Synthesis of polyethylene thermoplastic elastomer by using robust α‐diimine Ni(II) catalysts with abundant tBu substituents

Abstract

AbstractThe synthesis of polyethylene thermoplastic elastomers via α‐diimine‐nickel‐catalyzed ethylene polymerization using polymerization conditions of elevated temperatures and alkane solvents is highly desirable in industrial production. In this contribution, we constructed a series of highly sterically demanding α‐diimine Ni(II) catalysts with abundant tBu substituents for this purpose. These nickel catalysts were examined for ethylene polymerization in hexanes at elevated temperatures (up to 90°C) and proved to be thermally robust at temperatures as high as 90°C. Generally, these nickel catalysts can generate highly branched (ca. 70–80/1000°C) polyethylenes with very high molecular weight (Mn up to 55.79 × 104 g/mol) and the resultant polyethylenes displayed characteristics of thermoplastic elastomers with excellent elastic recovery (SR up to 84%). Compared with some similar α‐diimine Ni(II) catalysts, it is shown that the presence of axial remote tBu substituents not only facilitates the dissolution of the catalyst in alkanes, but also improves the elastic recovery value of the obtained polyethylene.