A series of α‐diimine nickel(II) catalysts bearing different para‐substituted groups, {[(4‐R‐2,6‐Me2‐C6H2NC)2Nap]NiBr2, Nap: 1,8‐naphthdiyl; R = CHMePh (C1); R = CHPh2 (C2); R = tBu (C3); R = Br (C4); R = Me (C5)}, were synthesized and characterized. The molecular structures of C1 and C3 were determined by single crystal X‐ray analysis and show distorted tetrahedron geometry with C2v symmetry. The catalytic behaviors of these catalysts toward ethylene polymerization were investigated in the presence of diethylaluminum chloride (Et2AlCl) as a cocatalyst. The fast chain‐walking process in N,N‐chelated nickel system can be efficiently modulated via the introduction of para‐sec‐phenethyl substituents with improved thermal stability and catalytic performance. C1‐Et2AlCl exhibited high thermal stabilities and high activities reaching 4.61 × 106 g PE (mol Ni h)−1, producing highly branched amorphous polyethylenes (up to 143 branches/1000C) with high molecular weight and narrow polydispersity. This catalyst system conducted successfully conducted 2‐octene polymerization in comparison with the corresponding 1‐octene polymerization. The result demonstrated 2‐octene polymerized slower than 1‐octene and produced the highly‐branched poly(2‐octene)s with approximately 120 branches/1000C, including methyl, ethyl, amyl, and hexyl branches and a small amount of the long methylene sequence due to monomer isomerization.

More importantly, the structure and properties of the polymer products can be controlled by catalyst structures, polymerization conditions and heterogenization to achieve good mechanical properties and elasticity.

Transition-metal-based olefin polymerization catalysts usually require activation with a cocatalyst to initiate polymerization reactions. Borane type cocatalyst is one of the most important classes of cocatalysts that can significantly influence the catalytic performances. In this contribution, we designed and prepared a series of borane cocatalysts, and subsequently investigated their properties in a titanium-based Constrained Geometry Catalyst (CGC-Ti) catalyzed ethylene polymerization and ethylene/1-octene copolymerization. Among these borane cocatalysts, B(C 6 F 5 ) 2 OtBu exhibited outstanding cocatalyst per-formances, achieving activity of up to 1.06 × 10 7 g mol À 1 h À 1 and polymer molecular weight of up to 88.2 × 10 4 g mol À 1 in ethylene polymerization. In ethylene/1-octene copolymerization, this borane enabled activity of up to 2.46 × 10 6 g mol À 1 h À 1 , affording copolymers with comonomer incorporation of up to 12.8 % and copolymer molecular weight up to 18.3 × 10 4 g mol À 1 . The superior properties of B(C 6 F 5 ) 2 OtBu originated from its unique activation mode with the oxygen atom being coordinated to the active metal center.

As polyolefins are a predominant class of polymers used globally, tandem ring-opening metathesis polymerization (ROMP) and hydrogenation represent a powerful strategy to prepare functionalized polyolefins. In this contribution, we demonstrated...

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