Triblock polymers having diene central block rich in ethylene and two end blocks of polystyrene and polyethylene, respectively

Abstract

The present invention relates to a triblock polymer of the formula A-B-C wherein the symbol A represents a polystyrene block, the symbol B represents a statistical copolymer block having a glass transition temperature of less than-10 DEG C, said statistical copolymer comprising 1, 3-diene units and greater than 50 mol% ethylene units, and the symbol C represents a polyethylene block having a melting temperature of greater than 90 DEG C. The triblock polymer provided by the invention has good elastic recovery.

Description

Technical Field

[0001] The field of the invention is that of diene copolymers rich in ethylene units. Background Art

[0002] It has been shown that statistical copolymers based on ethylene and 1,3-diene rich in ethylene units advantageously exhibit stiffness, hysteresis, wear and adhesion properties. Reference may be made, for example, to patent applications WO 2014114607A1, WO 2016012259 A1 and WO 2016087248 A1.

[0003] Another advantage of these copolymers is the use of ethylene, a common and commercially available monomer that can be obtained through fossil or biological routes. Another advantage of these copolymers is the presence of ethylene units along the polymer backbone, which are much less susceptible to oxidative or thermo-oxidative degradation mechanisms than diene units, which gives the material better stability and longevity.

[0004] The synthesis of diblock polymers in which one block is a statistical copolymer of ethylene and 1,3-diene and the other block is polystyrene is described in documents WO 2019077235 and WO 2021123590. These diblock polymers exhibit significant residual deformation when subjected to deformation or repeated deformation cycles, which reflects the relatively low elastic recovery of the polymers. For use, it is advantageous to use polymers with better elastic recovery (i.e., less residual deformation after one or more deformation instances). Summary of the invention

[0005] The applicant has discovered that the elastic recovery of a diblock polymer having a polystyrene block and a statistical copolymer block of ethylene and 1,3-diene is improved by changing the diblock polymer to a triblock polymer comprising a central block which is a statistical copolymer of ethylene and 1,3-diene and two terminal blocks, a polystyrene block and a polyethylene block.

[0006] A first subject of the invention is therefore a triblock polymer of formula ABC in which the symbol A represents a polystyrene block, the symbol B represents a statistical copolymer block having a glass transition temperature of less than -10°C, the statistical copolymer comprising 1,3-diene units and greater than 50 mol % of ethylene units, and the symbol C represents a polyethylene block having a melting temperature greater than 90°C.

[0007] A second subject matter of the present invention is a composition comprising the triblock polymer according to the invention and a further component.

[0008] Another subject of the invention is a process for the synthesis of a triblock polymer of formula ABC according to the invention, comprising the statistical copolymerization of a monomer mixture comprising ethylene and a 1,3-diene in the presence of a catalytic system based on at least one metallocene of formula (I) and an organomagnesium compound of formula (II), followed by the homopolymerization of ethylene,

[0009] P(Cp 1 Cp 2 )Nd(BH 4 ) (1+y) Li y (THF) x (I)

[0010] R-Mg-A (II)

[0011] Cp 1 and Cp 2 are the same or different and are selected from cyclopentadienyl and fluorenyl, said groups may be substituted or unsubstituted,

[0012] P is a bridge connecting two groups Cp 1 and Cp 2 And represents the group ZR 1 R 2 A group, Z represents a silicon atom or a carbon atom, R 1 and R 2 are the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group,

[0013] y is an integer equal to or greater than 0,

[0014] x is an integer or non-integer equal to or greater than 0,

[0015] R comprises a benzene ring having two carbon atoms substituted, one of the two carbon atoms being substituted by a methyl, ethyl or isopropyl group, or forming a ring with the carbon atom closest thereto, the second carbon atom being substituted by a methyl, ethyl or isopropyl group, and the magnesium atom being located in an ortho position relative to each of the two carbon atoms,

[0016] A represents a polystyrene block,

[0017] B represents a statistical copolymer block having a glass transition temperature of less than -10°C, the statistical copolymer comprising 1,3-diene units and more than 50 mol % of ethylene units,

[0018] C represents a polyethylene block having a melting temperature greater than 90°C. DETAILED DESCRIPTION

[0019] Any numerical interval expressed by the expression "between a and b" means a numerical range greater than "a" and less than "b" (i.e., excluding the limits a and b), while any numerical interval expressed by the expression "from a to b" means a numerical range extending from "a" to "b" (i.e., including the strict limits a and b).

[0020] Unless otherwise specified, the content of the unit resulting from the insertion of a monomer into a polymer is expressed as mole percent relative to all monomer units constituting the polymer.

[0021] The compounds mentioned in the description may be compounds of fossil origin or bio-based compounds. In the case of bio-based compounds, they may be derived partly or completely from biomass, or obtained by renewable raw materials derived from biomass. In the same way, the compounds mentioned may also be derived from the recycling of already used materials, i.e. they may be derived partly or completely from a recycling process, or obtained by raw materials that themselves are derived from a recycling process.

[0022] The block represented by the symbol B of the formula ABC and referred to hereinafter as the "central block" represents a block that is a statistical copolymer comprising ethylene units and 1,3-diene units, which means that the constituent monomer units of the central block are statistically distributed in the central block. The two other blocks represented by A and C are homopolymers, which are polystyrene and polyethylene, respectively.

[0023] In a known manner, an "ethylene unit" is understood to mean a unit having -(CH 2 -CH 2 )-subunit. The ethylene units present in block B (referred to as the center block) account for more than 50 mol% of the monomer units constituting the center block. In the present application, the content of ethylene units in the center block (i.e., the number of moles of ethylene units in the center block) is expressed as a molar percentage relative to the number of moles of monomer units constituting the center block.

[0024] According to any embodiment of the present invention, the central block is preferably a statistical copolymer of ethylene and 1,3-diene, in which case the monomer units of the central block are monomer units resulting from the copolymerization of ethylene and 1,3-diene and are statistically distributed in the central block.

[0025] According to the invention, the 1,3-diene constituting the monomer units of the central block is only one compound (i.e. only one 1,3-diene) or a mixture of 1,3-dienes whose chemical structures differ from one another. The 1,3-diene is preferably 1,3-butadiene or isoprene, or a mixture of 1,3-dienes (one of which is 1,3-butadiene). The 1,3-diene is more preferably 1,3-butadiene. Very preferably, the central block is a statistical copolymer of ethylene and 1,3-butadiene.

[0026] In a known manner, 1,3-dienes can be inserted into the growing polymer chain by 1,4 insertion or 2,1 insertion or 3,4 insertion (in the case of substituted dienes such as isoprene), thereby forming 1,3-diene units in 1,4 configuration, 1,3-diene units in 1,2 configuration or 3,4 configuration, respectively. Preferably, 1,3-diene units in 1,2 configuration and 1,3-diene units in 3,4 configuration account for more than 50 mol% of the 1,3-diene units.

[0027] According to one embodiment of the present invention, the central block comprises 1,4-configuration, preferably trans-1,4-configuration 1,3-diene units. Preferably, trans-1,4-configuration 1,3-diene units account for more than 50 mol% of 1,4-configuration 1,3-diene units. More preferably, trans-1,4-configuration 1,3-diene units account for 100 mol% of 1,4-configuration 1,3-diene units.

[0028] According to a particularly preferred embodiment of the invention, the central block comprises 1,3-diene units comprising more than 50 mol % of units in 1,2 or 3,4 configuration, the balance of 100% of 1,3-diene units being units in trans-1,4 configuration.

[0029] According to another particularly preferred embodiment of the present invention, in particular when the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes (one of which is 1,3-butadiene), the central block also contains 1,2-cyclohexane units or 1,4-cyclohexane units, preferably 1,2-cyclohexane units. The presence of these cyclic structures in the central block is produced by the very specific insertion of ethylene and 1,3-butadiene during its copolymerization. The mechanism for obtaining this microstructure is described, for example, in the document Macromolecules, 2009, 42, 3774-3779. The content of 1,2-cyclohexane units and 1,4-cyclohexane units in the central block varies depending on the respective content of ethylene and 1,3-butadiene in the central block. Preferably, it is less than or equal to 15%, the molar percentage being expressed relative to the number of moles of the monomer units constituting the central block. For the highest content of ethylene in the center block, the center block generally comprises less than 10 mol % of 1,2-cyclohexane units and 1,4-cyclohexane units, and for the lowest content of ethylene in the center block, the center block may comprise more than 10 %, for example up to 15 %, of 1,2-cyclohexane units and 1,4-cyclohexane units, the percentage being expressed relative to the number of moles of the monomer units constituting the center block. The 1,2-cyclohexane unit corresponds to the following formula.

[0030]

[0031] Since the stiffness of the triblock polymer increases with the content of ethylene units in the center block, a triblock polymer having a particularly high content of ethylene units in the center block may be desirable for applications requiring high stiffness of the material. Preferably, the ethylene units in the center block account for more than 60 mol% of the units constituting the center block, in which case the center block contains more than 60 mol% of ethylene units. More preferably, the ethylene units in the center block account for at least 70 mol% of the units constituting the center block, in which case the center block contains at least 70 mol% of ethylene units.

[0032] According to a particular embodiment of the invention, the ethylene units in the central block represent less than 90 mol % of the units constituting the central block, in which case the central block comprises less than 90 mol % of ethylene units.

[0033] According to another particular embodiment of the invention, the ethylene units in the central block represent at most 85 mol % of the units constituting the central block, in which case the central block comprises at most 85 mol % of ethylene units.

[0034] The glass transition temperature (Tg) of the central block is less than -10° C., preferably between -90° C. and -10° C. More preferably, the glass transition temperature of the central block is between -70° C. and -20° C., advantageously between -50° C. and -20° C. In a known manner, the glass transition temperature of the central block can be adjusted, for example, depending on the chemical structure of the 1,3-diene, the respective contents of ethylene units and 1,3-diene units in the central block.

[0035] The number average molar mass of the central block is preferably greater than 20,000 g / mol, more preferably greater than or equal to 50,000 g / mol.

[0036] The number-average molar mass of the central block is preferably less than or equal to 150 000 g / mol.

[0037] According to a preferred embodiment of the present invention, the number average molar mass of the central block ranges from 50,000 g / mol to 150,000 g / mol.

[0038] According to another preferred embodiment of the present invention, the number average molar mass of the central block is in the range of 50000 g / mol to 100000 g / mol.

[0039] The essential feature of the block represented by the symbol A of formula ABC is that it is polystyrene. Preferably, A represents linear polystyrene. Preferably, the polystyrene block is atactic polystyrene.

[0040] The number average molar mass of the polystyrene block is preferably greater than or equal to 5000 g / mol. Preferably, the number average molar mass of the polystyrene block is in the range of 5000 g / mol to 100000 g / mol, in particular in the range of 5000 g / mol to 65000 g / mol. More preferably, the Mn of the polystyrene block is greater than or equal to 10000 g / mol, in particular in the range of 10000 g / mol to 100000 g / mol, more particularly in the range of 10000 g / mol to 65000 g / mol. The glass transition temperature of the polystyrene block is generally greater than 80° C., preferably greater than or equal to 90° C., more preferably greater than or equal to 100° C. Since the glass transition temperature of the polystyrene block is in the same temperature range as the melting temperature of the polystyrene block, the glass transition temperature of the polystyrene block cannot be determined by analysis of the triblock polymer (e.g. differential scanning calorimetry, DSC). It can be determined during the synthesis of the triblock polymer before the polystyrene blocks are formed.

[0041] The essential feature of the block represented by the symbol C of the formula ABC is that it is a polyethylene having a melting temperature greater than 90°C, in particular greater than 90°C and less than 140°C. The melting temperature of the polyethylene block is more preferably greater than 100°C and less than 130°C. Preferably, C represents a linear polyethylene. The number average molar mass of the polyethylene block is preferably greater than or equal to 2000 g / mol and less than or equal to 12000 g / mol. The portion of the polystyrene block and the polyethylene block in the triblock polymer preferably accounts for less than 50% by mass of the mass of the triblock polymer, more preferably 15% to 40% by mass of the mass of the triblock polymer.

[0042] The number average molar mass (Mn) of the triblock polymer is preferably between 30,000 g / mol and 200,000 g / mol, more preferably in the range of 50,000 g / mol to 150,000 g / mol, in particular in the range of 50,000 g / mol to 100,000 g / mol.

[0043] Triblock polymers are most particularly thermoplastic elastomers, wherein the polystyrene blocks and the polyethylene blocks constitute the rigid phase of the triblock polymer and the central block constitutes the flexible phase of the triblock polymer.

[0044] The triblock polymers according to the invention can be prepared according to a process comprising the statistical copolymerization of a monomer mixture comprising ethylene and a 1,3-diene, followed by a subsequent polymerization of ethylene.

[0045] Catalytic system (or catalytic composition) for the statistical copolymerization of monomer mixtures and the homopolymerization of ethylene based on at least one metallocene of formula (I) and an organomagnesium compound of formula (II)

[0046] P(Cp 1 Cp 2 )Nd(BH 4 ) (1+y) Li y (THF) x (I)

[0047] R-Mg-A (II)

[0048] Cp 1 and Cp 2 are the same or different and are selected from cyclopentadienyl and fluorenyl, said groups may be substituted or unsubstituted,

[0049] P is a bridge connecting two groups Cp 1 and Cp 2 And represents the group ZR 1 R 2 A group, Z represents a silicon atom or a carbon atom, R 1 and R 2 are the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group,

[0050] y is an integer equal to or greater than 0,

[0051] x is an integer or non-integer equal to or greater than 0,

[0052] The symbol A represents a polystyrene chain which is identical in all respects to the styrene block of formula ABC,

[0053] R comprises a benzene ring having two carbon atoms substituted, one of the two carbon atoms being substituted by a methyl, ethyl or isopropyl group, or forming a ring with the carbon atom closest thereto, the second carbon atom being substituted by a methyl, ethyl or isopropyl group, and the magnesium atom being located in an ortho position relative to each of the two carbon atoms.

[0054] In formula (I), the neodymium atom is connected to a Cp 1 and Cp 2 The ligand molecule consists of two groups Cp 1 and Cp 2 The bridge P is connected together. Preferably, the symbol P represented by the term bridge corresponds to the formula ZR 1 R 2 , Z represents silicon atom, R 1 and R 2 are identical or different and represent an alkyl group containing 1 to 20 carbon atoms. More preferably, the bridge P has the formula SiR 1 R 2 , R 1 and R 2Even more preferably, P corresponds to the formula SiMe 2 .

[0055] As the substituted cyclopentadienyl group and fluorenyl group, there can be mentioned groups substituted with an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms or a trialkylsilyl group (e.g. SiMe 3 The selection of alkyl, aryl and trialkylsilyl groups also depends on the availability of the corresponding molecules (substituted cyclopentadiene and fluorene), because substituted cyclopentadiene and fluorene are commercially available or easily synthesized.

[0056] As the substituted cyclopentadienyl group, there can be mentioned a cyclopentadienyl group substituted at the 2 (or 5) position or the 3 (or 4) position, in particular a cyclopentadienyl group substituted at the 2 position, and more particularly a tetramethylcyclopentadienyl group. In the present application, in the case of a cyclopentadienyl group, as shown in the following figure, the 2 (or 5) position indicates the position of the carbon atom adjacent to the carbon atom connected to the bridge P.

[0057]

[0058] As substituted fluorenyl, mention may be made of fluorenyl substituted in position 2, 7, 3 or 6, in particular 2,7-di(tert-butyl)fluorenyl and 3,6-di(tert-butyl)fluorenyl. Positions 2, 3, 6 and 7 represent the positions of the carbon atoms of the ring as shown in the following diagram, respectively, and position 9 corresponds to the carbon atom connected to the bridge P.

[0059]

[0060] Preferably, Cp 1 and Cp 2 are the same and are selected from substituted fluorenyl and fluorenyl. Advantageously, in formula (I), Cp 1 and Cp 2 Each represents a substituted fluorenyl or fluorenyl, preferably a fluorenyl. The fluorenyl group is a group of formula C 13 H 8 Preferably, the metallocene is of formula (Ia), (Ib), (Ic), (Id) or (Ie), wherein the symbol Flu represents a metallocene of formula C 13 H 8 The fluorenyl group.

[0061] [{Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)} 2 ] (Ia)

[0062] [Me 2 SiFlu2 Nd(μ-BH 4 ) 2 Li(THF)] (Ib)

[0063] [Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)] (Ic)

[0064] [{Me2SiFlu 2 Nd(μ-BH 4 )(THF)} 2 ] (Id)

[0065] [Me 2 SiFlu 2 Nd(μ-BH 4 )] (Ie)

[0066] The metallocene for preparing the catalyst system can be in the form of crystallization or non-crystalline powder, or in the form of single crystal.Metallocene can be in monomeric form or dimer form, and these forms depend on the method for preparing metallocene, for example described in patent application WO 2007054224.Metallocene can be prepared conventionally by a method similar to the method described in patent application WO 2007054224, particularly by the reaction preparation of the alkali metal salt of the part and rare earth metal borohydride in a suitable solvent (for example ether (for example, diethyl ether or tetrahydrofuran) or any other solvent known to persons skilled in the art) under inertia and anhydrous conditions.After the reaction, metallocene is separated from reaction byproduct by technology known to persons skilled in the art (for example, filtering or precipitating in a second solvent).Finally, the metallocene is dried and separated in solid form.

[0067] As with any synthesis carried out in the presence of an organometallic compound, the synthesis of metallocenes is carried out under anhydrous conditions in an inert atmosphere. Typically, the reaction is carried out starting with anhydrous solvents and compounds under anhydrous nitrogen or argon.

[0068] The organomagnesium compound of formula (II) is used as a cocatalyst in the catalytic system. Preferably, the two substituents of the magnesium atom relative to the two carbon atoms located in the ortho position are the same. More preferably, they are methyl or ethyl. Advantageously, they are methyl.

[0069] Preferably, the organomagnesium compound of formula (II) corresponds to formula (II-1), wherein A represents a polystyrene chain, R 1 and R 5 are the same or different and represent methyl or ethyl, and R 2 , R 3 and R 4are the same or different and represent a hydrogen atom or an alkyl group. 1 and R 5 Represents methyl.

[0070] Preferably, R 2 and R 4 Represents a hydrogen atom.

[0071]

[0072] According to a preferred variant, R 1 , R 3 and R 5 According to a more preferred variant, R 2 and R 4 represents hydrogen, and R 1 , R 3 and R 5 In a more preferred variant, R 2 and R 4 represents hydrogen, and R 1 , R 3 and R 5 Represents methyl.

[0073] The organomagnesium compound of formula (II) can be prepared by a process comprising the reaction of an active anionic polystyrene ALi with an organomagnesium halide of formula R-Mg-X, R being as defined in formula (II), A representing a polystyrene block, X being a halogen atom, preferably a chlorine atom or a bromine atom, more preferably a bromine atom, and the symbol Li representing a lithium atom in a known manner. In a known manner, "anionic polystyrene" is understood to mean a polystyrene prepared by anionic polymerization. Also in a known manner, "active polystyrene" is understood to mean a polystyrene having a polymer chain having a reactive center, typically a carbon-lithium bond, with respect to the polymerization, in particular at the polymer chain ends.

[0074] Living anionic polystyrene is usually obtained by anionic polymerization of styrene in a solvent (called polymerization solvent). The polymerization solvent can be any hydrocarbon solvent known for the polymerization of styrene. The polymerization solvent is preferably a hydrocarbon solvent, more preferably cyclohexane, methylcyclohexane or toluene.

[0075] The ratio between the amount of solvent used to form the active anionic polystyrene and the amount of styrene is selected by a person skilled in the art according to the desired viscosity of the polymer solution of the active polystyrene. The viscosity depends not only on the concentration of the polymer solution, but also on many other factors, such as the length of the polymer chain, the intermolecular interaction of the active polystyrene chain, the complexing ability of the solvent and the temperature of the polymer solution. Therefore, a person skilled in the art will adjust the amount of solvent according to the specific circumstances.

[0076] In order to initiate the polymerization of styrene, compounds known to those skilled in the art as initiators for anionic polymerization of styrene can be used. For example, the initiator is a compound having a carbon-lithium bond. As initiators, mention may be made of organolithium compounds, such as n-butyllithium, sec-butyllithium and tert-butyllithium. The initiator is used in an amount selected according to the desired chain length of the active polystyrene.

[0077] The polymerization temperature for forming the active polystyrene can vary widely. Typically, it ranges from -20°C to 100°C, preferably from 20°C to 70°C.

[0078] In order to prepare the organomagnesium compound of formula (II), the reaction of active anion polystyrene with the organomagnesium halide can be carried out by adding a solution of active anion polystyrene to a solution of organomagnesium halide R-Mg-X, but it is preferably carried out by adding a solution of organomagnesium halide R-Mg-X to a solution of active anion polystyrene. The solution of active anion polystyrene is generally a solution in a hydrocarbon-based solvent (preferably a polymerization solvent for synthesizing active anion polystyrene). The solution of organomagnesium halide R-Mg-X is generally a solution in ether (preferably diethyl ether or dibutyl ether). The concentration of active anion polystyrene is preferably 0.01 mole lithium equivalent / liter to 1 mole lithium equivalent / liter, more preferably 0.05 mole lithium equivalent / liter to 0.2 mole lithium equivalent / liter, and the concentration of the solution of organomagnesium compound R-Mg-X is preferably 1 mol / l to 5 mol / l, more preferably 2 mol / l to 3 mol / l.

[0079] The reaction between the living anionic polystyrene and the organomagnesium halide R-Mg-X is generally 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.

[0080] As with any synthesis carried out in the presence of an organometallic compound, contacting and reacting are carried out under anhydrous conditions in an inert atmosphere. Typically, solvents and solutions are used under anhydrous nitrogen or argon. The various steps of the method are typically carried out under stirring.

[0081] After the organomagnesium compound of formula (II) is formed, the solution of the organomagnesium compound of formula (II) is typically stored in a sealed container (e.g., a bottle with a lid) at a temperature between -25°C and 23°C under an inert and anhydrous atmosphere before using it as a co-catalyst in a catalytic system.

[0082] The catalytic system can be prepared generally by a method similar to the method described in patent application WO 2007054224 or WO 2007054223. For example, the cocatalyst and the metallocene can generally react in a hydrocarbon solvent at a temperature ranging from 20°C to 80°C for a time between 5 minutes and 60 minutes. The amount of the cocatalyst and the metallocene reacted is such that the ratio between the mole number of Mg of the cocatalyst and the mole number of the rare earth metal of the metallocene is preferably changed from 1 to 100, more preferably from 1 to less than 10. The numerical range of 1 to less than 10 is particularly conducive to obtaining a polymer with a high molar mass. The catalytic system is generally prepared in an aliphatic hydrocarbon solvent (e.g., methylcycloethane) or an aromatic hydrocarbon solvent (e.g., toluene). Generally, after synthesis, the catalytic system is used in a method for synthesizing a polymer according to the present invention.

[0083] The catalytic system is usually in the form of a solution in a hydrocarbon solvent. The hydrocarbon solvent can be an aliphatic solvent (e.g., methylcyclohexane) or an aromatic solvent (e.g., toluene). The hydrocarbon solvent is preferably an aliphatic solvent, more preferably methylcyclohexane. Usually, before being used for polymerization, the catalytic system is stored in the form of a solution in a hydrocarbon solvent. Then, it can be referred to as a catalytic solution comprising a catalytic system and a hydrocarbon solvent. The concentration of the catalytic solution is usually limited by the content of the metallocene in the solution. The range of the value of the concentration of the metal of the metallocene is preferably 0.0001mol / l to 0.2mol / l, more preferably 0.001mol / l to 0.03mol / l.

[0084] As with any synthesis carried out in the presence of an organometallic compound, the synthesis of the catalytic system is carried out under anhydrous conditions in an inert atmosphere. Typically, the reaction is carried out starting with anhydrous solvents and compounds under anhydrous nitrogen or argon.

[0085] The catalytic system is used for two polymerization steps, which are the statistical copolymerization of the monomer mixture and the subsequent homopolymerization of ethylene. The two steps of the polymerization of the monomer mixture are preferably carried out continuously or batchwise in a reactor that is advantageously stirred in solution. The polymerization solvent can be an aromatic hydrocarbon solvent or an aliphatic hydrocarbon solvent. Examples of polymerization solvents that may be mentioned include toluene and methylcyclohexane.

[0086] The catalytic system is generally introduced into a reactor containing a polymerization solvent and a monomer mixture containing ethylene and 1,3-diene. In order to obtain the desired macrostructure of the central block, the skilled person will adjust the polymerization conditions, in particular the molar ratio of the organomagnesium compound to the metal Nd constituting the metallocene. The molar ratio can reach a value of 100, and a molar ratio of less than 10 is known to be more favorable for obtaining polymers with high molar mass.

[0087] The preparation of the central block is carried out by statistical copolymerization of a monomer mixture comprising ethylene and 1,3-diene. Preferably, ethylene and 1,3-diene are added continuously to the polymerization reactor, in which case the polymerization reactor is a feed reactor. This embodiment is most particularly suitable for the statistical introduction of ethylene and 1,3-diene.

[0088] The polymerization temperature generally varies within the range of 30° C. to 160° C., preferably 30° C. to 120° C. During the preparation of the central block, the temperature of the reaction medium is advantageously kept constant during the copolymerization, and the total pressure in the reactor is also advantageously kept constant. The preparation of the central block is completed by cutting off the monomer supply, in particular by reducing the pressure in the reactor, preferably to about 3 bar.

[0089] The preparation of the polyethylene block by subsequent polymerization of ethylene is continued by applying an ethylene pressure in the reactor, which is kept constant until the desired ethylene consumption is reached, thereby achieving the desired number average molar mass of the polyethylene block. The polymerization temperature of ethylene is preferably carried out at the same temperature as the temperature of the preparation of the center block. The polymerization temperature for the preparation of the polyethylene block is generally varied in the range of 30°C to 160°C, preferably 30°C to 120°C. The pressure for the preparation of the polyethylene block is generally varied in the range of 1 bar to 150 bar, preferably 1 bar to 10 bar. When the polyethylene block reaches the desired number average molar mass, the synthesis of the polyethylene block is completed.

[0090] The polymerization can be terminated by cooling the polymerization medium or by adding an alcohol, preferably an alcohol containing 1 to 3 carbon atoms, such as ethanol. The triblock polymer can be recovered according to conventional techniques known to those skilled in the art, such as precipitation, evaporation of the solvent under reduced pressure or steam stripping.

[0091] Alternatively, the triblock polymers can be prepared by another method which differs from the method described in that the cocatalyst is not an organomagnesium compound of formula (II) but an active anionic polystyrene ALi and the molar ratio between the number of moles of active polymer and the number of moles of Nd atoms in the metallocene is varied in the range of 0.8 to 1.2.

[0092] The triblock polymers can be used in compositions (another subject of the present invention) which usually contain another component. The other component can be a filler (e.g. carbon black or silica), a plasticizer (e.g. oil), a crosslinking agent (e.g. sulfur or peroxide), an antioxidant or a polymer (particularly an elastomer). The composition can be a rubber composition.

[0093] In summary, the present invention is advantageously implemented according to any one of the following embodiments 1 to 39:

[0094] Embodiment 1: A triblock polymer of formula ABC, wherein symbol A represents a polystyrene block, symbol B represents a statistical copolymer block having a glass transition temperature less than -10°C, the statistical copolymer comprising 1,3-diene units and greater than 50 mol% ethylene units, and symbol C represents a polyethylene block having a melting temperature greater than 90°C.

[0095] Embodiment 2: The triblock polymer according to Embodiment 1, wherein the statistical copolymer block is a statistical copolymer of ethylene and 1,3-diene.

[0096] Embodiment 3: A triblock polymer according to Embodiment 1 or 2, wherein the statistical copolymer blocks comprise greater than 60 mol% ethylene units.

[0097] Embodiment 4: The triblock polymer of any one of Embodiments 1 to 3, wherein the statistical copolymer blocks comprise at least 70 mol% ethylene units.

[0098] Embodiment 5: The triblock polymer of any one of Embodiments 1 to 4, wherein the statistical copolymer blocks comprise less than 90 mol% ethylene units.

[0099] Embodiment 6: The triblock polymer of any one of Embodiments 1 to 5, wherein the statistical copolymer blocks comprise up to 85 mol% ethylene units.

[0100] Embodiment 7: The triblock polymer according to any one of Embodiments 1 to 6, wherein the portion of the polystyrene blocks and the portion of the polyethylene blocks in the triblock polymer account for less than 50 mass % of the mass of the triblock polymer.

[0101] Embodiment 8: The triblock polymer according to any one of Embodiments 1 to 7, wherein the portion of the polystyrene blocks and the portion of the polyethylene blocks in the triblock polymer account for 15% to 40% by mass of the mass of the triblock polymer.

[0102] Embodiment 9: The triblock polymer of any one of Embodiments 1 to 8, wherein the statistical copolymer block has a glass transition temperature between -90°C and -10°C.

[0103] Embodiment 10: The triblock polymer of any one of Embodiments 1 to 9, wherein the statistical copolymer block has a glass transition temperature between -70°C and -20°C.

[0104] Embodiment 11: The triblock polymer of any one of Embodiments 1 to 10, wherein the statistical copolymer block has a glass transition temperature between -50°C and -20°C.

[0105] Embodiment 12: The triblock polymer of any one of Embodiments 1 to 11, wherein the number average molar mass of the statistical copolymer blocks is greater than 20,000 g / mol.

[0106] Embodiment 13: The triblock polymer of any one of Embodiments 1 to 12, wherein the number average molar mass of the statistical copolymer blocks is greater than or equal to 50,000 g / mol.

[0107] Embodiment 14: The triblock polymer of any one of Embodiments 1 to 13, wherein the number average molar mass of the statistical copolymer blocks is greater than or equal to 150,000 g / mol.

[0108] Embodiment 15: The triblock polymer of any one of Embodiments 1 to 14, wherein the number average molar mass of the statistical copolymer blocks ranges from 50,000 g / mol to 150,000 g / mol.

[0109] Embodiment 16: The triblock polymer of any one of Embodiments 1 to 15, wherein the number average molar mass of the statistical copolymer blocks ranges from 50,000 g / mol to 100,000 g / mol.

[0110] Embodiment 17: The triblock polymer of any one of Embodiments 1 to 16, wherein the 1,3-diene is 1,3-butadiene or isoprene.

[0111] Embodiment 18: The triblock polymer of any one of Embodiments 1 to 16, wherein the 1,3-diene is 1,3-butadiene.

[0112] Embodiment 19: The triblock polymer of any one of Embodiments 1 to 16, wherein the 1,3-diene is a mixture of 1,3-dienes, one of which is 1,3-butadiene.

[0113] Embodiment 20: A triblock polymer according to Embodiment 18 or 19, wherein the statistical copolymer blocks comprise 1,2-cyclohexane units or 1,4-cyclohexane units, preferably 1,2-cyclohexane units.

[0114] Embodiment 21: A triblock polymer according to Embodiment 20, wherein the content of 1,2-cyclohexane units and 1,4-cyclohexane units in the statistical copolymer block is less than or equal to 15%, and the molar percentage is expressed relative to the molar number of monomer units constituting the statistical copolymer block.

[0115] Embodiment 22: The triblock polymer of any one of Embodiments 1 to 21, wherein the 1,3-diene units in the 1,2 configuration and the 1,3-diene units in the 3,4 configuration account for greater than 50 mole percent of the 1,3-diene units.

[0116] Embodiment 23: A triblock polymer according to any one of Embodiments 1 to 22, wherein the statistical copolymer block comprises 1,3-diene units, the 1,3-diene units comprising greater than 50 mol% of units in the 1,2 configuration or the 3,4 configuration, the balance of the 100% 1,3-diene units being units in the trans-1,4 configuration.

[0117] Embodiment 24: The triblock polymer of any one of Embodiments 1 to 23, wherein the number average molar mass of the polystyrene blocks is greater than or equal to 5000 g / mol.

[0118] Embodiment 25: The triblock polymer according to any one of Embodiments 1 to 24, wherein the number average molar mass of the polystyrene blocks ranges from 5000 g / mol to 100000 g / mol.

[0119] Embodiment 26: The triblock polymer according to any one of Embodiments 1 to 25, wherein the number average molar mass of the polystyrene blocks ranges from 5000 g / mol to 65000 g / mol.

[0120] Embodiment 27: The triblock polymer of any one of Embodiments 1 to 26, wherein the number average molar mass of the polystyrene blocks is greater than or equal to 10,000 g / mol.

[0121] Embodiment 28: The triblock polymer of any one of Embodiments 1 to 27, wherein the number average molar mass of the polystyrene blocks ranges from 10,000 g / mol to 100,000 g / mol.

[0122] Embodiment 29: The triblock polymer according to any one of Embodiments 1 to 28, wherein the number average molar mass of the polystyrene blocks ranges from 10,000 g / mol to 65,000 g / mol.

[0123] Embodiment 30: The triblock polymer of any one of Embodiments 1 to 29, wherein the polystyrene block is a linear polystyrene.

[0124] Embodiment 31: The triblock polymer of any one of Embodiments 1 to 30, wherein the polystyrene block is atactic polystyrene.

[0125] Embodiment 32: The triblock polymer of any one of Embodiments 1 to 31, wherein the number average molar mass of the polyethylene block is greater than, or equal to, 2000 g / mol and less than, or equal to, 12000 g / mol.

[0126] Embodiment 33: The triblock polymer of any one of Embodiments 1 to 32, wherein the polyethylene block has a melting temperature greater than 100°C and less than 130°C.

[0127] Embodiment 34: The triblock polymer according to any one of Embodiments 1 to 33, wherein the number average molar mass of the triblock polymer is between 30,000 g / mol and 200,000 g / mol.

[0128] Embodiment 35: The triblock polymer according to any one of Embodiments 1 to 34, wherein the number average molar mass of the triblock polymer is in the range of 50,000 g / mol to 150,000 g / mol.

[0129] Embodiment 36: According to any one of Embodiments 1 to 35, the triblock polymer has a number average molar mass ranging from 50,000 g / mol to 100,000 g / mol.

[0130] Embodiment 37: The triblock polymer of any one of Embodiments 1 to 36, wherein the triblock polymer is a thermoplastic elastomer.

[0131] Embodiment 38: A composition comprising the triblock polymer defined in any one of Embodiments 1 to 37 and another component.

[0132] Embodiment 39: A process for synthesizing a triblock polymer of formula ABC as defined in any one of embodiments 1 to 37, comprising subjecting a monomer mixture comprising ethylene and a 1,3-diene to statistical copolymerization in the presence of a catalytic system based on at least one metallocene of formula (I) and an organomagnesium compound of formula (II), followed by homopolymerization of ethylene,

[0133] P(Cp 1 Cp 2 )Nd(BH 4 ) (1+y) Liy (THF) x (I)

[0134] R-Mg-A (II)

[0135] Cp 1 and Cp 2 are the same or different and are selected from cyclopentadienyl and fluorenyl, said groups may be substituted or unsubstituted,

[0136] P is a bridge connecting two groups Cp 1 and Cp 2 And represents the group ZR 1 R 2 A group, Z represents a silicon atom or a carbon atom, R 1 and R 2 are the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group,

[0137] y is an integer equal to or greater than 0,

[0138] x is an integer or non-integer equal to or greater than 0,

[0139] R comprises a benzene ring having two carbon atoms substituted, one of the two carbon atoms being substituted by a methyl, ethyl or isopropyl group, or forming a ring with the carbon atom closest thereto, the second carbon atom being substituted by a methyl, ethyl or isopropyl group, and the magnesium atom being located in an ortho position relative to each of the two carbon atoms,

[0140] A represents a polystyrene block,

[0141] B represents a statistical copolymer block having a glass transition temperature of less than -10°C, the statistical copolymer comprising 1,3-diene units and more than 50 mol % of ethylene units,

[0142] C represents a polyethylene block having a melting temperature greater than 90°C.

[0143] The above mentioned and other characteristics of the invention will be better understood on reading the following description of several exemplary embodiments of the invention given as non-limiting illustrations.

[0144] Example

[0145] 1-1-Size Exclusion Chromatography (SEC-THF):

[0146] Size exclusion chromatography analysis of polystyrene homopolymer and PS-b-EBR diblock polymer was performed using a Viscotek apparatus (Malvern Instruments) equipped with a guard column and 3 columns (SDVB, 5 μm, 330×7.5 mm, Polymer Standards) and 3 detectors (refractometer, viscometer and light scattering detector). Samples were concentrated at 3 mg ml -1 Up to 4 mg ml -1 The mixture was prepared at a concentration of 1.50 μg / mL and filtered through a 0.45 μm PTFE membrane and heated in stabilized THF at 40 °C at a rate of 1 ml min -1 The analysis was performed at a flow rate of 1.5 Å. The data were collected and processed using OmniSEC software. The number average molar mass (Mn) of the copolymers was determined using a refractometer detector by mixing with polystyrene standards (800 g mol -1 Up to 2500000 g mol -1 The dispersion was also determined using a conventional calibration obtained from Polymer Standard Service (Mainz).

[0147] The Mn of the polystyrene block of the triblock polymer can also be determined by size exclusion chromatography analysis during the synthesis of the triblock prior to forming the center block and polyethylene blocks (e.g., after deactivating the living polystyrene chains by adding methanol or ethanol to a polymer solution of the living polystyrene prior to adding a monomer mixture comprising ethylene and 1,3-diene).

[0148] The Mn of a diblock polymer formed as an intermediate in the synthesis of a triblock polymer and comprising a polystyrene block of a triblock as a first block and a central block of a triblock as a second block can also be determined by size exclusion chromatography analysis during the synthesis of the triblock before forming the polyethylene block (e.g., after deactivating the polymer chains of the diblock polymer).

[0149] The Mn of the center block of the triblock polymer can be determined from the previously determined Mn of the polystyrene block and the Mn of the diblock polymer.

[0150] 1-2-Size Exclusion Chromatography (SEC-HT) of Triblock Polymers:

[0151] High temperature size exclusion chromatography (HT-SEC or SEC-HT) analysis was performed using a Viscotek apparatus (Malvern Instruments) equipped with three columns (PLgel Olexis 300 mm × 7 mm ID, Agilent Technologies) and three detectors (differential refractometer and viscometer and light scattering detector). The analysis was performed at 150 °C in 1,2,4-trichlorobenzene using 1 ml min -1 The flow rate was 200 μl to elute at a concentration of 3 mg ml -1 Sample solution. 2,6-di(tert-butyl)-4-methylphenol (400 mg l -1 ) was used to stabilize the mobile phase. Data were collected and analyzed using OmniSEC software. The refractometer and viscometer detectors were used with polystyrene standards (peak molar mass M ) from Polymer Standard Service (Mainz). p :672gmol -1 Up to 12000000 g mol -1 The number average (Mn) molar mass and weight average (Mw) molar mass of the synthesized triblock polymer were calculated using a universal calibration curve calibrated with .

[0152] 2- Differential Scanning Calorimetry (DSC):

[0153] In a sealed aluminum crucible (40 μl) under nitrogen flow (30 ml min -1 DSC analysis was performed on a DSC 3+ apparatus (Mettler Toledo) under 40 °C. The temperature range was as follows:

[0154] 2-1- Thermograms of polystyrene homopolymers (Examples 1 and 2) were obtained according to the following procedure: ●Step 1: From 25℃ to 140℃ (10℃min -1 ), ● Step 2: Reduce from 140℃ to 25℃ (10℃min -1 ), ● Step 3: from 25℃ to 140℃ (10℃min -1 ), ● Step 4: Reduce from 140℃ to 25℃ (10℃min -1 ), ● Step 5: from 25℃ to 140℃ (10℃min -1 In step 5 (10°C min -1 The glass transition temperatures (Tg) of the PS (Examples 1 and 2) reported in Table 2 were determined in a 1% sintering reaction (ramp from 25°C to 140°C).

[0155] 2-2- The thermograms of polystyrene homopolymers (Examples 3, 4, 5, 6 and 7) were obtained according to the following procedure: ●Step 1: From 25℃ to 150℃ (10℃min -1), ● Step 2: Keep the temperature at 150℃ for 1min, ● Step 3: Reduce the temperature from 150℃ to 25℃ (10℃min -1 ), ● Step 4: Keep the temperature at 25℃ for 3min, ● Step 5: Increase the temperature from 25℃ to 150℃ (10℃min -1 In step 5 (10°C min -1 The glass transition temperatures (Tg) of the PS reported in Table 2 (Examples 4, 5, 6 and 7) were determined in a 1% sintering reaction (ramp from 25°C to 150°C).

[0156] 2-3- Thermograms of PS-b-EBR diblock polymers (Examples 1 and 2) were obtained according to the following procedure: ●Step 1: From 25℃ to 180℃ (10℃min -1 ), ● Step 2: Keep the temperature at 180℃ for 5min, ● Step 3: Reduce the temperature from 180℃ to -80℃ (10℃min -1 ), ● Step 4: Keep at -80℃ for 5min, ● Step 5: Increase the temperature from -80℃ to 180℃ (10℃min -1 ), ● Step 6: Keep the temperature at 180℃ for 5min, ● Step 7: Reduce the temperature from 180℃ to -80℃ (10℃min -1 ), ● Step 8: Keep at -80℃ for 5 min, ● Step 9: Increase the temperature from -80℃ to 180℃ (10℃min -1 In step 9 (10°C min -1 The glass transition temperatures (Tg) of the EBR and PS blocks (Examples 1 and 2) reported in Table 2 were determined in a 1% sintering reaction (from -80°C to 180°C).

[0157] 2-4- Thermograms of PS-b-EBR-b-PE triblock polymers (Examples 3, 4, 5, 6 and 7) were obtained according to the following procedure picture: ●Step 1: From 25℃ to 180℃ (10℃min -1 ), ● Step 2: Keep the temperature at 180℃ for 1min, ● Step 3: Reduce the temperature from 180℃ to -80℃ (10℃min -1 ), ● Step 4: Keep at -80℃ for 3min, ● Step 5: Increase the temperature from -80℃ to 180℃ (10℃min -1 ), ● Step 6: Keep the temperature at 180℃ for 1min, ● Step 7: Reduce the temperature from 180℃ to -80℃ (20℃min -1 ), ● Step 8: Keep at -80℃ for 3min, ● Step 9: Increase the temperature from -80℃ to 180℃ (20℃min -1 In step 5 (10°C min -1 The glass transition temperatures (Tg) and melting temperatures (Tf) of the EBR and PS blocks (Examples 4, 5, 5', 6 and 7) reported in Table 2 were determined in a heating cycle from -80°C to 180°C. -1The crystallization temperatures (Tc) of the PE blocks reported in Table 2 (Examples 3, 4, 5, 6 and 7) were determined in a sieve (100 °C) dropping from 180 °C to -80 °C.

[0158] The glass transition temperatures of the triblock polymers according to the present invention corresponding to the Tg of the polystyrene blocks and the Tg of the central block were determined according to the protocols described in Section 2-2 and Section 2-3, respectively.

[0159] The melting temperature (Tf) and crystallization temperature (Tc) of the triblock polymer according to the invention corresponding to the melting temperature (Tf) and crystallization temperature (Tc) of the central block and the polyethylene block are determined according to the protocol described in Sections 2-4.

[0160] The values ​​of Tg, Tf and Tc are determined by data reprocessing applying the STARe software from Mettler Toledo, based on the tangent method for determining Tg as described in standard ASTM 3418, the value of Tg corresponding to the point denoted by the well-known term "midpoint". The melting temperature (Tm) corresponds to the tip of the melting peak.

[0161] 3- Tensile test and elastic recovery cycle:

[0162] The application of tension was carried out at a crosshead speed of 500 mm / min on an MTS Criterion C42 device equipped with a 50 N sensor at the temperature of the analysis room (20°C to 25°C). The material was pressed at 4 / 5 tons at 150°C in a die of 80 mm*60 mm*1.5 mm. Standardized H2-type specimens (using dimensions of 30 mm×4 mm) were cut at room temperature using a suitable hollow punch.

[0163] The elastic recovery test quantifies the sensitivity of a polymer to permanent deformation after deformation or after repeated deformation cycles. The elastic recovery cycle consists of stretching the specimen up to 300% of the maximum nominal deformation (δ max ), then the stress is removed for 10 minutes, and the residual deformation (δi) of the specimen is subsequently measured in percentage. The specimen is subjected to 9 recovery cycles. After each recovery cycle, from the relation ε 回复 =(δ max -δi) / δ max Calculate elastic recovery ε 回复 .

[0164] 4-Synthesis

[0165] All reactions sensitive to air and / or moisture were performed under argon atmosphere. Dry polymerization solvents (toluene, methylcyclohexane and cyclohexane) were taken from a solvent jet (SPS800 MBraun).

[0166] 2-Bromo-mesitylene (Sigma-Aldrich) was stored over molecular sieves superior.

[0167] Methyltetrahydrofuran (MeTHF) was distilled over Na / benzophenone.

[0168] Ethyltetrahydrofurfuryl ether (ETE) was passed through activated alumina and then diluted in toluene to obtain 0.3 mol l -1 of solution (stored over molecular sieves).

[0169] Styrene (Sigma-Aldrich) was prepared in CaH2O under argon atmosphere. 2 The mixture was dried on ice for 24 h and then distilled under vacuum. n-Butyllithium (1.6 M in hexane, Sigma-Aldrich) was used as received.

[0170] MMB (2-mesityl magnesium bromide, Et 2 1 M in O, Sigma-Aldrich) was used as received.

[0171] Metallocene (in this case {Me 2 Si(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)} 2 The complex) was prepared according to the protocol described in patent application WO 2007054224 A2.

[0172] Ethylene (grade N35, Air Liquide) was used without purification.

[0173] 1,3-Butadiene was purified on an "Axens" alumina purification column before use.

[0174] 2,2'-Methylenebis(6-tert-butyl-4-methylphenol) (bi-BHT, Sigma-Aldrich) was used as the antioxidant.

[0175] Acetone and methanol (technical grade) were used to precipitate the polymer.

[0176] The name EBR is used to denote statistical copolymers of ethylene and 1,3-butadiene.

[0177] Example 1: Synthesis of PS-b-EBR diblock polymer

[0178] Step 1: Anionic polymerization and transmetallation of styrene (PS-MgMes). 40 ml of cyclohexane (m 溶剂 / m单体 ratio = 7), 5 g of styrene (in CaH 2 0.166 ml (0.05 mmol, 0.2 equivalent) of ETE (0.3 M in toluene and stored in molecular sieves) was introduced into a regulated Schlenk tube (3 vacuum argon cycles). Finally, 0.156 ml (0.25 mmol, 1 equivalent) of n-BuLi (1.6 M in hexane) was added to start polymerization. The solution turned dark orange. The reaction medium was stirred at 40 ° C for 20 min to achieve 100% conversion. A transmetallation reaction was carried out with the addition of 0.3 ml (0.3 mmol, 1.2 equivalent) of MMB to obtain an organomagnesium compound of formula (II), wherein A is polystyrene (PS) and R is mesitylene (Mes). Subsequently, the medium was transferred to a reactor pre-conditioned and heated to 90 ° C using a cannula under an argon stream.

[0179] Step 2: Formation of PS-b-EBR diblock polymer. 32.7 mg (51 μmol) of Nd{Me 2 Si(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)} 2 The complex was placed in a 50 ml flask. 160 ml of toluene from the solvent jet was placed in a 250 ml flask. 0.2 ml (0.2 mmol) of MMB (Et 2 O). The solution (toluene + MMB) was stirred for 5 min, and then Nd{Me 2 Si(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)} 2Complex. The solution was transferred to a reactor already containing a PS-MgMes solution using a cannula under an argon stream. The reactor was isolated and the pressure was reduced to 0.5 bar using a vacuum pump before starting stirring (1000 rpm). The reactor was then pressurized to 4 bar using an ethylene / butadiene mixture of 80 / 20 in a molar ratio. The pressure in the reactor was kept constant by a tank containing an ethylene / butadiene mixture, and polymerization was performed at 90°C. Monomer consumption was monitored by the pressure reduction in the tank until a consumption of 15g of ethylene / butadiene mixture was reached. The reactor was then carefully decompressed and degassed under an argon stream, and the medium was deactivated by adding EtOH (about 0.5ml) and then cooled to ambient temperature. 0.2g of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (di-BHT) antioxidant was added, the copolymer was precipitated in 600ml of MeOH, then recovered in a crystallizing dish and dried under vacuum at 80°C to 100°C for 6h. The PS-b-EBR diblock polymer was weighed and analyzed by SEC-THF and DSC.

[0180] Example 2: Synthesis of PS-b-EBR diblock polymer

[0181] The same experimental conditions as in Example 1 were used, except for the amounts of styrene (7.5 g), cyclohexane (67 ml) and toluene (133 ml). The polymerization time of styrene was also increased to 30 min.

[0182] Example 3: Synthesis of PS-b-EBR-b-PE triblock polymer

[0183] Step 1: Anionic polymerization and transmetallation of styrene (PS-MgMes). 13.5 ml of cyclohexane (m 溶剂 / m 单体 ratio = 7), 1.5 g of styrene (in CaH 2 0.166 ml (0.05 mmol, 0.2 equivalent) of ETE (0.3 M in toluene and stored in molecular sieves) was introduced into a regulated Schlenk tube (3 vacuum argon cycles). Finally, 0.156 ml (0.25 mmol, 1 equivalent) of n-BuLi (1.6 M in hexane) was added to start polymerization. The solution turned dark orange. The reaction medium was stirred at 40 ° C for 10 min to achieve 100% conversion. A transmetallation reaction was carried out with the addition of 0.3 ml (0.3 mmol, 1.2 equivalent) of MMB to obtain an organomagnesium compound of formula (II), wherein A is polystyrene (PS) and R is mesitylene (Mes). Subsequently, the medium was transferred to a reactor pre-conditioned and heated to 90 ° C using a cannula under an argon stream.

[0184] Step 2: Formation of PS-b-EBR-PE triblock polymer. 32 mg (50 μmol) of Nd{Me 2 Si(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)} 2 The complex was transferred to a 50 ml flask. 186.5 ml of toluene from the solvent jet was placed in a 250 ml flask. 0.2 ml (0.2 mmol) of MMB was added to the toluene. The solution (toluene + MMB (Et 2 O)) for 5 min, then add Nd{Me 2 Si(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)} 2 The solution was transferred to a reactor already containing the PS-MgMes solution using a cannula under an argon stream. The reactor was isolated and the pressure was reduced to 0.5 bar using a vacuum pump before starting stirring (1000 rpm). The reactor was then pressurized to 4 bar using an ethylene / butadiene mixture of 80 / 20 in a molar ratio. The reaction medium was raised to and maintained at a temperature of 90° C. The pressure in the reactor was kept constant by a tank containing an ethylene / butadiene mixture. Monomer consumption was monitored by the pressure reduction in the tank until 15 g of the ethylene / butadiene mixture was consumed. The reactor was then isolated and the remaining monomers were consumed until the pressure reached 2.5 bar, thereby obtaining a desired M n The EBR copolymer was simultaneously passed through 2 vacuum ethylene circulation adjustment tanks and then pressurized with 100% ethylene. The reactor was then pressurized to 4 bar and fed with ethylene. After consuming 1.5 g of ethylene, the reactor was carefully decompressed and degassed under an argon stream, and the medium was deactivated by adding EtOH (about 0.5 ml) and then cooled to ambient temperature. 0.2 g of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (di-BHT) antioxidant was added, the copolymer was precipitated in 600 ml of MeOH, then recovered in a crystallization dish and dried under vacuum at 80°C to 100°C for 6 h. The PS-b-EBR-b-PE triblock polymer was weighed and analyzed by DSC.

[0185] Example 4: Synthesis of PS-b-EBR-b-PE triblock polymer

[0186] The same experimental conditions as in Example 3 were used, except for the amounts of styrene (2.5 g), cyclohexane (22.5 ml) and toluene (177.5 ml).

[0187] Example 5: Synthesis of PS-b-EBR-b-PE triblock polymer

[0188] The same experimental conditions as in Example 3 were used, except for the amounts of styrene (2.5 g), cyclohexane (22.5 ml) and toluene (177.5 ml).

[0189] Example 6: Synthesis of PS-b-EBR-b-PE triblock polymer

[0190] The same experimental conditions as in Example 3 were used, except for the amounts of styrene (3.75 g), cyclohexane (33.7 ml) and toluene (166.3 ml).

[0191] Example 7: Synthesis of PS-b-EBR-b-PE triblock polymer

[0192] The same experimental conditions as in Example 3 were used, except for the amounts of styrene (5 g), cyclohexane (45 ml) and toluene (155 ml).

[0193] Table 1 shows the properties related to the macrostructure of the polymer. Mnexperimental is the number average molar mass determined by SEC analysis. Mntheoretical is the target number average molar mass. Table 1 also shows the amount of target polymer (m copo target) and the amount of polymer actually obtained through the experiment (m copo experiment). and They are the dispersibility of the polystyrene blocks and the dispersibility of the copolymers.

[0194] Table 2 shows the glass transition temperature (Tg), melting temperature (Tf) and crystallization temperature (Tc) of the polymers.

[0195] Table 3 shows the elastic recovery results of the polymers.

[0196] The results show that introducing the polyethylene block according to the present invention into the end of the EBR block of the PS-b-EBR diblock polymer, so that the EBR block becomes the central block of the triblock polymer according to the present invention, can significantly improve the elastic recovery of the polymer.

[0197] In the tables, "nd" is the abbreviation for not determined.

[0198] Table 1

[0199]

[0200] Table 2

[0201]

[0202] Table 3

[0203]

Claims

1. A triblock polymer of formula ABC, wherein: Symbol A represents a polystyrene block, symbol B represents a statistical copolymer block having a glass transition temperature of less than -10°C, said statistical copolymer comprising 1,3-diene units and more than 50 mol % of ethylene units, and symbol C represents a polyethylene block having a melting temperature of more than 90°C.

2. The triblock polymer according to claim 1, wherein The statistical copolymer block is a statistical copolymer of ethylene and 1,3-diene.

3. The triblock polymer according to claim 1 or 2, wherein The statistical copolymer blocks comprise more than 60 mol % of ethylene units, preferably at least 70 mol % of ethylene units.

4. The triblock polymer according to any one of claims 1 to 3, wherein The statistical copolymer blocks comprise less than 90 mol % ethylene units.

5. The triblock polymer according to any one of claims 1 to 4, wherein The statistical copolymer blocks comprise up to 85 mol % of ethylene units.

6. The triblock polymer according to any one of claims 1 to 5, wherein The fraction of polystyrene blocks and polyethylene blocks in the triblock polymer accounts for less than 50% by mass of the mass of the triblock polymer, preferably from 15% to 40% by mass of the mass of the triblock polymer.

7. The triblock polymer according to any one of claims 1 to 6, wherein The glass transition temperature of the statistical copolymer blocks is between -90°C and -10°C, preferably between -70°C and -20°C, more preferably between -50°C and -20°C.

8. The triblock polymer according to any one of claims 1 to 7, wherein The number average molar mass of the statistical copolymer blocks is greater than 20,000 g / mol, preferably greater than or equal to 50,000 g / mol.

9. The triblock polymer according to any one of claims 1 to 8, wherein The 1,3-diene is 1,3-butadiene or isoprene, or a mixture of 1,3-dienes, one of which is 1,3-butadiene, preferably 1,3-butadiene.

10. The triblock polymer according to any one of claims 1 to 9, wherein The 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene, and the statistical copolymer blocks comprise 1,2-cyclohexane units or 1,4-cyclohexane units, preferably 1,2-cyclohexane units.

11. The triblock polymer according to any one of claims 1 to 10, wherein The number average molar mass of the polystyrene block is greater than or equal to 5000 g / mol, preferably in the range of 5000 g / mol to 100000 g / mol.

12. The triblock polymer according to any one of claims 1 to 11, wherein The number average molar mass of the polyethylene block is greater than or equal to 2000 g / mol and less than or equal to 12000 g / mol.

13. The triblock polymer according to any one of claims 1 to 12, which is a thermoplastic elastomer.

14. A composition comprising the triblock polymer according to any one of claims 1 to 13 and a further component.

15. Process for the synthesis of a triblock polymer of formula ABC as defined in any one of claims 1 to 13, said process comprising subjecting a monomer mixture comprising ethylene and a 1,3-diene to a statistical copolymerization in the presence of a catalytic system based on at least one metallocene of formula (I) and an organomagnesium compound of formula (II), followed by subjecting ethylene to a homopolymerization, P(Cp 1 Cp 2 )Nd(BH4) (1+y) Li y (THF) x (I) R-Mg-A(II) Cp 1 and Cp 2 are the same or different and are selected from cyclopentadienyl and fluorenyl, said groups may be substituted or unsubstituted, P is a bridge connecting two groups Cp 1 and Cp 2 And represents the group ZR 1 R 2 A group, Z represents a silicon atom or a carbon atom, R 1 and R 2 are the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group, y is an integer equal to or greater than 0, x is an integer or non-integer equal to or greater than 0, R comprises a benzene ring having two carbon atoms substituted, one of the two carbon atoms being substituted by a methyl, ethyl or isopropyl group, or forming a ring with the carbon atom closest thereto, the second carbon atom being substituted by a methyl, ethyl or isopropyl group, and the magnesium atom being located in an ortho position relative to each of the two carbon atoms, A represents a polystyrene block, B represents a statistical copolymer block having a glass transition temperature of less than -10°C, the statistical copolymer comprising 1,3-diene units and more than 50 mol % of ethylene units, C represents a polyethylene block having a melting temperature greater than 90°C.

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