Synthesis of highly branched polyethylene and ethylene-MA copolymers using hybrid bulky α-diimine Pd(II) catalysts

Abstract

The types and sizes of N-o-aryl substituents in the α-diimine ligands strongly influence the ethylene (co)polymerization. Also, the combination of different substituents may play an unexpected role. A new class of bulky unsymmetrical acenaphthene-based α-diimine Pd(II) catalysts utilizing bulky “hybrid” anilines were designed, synthesized and characterized in this study. In ethylene polymerization, the α-diimine Pd(II) catalysts exhibited moderate activities, generating highly branched polyethylene with reasonable molecular weight. Moreover, these Pd(II) catalysts were also capable of preparing polar functionalized E-MA copolymers with moderate molecular weights and high incorporation ratios in the copolymerization of ethylene with methyl acrylate. Notably, compared to symmetrical bulky Pd(II) catalysts, the “hybrid” unsymmetrical system produced highly branched polyethylene and E-MA copolymers significantly.