Synthesis of two novel α-diamine nickel catalysts, supported on carbon nanotubes, and their properties of alkene polymerization

Based on the conventional α-diamine framework, two novel nickel-based catalysts ( Ni1 and Ni2 ) were designed and synthesized by using acenaphthenequinone and Ni(DME)Cl ₂ , with 2,6-R ₂ -aniline [R = OMe ( 1 ) or Ph ( 2 )] as precursors. To evaluate the catalytic activity of Ni1 and Ni2 , three alkene monomers — styrene, 1,3-butadiene, and isoprene — were polymerized under varying reaction conditions. The results demonstrated that the maximum yields achieved with Ni1 were 93.72%, 81.71% and 93.15%, respectively, while Ni2 yielded 88.21%, 65.39%, and 95.60% for the same monomers. Subsequently, two supported catalysts ( Ni1@CNT and Ni2@CNT ) were synthesized by immobilizing Ni1 and Ni2 onto carbon nanotubes (CNTs). The reusability of these supported catalysts was investigated. Under the optimal conditions for Ni1 and Ni2 , it was observed that after five consecutive cycles, the catalytic activities of Ni1@CNT and Ni2@CNT remained nearly unchanged, maintaining performance levels comparable to the initial cycle.