Phosphinobenzenamine Nickel Catalyzed Efficient Copolymerization of Methyl Acrylate with Ethylene and Norbornene

A series
of phosphinobenzenamine-based nickel complexes bearing
substituted phenylphosphine ligands were synthesized and characterized.
These nickel complexes combined with methylaluminoxane (MAO) exhibited
very high activity (∼106 g mol–1 h–1) and good thermal stability for norbornene
polymerization. The nickel catalysts were able to conduct copolymerization
of norbornene and methyl acrylate (MA) with high activity (3.76 ×
105 g mol–1 h–1) to
give high-molecular-weight functionalized cyclic olefin copolymer
(COC) with reasonable MA incorporation (2.39–6.47 mol %). Moreover,
the nickel catalysts also promote the copolymerization of ethylene
and MA with moderate activity (∼104 g mol–1 h–1) to produce semicrystalline high-molecular-weight
polar functionalized polyethylene (PE). The MA incorporation in the
copolymer was controlled in a wide range (up to 15.5 mol %). These
complexes without any sterically bulky substituent on the ligand are
distinctive examples of earth-abundant nickel complexes toward the
direct copolymerization of ethylene or norbornene with the challenging
vinyl polar monomer MA.