Journal
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
Volume 45, Issue 20, Pages 4733-4743Publisher
WILEY
DOI: 10.1002/pola.22221
Keywords
catalytic polymerization; late transition metal; metal-organic catalysts/organometallic; catalysts; microstructure; norbornene; polyolefins; transition metal; chemistry; vinyl-addition polymerization
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Norbornene polymerizations proceeded in toluene with bis(f-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(/l-ketoamino)nickel(II)/B(C6F5)(3) catalytic systems showed noticeably high conversions and activities. The polymerization activities were up to 3.64 x 10(7) g of polymer/mol of Ni h for complex 1/(B(C6F5)(3) and 3.80 x 10(7) 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, H-1 NMR, and C-13 NMR spectra, and the thermogravimetric analysis results showed that the polynorbornenes exhibited good thermal stability (decomposition temperature > 410 degrees C). (c) 2007 Wiley Periodicals, Inc.
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