CGC-Scandium-Mediated Copolymerization of Ethylene with Amine-Functionalized Cyclic Olefins

Direct coordination copolymerization of polar monomers with olefin should be the most atom- and energy-efficient strategy to prepare functional polyolefins, which encounters challenges to trade-off the activity and polar monomer incorporation and molecular weight of the afforded product. Herein, we report that using the fluorenyl-modified N-heterocyclic carbene-ligated scandium complex, the copolymerization of ethylene with N-(phenyl)-cis-5-norbornene-endo-2,3-dimethylene (NPh) was achieved with high activity (2580 kg·molSc–1·h–1) and high incorporation of NPh (31.6%). The investigation of several amine-substituted polar monomers indicated that the high activity and incorporation ability were attributed to the moderate steric and weak basicity of the amine group, which not only ensure the coordination priority of NPh but also facilitate its swift swing from the Sc–σ–N chelation mode to the Sc–π–C═C polymerization mode illustrated by density functional theory (DFT) calculation. This established a new polar group self-assisted mechanism, which will give inspirations to tackle the challenging issue in the copolymerization of olefin with polar monomers.