A Facile Neutral Nickel Catalyst Platform for High-Temperature Solution Copolymerization of Ethylene and Acrylate

Polyolefins are among the most important large-scale polymers. High-temperature solution polymerization is one of the most effective methods for preparing high-performance polyolefins. Although advanced high-temperature solution copolymerization of ethylene and polar olefins (especially acrylates) is highly desirable for producing value-added polar polyolefins, it poses significant challenges in chemistry and catalysis, including low catalyst thermostability and low polymer molecular weight at temperatures exceeding 100°C. To address these issues, this study proposes design principles for an innovative neutral α-ketocarboxamide nickel catalyst platform rather than modifying previously reported nickel catalysts. This new generation of nickel catalysts not only offers inherent advantages, including facile synthesis, air stability, and exceptional thermostability (150°C), but also enables high-temperature solution copolymerization of ethylene and acrylates (methyl, n-butyl, and tert-butyl acrylates), producing high-molecular-weight copolymers without the need for cocatalysts. At the industrially preferred 110°C-150°C, ethylene-acrylate copolymers with molecular weights of 103-627 kDa were obtained, which are 4-19 times higher than those produced by previous catalysts. Transitioning from low- to high-molecular-weight ethylene-acrylate copolymers is vital for practical industrial applications. Mechanistic insights revealed the feasibility of ethylene-acrylate copolymerization. Overall, this study establishes a conceptual foundation for high-temperature solution copolymerization of ethylene and acrylates.