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Keywords:

  • norbornene;
  • addition polymerization;
  • copolymerization;
  • neutral nickel complex

Abstract

The facile and efficient functionalization of polynorbornene has been achieved through direct copolymerization of norbornene (NB) with 5-norbornene-2-yl acetate (NBA) or 5-norbornene-2-methanol (NBM) using a series of β-ketiminato Ni(II)-Me pyridine complexes 1–4 (Scheme 2) in the presence of B(C6F5)3. Remarkably, the monomer conversion could reach up to about 96% in 10 min in the NB/NBA copolymerization. The copolymers with wide NBA contents (3.3–38.4 mol %) were obtained by variation of reaction conditions. These copolymers have high molecular weights (MWs) (Mn = 41.8–144 kg/mol) and narrow MW distributions (Mw/Mn = 1.80–2.27). In the absence of alkyl aluminum compounds, a monomer conversion of 81% was observed in the NB/NBM copolymerization, and copolymers with NBM content in the range of 11.2–21.8 mol % were obtained by variation of reaction conditions. In addition, Ni(II)-Me pyridine complexes 2 was very active at a low B/Ni molar ratio of 6, while bis-ligand complex 6 bearing the same ligand just showed moderate efficiency at a high B/Ni molar ratio of 20. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011