Radical co-polymerization of diiminedibromidenickel(II)-functionalized olefin with styrene: synthesis of polymer-incorporated nickelII α-diimine catalysts for ethylene polymerization Original Research Article

α-Diimine nickel catalyst bearing two allyl groups [ArN=C]2C10H6NiBr2 (Ar=4-allyl-2,6-(i-Pr)2C6H2)] (Cat-1) has been synthesized and characterized. The corresponding polymer-incorporated nickel catalysts PC and the SiO2-supported shell-core structure catalyst SC-1 were obtained by the co-polymerization of the olefin groups of Cat-1 with styrene in the presence of a radical initiator. Radical co-polymerizations with styrene in solution were investigated in detail, and the compositions and molecular weight of the copolymers were determined. All three types of catalysts (Cat-1, PC and SC-1) have been investigated for ethylene polymerization. These catalysts were found to exhibit high activity in the presence of modified methylaluminoxane (MMAO) as a co-catalyst. Among them, the polymer-incorporated PC and SiO2 shell-core catalyst SC-1 displayed very high activity (∼2.62 and ∼1.11 kg (mmol Ni)−1 h−1, respectively) with product molecular weights (Mw) in the range 26×104 to 47×104 under 0.1 MPa ethylene pressure. The particle morphology of polyethylene produced by the shell-core structure catalyst SC-1 was improved.