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

Abstract α-Diimine nickel catalyst bearing two allyl groups [ArN=C] 2 C 10 H 6 NiBr 2 (Ar=4-allyl-2,6-(i-Pr) 2 C 6 H 2 )] ( Cat-1 ) has been synthesized and characterized. The corresponding polymer-incorporated nickel catalysts PC and the SiO 2 -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 SiO 2 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 ( M w ) in the range 26×10 4 to 47×10 4 under 0.1 MPa ethylene pressure. The particle morphology of polyethylene produced by the shell-core structure catalyst SC-1 was improved.