RR Schrock et al. (J. Am.Chem.Soc. 1990, 112, 3875 for molybdenum, and Organometallics 1990, 9, 2262 for tungsten).

In the cometathesis reaction the molar ratio of dienes I and II has a decisive effect on the energy contained in the copolymer and the physicomechanical properties of the copolymer. The 1:11 mole ratio can be any 1: 0.01 to 1: 10 and preferably 1: 0.01 to 1: 3.

By way of example, the monomers I may be 1,4-bishomoallylcubane, 1,4-bishomoallylhomocubane or 9,1 O -divinyl-1,8-bishomocubane. The monomers include 1,4-pentadiene, 1,5-hexadiene and 1,7-octadiene.

 The acyclic dienes I which are the subject of the present invention are prepared from derivatives of cage molecules such as, for example, diesters, diacids or carboxylic anhydrides.

In the most common case, the synthetic methods used lead to dienes for which all the R substituents are hydrogen atoms. During the polymerization of the diene, ethylene is released.

1,4-Bishomoallylcubane, for which A is the cubane unit, x = 2 and all the substituents R are hydrogen atoms, is prepared according to the following sequence of reactions:

<tb><SEP> CO2Me <SEP> CH20H
<tb><SEP> LiAlH4
<tb><SEP> THF
<tb> ss <SEP>'<SEP> A
<tb> MeO2C <SEP> HOCH2
<tb><SEP>,<CBr4
<tb><SEP>, (: H2Br <SEP> V
<tb><SEP> 71
<tb> BrCH2
<Tb>
The 1,4-dibromomethylcubane was prepared according to the method described by PE

Eaton et al. (J. Am Chem Soc 1991, 113, 7692) illustrated ciclessus, then we found that this dibromide reacts with allyllithium in ether to yield 1,4-bishomoallylcubane in greater than 90% yield.

More generally, the diene (I) is prepared by reaction with an unsaturated organometallic compound (lithium or magnesium for example) in an aprotic solvent, preferably ether, of a compound of general formula:
Z- (CH2) xA- (CH2) xZ wherein A represents a cage moiety as previously defined, x is 0, 1, 2, or 3 and Z is halogen (preferably Bromine).

The following examples illustrate the invention without limiting its scope.

EXAMPLE t Preparation of 1,4-bishomoallylcubane
In a three-necked 100 ml, 1.2 g (4.14 mmol) of 1,4 bis (bromomethyl) cubane prepared according to the PE Eaton method (reference above) are introduced and are dissolved in 4.5 ml. of anhydrous ether and which is cooled to OOC. A solution of allyllithium (13.7 mmol) in solution in 20 ml of ether is added dropwise, with stirring, and the mixture is stirred at 0 ° C. for 4 hours.

Excess allyllithium is destroyed by addition of water (3 mL) and the products are recovered by decantation and extraction with ether (20 mL). After drying over sodium sulphate and evaporation of the solvent, an oil is obtained. The product, which is liquid, is isolated pure by chromatography on a silica column with elution with hexane: 800 mg (yield = 90%).

Mass Spectrum: m / e (%) 212 (M, 35%)
1H NMR (CDCl 3); 6 (ppm): 5.7 to 6 (m, 2H); 4.7 to 5.1 (m, 4H); 3.56 (s, 6H); 1.95 to 2.15 (m 4H); 1.6 to 1.7 (m, 4H).

13C (CDCl3); 6 (ppm) 139 (CH); 114 (CH2); 59.8 (C); 44.8 (CH); 32.5 (CH2); 28.7 (CH2).

Infrared (c / o 3080 (w), 2960 (s), 2920 (s, sh), 2905 (s, sh), 2840 (m), 1638 (m), 1442 (m), 1430 (w, sh), 1412 (w), 990 (m), 910 (s), 838 (m), 735 (m).

(s = strong, m = medium, w = low, sh = shoulder).

The 1,4-bishomoallylcubane can also be purified by spraying between 20 and 450 ° C. under a vacuum of 4 × 10 -6 Torr or 5.33 × 10 -4 Pa and condensation on a wall cooled to -7 ° C.

EXAMPLE 2
Polymerization of 1 .4-bishomoallylcubane
The 1,4-bishomoallylcubane (300 mg), dissolved in 2 ml of benzene, is dried on a sodium mirror in a Schlenck tube for 24 hours.

The bis homoallylcubane solution (1 mL, 150 mg of monomer, 0.7 mmol) is transferred to a Schlenck tube containing 15 mg (0.02 mmol) of molybdenum carbene [(CF 3) 2 MeCO] (N-). 2,6-C6H3-i-Pr) Mo = CHC (Me) 2 Ph.

Immediately after the dissolution of the catalyst, there is a release of ethylene, the solution changes from yellow to yellow brown and becomes thicker with precipitation of a solid. The reaction is stopped after about one hour, when no more stirring, by adding a drop of pivaldehyde dissolved in benzene.

 The white solid obtained is filtered and then dried under vacuum: 90 mg (60%). It is very slightly soluble in the usual solvents. It is slightly soluble in hot in chloroform.

The proton NMR spectrum was recorded at 40 ° C in CDCl3, it reveals the presence of protons of internal olefins at 5.4 ppm, protons of terminal vinyl groups (= CH2 at 5 ppm, -CH = at 5 , 4 ppm), as well as that of the protons of the cubane unit (several singlets towards 3.5 ppm) .The two massifs centered at 1.6 and 2 ppm correspond to the two types of CH2 of the chain.

The calculations made from the integrations of these signals allow us to estimate that the average degree of polymerization is low (n = 6 or 7).

Analysis of the soluble part in methanol reveals the predominant presence of monomer.

Differential thermal analysis between 1000 and 4000C, under an argon atmosphere, makes it possible to detect a peak due to the exothermic decomposition of the polymer between 140 ° C and 2700C (1891.8 J / g), which corresponds to 346.9 kJ per mole of recurring unit, point of softening: 19000.

Infrared (KBr, cm-1): 2960 (s), 2900 (s), 2835 (s), 1663 (w), 1635 (m), 1440 (s), 1425 (m), 1315 (m), 1260 (m), 1070 (m), 1035 (m), 970 (s) trans olefin, 910 (s), 835 (s), 800 (m), 750 (w).

(s = strong, m = medium, w = low, sh = shoulder).

13C NMR (CDCl3): 139.2 and 113.9 (CH2 and CH, vinyl terminal), 130.18 (CH, internal double bond), 59.9 (C), 44.9 (CH), 33.1 (allylic CH2), 32.6 (allylic CH2) of the unit end of chain), 28.6 (CH2 of end of chain pattern), 27.5 (CH2).

The presence in the infrared spectrum of an intense band at 970 cm-1 and the appearance in NMR of a single peak at 130.2 ppm in the zone of the sp2 carbons of the internal double bonds show that the polymer is trans.

EXAMPLE 3
Copolymerization of bis 1,4-homoallylcubane and 1,5-hexadiene.

- Bis 1,4-homoallylcubane / 1,5-hexadiene molar ratio = 1
Bis 1,4-homoallylcubane (0.193 g, 0.912 mmol) and 1,5-hexadiene (0.0759, 0.908 mmol) are dissolved in benzene (3 mL) and the mixture is dried overnight on a mirror. sodium.

The monomer solution is transferred, at 200C, by cannula into a Schlenck tube containing catalyst 7 (15 mg, 0.018 mmol) and the evolution of ethylene is immediately observed. The solution changes from yellow to red and remains homogeneous.

After 22 hours, the solution is transferred by cannula into another tube containing catalyst 7 (15 mg) to initiate the polymerization again.

After 48 hours of reaction, the polymerization is stopped by the addition of 25 FL of puddehyde, and then the polymer P1 (120 mg) is isolated by precipitation with methanol (20 mL).

Infrared of the copolymer P1 (KBr, cm-1): 2970 (s), 2910 (s), 2840 (s), 1665 (w), 1640 (m), 1448 (s), 1432 (m, sh), 1310 (m), 1262 (m), 1080 (m), 1040 (m), 970 (s), 912 (m), 840 (s), 805 (m), 750 (w), 725 (w), 700 (w).

The polymer P1 (test 1), which is sufficiently soluble in THF, could be analyzed by GPC: Mn = 2478, Mp = 4070, polydispersity = 1.64 (/ polystyrene standard).

1H NMR (CDCl3): 5.7-6.0 (m, vinyl terminal, CH), 5.3-5; 6 (m, -CH = CH-), 4.85.1 (vinyl terminal, CH2), 3.56 and 3.55 (s, H cubane), 1.9-2.1 (m, allylic CH 2), 1.5-1.7 (CH 2).

The degree of polymerization, the composition of the copolymer and the average molecular weight can be calculated from the integrations of the signals of internal olefins (5.4 ppm) and vinyl terminal groups (5 and 5.8 ppm), cubane signals (3.5ppm), CH2 signals in a cubane (1.6 ppm) and allylic CH2 (2 ppm).

The repeating units butenylene (C4H6) and cubylene (C14H16) are defined below:
Oubylene pattern:

Butenylene pattern:

According to the NMR data, the copolymer P1 contains an average number of 14 repeating units with a butenylene / cubylene ratio of 0.56 / 1.

Concentration in vacuo of the methanol solution gives a pasty solid P2 (60 mg). NMR analysis shows that this copolymer contains an average number of 4 repeating units with a butenylene / cubylene ratio of 1.7 / 1.

EXAMPLE 4 - 1,4-Bis homoallylcubane / 1,5-hexadiOne molar ratio of 2:
This test was carried out under the same conditions as Example 3 from
Bis 1,4-homoallylcubane (0.155 g, 0.7322 mmol) and 1,5-hexadiene (0.032 g, 0.398 mmol) dissolved in benzene (3 mL). The mixture was transferred to a Schlenck tube containing catalyst 7 (13mg, 0.015mmol) and after 4 hours of reaction a second dose of catalyst (13mg) was added.

The copolymer obtained was separated into three fractions by precipitation with methanol: Psi: polymer obtained after dissolution in dichloromethane and methanol precipitation of the solid obtained during the precipitation with methanol at the end of the reaction (41 mg, yield calculated according to the average composition: 26%).

According to the NMR data, this copolymer contains an average number of 10 repeating units with a butenylene / cubylene ratio of 0.13 / 1. The average molecular weight can be calculated from these results: Mn = 1700.

GPC (THF): Mn = 1691, Mp = 2338, polydispersity: 1.41.

 P2: pasty solid obtained by concentration of the methanolic solution resulting from the purification of the precipitate obtained during the precipitation with methanol at the end of the reaction (32 mg, yield calculated according to the average composition: 21%).

According to the NMR data, this copolymer contains an average number of 6.2 repeating units with a butenylene / cubylene ratio of 0.48 / 1. The average molecular weight can be calculated from these results: Mn = 900.

 P3: pasty solid obtained by concentration of the methanolic solution resulting from the precipitation at the end of the reaction (72 mg, yield calculated from the average composition: 46%).

According to the NMR data, this copolymer contains an average number of 4.2 repeating units with a butenylene / cubylene ratio of 0.7 / 1. The average molecular weight can be calculated from these results: Mn = 600.

GPC (THF): Mn = 570, Mp = 1026, polydispersity: 1.8
FIGS. 1 and 2 show, respectively, the 1 3 C NMR spectra of the bis-1,4 homoallylcubane homopolymer (example 2, spectrum a) and of a copolymer of bis-1,4 homoallylcubane with 1,5-hexadiene ( example 3
P1, spectrum b) and Figure 3 an enlargement of the sp2 carbon region of the latter (spectrum c).

Spectrum
Since the degree of polymerization is low, we observe two peaks at 113.9 and 139.2 ppm which correspond respectively to CH2 and CH of the terminal vinyl groups, in addition to the peak at 130.2 ppm of the sp2 carbons of the internal double bonds. .

59.91: signal of the two quaternary carbons of the cube 44.96: signal of the 6 CH of the cube 33.1: signal of the allylic CH2 of the 32.6 chain: signal of the allylic CH2 of the end chain units 27.5: signal of the chain CH2 linked to the cube 28,6: signal of the CH2 linked to the cube of the end-of-line motifs
Spectrum b
The sp2 carbon region is more complex due to the presence of butenylene units.

59.88: signal of the 2 quaternary carbons of cubane 44.93: signal of the 6 CH of cubane
The region corresponding to carbons of allylic CH2 and CH2 of the chain bonded to cubane is also more complex.

Spectrum c
The enlargement of the sp2 carbon region of the copolymer spectrum (figure above) reveals the presence of 5 or 6 peaks 130.68 (medium); 130.15 (large); 129.97 (small); 129.77 (small); 129.47 (medium); 129.42 (small or due to background noise).

The peak at 130.15 ppm is attributed to the trans-cuboid-cubylene sequence according to the homopolymer spectrum, which is analogous to the work of KB
Wagener et al. on the copolymerization of acyclic dienes (KB Wagener,
JG Nel, J. Konzelman, JM Boncella. Macromolecules, 1990, 23, 51557). Eight types of concatenation are possible:
Type of sequence
A Cubyl Cubyl Trans
B Cis cubylene-cubylene
C Trans butenylene-butenylene
D butenylene-butenylene
E Trans cubylene-butenylene
F Cis cubylene-butenylene
G Trans butenylene-cubylene
H cis butenylene-cubylene
Homopolymerization of bis-1,4-homoallylcubane resulting in only trans polymer and homopolymerization of 1,5-hexadiene resulting in 80% trans polymer (Ofstead, EA; Wagener, KB in New Methods for
Polymer Synthesis, edited by WJ Mijs, Plenum Press, New York, 1992).

If we admit that the sequences with a Cuban pattern of type Cis (B, F,
H) are unlikely, there are still 5 types of concatenation. What can explain the presence of 5 peaks in 13C NMR and the three main ones are to be attributed to the sequences A, E and G.

Claims (23)

1 - Polymer of general formula:  ## STR2 ##  in which A represents at least one cage unit and the substituents R  identical or different represent a hydrogen atom or a residue  hydrocarbyl, x and y can take all integer values 0, 1, 2, 3. 2 - Polymer according to claim 1 wherein the cage pattern is chosen from  the group formed by cubane diyl, homocubane diyl, syn  tricyclooctane diyl, secocubane diyl, 1,8-bishomocubane diyl and  their substitutes. 3 - Polymer according to one of the preceding claims wherein the pattern  cage is substituted by the macromolecular chain in position 1-2, or 1-3,  or 14 for the cuban pattern. 4 - Polymer according to one of the preceding claims wherein the remainder  hydrocarbyl has from 1 to 6 carbon atoms. 5 - Process for preparing a polymer according to one of claims 1 to 4  by catalytic metathesis reaction of dienes po of general formula:  RHC = CR- (CH2) x-A- (CH2) x-CR = CHR  in which A represents at least one cage unit and the substituents R  identical or different represent a hydrogen atom or a residue  hydrocarbyl, x being able to take all the integer values 0, 1, 2, 3. 6 - Preparation process according to claim 5 wherein the cage pattern  is selected from the group consisting of cubane diyl, homocubane diyl,  syn-tricyclooctane diyl, secocubane diyl, 1,8-bishomocubane  diyl and their substitutes. 7 - Preparation process according to claim 6 wherein the cage pattern  is substituted by the macromolecular chain in position 1-2, 1-3, or 1-4  for the cuban pattern. 8 - Preparation process according to one of claims 6 or 7 wherein  the hydrocarbyl residue has 1 to 6 carbon atoms. 9 - Preparation process according to one of the preceding claims by  cometathesis of dienes of different formula (I). 10 - Preparation process according to one of the preceding claims by  Cometathesis of the diene of formula (I) with a diene of general formula  (II): CHR = CR [- (CH2) y-CR = CHR  wherein R represents a hydrocarbyl residue, and may take  all integer values 0, 1, 2, 3.  1 1 - Preparation process according to claim 10 wherein the  substituent R of formula (II) is a hydrocarbyl residue having from 1 to 6  carbon atoms. 12 - Preparation process according to one of claims 5 to 1 1 operating at  a temperature between -50 and 200 ° C, with a molar ratio  diene of formula (I) on a catalyst of between 25: 1 and 5000: 1, under a  pressure of 1.333x10-3 Pa at 106 Pa. 13 - Preparation process according to one of claims 5 to 12 wherein  the catalyst is a molybdenum or tungsten carbene of formula  General

 wherein Rt, R2, R3, R4, which are the same or different, represent alkyl, aryl, aralkyl, haloalkyl, haloaryl or haloalkyl groups, and M represents molybdenum or tungsten. 14 - Preparation process according to one of claims 10 or 1 1 in  wherein the molar ratio of dienes (I) and (II) is between 1: 0.01 and 1: 1 O. 15 - Preparation process according to one of claims 5 to 14 wherein  the diene (I) is selected from the group consisting of 1-4 bishomoallylcubane,  1-4 bishomoallylhomocubane, 9,1 0-divinyl-1,8-bishomocuban. 16 - Preparation process according to one of claims 10 or 1 1 in  wherein the diene (II) is selected from the group consisting of 1,4-pentadiene,  1,5-hexadiene and 1,7-octadiene. 17 - Compound of formula RCH = CR- (CH2) x-A- (CH2) x-CR = CHR in which A  is a cage motif and the identical or different substituents R represent  a hydrogen atom or a hydrocarbyl residue and x taking the values 0, 1,2,3. 18 - Compound according to claim 17 wherein the cage pattern is chosen  in the group formed by cubane diyl, homocubane diyl, syn  tricyclooctane diyl, secocubane diyl, 1,8-bishomocubane diyl and  their substitutes. 19 - Compound according to one of claims 17 or 18 wherein the pattern  cage is substituted by the macromolecular chain in position 1-2, or 1-3,  or 1-4 for the cuban pattern. 20 - Compound according to one of claims 17 to 19 wherein the remainder  hydrocarbyl has from 1 to 6 carbon atoms. 21 - Process for preparing a compound according to one of claims 17 to  In which a compound of formula (III) is reacted:  Z- (CH2) x-A- (CH2) x-Z  where A represents a cage motif, x is 0, 1, 2, or 3 and Z  represents a halogen, with an organometallic compound in a  solvent. 22 - Process according to claim 21, wherein the cage pattern is chosen  in the group formed by cubane diyl, homocubane diyl, syn  tricyclooctane diyl, secocubane diyl, 1,8-bishomocubane diyl and  their substitutes, and in which the cage motif is substituted by the chain  macromolecular in position 1-2, or 1-3, or 1-4 for the cuban pattern. 23 - Use of a polymer according to one of claims 1 to 4 as  filler or binder used in the composition of composite fuels. 24 - Use according to claim 23 for the preparation of propellants or  semi-propellants.