6533b837fe1ef96bd12a1f09

RESEARCH PRODUCT

Effect of AlR3 (R = Me, Et, iBu) addition on the composition and microstructure of ethylene/1-olefin copolymers made with post-metallocene complexes of group 4 elements

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The effect of trialkylaluminum compound (AlR3, where R = Me, Et, iBu) addition on the performance of the [LigZrCl]2(μ-O)/AliBu3/Ph3CB(C6F5)4 and LigTiCl2/AliBu3/Ph3CB(C6F5)4 (Lig = Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)2) catalysts in ethylene/1-olefin copolymerization was investigated. The presence of AlMe3 in the feed during the copolymerization process catalyzed by the diamine-bis(phenolate) zirconium catalyst greatly increases the amount of incorporated comonomer and leads to microstructural changes, e.g., the formation of blocky and alternating sequences of 1-olefin units. Moreover, the use of AlMe3 limits the reaction yield and decreases the molecular weight of the produced copolymers. The catalytic properties of the diamine-bis(phenolate) titanium catalyst were much less affected by trimethylaluminum; its use slightly decreased the catalyst activity and copolymer molecular weight. A lower molecular weight was also detected for the copolymers produced by catalysts in the presence of both AlEt3 and AliBu3, whereas they did not cause any important changes in the catalytic activity, overall composition or microstructure of the produced copolymers. Copolymerization tests with other catalytic systems, (LigFI)2ZrCl2/AliBu3/Ph3CB(C6F5)4 (LigFI = (C6H5)N = CH(2-O-3,5-tBu2-C6H2)) and Et(Ind)2ZrCl2/MMAO, in the presence of AlMe3, were also carried out for the purpose of comparison. The effect of trialkylaluminium compound (AlR3, where R = Me, Et, iBu) addition on the performance of the transition metal complex/AliBu3/Ph3CB(C6F5)4 catalysts in ethylene/1-olefin copolymerization was investigated. It was shown that AlR3 may affect the catalytic properties of the system (activity, comonomer incorporation, and copolymer microstructure). This influence is dependent on the type of organoaluminum compound and on the structure of the complex, i.e., on the structure of the ligand and on the type of transition metal.