Highly Active and Thermally Robust Nickel Enolate Catalysts for the Synthesis of Ethylene-Acrylate Copolymers

The insertion copolymerization of polar olefins and ethylene remains a significant challenge in part due to catalysts ' low activity and poor thermal stability. Herein we demonstrate a strategy toward addressing these obstacles through ligand design. Neutral nickel phosphine enolate catalysts with large phosphine substituents reaching the axial positions of Ni achieve activity of up to 7.7x10(3) kg mol(-1) h(-1) (efficiency >35x10(3) g copolymer/g Ni) at 110 degrees C, notable for ethylene/acrylate copolymerization. NMR analysis of resulting copolymers reveals highly linear microstructures with main-chain ester functionality. Structure-performance studies indicate a strong correlation between axial steric hindrance and catalyst performance.

Automated summary

We address the challenge of insertion copolymerization of polar olefins and ethylene by designing ligands. The neutral nickel phosphine enolate catalysts with large phosphine substituents at the axial positions of Ni exhibit high activity and result in highly linear copolymers. The study reveals a strong correlation between axial steric hindrance and catalyst performance.