Catalytic synthesis of polyethylene-block-polynorbornene copolymers using a living polymerization nickel catalyst

Abstract

Polyethylene-block-polynorbornene (PE-b-PNB) copolymers were synthesized using an amine–imine nickel catalyst by sequential monomer addition in a living fashion. Norbornene homopolymerizations catalyzed by amine–imine nickel catalyst were firstly evaluated and high-molecular-weight polynorbornenes (PNBs) with polydispersities of 1.9–3.0 were produced. Introduction of the PE building block can significantly slow down the insertion rate of the norbornene monomer to afford a low-molecular-weight PNB block. Well-defined PE-b-PNB block copolymers (M_w/M_n < 1.16) were prepared by combination of living polymerization of ethylene for 15 min and sequential polymerization of norbornene. The block copolymer architecture was studied and confirmed by FT-IR, NMR, DSC, and transmission electron microscopy (TEM).