Abstract: A catalytic system based on at least one rare-earth metallocene and an organomagnesium reagent as co-catalyst of formula RB—(Mg—RA)m—Mg—RB is provided. According to the formula, RB comprises a benzene nucleus substituted with the magnesium atom. One of the carbon atoms of the benzene nucleus ortho to the magnesium is substituted with a methyl, an ethyl or an isopropyl or forms a ring with the carbon atom which is its closest neighbour and which is meta to the magnesium. The other carbon atom of the benzene nucleus ortho to the magnesium is substituted with a methyl, an ethyl or an isopropyl. RA is a divalent aliphatic hydrocarbon-based chain, optionally interrupted with one or more oxygen or sulfur atoms or with one or more arylene groups. The m is a number greater than or equal to 1, preferably 1. The catalytic system allows the synthesis of dienic and/or ethylenic telechelic polymers.

Abstract: A triblock polymer of formula B-A-B is provided. According to the formula, the symbol A represents a “central” block which is a statistical copolymer comprising units of a 1,3-diene and more than 50 mol % of ethylene units. The symbols B each represent an “end” block which is a polyethylene with a melting point of greater than 90° C. and a number-average molar mass of greater than or equal to 2000 g/mol and less than or equal to 10 000 g/mol. The polymer has improved rheological properties relative to a statistical copolymer based on ethylene and 1,3-diene of the same microstructure without changing its mechanical and dynamic or thermal properties.

Abstract: A process for preparing a multiblock polymer by statistical copolymerization of a mixture containing ethylene and a 1,3-diene and subsequent polymerization of ethylene in the presence of a rare-earth metallocene and an organomagnesium reagent RB—(Mg—RA)m—Mg—RB or X—Mg—RA—Mg—X is provided. According to the formula, RA is a divalent aliphatic hydrocarbon-based chain optionally interrupted with one or more oxygen or sulfur atoms or arylene groups, RB comprises a benzene nucleus substituted with the Mg atom, one of the carbon atoms of the benzene nucleus ortho to the Mg is substituted with a methyl, an ethyl or an isopropyl or forms a ring with the carbon atom which is its closest neighbour and which is meta to the Mg. The other carbon atom of the benzene nucleus ortho to the Mg is substituted with a methyl, ethyl or isopropyl, X being a halogen atom, m being greater than or equal to 1.

Abstract: A telechelic polymer of formula Z1-POLY-Z2 is provided. The term “POLY” denotes a polymer chain comprising units of a 1,3-diene, ethylene units and cyclic units, 1,2-cyclohexane units, Z1 and Z2 denoting a group containing a function, Z1 and Z2 being identical. The polymer has a macrostructure defined by a dispersity of less than 1.5 or by a number-average molar mass of greater than 10 000 g/mol.

Abstract: A catalytic system based on at least one rare-earth metallocene and as co-catalyst an organomagnesium reagent of formula X—Mg—RA—Mg—X is provided. In the formula, RA is a divalent aliphatic hydrocarbon-based chain, optionally interrupted with an oxygen atom, a sulfur atom or with an arylene group, and X is a halogen atom. The catalytic system allows the synthesis of dienic and/or ethylenic telechelic polymers.

Abstract: A catalytic system based on at least one metallocene and on a diorganomagnesium compound of formula RB—Mg—RA is provided, RB being different from RA and comprising a benzene nucleus substituted with a magnesium atom, one of the carbon atoms of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl, an isopropyl or forming a ring with the carbon atom which is its closest neighbour and which is meta to the magnesium, the other carbon atom of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl or an isopropyl, RA being an alkyl, a cycloalkyl or a benzyl, which may be substituted or unsubstituted. The catalytic system makes it possible to increase the functional group content in the synthesis of a functional polymer.

Abstract: The invention relates to a diorganomagnesium compound of formula RB—Mg—RA, RA being different from R8, RA being a polymer chain containing units of a monomer chosen from the group of monomers consisting of 1,3-dienes, aromatic ?-monoolefins and mixtures thereof, RB comprising a benzene nucleus substituted with a magnesium atom, one of the carbon atoms of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl, an isopropyl or forming a ring with the carbon atom which is its closest neighbour and which is meta to the magnesium, the other carbon atom of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl or an isopropyl, on condition that if one of the two ortho carbon atoms is substituted with an isopropyl, the second ortho carbon atom is not substituted with an isopropyl.

Abstract: The invention relates to a diorganomagnesium compound of formula RB—Mg—RA, RB being different from RA, RB comprising a benzene nucleus substituted with a magnesium atom, one of the carbon atoms of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl, an isopropyl or forming a ring with the carbon atom which is its closest neighbour and which is meta to the magnesium, the other carbon atom of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl or an isopropyl, RA being an alkyl, a cycloalkyl or a benzyl, which may be substituted or unsubstituted, which diorganomagnesium compound is other than n-butylmesitylmagnesium. When used as co-catalyst of a metallocene, it makes it possible to increase the functional group content in the synthesis of a functional polymer.

Abstract: A process for the synthesis of an ethylene/butadiene copolymer is provided. The process is continuous and comprises the following steps: a. feeding at least one stirred polymerization reactor with a mixture of ethylene, butadiene, hydrocarbon-based solvent and catalytic system allowing the formation of cyclic trans-1,2-cyclohexane units in the polymer chain with a mole ratio of ethylene to the sum of the ethylene and butadiene monomers ranging from 0.5 to 0.99; the concentration of ethylene and butadiene monomers in the polymerization reaction medium being less than 15% by weight; the operating pressure of the reactor is greater than or equal to the saturated vapour pressure of the polymerization reaction medium; and the polymerization temperature is greater than 90° C.; b.

Abstract: A diblock polymer composed of a first block and a second block is provided. The first block is a statistical copolymer comprising units of a 1,3-diene and more than 50 mol % of ethylene units. The second block is a polyethylene with a melting point above 90° C. and a number-average molar mass greater than or equal to 2000 g/mol and less than or equal to 10 000 g/mol. Such a diblock polymer has improved rheology compared to a statistical copolymer of the same microstructure and of the same macrostructure as the first block of the diblock polymer.

Abstract: A process for the synthesis of an ethylene/butadiene copolymer is provided. The process is continuous and comprises the following steps: a. feeding at least one stirred polymerization reactor with a mixture of ethylene, butadiene, hydrocarbon-based solvent and catalytic system allowing the formation of cyclic trans-1,2-cyclohexane units in the polymer chain with a mole ratio of ethylene to the sum of the ethylene and butadiene monomers ranging from 0.5 to 0.99; the concentration of ethylene and butadiene monomers in the polymerization reaction medium being less than 15% by weight; the operating pressure of the reactor is greater than or equal to the saturated vapour pressure of the polymerization reaction medium; and the polymerization temperature is greater than 90° C.; b.

Abstract: A terpolymer of ethylene, of 1,3-butadiene and of an aromatic ?-monoolefin is provided. The terpolymer contains more than 60 mol %, preferably at least 70 mol %, and preferably at most 90 mol % of ethylene units, at most 10 mol % of aromatic ?-monoolefin units and 1,2-cyclohexanediyl units. Such a diene terpolymer rich in ethylene units has the advantage of exhibiting a reduced, or even zero, crystallinity.

Abstract: An ethylene/1,3-butadiene copolymer containing ethylene units, butadiene units and UD units of cyclic, 1,2-cyclohexanediyl structure, and bearing, at one of its chain ends, an alkoxysilyl or silanol function, functional group F1 is provided.

Abstract: A process for the synthesis of an ethylene/butadiene copolymer is provided. The process is continuous and comprises: a. feeding at least one stirred polymerization reactor with a mixture of ethylene, butadiene, hydrocarbon-based solvent and catalytic system allowing the formation of cyclic trans-1,2-cyclohexane units in the polymer chain with a mole ratio of ethylene to the sum of the ethylene and butadiene monomers ranging from 0.5 to 0.99; the concentration of ethylene and butadiene monomers in the polymerization reaction medium being at least 10% by weight relative to the total weight; the operating pressure of the reactor is greater than or equal to the saturated vapour pressure of the polymerization reaction medium; b. recovering the ethylene/butadiene copolymer, this copolymer comprising, statistically distributed, ethylene units, butadiene units and trans-1,2-cyclohexane units, the molar fraction of ethylene units in the copolymer being greater than or equal to 50%.

Abstract: A catalytic system based at least on a preformation monomer selected from the group consisting of 1,3-dienes, ethylene, ?-olefins and their mixtures, on a metallocene of formula {P(Cp)(Flu)LnG} and on an organometallic compound as cocatalyst is provided. In the formula, Ln denotes a metal atom which is a rare earth metal, G denotes a group comprising the borohydride BH4 unit or denotes a halogen atom X selected from the group consisting of chlorine, fluorine, bromine and iodine, Cp denotes a cyclopentadienyl group of formula C5H4, Flu denotes a fluorenyl group of formula C13H8, P being a group bridging the two Cp and Flu groups and comprising a silicon or carbon atom. Such a catalytic system exhibits an improved stability of the catalytic activity over time, in particular on storage.

Abstract: A copolymer of a 1,3-diene and of an olefin selected from the group consisting of ?-monoolefins, ethylene and mixtures thereof is provided. The copolymer bears, at one of its chain ends, an alkoxysilyl or silanol function, functional group F1, and the copolymer is different from a copolymer of a 1,3-diene and a vinylaromatic monomer.

Abstract: A copolymer of ethylene and of isoprene, which comprises from 10 to 35 mol % of isoprene units, at least 70% of which are in the 3,4 configuration and a portion of which is in the 1,2 configuration is provided. A copolymer of this type with a reduced crystallinity is synthesized with a much higher productivity than its homologues of ethylene and of butadiene, and also confers improved curing properties on rubber compositions.

Abstract: A rubber composition which comprises at least one reinforcing inorganic filler and a highly saturated elastomer comprising 1,3-diene units and ethylene units and bearing, at the chain end, a functional group F1 which is a silanol or alkoxysilane function is provided. The ethylene units represent more than 50 mol % of all the monomer units of the elastomer. The rubber composition has an improved hysteresis/stiffness compromise.

Abstract: A catalytic system based at least on a preformation monomer which is ethylene or a mixture of ethylene and of a conjugated diene, on a metallocene of formula {P(Cp1)(Cp2)Y} or Cp3Cp4Y and on an organometallic compound as cocatalyst, Y denoting a group comprising a metal atom which is a rare earth metal, the Cp1, Cp2, Cp3 and Cp4 groups, which are identical or different, being selected from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, and P being a group bridging the two Cp1 and Cp2 groups and comprising a silicon or carbon atom, is provided. Such a catalytic system exhibits an improved stability of the catalytic activity over time, in particular on storage.

Abstract: An ethylene/butadiene copolymer comprising statistically distributed ethylene units and butadiene unit is provided. The molar fraction of the ethylene units in the copolymer is greater than or equal to 50%, relative to the total number of moles of ethylene and butadiene units. The microstructure of the copolymer is homogeneous. A process for preparing such a copolymer and also the uses of this copolymer, in particular in rubber compositions for tires is also provided.