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.

Abstract: An ethylene/butadiene copolymer comprising statistically distributed ethylene units butadiene units, and trans-1,2-cyclohexane units is provided. The molar fraction of ethylene units in the copolymer is greater than or equal to 50%, relative to the total number of moles of ethylene, butadiene and trans-1,2-cyclohexane units. The microstructure of the copolymer is homogeneous. A process for preparing such a copolymer and also to the uses of this copolymer, in particular in rubber compositions for tires, is also provided.

Abstract: An ethylene/butadiene copolymer comprising statistically distributed ethylene units and butadiene units 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.

Abstract: A catalytic system based at least on a preformation conjugated diene monomer, on an organometallic compound as cocatalyst and on a metallocene of formula {P(Cp1)(Cp2)Y} is provided. In the formula, Y denotes a group comprising a metal atom which is a rare earth metal, Cp1 and Cp2, which are identical or different, are selected from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, and P is a group bridging the two Cp1 and Cp2 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 comprising a copolymer chain A bearing a function B selected from the group consisting of the functions B1 and B2, the copolymer chain A being a copolymer chain comprising monomer units M1 and monomer units M2, M1 being a conjugated diene and M2 being a monomer selected from the group consisting of ?-monoolefins, ethylene and mixtures thereof, B1 being selected from the group consisting of N(SiMe3)2; N(SiMe2CH2CH2SiMe2); para-C6H4(NMe2); para-C6H4(OMe); para-C6H4(N(SiMe3)2); ortho-CH2-C6H4NMe2; ortho-CH2-C6H4OMe; C6F5; C3F7; C6F13; CH(OCH2CH2O); B2 being a function that is derived from B1, is provided. Such a copolymer is synthesized by using a transfer agent bearing the function B1 and a carbon-metal bond, the metal being an alkaline-earth metal, zinc or aluminium.

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: 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.