Heterogeneous Nickel Catalysts for the Synthesis of Ethylene-Based Polyolefin Elastomers

Ethylene-based polyolefin elastomers (EPOEs) represent a novel class of polyolefin material prepared using ethylene as the only feedstock and bear comparable mechanical and elastic properties versus traditional polyolefin elastomers (POEs). EPOEs are prepared from late-transition-metal (nickel or palladium)-catalyzed chain walking polymerization of ethylene. However, the literature-reported potent catalysts are homogeneous systems that operate at relatively low temperatures (<90 °C), while the industrial production of POE materials requires high temperatures (>120 °C). In this contribution, we install some OM (M = H, Na, and K) tags in an α-diimine ligand framework, enabling facile heterogenization of the homogeneous nickel complexes onto a MgCl2-based solid support. The resulting heterogeneous nickel complexes are highly active in ethylene polymerization and demonstrate much better thermal stability (up to 150 °C) than their homogeneous counterparts. More importantly, the polyethylene products demonstrate super-stretchability (up to 2160%) while maintaining high tensile strength (up to 15.4 MPa) and high elasticity (strain recovery value of up to 83%). These EPOE materials can also be used to toughen polypropylene, as well as to compatibilize the blends of polyethylene and polypropylene.