Addition polymerization of norbornene using bis(β‐ketoamino)nickel(II)/tris(pentafluorophenyl)borane catalytic systems

Abstract

AbstractNorbornene polymerizations proceeded in toluene with bis(β‐ketoamino)nickel(II) {Ni[CH3C(O)CHC(NR)CH3]2 [R = phenyl (1) or naphthyl (2)]} complexes as the catalyst precursors and the organo‐Lewis compound tris(pentafluorophenyl)borane [B(C6F5)3] as a unique cocatalyst. The polymerization conditions, such as the cocatalyst/catalyst ratio (B/Ni), catalyst concentration, monomer/catalyst ratio (norbornene/Ni), polymerization temperature, and polymerization time, were studied in detail. Both bis(β‐ketoamino)nickel(II)/B(C6F5)3 catalytic systems showed noticeably high conversions and activities. The polymerization activities were up to 3.64 × 107 g of polymer/mol of Ni h for complex 1/(B(C6F5)3 and 3.80 × 107 g of polymer/mol of Ni h for complex 2/B(C6F5)3, and very high conversions of 90–95% were maintained; both polymerizations provided high‐molecular‐weight polynorbornenes with molecular weight distributions (weight‐average molecular weight/number‐average molecular weight) of 2.5–3.0. The achieved polynorbornenes were confirmed to be vinyl‐addition and atactic polymers through the analysis of Fourier transform infrared, 1H NMR, and 13C NMR spectra, and the thermogravimetric analysis results showed that the polynorbornenes exhibited good thermal stability (decomposition temperature > 410 °C). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4733–4743, 2007