Direct synthesis of fluorinated hyperbranched polyethylenes by chain walking copolymerization

Abstract

Hyperbranched polyethylenes synthesized via Pd-diimine chain walking polymerization possess distinctive structural features. Incorporation of fluorine is anticipated to further enhance their performance by imparting valuable attributes and thereby expanding their potential applications. In this work, we present the synthesis of a new series of fluorinated hyperbranched polyethylenes through chain walking copolymerization of ethylene with various fluorinated comonomers. The comonomers investigated include hexafluoroisopropyl acrylate (HFIPA), allylpentafluorobenzene (APFB), tridecafluorooctyl(allyl) ether (13FOAE), and 1H,1H,2H-perfluoro-1-hexene (PFH), with APFB, 13FOAE, and PFH employed for the first time in this polymerization system. The choice of comonomers markedly influenced catalyst activity and incorporation efficiency. Three comonomers, i.e., HFIPA, APFB, and 13FOAE, were found to be copolymerizable under the reaction conditions, with APFB delivering the highest catalytic activity and 13FOAE rendering highest comonomer incorporation at identical feed concentrations. Notably, even a low-level incorporation of fluorinated comonomers substantially reduced the surface energy of the resulting copolymers, while retaining their hyperbranched topology and low glass-transition temperature (ca. -69 °C).