Process for the synthesis of polyethylenes or copolymers of ethylene and 1,3-diene having a terminal ketone function

Abstract

The invention relates to a method for preparing a polyethylene having a terminal ketone function or a copolymer of ethylene and a 1,3-diene and optionally a vinyl aromatic compound which contains more than 50 mol% of ethylene and has a terminal ketone function; said method comprises a polymerization reaction of the monomers in the presence of a borohydrido-neodymocene complex and an organo-magnesium compound, followed by a coupling reaction with a compound having a nitrile function, and then a hydrolysis reaction.

Description

Process for the synthesis of polyethylenes or copolymers of ethylene and 1,3-diene bearing a terminal ketone function

[0001] The field of the invention is that of polyethylenes and copolymers of ethylene and α-olefins which are rich in ethylene units and which are functionalized at the chain end by a polar function, a ketone.

[0002] The synthesis of polyethylenes and α-olefin copolymers is widely described in scientific literature. It is well known that the choice of the polymerization route will determine the structure of the polymer chain. Polymerization by means of coordination catalysis that uses certain neodymium-based metallocenes can lead to the production of ethylene-rich polyethylenes and diene copolymers that contain more than 50 mol% of ethylene units, as described for example in WO 2014114607 A1. In particular, copolymers containing ethylene units and diene units are synthesized by a polymerization mechanism involving very specific reactive species and numerous transfer reactions as described for example in ACS Catalysis, 2016, Volume 6, Issue 2, pages 1028-1036.

[0003] Highly saturated polymers such as polyethylenes and diene copolymers rich in ethylene units are essentially hydrocarbon-based and have little affinity for polar materials, which has the consequence of restricting the field of application of these highly saturated hydrocarbon-based polymers. In order to improve this affinity, the introduction of a single or several ketone functions has been described in the case of polyethylenes. For example, the synthesis of a copolymer of ethylene and carbon monoxide is widely described, but the synthesis process does not apply to copolymers of ethylene and an α-olefin such as a 1,3-diene or a mixture of a 1,3-diene and a vinyl aromatic compound. Furthermore, the synthesis process does not selectively lead to the introduction of a ketone function at the chain end. The introduction of a single ketone function at the chain end of a polyethylene is also described.For example, Polymer Science, Ser. B, Vol. 46, Nos. 9-10, 2004, 308-311 describes the reaction of nitrous oxide and a polyethylene that carries a vinyl group at the chain end. The introduction of the ketone function at the chain end of the polyethylene results from the oxidation reaction of the double bond of the vinyl group by nitrous oxide. Therefore, it appears that the synthesis method is not applicable to the selective chain-end functionalization of copolymers of ethylene and a 1,3-diene that contain double bonds also outside the chain ends.

[0004] Finally, the methods described for introducing ketone functions also do not allow the simultaneous introduction of a second function other than a ketone function. To do this, they must resort to the use of an additional functionalization agent.

[0005] The Applicants have developed a process which makes it possible to introduce a ketone function at the end of a polymer chain and which is applicable both to polyethylenes and to ethylene-rich diene copolymers, such as copolymers of ethylene and a 1,3-diene or a copolymer of ethylene, a 1,3-diene and a vinylaromatic compound. Furthermore, the process is entirely suitable for introducing two functions simultaneously, one ketone function and a second function different from a ketone function, without having to resort to an additional functionalizing agent.

[0006] A first subject of the invention is a process for preparing a polymer containing more than 50 mol% of ethylene units and carrying at one of its chain ends a ketone function, which process comprises the successive steps a), b) and c) - step a) being the polymerization of a monomer mixture containing ethylene in the presence of a catalytic system based at least on one metallocene of formula (I) and an organomagnesium compound {P(Cp 1 )(Cp 2 )Nd(BH4)(i+y)-Ly-Nx} (I) CP 1 and Cp 2 , identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P being a group bridging the two Cp groups 1 and Cp 2 , and comprising a silicon or carbon atom, Nd denoting the neodymium atom, L representing an alkali metal chosen from the group consisting of lithium, sodium and potassium, N representing a molecule of an ether, x, integer or not, being equal to or greater than 0, y, integer, being equal to or greater than 0, - step b) being the reaction of a compound having a nitrile function with the reaction product of the polymerization of step a), - step c) being a hydrolysis reaction, the polymer being a polyethylene or a copolymer of ethylene and a 1,3-diene and optionally a vinylaromatic compound.

[0007] A second subject of the invention is a polymer containing more than 50 mol% of ethylene units and carrying at one of its chain ends a ketone function and optionally a second function which is carried on the same chain end as the ketone function and which is chosen from ether, thioether, amine, alkoxysilane, silanol and imidazole functions, which polymer is a copolymer of ethylene and a 1,3-diene or a copolymer of ethylene, a 1,3-diene and a vinylaromatic compound and is capable of being obtained by particular embodiments of the process according to the invention.

[0008] A third subject of the invention is a polyethylene carrying at one of its chain ends a ketone function and a second function which is carried on the same chain end as the ketone function and which is chosen from ether, thioether, amine, alkoxysilane, silanol and imidazole functions, which polyethylene is capable of being obtained by particular embodiments of the process in accordance with the invention. Description

[0009] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​greater than "a" and less than "b" (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from "a" to "b" (i.e., including the strict limits a and b).

[0010] Unless otherwise indicated, the rates of units resulting from the insertion of a monomer into a polymer are expressed as a molar percentage relative to the total number of units resulting from the polymerization of the monomers.

[0011] The compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of materials already in use, that is to say, they may be, partially or totally, derived from a recycling process, or obtained from raw materials themselves derived from a recycling process.

[0012] The expression "based on" used to define the constituents of the catalytic system means the mixture of these constituents, or the product of the reaction of some or all of these constituents with each other.

[0013] Step a) of the process according to the invention is a polymerization reaction of a monomer mixture containing ethylene which makes it possible to prepare the polymer chains, growing chains intended to react in the following step, step b), with a functionalization agent, a compound having a nitrile function.

[0014] According to a first alternative, the monomer mixture containing ethylene is ethylene, i.e. a monomer mixture consisting only of ethylene. According to this alternative, the reaction product of the polymerization of step a) is a polymer chain whose constituent units result from the insertion of ethylene. The polymer prepared by this alternative is an ethylene homopolymer, a polyethylene.

[0015] According to a second alternative, the monomer mixture containing ethylene is a mixture of ethylene and a 1,3-diene. According to this alternative, the reaction product of the polymerization of step a) is a polymer chain whose constituent units result from the insertion of ethylene and 1,3-diene. The polymer prepared by this second alternative is a copolymer of ethylene and a 1,3-diene.

[0016] According to a third alternative of the invention, the monomer mixture containing ethylene is a mixture of ethylene, a 1,3-diene and a vinylaromatic compound. According to this alternative, the reaction product of the polymerization of step a) is a polymer chain whose constituent units result from the insertion of ethylene, 1,3-diene and the vinylaromatic compound. The polymer prepared by this third alternative is a copolymer of ethylene, a 1,3-diene and a vinylaromatic compound.

[0017] The 1,3-diene of the monomer mixture of step a) useful for the purposes of the second alternative and the third alternative is a single compound, i.e., a single (in English "one") 1,3-diene, or a mixture of 1,3-dienes which differ from each other in chemical structure. Suitable 1,3-dienes are 1,3-dienes having from 4 to 20 carbon atoms, such as 1,3-butadiene, isoprene, myrcene, p-farnesene and mixtures thereof. The 1,3-diene is preferably 1,3-butadiene, isoprene, myrcene, -farnesene or mixtures thereof, in particular a mixture of at least two of them.

[0018] The vinylaromatic compound of the monomer mixture of step a) useful for the purposes of the third alternative is a single compound, i.e. a single (in English "one") vinylaromatic compound or a mixture of vinylaromatic compounds which differ from each other by the chemical structure. A vinylaromatic compound is understood to mean an aromatic compound substituted by a vinyl function of well-known formula (-CH=CH2). Suitable particularly as vinylaromatic compound compounds having an aryl group substituted by a vinyl function, more particularly compounds having a phenyl group substituted by a vinyl function. The vinylaromatic compound is preferably styrene or a styrene whose benzene ring is substituted by alkyl groups. The vinylaromatic compound is more preferably styrene. The copolymer prepared by a preferred embodiment of the third alternative is a copolymer of ethylene, a 1,3-diene and styrene.

[0019] Preferably, the monomer mixture of step a) contains more than 50 mol% of ethylene, the percentage being expressed relative to the total number of moles of monomers of the monomer mixture of step a). When the monomer mixture contains a vinylaromatic compound, such as styrene, it preferably contains less than 40 mol% of the vinylaromatic compound, the percentage being expressed relative to the total number of moles of monomers of the monomer mixture of step a).

[0020] The polymerization of the monomer mixture can be carried out in accordance with patent applications WO 2007054223 A2 and WO 2007054224 A2 using a catalytic system (or catalytic composition) composed of a metallocene and an organomagnesium.

[0021] In the present application, metallocene means an organometallic complex in which the metal, in this case the neodymium atom, is linked to a molecule called ligand and consisting of two Cp groups 1 and Cp2 connected to each other by a P bridge. These Cp groups 1 and Cp 2 , identical or different, are chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, these groups being able to be substituted or unsubstituted.

[0022] According to the invention, the metallocene used as a basic constituent in the catalytic system corresponds to the formula (Ia) {P(Cp 1 )(Cp 2 )Nd(BH4) (i+v) .L v -N x} (I) P being a group bridging the two Cp groups 1 and Cp 2 , and comprising a silicon or carbon atom, CP 1 and Cp 2 , identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, Nd denoting the neodymium atom, L representing an alkali metal chosen from the group consisting of lithium, sodium and potassium, N representing a molecule of an ether, x, integer or not, being equal to or greater than 0, y, integer, being equal to or greater than 0.

[0023] In formula (I), the neodymium atom is linked to a ligand molecule consisting of the two Cp groups 1 and Cp 2 connected to each other by a bridge P. Preferably, the symbol P, designated by the term bridge, corresponds to the formula ZR 1 R 2 , Z representing a silicon or carbon atom, R 1 and R 2 , identical or different, representing an alkyl group comprising from 1 to 20 carbon atoms. More preferably, the bridge P is of formula SiR 1 R 2 , R 1 and R 2 , being identical and as defined previously. Even more preferably, P corresponds to the formula SiMej.

[0024] In formula (I), any ether which has the power to complex the alkali metal is suitable as ether, in particular diethyl ether, methyltetrahydrofuran and tetrahydrofuran, preferably tetrahydrofuran.

[0025] As substituted cyclopentadienyl, fluorenyl and indenyl groups, mention may be made of those substituted by alkyl groups having 1 to 6 carbon atoms or by aryl groups having 6 to 12 carbon atoms or by trialkylsilyl groups such as SiMea- When the Cp ligands 1 and Cp 2 are substituted, they are preferentially substituted by methyl groups, by butyl groups, in particular tert-butyls, or by trimethylsilyl groups. The choice of groups is also guided by the accessibility of the corresponding molecules that are cyclopentadienes, substituted fluorenes and indenes, because the latter are commercially available or easily synthesized.

[0026] As substituted fluorenyl groups, mention may be made of those substituted in position 2, 7, 3 or 6, particularly 2,7-ditertiobutyl-fluorenyl, 3,6-ditertiobutyl-fluorenyl. Positions 2, 3, 6 and 7 respectively designate the position of the carbon atoms of the rings as shown in the diagram below, position 9 corresponding to the carbon atom to which

[0027] As substituted cyclopentadienyl groups, mention may be made of those substituted both in position 2 (or 5) and in position 3 (or 4), particularly those substituted in position 2, more particularly the tetramethylcyclopentadienyl group. Position 2 (or 5) designates the position of the carbon atom which is adjacent to the carbon atom to which the P bridge is attached, as shown in the diagram below. It is recalled that a substitution in position 2 or 5 is also called alpha substitution of the bridge.

[0028] As substituted indenyl groups, mention may be made in particular of those substituted in position 2, more particularly 2-methylindenyl, 2-phenylindenyl. Position 2 designates the position of the carbon atom which is adjacent to the carbon atom to which the P bridge is attached, as shown in the diagram below.

[0029] Preferably, Cp 1 and Cp 2 , identical or different, are cyclopentadienyls substituted in alpha of the bridge, substituted fluorenyls, substituted indenyls or fluorenyl of formula CiaHg or indenyl of formula CgHg. More preferably, Cp 1 and Cp 2 , identical or different, are substituted fluorenyl groups or unsubstituted fluorenyl groups of formula CI3H8. Advantageously, Cp 1 and Cp 2 are unsubstituted fluorenyl groups of formula CI3H8, represented by the symbol Flu.

[0030] Better, the metallocene is of formula (1-1), (1-2), (1-3), (1-4) or (1-5): [Me2Si(Flu)2Nd(p-BH4)2Li(THF)] (1-1) [{Me2SiFlu2Nd(p-BH4)2Li(THF)}2] (1-2) [Me2SiFlu2Nd(p-BH4)(THF)] (1-3) [{Me2SiFlu2Nd(p-BH4)(THF)}2] (1-4) [Me2SiFlu2Nd(p-BH4)] (1-5) in which Flu represents the C Hs group.

[0031] The metallocene useful for the synthesis of the catalytic system may be in the form of a crystallized or non-crystalline powder, or in the form of single crystals. The metallocene may be in a monomeric or dimeric form, these forms depending on the method of preparation of the metallocene, as for example described in patent application WO 2007054224 A2 or WO 2007054223 A2. The metallocene may be prepared in a conventional manner by a process analogous to that described in patent application WO 2007054224 A2 or WO 2007054223 A2, in particular by reaction under inert and anhydrous conditions of the salt of an alkali metal of the ligand with a borohydride of the rare earth, neodymium, in a suitable solvent, such as an ether, such as diethyl ether or tetrahydrofuran or any other solvent known to those skilled in the art.After reaction, the metallocene is separated from the reaction by-products by techniques known to those skilled in the art, such as filtration or precipitation in a second solvent. The metallocene is finally dried and isolated in solid form.

[0032] The organomagnesium, another basic constituent of the catalytic system, is the co-catalyst of the catalytic system. Typically, the organomagnesium can be a diorganomagnesium or a halide of an organomagnesium. The organomagnesium can be of formula (IIa), (IIb), (IIe) or (I Id) in which R 3 , R 4 , R 5 , R B identical or different, represent a carbon group, R A represents a divalent carbon group, X is a halogen atom, m is a number greater than or equal to 1, preferably equal to 1. MgR 3 R 4 (lia) XMgR 5 (llb) R B -(Mg-R A ) m -Mg-R B (Island) X-Mg-RA -Mg-X (lld).

[0033] R A may be a divalent aliphatic hydrocarbon chain, interrupted or not by one or more oxygen or sulfur atoms or by one or more arylene groups.

[0034] A carbon group is understood to mean a group that contains one or more carbon atoms. The carbon group may be a hydrocarbon group (hydrocarbyl group) or a heterohydrocarbon group, i.e. a group containing one or more heteroatoms in addition to carbon and hydrogen atoms. Suitable organomagnesium compounds having a heterohydrocarbon group are the compounds described as transfer agents in patent application WO2016092227 A1. The carbon group represented by the symbols R 3 , R 4 , R 5 , R B and R A are preferentially hydrocarbon groups.

[0035] Preferably, R Acontains 3 to 10 carbon atoms, especially 3 to 8 carbon atoms.

[0036] Preferably, R A is a divalent hydrocarbon chain. Preferably, R A is a branched or linear alkanediyl, a cycloalkanediyl or a xylenediyl radical. More preferably, R A is an alkanediyl. Even more preferably, R A is an alkanediyl having 3 to 10 carbon atoms. Advantageously, R A is an alkanediyl having 3 to 8 carbon atoms. Very advantageously, R A is a linear alkanediyl. As the R group A 1,3-propanediyl, 1,4-butanediyl, 1,5-pentanediyl, 1,6-hexanediyl, 1,7-heptanediyl, 1,8-octanediyl are particularly suitable.

[0037] The carbon groups represented by R 3 , R 4 , R 5 , R B, may be aliphatic or aromatic. They may contain one or more heteroatoms such as oxygen, nitrogen, silicon or sulfur. Preferably, they are alkyl, phenyl or aryl. They may contain 1 to 20 carbon atoms.

[0038] The alkyls represented R 3 , R 4 , R 5 , R B can contain 2 to 10 carbon atoms and include ethyl, butyl, octyl.

[0039] The aryls represented R 3 , R 4 , R 5 , R B may contain 7 to 20 carbon atoms and are in particular a phenyl substituted by one or more alkyls such as methyl, ethyl, isopropyl.

[0040] According to a particular embodiment of the invention, R 3comprises a benzene ring substituted by the magnesium atom, one of the carbon atoms of the benzene ring ortho to magnesium being substituted by methyl, ethyl, isopropyl or forming a ring with the carbon atom which is its nearest neighbor and which is meta to magnesium, the other carbon atom of the benzene ring ortho to magnesium being substituted by methyl, ethyl or isopropyl and R 4 is an alkyl. In other words, said substituents cited methyl, ethyl, isopropyl of the benzene ring are in the ortho position relative to the magnesium atom according to this particular embodiment. R 3 may be 1,3-dimethylphenyl, 1,3-diethylphenyl, mesityl, or 1,3,5-triethylphenyl and R 4 can be ethyl, butyl, octyl.

[0041] According to another particular embodiment of the invention, R 3 and R 4are alkyls containing 2 to 10 carbon atoms, in particular ethyl, butyl, octyl.

[0042] R 5 is preferably an alkyl containing 2 to 10 carbon atoms, more preferably an ethyl, a propyl, a butyl, a pentyl, a hexyl, a heptyl or an octyl.

[0043] R B may comprise a benzene ring substituted by the magnesium atom, one of the carbon atoms of the benzene ring ortho to the magnesium being substituted by a methyl, an ethyl, an isopropyl or forming a ring with the carbon atom which is its nearest neighbor and which is meta to the magnesium, the other carbon atom of the benzene ring ortho to the magnesium being substituted by a methyl, an ethyl or an isopropyl. R B may be 1,3-dimethylphenyl, 1,3-diethylphenyl, mesityl, or 1,3,5 triethylphenyl.

[0044] Suitable organomagnesium compounds are, for example, butylethylmagnesium, butyloctylmagnesium, ethylmagnesium chloride, butylmagnesium chloride, pentylmagnesium chloride, ethylmagnesium bromide, butylmagnesium bromide, pentylmagnesium bromide, octylmagnesium chloride, octylmagnesium bromide, 2,6-dimethylphenylbutylmagnesium, 2,6-diethylphenylethylmagnesium, butyl-2-mesitylmagnesium, ethyl-2-mesitylmagnesium, 2,6-diethylphenylbutylmagnesium, 2,6-diethylphenylethylmagnesium, 2,6-diisopropylphenylbutylmagnesium, 2,6-disopropylphenylethylmagnesium, 2,4,6-triethylphenylbutylmagnesium, 2,4,6-triethylphenylethylmagnesium, 2,4,6-triisopropylphenylbutylmagnesium, 2,4,6- triisopropylphenylethylmagnesium, 1,3-di(magnesium bromide)-propanediyl, 1,3-di(magnesium chloride)-propanediyl, 1,5-di(magnesium bromide)-pentanediyl, 1,5-di(magnesium chloride)-pentanediyl, 1,8-di(magnesium bromide)-octanediyl, 1,8-di(magnesium chloride)-octanediyl.

[0045] The organomagnesium compound of formula (Ile) may be prepared by a process, which comprises reacting a first organomagnesium compound of formula X'Mg-R A -MgX' with a second organomagnesium of formula R B -Mg-X', X' representing a halogen atom, preferably bromine or chlorine, R B and R Abeing as defined above. X' is more preferably a bromine atom. The stoichiometry used in the reaction determines the value of m in formula (Ile). For example, a molar ratio of 0.5 between the quantity of the first organomagnesium and the quantity of the second organomagnesium is favorable to the formation of an organomagnesium compound of formula (Ile) in which m is equal to 1, while a molar ratio greater than 0.5 will be more favorable to the formation of an organomagnesium compound of formula (Ile) in which m is greater than 1.

[0046] To carry out the reaction of the first organomagnesium compound with the second organomagnesium compound, a solution of the second organomagnesium compound is typically added to a solution of the first organomagnesium compound. The solutions of the first organomagnesium compound and the second organomagnesium compound are generally solutions in an ether, such as diethyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, or a mixture of two or more of these ethers. A hydrocarbon solvent, aliphatic or aromatic, as a cosolvent may be added to the ether. Preferably, the respective concentrations of the solutions of the first organomagnesium compound and the second organomagnesium compound are 0.01 to 3 mol / L and 0.02 to 5 mol / L, respectively. More preferably, the respective concentrations of the first organomagnesium and the second organomagnesium are respectively 0.1 to 2 mol / L and 0.2 to 4 mol / L.

[0047] The first organomagnesium and the second organomagnesium, Grignard reagents, can be prepared in advance from magnesium metal and a suitable halogenated precursor in a reactor. For the first organomagnesium and the second organomagnesium, the respective precursors are of the formula X'-R A -X' and R B -X', R A , R B and X' being as defined above. The preparation of Grignard reagents is typically carried out by adding the precursor to magnesium metal which is generally in the form of chips. Preferably, iodine (l2) typically in the form of beads is introduced into the reactor before the addition of the precursor in order to activate the Grignard reaction in a known manner.

[0048] Alternatively, the organomagnesium compound of formula (Ile) can be prepared by reacting an organometallic compound of formula MR A -M and the organomagnesium of formula R B-Mg-X', M representing an atom of lithium, sodium or potassium, X', R B and R A being as defined above. Preferably, M represents a lithium atom, in which case the organometallic of formula MR A -M is an organolithium.

[0049] The reaction of the organolithium and the organomagnesium is typically carried out in an ether such as diethyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, methylcyclohexane, toluene or a mixture thereof. The reaction is also typically carried out at a temperature ranging from 0°C to 60°C. The contacting is preferably carried out at a temperature between 0°C and 23°C. The contacting of the organometallic compound of formula MR A -M with the organomagnesium of formula R B -Mg-X' is preferably done by adding a solution of the organometallic compound MR A -M to a solution of organomagnesium RB -Mg-X'. The solution of the organometallic compound MR A -M is generally a solution in a hydrocarbon solvent, preferably n-hexane, cyclohexane or methylcyclohexane, the solution of the organomagnesium R B -Mg-X' is generally a solution in an ether, preferably diethyl ether or dibutyl ether. Preferably, the respective concentrations of the solutions of the organometallic compound and the organomagnesium MR A -M and R B -Mg-X' are respectively 0.01 to 1 mol / L and 0.02 to 5 mol / L. More preferably, the respective concentrations of the solutions of the organometallic compound and the organomagnesium MR A -M and R B -Mg-X' are 0.05 to 0.5 mol / L and 0.2 to 3 mol / L respectively.

[0050] Like any synthesis carried out in the presence of organometallic compounds, the syntheses described for the synthesis of organomagnesiums take place under anhydrous conditions under an inert atmosphere, in stirred reactors. Typically, solvents and solutions are used under anhydrous nitrogen or argon.

[0051] Once the organomagnesium compound of formula (Ile) is formed, it is generally recovered in solution after filtration carried out under an inert and anhydrous atmosphere. It can be stored before use in its solution in airtight containers, for example capped bottles, at a temperature between -25°C and 23°C.

[0052] Compounds of formula (I Id) which are Grignard reagents are described for example in the work “Advanced Organic Chemistry” by J. March, 4 thEdition, 1992, page 622-623 or in the book "Handbook of Grignard Reagents", Edition Gary S. Silverman, Philip E. Rakita, 1996, page 502-503. They can be synthesized by bringing magnesium metal into contact with a dihalogenated compound of formula XR A -X, R A being as defined according to the invention. For their synthesis, one can for example refer to the collection of volumes of “Organic Synthesis”.

[0053] Compounds of formula (IIa) and (IIb) which are also Grignard reagents are well known, even some of them are commercial products. For their synthesis, one can for example also refer to the collection of volumes of "Organic Synthesis".

[0054] Like any organomagnesium compound, the organomagnesium compound constituting the catalytic system, in particular of formula (Ha), (llb), (Ile) or (I Id) can be in the form of a monomeric entity or in the form of a polymeric entity. By way of illustration, the organomagnesium (Ile) can be in the form of a monomeric entity (R B -(Mg-R A ) m - Mg-R B )i or in the form of a polymeric entity (R B -(Mg-R A ) m -Mg-R B ) p , p being an integer greater than 1, in particular dimer (R B -(Mg-R A ) m -Mg-R B )2, m being as defined previously. Similarly, also for illustration, the organomagnesium of formula (lld) can be present in the form of a monomeric entity (X-Mg-R A -Mg-X)i or in the form of a polymeric entity (X-Mg-R A -Mg-X) p, p being an integer greater than 1, in particular dimer (X-Mg- R A -Mg-X)2.

[0055] Furthermore, whether in the form of a monomeric or polymeric entity, the organomagnesium compound can also be in the form of an entity coordinated by one or more molecules of a solvent, preferably an ether such as diethyl ether, tetrahydrofuran or methyltetrahydrofuran.

[0056] In formulas (llb) and (lld), X is preferably a bromine or chlorine atom.

[0057] According to a very preferred variant of the invention, the organomagnesium is an organomagnesium halide, preferably of formula (llb) or (lld), more preferably of formula (llb), even more preferably of formula (llb) XMgR 5 , in which X is a chlorine or bromine atom, R 5 an alkyl or an aryl, preferably an alkyl. According to this very preferred variant, R5 is advantageously an alkyl containing 2 to 10 carbon atoms, more preferably an ethyl, a propyl, a butyl, a pentyl, a hexyl, a heptyl or an octyl. When the organomagnesium is a halide of an organomagnesium of formula (II b) or (IId), preferably of formula (II b), the process according to the invention leads to yields of polymer carrying a ketone function at one of its chain ends which are among the highest, compared to the yields obtained using a diorganomagnesium.

[0058] The quantities of co-catalyst and metallocene reacted are such that the ratio between the number of moles of Mg in the co-catalyst and the number of moles of the rare earth metallocene, neodymium, preferably ranges from 0.5 to 200, more preferably from 1 to less than 20. These preferred ranges may apply to any of the embodiments of the invention. The range of values ​​from 1 to less than 20 is particularly more favorable for obtaining copolymers with high molar masses.

[0059] According to one embodiment, the catalytic system can be prepared in a traditional manner by a process analogous to that described in patent applications WO 2007054224 A2 or WO 2007054223 A2. For example, the co-catalyst, in this case the organomagnesium compound, and the metallocene are reacted in a hydrocarbon solvent, typically at a temperature ranging from 20 to 80°C for a period of between 5 and 60 minutes. The catalytic system is generally prepared in a hydrocarbon solvent, aliphatic such as methylcyclohexane or aromatic such as toluene. Generally, after its synthesis, the catalytic system is used as is for step a).

[0060] According to another embodiment, the catalytic system can be prepared by a process analogous to that described in patent application WO 2017093654 A1 or in patent application WO 2018020122 A1: it is said to be of the preformed type. For example, the organomagnesium compound and the metallocene are reacted in a hydrocarbon solvent, typically at a temperature of 20 to 80°C for 10 to 20 minutes to obtain a first reaction product, then a preformed monomer is reacted with this first reaction product at a temperature ranging from 40 to 90°C for 1 to 12 hours. The pre-forming monomer is preferably used in a molar ratio (pre-forming monomer / metal of the metallocene) ranging from 5 to 1000, preferably from 10 to 500. Before its use in polymerization, the pre-formed type catalytic system can be stored in an inert atmosphere, in particular at a temperature ranging from -20°C to room temperature (23°C).According to this second embodiment, the preformed type catalytic system has as its basic constituent a preformation monomer chosen from 1,3-dienes, ethylene and their mixtures. In other words, the so-called preformed catalytic system contains, in addition to the metallocene and the co-catalyst, a preformation monomer. The 1,3-diene as preformation monomer can be 1,3-butadiene, isoprene or a 1,3-diene of formula CH2=CR. 6 -CH=CH2, the symbol R 6 representing a hydrocarbon group having 3 to 20 carbon atoms, in particular myrcene or [3-farnesene. The preformation monomer is preferably 1,3-butadiene.

[0061] The catalytic system is typically present in a solvent which is preferably the solvent in which it was prepared, and the concentration of rare earth metal, i.e. neodymium, of metallocene is then included in a range preferably from 0.0001 to 0.2 mol / L more preferably from 0.001 to 0.03 mol / L.

[0062] Like any synthesis carried out in the presence of organometallic compounds, the synthesis of metallocene, the synthesis of organomagnesium and the synthesis of the catalytic system take place under anhydrous conditions under an inert atmosphere. Typically, the reactions are carried out from solvents and anhydrous compounds under anhydrous nitrogen or argon.

[0063] The polymerization of the monomer mixture is preferably carried out in solution, continuously or batchwise. The polymerization solvent is typically a hydrocarbon solvent, aromatic or aliphatic, such as toluene, cyclohexane, methylcyclohexane or a mixture of two of them or a mixture of all three. The monomer mixture can be introduced into the reactor containing the polymerization solvent and the catalytic system or conversely the catalytic system can be introduced into the reactor containing the polymerization solvent and the monomer mixture. The monomer mixture and the catalytic system can be introduced simultaneously into the reactor containing the polymerization solvent, in particular in the case of continuous polymerization. The polymerization is typically carried out under anhydrous conditions and in the absence of oxygen, in the possible presence of an inert gas.The polymerization temperature generally varies in a range from 40 to 150°C, preferably 40 to 120°C. A person skilled in the art adapts the polymerization conditions such as the polymerization temperature, the concentration of each of the reactants, the pressure in the reactor according to the composition of the monomer mixture, the polymerization reactor, the desired microstructure and macrostructure of the copolymer chain.

[0064] The polymerization is preferably carried out at constant pressure in monomers. A continuous addition of each of the monomers or one of them can be carried out in the polymerization reactor, in which case the polymerization reactor is a fed reactor. This embodiment is particularly suitable for a statistical incorporation of the monomers. Preferably, the polymerization of step a) is a statistical polymerization, which results in a statistical incorporation of the monomers of the monomer mixture used in step a).

[0065] Once the desired monomer conversion rate is reached in the polymerization reaction of step a), we proceed to step b), which is a functionalization reaction.

[0066] Step b) of the process according to the invention brings into contact a functionalizing agent, a compound having a nitrile function, with the reaction product of step a).

[0067] Preferably, step b) is also carried out in a hydrocarbon solvent. Advantageously, it is carried out in the reaction medium resulting from step a). It is generally carried out by adding the compound having a nitrile function to the reaction product of step a) in its reaction medium with stirring.

[0068] Before adding the compound having a nitrile function, the reactor is preferably degassed and inerted. Degassing the reactor makes it possible to eliminate the gaseous residual monomers and also facilitates the addition of the compound having a nitrile function to the reactor. Inerting the reactor, for example with nitrogen, makes it possible not to deactivate the carbon-metal bonds present in the reaction medium and necessary for the polymer functionalization reaction. The compound having a nitrile function can be added pure or diluted in a hydrocarbon, aliphatic or aromatic solvent. The compound having a nitrile function is left in contact with the reaction product of step a), preferably with stirring, for the time necessary for the functionalization reaction of the polymer chain end. The functionalization reaction can typically be followed by chromatographic analysis to monitor the consumption of the compound having a nitrile function. The functionalization reaction is preferably carried out at a temperature ranging from 23 to 120°C, preferably from 40°C to 100°C.

[0069] The functionalization reaction, step b), is preferably carried out with at least one molar equivalent of nitrile function relative to the number of carbon-magnesium bonds per mole of organomagnesium compound. The ratio between the number of molar equivalents of nitrile function and the number of carbon-magnesium bonds per mole of organomagnesium compound can vary to a large extent provided that it is at least 1, i.e. at least one molar equivalent of nitrile function is used relative to the number of carbon-magnesium bonds per mole of organomagnesium compound. An excess of compound having a nitrile function may be used, but it is preferable to use at most 3 molar equivalents of nitrile function relative to the number of carbon-magnesium bonds, in particular for cost reasons.For example, in a halide of an organomagnesium compound of formula (II b) such as n-butylmagnesium chloride, there is one carbon-magnesium bond per mole of halide; in magnesium compounds of formula (IIa) such as butyloctylmagnesium (BOMAG) or in magnesium compounds of formula (IId) there are two carbon-magnesium bonds per mole of magnesium compound. One mole of a compound having a single nitrile function is equivalent to one molar equivalent of nitrile function; one mole of a compound having two nitrile functions is equivalent to two molar equivalents of nitrile function; more generally, one mole of a compound having n nitrile functions is equivalent to n molar equivalents of nitrile function, n being an integer greater than or equal to 1.

[0070] The compound having a nitrile function may be an aliphatic compound or an aromatic compound, preferably aromatic, and preferably contains a single nitrile function. The compound having a nitrile function is typically a compound having a hydrocarbon chain substituted by a single nitrile function or by several nitrile functions, preferably a single nitrile function. The hydrocarbon chain of the compound having a nitrile function may also be substituted by another functional group containing one or more heteroatoms selected from the oxygen atom, the sulfur atom, the nitrogen atom and the silicon atom. The hydrocarbon chain of the compound having a nitrile function may be linear, cyclic or branched.

[0071] Preferably, the compound having a nitrile function contains a second function which is chosen from ether, thioether, protected amine, tertiary amine, alkoxysilane and imidazole functions, which is preferentially an ether function, a tertiary amine function, an alkoxysilane function or an imidazole function.

[0072] According to a first embodiment of the invention, the compound having a nitrile function is an alkane substituted by a nitrile function, preferably a single nitrile function. The length of the hydrocarbon chain of the alkane substituted by a nitrile function is not limited in itself and the number of carbon atoms in the hydrocarbon chain can vary widely, for example from 1 to 11 carbon atoms. The choice of an alkane substituted by a nitrile function may be motivated by the fact that it is commercially available or easily synthesized. Particularly suitable are ethanenitrile or acetonitrile, propanenitrile or propionitrile, butanenitrile or butyronitrile, pentanenitrile or valeronitrile, hexanenitrile or capronitrile, dodecanenitrile or laurylnitrile.

[0073] According to a second embodiment of the invention, the compound having a nitrile function is an alkane substituted by a nitrile function and also by another function which contains one or more heteroatoms chosen from the oxygen atom, the sulfur atom, the nitrogen atom and the silicon atom and which is different from a nitrile function. According to this embodiment, the compound having a nitrile function preferably contains a single nitrile function. The other function is preferably chosen from ether, thioether, protected amine, tertiary amine and alkoxysilane functions, more preferably is a tertiary amine function or an alkoxysilane function. Particularly suitable are dialkylaminoalkanenitriles, alkyloxyalkanenitriles, trialkoxysilylalkanenitriles, alkyldialkoxysilylalkanenitriles and dialkylalkoxysilylalkanenitriles in which the alkyl and alkoxy chains preferably contain 1 to 2 carbon atoms and the alkane chains preferably contain 2 to 6 carbon atoms, more preferably 2 to 3 carbon atoms. The choice of the substituted alkane can be motivated by whether it is commercially available or easily synthesized.Examples of such compounds include dimethylaminopropionitrile, dimethylaminobutyronitrile, diethylaminopropionitrile, diethylaminobutyronitrile, methoxypropionitrile, methoxybutyronitrile, ethoxypropionitrile, ethoxybutyronitrile, triethoxysilylpropionitrile, triethoxysilylbutyronitrile, trimethoxysilylpropionitrile, trimethoxysilylbutyronitrile, methyldimethoxysilylpropionitrile, methyldimethoxysilylbutyronitrile, methyldiethoxysilylpropionitrile, methyldimethoxysilylbutyronitrile, ethyldimethoxysilylpropionitrile, ethyldimethoxysilylbutyronitrile, ethyldiethoxysilylpropionitrile, ethyldiethoxysilylbutyronitrile, dimethylmethoxysilylpropionitrile, dimethylmethoxysilylbutyronitrile, dimethylethoxysilylpropionitrile, dimethylmethoxysilylbutyronitrile, diethylmethoxysilylpropionitrile, diethylmethoxysilylbutyronitrile, diethylethoxysilylpropionitrile, diethylethoxysilylbutyronitrile.

[0074] According to a third particularly preferred embodiment, the compound having a nitrile function is an arene substituted by a nitrile function, preferably a single nitrile function. The arene may also carry one or more other substituents different from a nitrile function. The arene may be substituted by a hydrocarbon chain or a functional group which is different from a nitrile function and which contains one or more heteroatoms such as the oxygen atom, the sulfur atom, the nitrogen atom and the silicon atom. The functional group is preferably chosen from ether, thioether, protected amine, tertiary amine and imidazole functions. The arene may be substituted by a hydrocarbon chain which is also substituted by a function chosen from ether, thioether, protected amine, tertiary amine and imidazole functions. The hydrocarbon chains in the compound having a nitrile function are preferably alkyls.The alkyls in the compound having a nitrile function preferably contain 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms.

[0075] The compound having a nitrile function is more preferably a benzonitrile, benzonitrile or a substituted benzonitrile, preferably substituted by a function chosen from ether, thioether, protected amine, tertiary amine and imidazole functions, more preferably substituted by an ether, tertiary amine or imidazole function. The benzonitrile useful for the purposes of the invention is typically of formula (III) in which the symbols Xi to X5, which may be identical or different, each represent a hydrogen atom, an alkyl or a function which is chosen from ether, thioether, protected amine, tertiary amine and imidazole functions, preferably which is an ether function, a tertiary amine function or an imidazole function. Advantageously, 4 of the symbols Xi to X5 of formula (III) represent a hydrogen atom or an alkyl, preferably a hydrogen atom, and the fifth symbol represents an ether function, a thioether function, a protected amine function, a tertiary amine function or an imidazole function, preferably an ether function, a tertiary amine function or an imidazole function. The alkyl of the benzonitrile compound preferably contains 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms.Particularly suitable are benzonitrile and the following substituted benzonitriles, whether para-, meta- or ortho-substituted, preferably para- or ortho-substituted, such as alkoxybenzonitriles such as methoxybenzonitrile, ethoxybenzonitrile, thioalkoxybenzonitriles such as thiomethoxybenzonitrile, thioethoxybenzonitrile, N,N-dialkylaminobenzonitrile such as N,N-dimethylaminobenzonitrile, N,N-diethylaminobenzonitrile, imidazolylbenzonitriles such as 2-(1H-imidazol-1-yl)benzonitrile, 4-(1H-1midazol-1-ylmethyl)benzonitrile.

[0076] Once the chain end has been modified, step b) is followed by step c). Step c) is typically a hydrolysis reaction which forms the ketone function in the polymer chain and, if necessary, deactivates the reactive sites still present in the reaction medium. The hydrolysis reaction is generally carried out by adding water to the reaction medium or vice versa, optionally in the presence of an acid. Typically, the reaction medium resulting from step b) is placed in the presence of an aqueous hydrochloric acid solution. The hydrolysis reaction can be carried out at a temperature ranging from 0°C to 100°C, preferably at room temperature (23°C) or at the reaction temperature of step b) or at a temperature in a range from room temperature to the reaction temperature of step b).In the case where the polymer also contains a protected amine function or an alkoxysilane function, step c) may be followed or accompanied by a hydrolysis reaction of the protected amine function into an amine function or of the alkoxysilane function into a silanol function, as described for example in patent application EP 2 266819 A1.

[0077] At the end of step c), the polymer can be separated from the reaction medium according to methods well known to those skilled in the art, for example by an operation of evaporation of the solvent under reduced pressure or by a steam stripping operation. According to a variant of the invention, step c) and the separation of the polymer from the reaction medium can be carried out in the same operation, for example a steam stripping operation, in particular in the presence of an acid.

[0078] The polymers which can be synthesized by the process according to the invention have the characteristic of carrying at the end of the chain, that is to say at one of its chain ends, a ketone function, in particular a ketone function whose CO group is attached directly to a monomer unit of the polymer. The term "a ketone function whose CO group is attached directly to a monomer unit of the polymer" means a ketone function in which the carbon of the CO group of the ketone function is engaged in a covalent bond with a carbon atom of a monomer unit of the polymer. Preferably, the polymers carry a second function which is carried on the same chain end as the ketone function and which is chosen from ether, thioether, amine, alkoxysilane, silanol and imidazole functions. The second function is preferably an amine function, preferably tertiary, an alkoxysilane function, a silanol function or an imidazole function, more preferably a tertiary amine function, a silanol function or an imidazole function. The alkoxysilane function is advantageously of formula Si(OR)3- n Rn, R , identical or different, being methyl or ethyl, n being an integer ranging from 0 to 3.

[0079] According to a first variant, the polymer carries a ketone function at only one of its chain ends. This variant can be implemented by the synthesis process in accordance with the invention in which the organomagnesium compound is of formula (IIa) and (IIb).

[0080] According to a second variant, the polymer carries a ketone function at each of its chain ends. This variant can be implemented by the synthesis process in accordance with the invention in which the organomagnesium compound is of formula (IIe) and (I Id).

[0081] According to a first embodiment applicable to the first variant and to the second variant, the ketone function is a substituent of an aliphatic hydrocarbon chain. The hydrocarbon chain may be linear, cyclic or branched. The hydrocarbon chain is preferably an alkyl having 1 to 11 carbon atoms. Suitable hydrocarbon chains are in particular ethyl, propyl, pentyl, lauryl. The polymers defined according to this first embodiment can be prepared by implementing the first embodiment of the process according to the invention.

[0082] According to a second embodiment applicable to the first variant and to the second variant, the ketone function is a substituent of an aliphatic hydrocarbon chain which is also substituted by another function which contains one or more heteroatoms chosen from the oxygen atom, the sulfur atom, the nitrogen atom and the silicon atom and which is different from a ketone function. The other function is preferentially chosen from the ether, thioether, amine functions, more preferentially a tertiary amine function, an alkoxysilane function or a silanol function, even more preferentially a tertiary amine function or a silanol function. The polymers defined according to this second embodiment can be prepared by implementing the second embodiment of the process according to the invention.

[0083] According to a third embodiment applicable to the first variant and to the second variant, the ketone function is a substituent of an aryl, preferably phenyl. The aryl group may also be substituted by a hydrocarbon chain or a functional group which is different from a nitrile function and which contains one or more heteroatoms such as the oxygen atom, the sulfur atom, the nitrogen atom and the silicon atom. The functional group is preferentially chosen from ether, thioether, amine, preferably tertiary amine, and imidazole functions. The arene may be substituted by a hydrocarbon chain which is also substituted by a function chosen from ether, thioether, amine, preferably tertiary amine functions. The hydrocarbon chains substituting the aryl group, in particular phenyl, are preferentially alkyls. These alkyls preferably contain 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms.The polymers defined according to this third mode can be prepared by implementing the third embodiment of the process according to the invention.

[0084] According to a fourth embodiment applicable to the first variant and to the second variant, the ketone function is a substituent of a phenyl substituted by an alkyl or a function which is chosen from ether, thioether, amine, preferably tertiary amine, and imidazole functions, which is preferably an ether function, a tertiary amine function or an imidazole function. The alkyl substituent of the phenyl preferably contains 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. The polymers defined according to this fourth embodiment can be prepared by implementing the third embodiment of the process according to the invention in which the compound having a nitrile function is a substituted benzonitrile.

[0085] The second subject of the invention is a copolymer of ethylene, a 1,3-diene and optionally a vinylaromatic compound, which copolymer carries at one of its chain ends a ketone function and optionally a second function which is carried on the same chain end as the ketone function and which is chosen from ether, thioether, amine, alkoxysilane, silanol and imidazole functions. It can be obtained by the process according to the invention according to the alternative in which the monomer mixture to be polymerized containing ethylene is a mixture of ethylene, a 1,3-diene and optionally a vinylaromatic compound. The two variants described above which define the polymers which can be obtained by the process according to the invention, as well as the four methods described as applicable to these two variants can be applied to the copolymer, second subject of the invention.The amine function carried by the copolymer in accordance with the invention is preferably a tertiary amine function.

[0086] The copolymer also has the essential characteristic of containing more than 50% by mole of ethylene unit, the percentage being expressed relative to all the units resulting from the polymerization of the monomers of the monomer mixture, in this case ethylene, 1,3-diene and, where appropriate, the vinylaromatic compound. The 1,3-diene and the vinylaromatic compound are as defined in any one of the embodiments of the process according to the invention.

[0087] Preferably, the copolymer also contains 1,2-cyclohexane ring units. The 1,2-cyclohexane ring units are of formula (IV).

[0088] When the copolymer contains 1,2-cyclohexane cyclic units, it is a copolymer according to a particular embodiment of the invention in which the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene and in which the cyclic units result from a particular insertion of the ethylene and 1,3-butadiene monomers into the polymer chain, in addition to the conventional ethylene and 1,3-butadiene units, respectively -(CH2-CH2)-, (CH2-CH=CH-CH2)- and (CH2-CH(C=CH2))-. It is in particular obtained by the process according to the invention according to the embodiment in which the metallocene of the catalytic system has as ligand two fluorenyl groups, substituted or not. The mechanism for obtaining such a microstructure is for example described in the document Macromolecules 2009, 42, 3774-3779. When the polymer in accordance with the invention contains cyclic units 1,2-cyclohexane, it preferably contains at most 15% by mole, the percentage being expressed relative to all the units resulting from the polymerization of the monomers of the monomer mixture.

[0089] According to any one of the embodiments of the invention, the copolymer in accordance with the invention is preferably statistical.

[0090] The third subject of the invention is a polyethylene which carries at one of its chain ends a ketone function and a second function which is carried on the same chain end as the ketone function and which is chosen from ether, thioether, amine, alkoxysilane, silanol, and imidazole functions. It can be obtained by the process according to the invention according to the alternative in which the monomer mixture to be polymerized containing ethylene is a monomer mixture consisting only of ethylene. The two variants described previously which define the polymers which can be obtained by the process according to the invention, and combined with the second mode or the fourth mode described as applicable to these two variants can be applied to polyethylene, third subject of the invention. The amine function carried by the polyethylene according to the invention is preferably a tertiary amine function.

[0091] The polymer in accordance with the invention, whether it is a copolymer or a polyethylene, respectively the second subject of the invention and the third subject of the invention, can be used in compositions containing one or more ingredients or constituents other than the polymer in accordance with the invention, for example additives traditionally used in polymer compositions such as antioxidants, plasticizers, pigments, fillers.

[0092] In summary, the invention is advantageously implemented according to any one of the following embodiments 1 to 34:

[0093] Method 1: Process for preparing a polymer containing more than 50 mol% of 1 ethylene units and carrying at one of its chain ends a ketone function, which process comprises the successive steps a), b) and c) - step a) being the polymerization of a monomer mixture containing ethylene in the presence of a catalytic system based at least on one metallocene of formula (I) and an organomagnesium compound {P(Cp 1 )(Cp 2 )Nd(BH4)(i+y)-Ly-Nx} (I) CP 1 and Cp 2 , identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P being a group bridging the two Cp groups 1 and Cp 2 , and comprising a silicon or carbon atom, Nd designating the neodymium atom, L representing an alkali metal chosen from the group consisting of lithium, sodium and potassium, N representing a molecule of an ether, x, integer or not, being equal to or greater than 0, y, integer, being equal to or greater than 0, - step b) being the reaction of a compound having a nitrile function with the reaction product of the polymerization of step a), - step c) being a hydrolysis reaction, the polymer being a polyethylene or a copolymer of ethylene and a 1,3-diene and optionally a vinyl aromatic compound.

[0094] Mode 2: Process according to mode 1 in which the 1,3-diene monomer is 1,3-butadiene, isoprene, myrcene, p-farnesene or mixtures thereof.

[0095] Mode 3: Process according to mode 1 or 2 in which the monomer mixture is ethylene.

[0096] Mode 4: Process according to mode 1 or 2 in which the monomer mixture is a mixture of ethylene and a 1,3-diene.

[0097] Mode 5: Process according to mode 1 or 2 in which the monomer mixture is a mixture of ethylene, a 1,3-diene and a vinyl aromatic compound.

[0098] Mode 6: Process according to mode 5 in which the vinyl aromatic compound is styrene.

[0099] Method 7: Process according to any one of methods 1 to 6 in which the monomer mixture of step a) contains more than 50% by mole of ethylene, the percentage being expressed relative to the total number of moles of monomers of the monomer mixture of step a). [000100] Mode 8: Method according to any one of modes 1 to 7 in which Cp 1 and Cp 2 , identical or different, are substituted fluorenyl groups or unsubstituted fluorenyl groups of formula C Hg., preferably unsubstituted fluorenyl groups. [000101] Mode 9: Process according to any one of modes 1 to 8 in which the metallocene is of formula (1-1), (1-2), (1-3), (1-4) or (1-5): [Me2Si(Flu)2Nd(p-BH4)2Li(THF)] (1-1) [{Me2SiFlu2Nd(p-BH4)2Li(THF)}2] (1-2) [Me2SiFlu2Nd(p-BH4)(THF)] (1-3) [{Me2SiFlu2Nd(p-BH4)(THF)}2] (1-4) [Me2SiFlu2Nd(p-BH4)] (1-5) in which Flu represents the C Hg group. [000102] Mode 10: Process according to any one of modes 1 to 9 in which the organomagnesium compound is of formula (IIa), (IIb), (IIe) or (I Id) in which R 3 , R 4 , R 5 , R B identical or different, represent a carbon group, R A represents a divalent carbon group, X is a halogen atom, m is a number greater than or equal to 1, preferably equal to 1. MgR 3 R 4 (lia) XMgR 5 (llb) R B -(Mg-R A ) m -Mg-R B (Island) X-Mg-R A -Mg-X (lld). [000103] Mode 11: Method according to mode 10 in which R Ais a divalent aliphatic hydrocarbon chain, interrupted or not by one or more oxygen or sulfur atoms or by one or more arylene groups. [000104] Mode 12: Method according to mode 10 or 11 in which R A is a branched or linear alkanediyl, a cycloalkanediyl or a xylenediyl radical. [000105] Mode 13: Method according to any one of modes 10 to 12 in which R A is an alkanediyl having 3 to 8 carbon atoms. [000106] Mode 14: Method according to any one of modes 10 to 13 in which R Bcomprises a benzene ring substituted by the magnesium atom, one of the carbon atoms of the benzene ring ortho to the magnesium being substituted by a methyl, an ethyl, an isopropyl or forming a ring with the carbon atom which is its nearest neighbor and which is meta to the magnesium, the other carbon atom of the benzene ring ortho to the magnesium being substituted by a methyl, an ethyl or an isopropyl. [000107] Mode 15: Method according to mode 14 in which R B is 1,3-dimethylphenyl, 1,3-diethylphenyl, mesityl, or 1,3,5 triethylphenyl. [000108] Mode 16: Method according to mode 10 in which R 3comprises a benzene ring substituted by the magnesium atom, one of the carbon atoms of the benzene ring ortho to magnesium being substituted by methyl, ethyl, isopropyl or forming a ring with the carbon atom which is its nearest neighbor and which is meta to magnesium, the other carbon atom of the benzene ring ortho to magnesium being substituted by methyl, ethyl or isopropyl and R 4 is an alkyl. [000109] Mode 17: Method according to mode 16 in which R 3 is 1,3-dimethylphenyl, 1,3-diethylphenyl, mesityl, or 1,3,5-triethylphenyl and R 4 is ethyl, butyl, octyl. [000110] Mode 18: Method according to mode 10 in which R 3 and R 4 are alkyls containing 2 to 10 carbon atoms. [000111] Mode 19: Method according to mode 10 in which R 5 is an alkyl containing 2 to 10 carbon atoms. [000112] Mode 20: Process according to any one of modes 10 to 13 or 19 in which X is a bromine or chlorine atom. [000113] Mode 21: Process according to any one of modes 10 to 13 or 19 to 20 in which the organomagnesium is a halide of an organomagnesium, preferably of formula (llb) or (I Id) defined in mode 10. [000114] Mode 22: Process according to any one of modes 10 to 13 or 19 to 21 in which the organomagnesium is a halide of an organomagnesium of formula XMgR 5 , X being a chlorine or bromine atom, R 5 an alkyl or an aryl. [000115] Mode 23: Process according to any one of modes 10 to 13 or 19 to 22 in which the organomagnesium is a halide of an organomagnesium of formula XMgR 5 , X being a chlorine or bromine atom, R 5 being an alkyl containing 2 to 10 carbon atoms. [000116] Mode 24: Process according to any one of modes 10 to 13 or 19 to 23 in which the organomagnesium is a halide of an organomagnesium of formula XMgR 5 , X being a chlorine or bromine atom, R 5 being ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl. [000117] Mode 25: Process according to any one of modes 1 to 24 in which the compound having a nitrile function contains a single nitrile function. [000118] Mode 26: Process according to any one of modes 1 to 25 in which the compound having a nitrile function is an alkane substituted by a nitrile function, preferably having 1 to 11 carbon atoms. [000119] Mode 27: Process according to any one of modes 1 to 25 in which the compound having a nitrile function is an arene substituted by a nitrile function, preferably benzonitrile. [000120] Mode 28: Process according to any one of modes 1 to 25 in which the compound having a nitrile function is a compound which contains a second function which is chosen from ether, thioether, protected amine, tertiary amine, alkoxysilane and imidazole functions, preferably an ether function, a tertiary amine function, an alkoxysilane function or an imidazole function. [000121] Mode 29: Process according to any one of modes 1 to 25 in which the compound having a nitrile function is an alkane substituted by a nitrile function and by a function which is chosen from ether, thioether, protected amine, tertiary amine and alkoxysilane functions, preferably a tertiary amine function or an alkoxysilane function. [000122] Mode 30: Process according to any one of modes 1 to 25 in which the compound having a nitrile function is an arene substituted by a nitrile function, preferably a substituted benzonitrile. [000123] Method 31: Process according to any one of methods 1 to 25 in which the compound having a nitrile function is a benzonitrile substituted by a function chosen from ether, thioether, protected amine, tertiary amine and imidazole functions, preferably an ether function, a tertiary amine function or an imidazole function. [000124] Mode 32: Process according to any one of modes 1 to 31 in which step b) is carried out with at least one molar equivalent of nitrile function relative to the number of carbon-magnesium bonds per mole of organomagnesium compound. [000125] Mode 33: Polymer containing more than 50 mol% of ethylene units and carrying at one of its chain ends a ketone function and optionally a second function which is carried on the same chain end as the ketone function and which is chosen from the ether, thioether, amine, alkoxysilane, silanol and imidazole functions, which polymer is a copolymer of ethylene and a 1,3-diene or a copolymer of ethylene, a 1,3-diene and a vinylaromatic compound. [000126] Mode 34: Polyethylene carrying at one of its chain ends a ketone function and a second function which is carried on the same chain end as the ketone function and which is chosen from the ether, thioether, amine, alkoxysilane, silanol and imidazole functions. [000127] The above-mentioned characteristics of the present invention, as well as others, will be better understood on reading the following description of the exemplary embodiments of the invention, given for illustrative and non-limiting purposes. Examples [000128] Characterization of polymers: [000129] High temperature size exclusion chromatography (HT-SEC) to characterize polyethylenes: High temperature size exclusion chromatography (HT-SEC) analyses were performed using a Viscotek instrument (Malvern Instruments) equipped with 3 columns (PLgel Olexis 300 mm x 7 mm ID from Agilent Technologies) and 3 detectors (differential refractometer and viscometer, and light scattering). 200 pL of a sample solution at a concentration of 8 mg mL 1 were eluted in 1,2,4-trichlorobenzene using a flow rate of 1 mL min 1at 150 °C. The mobile phase was stabilized with 2,6-di(tert-butyl)-4-methylphenol (400 mg L 1 ). OmniSEC software was used for data acquisition and analysis. The number-average molar masses (M n ) and in mass (M w ) of synthesized polyethylenes were calculated using a calibration curve obtained from standard polyethylenes (M p : 338, 507, 770, 1,890, 17,000, Tl 300, 43,400, 53,100, 65,700, 78,400 g mol 1 ) from Polymer Standard Service (Mainz). [000130] THF size exclusion chromatography (SEC-THF) to characterize ethylene and 1,3-butadiene copolymers: Size exclusion chromatography analyses were performed using a Viscotek apparatus (Malvern Instruments) equipped with 3 columns (SDVB, 5 μm, 300 x 7.5 mm of Polymer Standard Service), a guard column and 3 detectors (differential refractometer and viscometer, and light scattering). 1 mL of a sample solution with a concentration of 5 mg mL 1 in THF was filtered through a 0.45 μm PTFE membrane. 100 pL of this solution was eluted in THF using a flow rate of 0.8 mL min 1 at a temperature of 35 °C. OmniSEC software was used for data acquisition and analysis. The number-averaged molar masses (M n ) and in mass (M w ) of the synthesized ethylene and 1,3-butadiene copolymers and their dispersity (£)) were calculated using a universal calibration curve obtained from standard polystyrenes (M p : 1,306 to 2,520,000 g mol 1 ) from Polymer Standard Service (Mainz). [000131] Nuclear magnetic resonance (NMR): High-resolution NMR spectroscopy of the polymers was performed on a Bruker 400 Avance III spectrometer operating at 400 MHz equipped with a 5 mm BBFO proton probe and on a Bruker 400 Avance II spectrometer operating at 400 MHz equipped with a PSEX probe. 13 C 10 mm for carbon. Acquisitions were made in a mixture of tetrachloroethylene (TCE) and deuterated benzene (CgDg) (2 / 1 v / v) at 363 K for ethylene homopolymers, and in deuterated chloroform (CDCU) at 298 K for ethylene and 1,3-butadiene copolymers. Samples were analyzed at a concentration of 1% by mass for the proton and 5% by mass for carbon. Chemical shifts are given in ppm, relative to the proton signal of deuterated benzene set at 7.16 ppm (respectively of deuterated chloroform at 7.26 ppm) and to the carbon signal of TCE set at 120.65 ppm. [000132] Preparation of polymers: [000133] The metallocene [{Me2SiFlu2Nd(p-BH4hLi(THF)}h is prepared according to the procedure described in patent application WO 2007054224. BOMAG butyloctylmagnesium (20% in heptane, at 0.88 mol L 1 ) is from Chemtura and is stored in a Schlenk tube under an inert atmosphere. Unless otherwise stated, magnesium halides are from Sigma-Aldrich. Ethylene, grade N35, is from Air Liquide and is used without prior purification. 1,3-Butadiene is purified on alumina guards. Toluene and methylcyclohexane are purified on alumina guards. 4-Methoxybenzonitrile is from Sigma-Aldrich. In the procedures described, "cannulate" means transfer using a cannula. [000134] Synthesis of ketone-functional polyethylenes at the chain end: [000135] Example PE1: 198 mL of toluene collected from the solvent fountain (SPS800 MBraun) are introduced into a 250 mL inerted flask equipped with a magnetic olive. 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether are introduced into the flask while stirring. 8.0 mg (12.5 pmol as neodymium) of {(Me2Si(Ci3H8)2)Nd(p-BH4)[(p-BH4)Li(THF)]}2 are then introduced into the flask. The catalytic solution is cannulated into a 250 mL reactor under an inert atmosphere. The pressure in the reactor is reduced to 0.5 bar and then the reactor is pressurized to 4 bar of ethylene and the temperature is simultaneously brought to 80 °C. The pressure is kept constant in the reactor using a tank containing ethylene.When the desired quantity of ethylene has been consumed, here after 15 min, the reactor is degassed and 10 mL (5%) of the polymer solution is cannulated out of the reactor, then the polymer thus collected is precipitated in methanol, recovered by filtration and dried under vacuum at 80°C. It is noted PE1NF. 10 mL of a degassed and stored solution on 0.38 M benzonitrile molecular sieve in the Toluene (3.8 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond) are added to the polymer solution remaining in the reactor. After stirring for 40 min at 80 °C, 3 mL of a 15% aqueous hydrochloric acid solution are added to deactivate the system and the temperature is brought back to 20 °C. The polymer solution is poured onto methanol with stirring to precipitate the polymer. The precipitated polymer is filtered, washed with methanol, then dried under vacuum at 80 °C and characterized. 4.68 g of PE1F polymer of formula H-(CH2-CH2)nC(O)-(C6H5) and 0.21 g of PE1NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. The proton NMR spectrum of the PE1F polymer (TCE / CgDg 2 / 1 v / v, 400 MHz, 363 K) allows the observation of the protons in the a position of the ketone formed at 6 = 2.70 ppm (triplet, CHg- (CH2-CH2)n-CH2-C(O)-(CgH5)). The functional rate in the PE1F polymer is calculated by normalizing the sum of the integrals of the chain end signals of the NMR spectrum to 2. Thus in PE1F, 93% of the polymer chain ends have been functionalized with a ketone. No secondary products are identified by NMR. [000136] Example PE2: The synthesis of the polymer PE2 is identical to that described in example PE1, except that the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.0 mL of a 2.0 M pentylmagnesium bromide solution in diethyl ether. 4.21 g of PE2F polymer of formula H-(CH2-CH2)nC(O)-(CgH5) and 0.29 g of PE2NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE2F, 89% of the polymer chain ends were functionalized with a ketone. No side products are identified by NMR. [000137] Example PE3: The synthesis of the PE3 polymer is identical to that described in example PE1, except that the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.0 mL of a 2.0 M pentylmagnesium bromide solution in diethyl ether, that the functionalization reaction is carried out by the addition of benzonitrile at a level of 3 molar equivalents of nitrile function / carbon-Mg bond at the end of polymerization and that the deactivation reaction is carried out after 10 minutes of stirring at 80 °C. 3.8 g of PE3F polymer of formula H-(CH2-CH2)nC(O)-(CgH5) and 0.24 g of PE3NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE3F, 93% of the polymer chain ends were functionalized with a ketone. No side products are identified by NMR. [000138] Example PE4: The synthesis of the PE4 polymer is identical to that described in example PE1, except that the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.0 mL of a 2.0 M pentylmagnesium bromide solution in diethyl ether and the functionalization reaction is carried out by the addition of benzonitrile (3 molar equivalents of nitrile function / carbon-Mg bond) in solution in 5 mL of methyltetrahydrofuran and the deactivation reaction is carried out after 10 minutes of stirring at 80 °C. 3.97 g of PE4F polymer of formula H-(CH2-CH2)nC(O)-(CgH5) and 0.29 g of PE4NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE4F, 88% of the polymer chain ends were functionalized with a ketone. No side products were identified by NMR. [000139] Example PE5: The synthesis of the PE5 polymer is identical to that described in example PE1, except that the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.0 mL of a 2.0 M pentylmagnesium bromide solution in diethyl ether and that the functionalization reaction is carried out by the addition of benzonitrile (3 molar equivalents of nitrile function / carbon-Mg bond) in solution in 5 mL of methyltetrahydrofuran and that the deactivation reaction is carried out after 10 minutes of stirring at 90 °C. 4.35 g of PE5F polymer of formula H-(CH2-CH2)nC(O)-(C6H5) and 0.20 g of PE5NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE5F, 86% of the polymer chain ends were functionalized with a ketone. No side products are identified by NMR. [000140] Example PE6: The synthesis of the PE6 polymer is identical to that described in example PE1, except that the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.5 mL of a solution of 1,5-di(magnesium bromide)pentanediyl synthesized in methyltetrahydrofuran then diluted in 0.4 M toluene (1.0 mmol, 5 mM in toluene) and the functionalization reaction is carried out by adding 5 mL of a degassed and molecular sieve-stored solution of 0.38 M benzonitrile in toluene (1.9 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond). 3.83 g of PE6F polymer of formulas (C6H5)-C(O)-(CH2-CH2)nC(O)-(C6H5) (telechelic polymer) or H-(CH2-CH2)nC(O)-(C6H5) (mono-functional polymer) and 0.26 g of PE6NF polymer of formula H-(CH2-CH2) n-H from the sample taken before the functionalization reaction are recovered. In PE6F, 22% of the polymer chain ends are non-functional and 78% of the polymer chain ends have been functionalized with a ketone, which corresponds to 42% mono-functional chains and 18% telechelic chains. No side products are identified by NMR. [000141] 1,5-Di(magnesium bromide)-pentanediyl is prepared according to the following procedure: 9.72 g of magnesium (400 mmol, 10 equivalents), 80 mL of MeTHF (64 mL of which was in the dropping funnel), 60 mg of iodine (0.23 mmol, 0.006 equivalents), and 5.45 mL of 1,5-dibromopentane (40 mmol, 1 equivalent) were used in the synthesis. The glassware used consisted of a 200 mL round-bottomed flask and a 100 mL dropping funnel. Once the synthesis of the Grignard reagent was complete, the solution was transferred to a second inerted 200 mL round-bottomed flask using a filter cannula. This solution was concentrated under vacuum and then diluted in 55 mL of toluene. The concentration of pentanediyl group was estimated at 0.4 mol L 1 This oil is immiscible in methylcyclohexane. Aliquot of concentrated oil: 1 H NMR (Toluene-Dg - 500 MHz - 298 K) 6: ppm = 2.21 (quin, J = 7.2 Hz, “b”), 1.88 (quin, J = 7.0 Hz, “c”), 0.11 (t, J = 7.4 Hz, “a”); quin for quintuplet. [000142] Example PE7: The synthesis of the PE7 polymer is identical to that described in example PE1, except that: - the 198 mL of toluene are replaced by 196 mL of toluene and 2 mL of diethyl ether, - the functionalization reaction is carried out by adding 10 mL of a degassed and stored solution on molecular sieve of 4-methoxybenzonitrile at 0.38 M in toluene (3.8 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond) - and that the deactivation reaction is carried out after 60 min of stirring at 80°C. 4.17 g of PE7F polymer of formula H-(CH2-CH2)nC(O)-(CsH4)-OCH3 and 0.23 g of PE7NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE7F, 89% of the polymer chain ends were functionalized with a ketone. No side products are identified by NMR. [000143] Example PE8: The synthesis of the PE8 polymer is identical to that described in example PE7, except that the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.0 mL of a 2.0 M pentylmagnesium bromide solution in diethyl ether. 4.27 g of PE8F polymer of formula H-(CH2-CH2)nC(O)-(CsH4)-OCH3 and 0.16 g of PE8NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE8F, 82% of the polymer chain ends were functionalized with a ketone. No side products are identified by NMR. [000144] Example PE9: The synthesis of the PE9 polymer is identical to that described in example PE7, except that: - the 196 mL of toluene are replaced by 194 mL of toluene, - the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether are replaced by 4.0 mL of a 1.0 M mesitylmagnesium bromide solution in diethyl ether - 2.4 mL of a 1.6 M solution of n-butyl lithium in hexane (3.84 mmol, 19.2 mM) are added after the mesitylmagnesium bromide solution and before the introduction of the metallocene, - 20 mL of polymer solution instead of 10 mL are taken before the functionalization reaction, - the functionalization reaction is carried out by adding 18.5 mL of a degassed and molecular sieve-stored solution of 4-methoxybenzonitrile at 0.38 M in toluene (7.0 mmol) - and the deactivation reaction is carried out after 1 h of stirring at 80 °C by pouring the polymer solution onto methanol with stirring to precipitate the polymer. 5.02 g of PE9F polymer of formula H-(CH2-CH2)nC(O)-(CsH4)-OCH3 and 0.18 g of PE9NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE9F, 35% of the polymer chain ends are non-functional and 52% of the polymer chain ends have been functionalized with a ketone. [000145] Example PE10: The synthesis of the PE10 polymer is identical to that described in example PE7, except that: - the 196 mL of toluene are replaced by 194 mL of toluene, - the 2 mL of diethyl ether are replaced by 4 mL of diethyl ether - the 2.0 L of a 2.0 M butylmagnesium chloride solution in diethyl ether are replaced by 2.27 mL of a 0.88 M butylloctylmagnesium (BOMAG) solution in hexane - the functionalization reaction is carried out by adding 10 mL of a degassed and stored solution on molecular sieve of 4-methoxybenzonitrile at 0.38 M in toluene (3.8 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond). 4.55 g of PE10F polymer of formula H-(CH2-CH2)nC(O)-(CsH4)-OCH3 and 0.18 g of PE10NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE10F, 48% of the polymer chain ends are non-functional and 46% of the polymer chain ends have been functionalized with a ketone. [000146] Example LITTLE: The synthesis of the PEU polymer is identical to that described in example PE7, except that: - the 196 mL of toluene and the 2 mL of diethyl ether are replaced by 198 mL of toluene, - the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether are replaced by 2.27 mL of a 0.88 M BOMAG solution in hexane 3.65 g of PE11F polymer of formula H-(CH2-CH2)nC(O)-(CsH4)-OCH3 and 0.24 g of PE11NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE11F, 44% of the polymer chain ends are non-functional and 49% of the polymer chain ends have been functionalized with a ketone. [000147] Example PE12: The synthesis of the PE12 polymer is identical to that described in example PE1, except that the functionalization reaction is carried out by adding 10 mL of a degassed and molecular sieve-stored solution of 0.38 M valeronitrile in toluene (3.8 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond). 4.48 g of PE12F polymer of formula H-(CH2-CH2)nC(O)-(C4Hg) and 0.27 g of PE12NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE12F, 2% of the polymer chain ends are non-functional and 98% of the polymer chain ends have been functionalized with a ketone. No side products are visible by NMR. [000148] Example PE13: The synthesis of the PE13 polymer is identical to that described in example PE1, except that: - the 2.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether are replaced by 2.27 mL of a 0.88 M butylloctylmagnesium (BOMAG) solution in hexane - the functionalization reaction is carried out by adding 10 mL of a degassed and stored solution on a 0.38 M valeronitrile molecular sieve in toluene (3.8 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond). 3.59 g of PE13F polymer of formula H-(CH2-CH2)nC(O)-(C4Hg) and 0.26 g of PE13NF polymer of formula H-(CH2-CH2) n -H from the sample taken before the functionalization reaction are recovered. In PE13F, 51% of the polymer chain ends are non-functional and 43% of the polymer chain ends have been functionalized with a ketone. [000149] The conditions for polymerization of ethylene are given in Table 1. Table 1 also shows for each example the average catalytic activity expressed in kg mol' 1 h' 1 The characteristics of the synthesized polyethylenes are shown in Table 2. [000150] Synthesis of ketone-functional ethylene and butadiene copolymers at the chain end: [000151] Example EBR1: 199 mL of toluene taken from the solvent fountain (SPS800 MBraun) are introduced into a 250 mL inerted flask equipped with a magnetic olive. 1.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether are introduced into the flask while stirring. 32.0 mg (50 pmol as neodymium) of {(Me2Si(Ci3H8h)Nd(p-BH4)[(p-BH4)Li(THF)]}2 are then introduced into the flask. The catalytic solution is cannulated into a 250 mL reactor under an inert atmosphere. The pressure in the reactor is reduced to 0.5 bar and then the reactor is pressurized to 4 bar with an 80 / 20 mol / mol ethylene / butadiene mixture and the temperature is simultaneously brought to 80 °C. The pressure is kept constant in the reactor using a tank containing a gaseous mixture of 80 / 20 mol / mol ethylene / butadiene. When the desired quantity of monomers has been consumed, here after 35 min, the reactor is degassed and the temperature is brought back to 20 °C.10 mL (5%) of the polymer solution is cannulated out of the reactor, then the polymer is precipitated in methanol containing 2,6-di-tert-butyl-4-methylphenol, washed with methanol and dried under vacuum at 80°C. It is denoted EBR1NF. 5 mL of a degassed and molecular sieve-stored solution of 0.38 M 4-methoxybenzonitrile in toluene (1.9 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond) is added to the polymer solution remaining in the reactor. After stirring for 1 h at 80 °C, 3 mL of a 15% aqueous hydrochloric acid solution is added to deactivate the system. The polymer solution is poured onto methanol with stirring to precipitate the polymer. The precipitated polymer is filtered, washed with methanol, then dried under vacuum at 80 °C and characterized. 2.92 g of EBR1F polymer and 0.17 g of EBR1NF polymer from the sample taken before the functionalization reaction are thus recovered. The proton NMR spectrum of the EBR1F polymer (CDCh, 400 MHz, 298 K) allows the observation of the protons of the methylenes in the a position of the different ketones formed at 6 = 2.5-3.8 ppm depending on the structure of the monomer units constituting the end of the polymer chain to which the CO group of the ketone function, the OCH3 protons and the aromatic protons C(O)-CsH4-OCH3 are linked. A number-average molar mass is calculated by NMR assuming 100% functionalization. The functional rate in the EBR1F polymer is calculated by dividing the molar mass determined by size exclusion chromatography by that calculated by NMR. Thus in EBR1F, 49% of the polymer chain ends were functionalized with a ketone. [000152] Example EBR2: The synthesis of the EBR2 polymer is identical to that described in the EBR1 example, except that: - the 199 mL of toluene are replaced by 197 mL of toluene, - 1.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 2.1 mL of a 1.0 M mesitylmagnesium bromide solution in diethyl ether, - 1.25 mL of a 1.6 M solution of n-butyl lithium in hexane (2.0 mmol, 10.0 mM) is added before the introduction of the metallocene, - the functionalization reaction is carried out by adding 10.25 mL of a degassed solution and Tl stored on 4-methoxybenzonitrile molecular sieve at 0.38 M in toluene (3.9 mmol) - the deactivation reaction is carried out after 1 h of stirring at 80 °C by pouring the polymer solution onto methanol with stirring to precipitate the polymer. 3.94 g of EBR2F polymer and 0.17 g of EBR2NF polymer from the sample taken before the functionalization reaction are recovered. In EBR2F, 30% of the polymer chain ends were functionalized with a ketone. [000153] Example EBR3: The synthesis of the EBR3 polymer is identical to that described in example EBR1, except that the 1.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 1.14 mL of a 0.88 M BOMAG solution in hexane (1.0 mmol, 5 mM in toluene / hexane mixture). 4.04 g of EBR3F polymer and 0.20 g of EBR3NF polymer from the sample taken before the functionalization reaction are recovered. In EBR3F, T1% of the polymer chain ends were functionalized with a ketone. [000154] Example EBR4: The synthesis of the EBR4 polymer is identical to that described in example EBR1, except that the butadiene is first purified by being condensed in an ampoule in the presence of trioctylaluminium. 3.51 g of EBR4F polymer and 0.19 g of EBR4NF polymer from the sample taken before the functionalization reaction are recovered. In EBR4F, 57% of the polymer chain ends were functionalized with a ketone. [000155] Example EBR5: The synthesis of the EBR5 polymer is identical to that described in example EBR4, except that the functionalization reaction is carried out by adding 4-methoxybenzonitrile at a rate of 3 molar equivalents of nitrile function / carbon-Mg bond 3.4 g of EBR5F polymer and 0.17 g of EBR5NF polymer from the sample taken before the functionalization reaction are recovered. In EBR5F, 62% of the polymer chain ends were functionalized with a ketone. [000156] Example EBR6: The synthesis of the EBR6 polymer is identical to that described in the EBR1 example, except that: - the 199 mL of toluene are replaced by 280 mL of methylcyclohexane taken from the solvent fountain (SPS800 MBraun), - 1.0 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether is replaced by 0.125 mL of a 2.0 M butylmagnesium chloride solution in diethyl ether - the 32 mg of metallocene are replaced by 40.0 mg (62.5 pmol in neodymium) of {(Me2Si(Ci3H8)2)Nd(p-BH4)[(p-BH4)Li(THF)]}2 - the 250mL reactor is replaced by a 500mL reactor - there is no sampling before the functionalization reaction, - the functionalization reaction is carried out by adding 10 mL of a degassed and stored solution on molecular sieve of 4-methoxybenzonitrile at 0.025 M in methylcyclohexane (0.25 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond). 13.97 g of EBR6F polymer were recovered. 36% of the polymer chain ends were functionalized with a ketone. [000157] Example EBR7: The synthesis of the EBR7 polymer is identical to that described in example EBR6, except that at the end of polymerization, the functionalization reaction is carried out by adding 10 mL of a degassed and molecular sieve-stored solution of 4-dimethylaminobenzonitrile at 0.025 M in methylcyclohexane (0.25 mmol, 1 molar equivalent of nitrile function / carbon-Mg bond). 12.14 g of EBR7F polymer were recovered. 42% of the polymer chain ends were functionalized with a ketone. [000158] The conditions for copolymerization of ethylene and 1,3-butadiene are given in Table 3. Table 3 also shows for each example the average catalytic activity expressed in kg mol 1 h 1 . The characteristics of the synthesized copolymers are shown in Tables 4 and 5. The SEC-THF method was used to determine the molar masses of the polymers EBR1 to EBR7. The microstructure of the polymers was determined by NMR. The ethylene unit rate, the 1,3-butadiene unit rate in the 1,2 configuration (1,2 unit), in the 1,4 configuration (1,4 unit) and the 1,2-cyclohexane unit rate (cycle unit) are expressed as molar percentage relative to all the monomer units of the polymer. The synthesized copolymers are statistical. [000159] Table 1 [000160] Table 2 * Measured by 1H NMR [000161] Table 3 [000162] Table 4 [000163] Table 5 [000164] Whether the polymers are polyethylenes or ethylene-rich diene copolymers, it is observed that the process according to the invention leads to the synthesis of ethylene-rich polymers which carry a ketone function at the chain end, [000165] It is also noted that the use as a co-catalyst of an organomagnesium halide such as butylmagnesium chloride and pentylmagnesium bromide makes it possible to obtain the highest levels of ketone function at the chain end. In the case of the synthesis of functional polyethylenes, it is also remarkable to note that the functionalization reaction is selective, since no secondary products are formed. [000166] It is also notable that the process allows the simultaneous introduction into the polymer of a ketone function and a second function distinct from a ketone function, both located at the same end of the polymer chain, without having to resort to an additional functionalization agent.

Claims

Demands 1. A process for preparing a polymer containing more than 50 mole percent of ethylene units and having a ketone function at one of its chain ends, which process comprises the successive steps a), b) and c) - step a) being the polymerization of a monomer mixture containing ethylene in the presence of a catalytic system based on at least one metallocene of formula (I) and an organomagnesium compound {P(Cp 1 )(Cp 2 )Nd(BH4)(i+y)-Ly-Nx} (I) CP 1 and Cp 2 , identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P being a group bridging the two groups Cp 1 and Cp 2 and comprising a silicon or carbon atom, Nd designating the neodymium atom, L represents an alkali metal chosen from the group consisting of lithium, sodium, and potassium, N representing a molecule of an ether, x, an integer or not, being equal to or greater than 0, y, an integer, being equal to or greater than 0, - step b) being the reaction of a compound having a nitrile function with the reaction product of the polymerization of step a), - step c) being a hydrolysis reaction, the polymer being a polyethylene or a copolymer of ethylene and a 1,3-diene and possibly a vinylaromatic compound.

2. A process according to claim 1 wherein the monomer mixture is ethylene, a mixture of ethylene and a 1,3-diene or a mixture of ethylene, a 1,3-diene and a vinylaromatic compound, preferably styrene.

3. A process according to claim 1 or 2 wherein the 1,3-diene monomer is 1,3-butadiene, isoprene, myrcene, -farnesene or mixtures thereof.

4. A method according to any one of claims 1 to 3, wherein Cp 1 and Cp 2 , identical or different, are substituted fluorenyl groups or unsubstituted fluorenyl groups of formula C Hg, preferably unsubstituted fluorenyl groups.

5. A method according to any one of claims 1 to 4, wherein the organomagnesium compound has the formula (IIa), (IIb), (IIe) or (IId), in which R 3 , R 4 , R 5 , R B identical or different, represent a carbon group, R A represents a divalent carbon group, X is a halogen atom, m is a number greater than or equal to 1, preferably equal to 1. MgR 3 R 4 (lia) XMgR 5 (llb) R B -(Mg-R A ) m -IVIg-R B (Island) X-Mg-R A -Mg-X (lld).

6. A method according to any one of claims 1 to 5 wherein the organomagnesium compound is a halide of an organomagnesium compound, preferably of formula (llb) or (lld) defined in claim 5.

7. A process according to any one of claims 1 to 6, wherein the organomagnesium compound is a halide of an organomagnesium compound of formula XMgR 5 , X being a chlorine or bromine atom, R 5 an alkyl or an aryl.

8. A process according to any one of claims 1 to 7 wherein the compound having a nitrile function contains a single nitrile function. 9 A process according to any one of claims 1 to 8 wherein the compound having a nitrile function is a compound which contains a second function which is selected from the ether, thioether, protected amine, tertiary amine, alkoxysilane and imidazole functions, preferably an ether function, a tertiary amine function, an alkoxysilane function or an imidazole function. 10 A process according to any one of claims 1 to 9 wherein the compound having a nitrile function is an alkane substituted by a nitrile function and by a function which is selected from the ether, thioether, protected amine, tertiary amine and alkoxysilane functions, preferably a tertiary amine or an alkoxysilane function. 11 A process according to any one of claims 1 to 9 wherein the compound having a nitrile function is an arene substituted with a nitrile function, preferably a substituted benzonitrile. 12 A process according to any one of claims 1 to 9 or claim 11 wherein the compound having a nitrile function is a benzonitrile substituted by a function selected from the ether, thioether, protected amine, tertiary amine and imidazole functions, preferably an ether, a tertiary amine or an imidazole function. 13 Polymer containing more than 50 mole percent of ethylene units and bearing on one of its chain ends a ketone function and optionally a second function which is borne on the same chain end as the ketone function and which is selected from the ether, thioether, amine, alkoxysilane, silanol and imidazole functions, which polymer is a copolymer of ethylene and a 1,3-diene or a copolymer of ethylene, a 1,3-diene and a vinylaromatic compound. 14 Polyethylene bearing at one of its chain ends a ketone function and a second function which is borne on the same chain end as the ketone function and which is chosen from the ether, thioether, amine, alkoxysilane, silanol and imidazole functions.

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