Recent Advancements in Nickel-catalyzed Olefin Polymerization: Molecular Design, Mechanistic Insights, and Sustainable Polyolefin Materials

Abstract

Polyolefins, defined as polymers that are widely synthesized, are significant to modern civilization owing to their flexibility and affordability. Nevertheless, conventional polyolefins have limitations in terms of their sustainability and usefulness. Recent innovations in nickel-based catalysts have radically altered olefin polymerization, facilitating precise regulation of the polymer microstructure and integration of polar monomers. This review addresses the recent developments in α-diimine nickel catalysts, SHOP-type systems, and iminopyridyl-based complexes, focusing on the impact of steric and electronic ligand alterations on thermal robustness, catalytic activity, and molecular weight control. To clarify its function in adjusting the mechanical and thermal characteristics, the chain-walking mechanism, which is essential for creating branched architectures, was broken down. Breakthroughs, including supramolecular shielding and fluorine effects, in addition to dinuclear architectures, have led to ultrahigh-molecular-weight polyethylenes (UHMWPEs), semicrystalline materials, and thermoplastic elastomers directly from ethylene. In addition, the resulting approaches for copolymerizing ethylene with polar monomers (acrylates, norbornene) or carbon monoxide have revealed routes to functionalized and photodegradable polyolefins. Despite these outcomes, challenges remain in accomplishing highly polar comonomer incorporation and commercial scalability. This review highlights nickel catalysts as an adaptable framework for sustainable polyolefin innovation, connecting academic research with applications in packaging, biomedicine, and recyclable materials.