Palladium-Catalyzed Synthesis of Hyperbranched Polar Functionalized Polyethylene with High Density Hydrophilic Groups

The chain-walking polymerization (CWP) strategy is a promising concept for the convenient synthesis of hyperbranched polar functionalized polyethylene with unique properties. In this study, we synthesized and described a series of o-aryl monosubstituted dibenzosuberyl iminopyridine ligands containing benzocycloalkyl or naphthyl moieties as well as the corresponding Pd(II) complexes, in a highly efficient manner. The Pd(II) complexes catalyzed efficient ethylene chain walking polymerization to produce hyperbranched polyethylenes (HBPEs) with high molecular weights (M- n values up to 71.4 kg/mol). Notably, copolymerization of ethylene and methyl acrylate, catalyzed by iminopyridine Pd(II) complexes, resulted in successful polar functionalized HBPEs with high density hydrophilic groups (21.4 mol %) at the end of branching. The polar functionalized HBPEs resulting from the process are saponified or reduced to yield more hydrophilic polymers that can solubilize water-insoluble drug molecules.

Automated summary

In this study, hyperbranched polar functionalized polyethylene was conveniently synthesized using the chain-walking polymerization (CWP) strategy. The ethylene chain walking polymerization catalyzed by Pd(II) complexes produced high molecular weight hyperbranched polyethylenes (HBPEs), and copolymerization of ethylene and methyl acrylate resulted in polar functionalized HBPEs with high density hydrophilic groups.