Abstract: The present invention relates to a catalyst system, to a method of manufacturing this system, and also to uses of this system. The catalyst system of the invention is characterized in that it comprises molecules of a polymer having, at one of its ends or along the chain, one or more polar functional groups; a solvent, said solvent, due to the fact of said polar functional group of said polymer, provoking and maintaining, when said molecules of the polymer are introduced thereinto, an organization of said molecules of the polymer into aggregates, micelles or vesicles so that the polar functional groups of said polymer are located inside the aggregates, micelles or vesicles formed; and a catalyst activator and a catalyst trapped in said aggregates, micelles or vesicles of said polymer. The catalyst system of the present invention may be used, for example, for catalyzing a (co)polymerization of olefins.

Abstract: Stage I Group 1 metal/porous metal oxide compositions or Stage II Group 1 metal/porous metal oxide compositions are shown to be useful to remove impurities and act as drying agents for various types of solvents and for olefinic monomers used in anionic polymerizations. One important advantage of these compositions is their ability to dry simultaneously solvent and monomers, without inducing a significant polymerization of the latter. Another important characteristic is the capacity of the compositions to be totally inactive toward conventional anionic polymerization which allows them to be left in situ during the polymerization itself.

Abstract: The present invention relates to a catalyst system, to a method of manufacturing this system, and also to uses of this system. The catalyst system of the invention is characterized in that it comprises molecules of a polymer having, at one of its ends or along the chain, one or more polar functional groups; a solvent, said solvent, due to the fact of said polar functional group of said polymer, provoking and maintaining, when said molecules of the polymer are introduced thereinto, an organization of said molecules of the polymer into aggregates, micelles or vesicles so that the polar functional groups of said polymer are located inside the aggregates, micelles or vesicles formed; and a catalyst activator and a catalyst trapped in said aggregates, micelles or vesicles of said polymer. The catalyst system of the present invention may be used, for example, for catalyzing a (co)polymerization of olefins.

Abstract: The invention concerns an implant forming an intraocular lens comprising a central optical part, a globally circular outline, at least partly made of a flexible material and a haptic part, at said optical part periphery, made at least partially of a rigid material. Said implant has a single-piece structure. The implant rigid material is a shape modified by at least one process selected among chemical reactions and polymerisation reactions of the starting flexible material, for example based on PMMA-PHMA, cross-linked by adding a multifunctional agent such as diethyleneglycol dimethacrylate.

Abstract: Stage I Group 1 metal/porous metal oxide compositions or Stage II Group 1 metal/porous metal oxide compositions are shown to be useful to remove impurities and act as drying agents for various types of solvents and for olefinic monomers used in anionic polymerizations. One important advantage of these compositions is their ability to dry simultaneously solvent and monomers, without inducing a significant polymerization of the latter. Another important characteristic is the capacity of the compositions to be totally inactive toward conventional anionic polymerization which allows them to be left in situ during the polymerization itself.

Abstract: A process for the preparation of a silicon containing transition metal compound that includes the steps of (a) non-hydrolytic sol-gel condensation of a silane of formula LxSiQn wherein L is a ?-bonded ligand, Q is an anionic ligand, and x+n=4 with a halogenated silane (or siloxane) and an alkoxysilane, (b) optionally alkylation, (c) deprotonation and (d) addition of a transition metal compound. The process allows for the preparation of transition metal compounds which may suitably be used with cocatalysts for the polymerization of olefins, in particular for such processes carried out in the gas phase.

Abstract: The invention relates to an initiator composition for anionic polymerization, comprising at least one alkali metal hydride selected from LiH, NaH, and KH, and at least one organylaluminum compound, and to a process for the anionic polymerization of styrene monomers or of diene monomers using the initiator composition.

Abstract: The invention relates to a process for preparation of homopolymers composed of oxiranes, or of copolymers composed of oxirans and comonomers, via anionic polymerization, which comprises carrying out a polymerization in the presence of a quaternary ammonium and/or phosphonium compound and of a mononuclear organylaluminum compound.

Abstract: Process for preparing homopolymers of oxiranes, or for preparing copolymers of oxiranes and comonomers, via anionic polymerization in the presence of an alkali metal compound and of an organylaluminum compound, which comprises avoiding any use of crown ethers or of cryptands during the polymerization.

Abstract: Process for preparing homopolymers of ?-methylstyrene, or copolymers of ?-methylstyrene and comonomers, by anionic polymerization in the presence of an initiator composition, which comprises using an initiator composition in which potassium hydride and at least one organylaluminum compound are present.

Abstract: Process for preparing homopolymers of ?-methylstyrene, or copolymers of ?-methylstyrene and comonomers, by anionic polymerization in the presence of an initiator composition, which comprises using an initiator composition in which potassium hydride and at least one organylaluminum compound are present.

Abstract: A process for the preparation of a silicon containing transition metal compound comprises the steps of (a) non-hydrolytic sol-gel condensation of a silane of formula LxSiQn wherein L is a ?-bonded ligand, Q is an anionic ligand, and x+n=4 with a halogenated silane (or siloxane) and an alkoxysilane, (b) optionally alkylation, (c) deprotonation and (d) addition of a transition metal compound. The novel process allows for the preparation of transition metal compounds which may suitably be used with cocatalysts for the polymerisation of olefins, in particular for such processes carried out in the gas phase.

Abstract: The invention relates to an initiator composition for anionic polymerization, comprising at least one alkali metal hydride selected from LiH, NaH, and KH, and at least one organylaluminum compound, and to a process for the anionic polymerization of styrene monomers or of diene monomers using the initiator composition.

Abstract: In a process for the anionic polymerization of vinylaromatic monomers or dienes in the presence of a lithium organyl or lithium alcoholate and a magnesium and/or an aluminum compound, a sterically hindered phenol or amine is added.

Abstract: Process for polymerising alpha-olefins in which at least one alpha-olefin is placed in contact, in polymerising conditions, with a catalytic system comprising at least one catalytic complex (a) based on a metal (M) of groups 6 to 12 of the Periodic Table, at least one trialkylaluminium (b) corresponding to the general formula AIR3, in which each R represents, independently, a linear alkyl group containing from 1 to 30 carbon atoms, at least one trialkylaluminium (c) corresponding to the general formula AIR′3, in which each R′ represents, independently, a branched alkyl group containing from 3 to 30 carbon atoms, such that the molar ratio of trialkylaluminium (c) to trialkylaluminium (b) is at least 2.

Abstract: Process for polymerizing &agr;-olefins Process for polymerizing x-olefins, in which at least one &agr;-olefin is placed in contact, under polymerizing conditions, with a catalytic system comprising

Abstract: A polymerization process for styrene derivatives in which a styrene monomer is placed in contact with a catalyst system in a solvent, including at least:

Abstract: A process for the continuous anionic polymerization or copolymerization of styrene or diene monomers using an alkali metal alkyl compound as polymerization initiator is carried out in the presence of an alkyl- or arylmetal compound of an element which occurs in at least divalent form as rate regulator, preferably under non-isothermal conditions and without back-mixing in a tubular or tube-bundle reactor, preferably using an alkyl- or arylmetal compound A of the formula R1M1 and an alkyl- or arylmetal compound B of the formula R2nM2 in a molar ratio between B and A of from 0.1:1 to 500:1, where M1 is Li, Na or K; R1 is hydrogen, C1-C20-alkyl, C6-C20-aryl, or C7-C20-alkyl-substituted aryl; M2 is an n-valent element from group 2a, 2b or 3a of the Periodic Table; and R2 is hydrogen, halogen, C1-C20-alkyl or C6-C20-aryl; and a special anionic polymerization initiator containing no Lewis base.

Abstract: In a process for the homopolymerization of vinylaromatic monomers or the copolymerization of vinylaromatic monomers and dienes, the monomers are polymerized in the presence of at least one alkali metal organyl, at least one magnesium organyl and at least one aluminum organyl. The invention also provides an initiator composition for carrying out the process.

Abstract: In a process for the homopolymerization of vinylaromatic monomers or the copolymerization of vinylaromatic monomers and dienes in the presence of at least one alkali metal compound and at least one compound of an element of group 3a of the Periodic Table of the elements, the compounds contain, based on the sum of molar equivalents of alkali metal and elements of group 3a, in each case a) from 0.1 to 3.9 molar equivalents of oxygen, sulfur, nitrogen or phosphorus and b) from 0.1 to 3.9 molar equivalents of an organyl ligand.