Homo- and hetero-polymerization of ethylene catalyzed by α-diimine nickel complexes with hydroxyl groups

Abstract

Heterogeneous olefin polymerization catalysts have received wide interests from academia and industry because their distinct advantages in thermostability, avoidance of reactor fouling and continuous production operations. In this work, hydroxy functional groups are introduced to the α-diimine nickel framework, which can serve as reactive functionality to react with MgCl2/AlRn(OEt)3-n and form ionic anchoring interaction that bind the catalyst strongly to the surface of the supports. These heterogeneous catalysts are highly active in ethylene polymerization to produce polyethylene with higher molecular weight (up to 280.5 × 104 g·mol−1), lower branching density and higher tensile strength (up to 26.7 MPa) than those generated by the homogeneous counterparts. More importantly, the nickel complexes with multiple hydroxy groups lead to high loading capacity on MgCl2/AlRn(OEt)3-n supports, affording polyethylene products with minimum inorganic contamination.