Vinyl polymerization of norbornene with pyrazolylimine nickel(II)/methylaluminoxane catalytic systems

✍ Scribed by Yuan-Yuan Wang; Shang-An Lin; Fang-Ming Zhu; Hai-Yang Gao; Qing Wu

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 89 KB
• Volume: 110
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.28759

✦ Synopsis

Abstract

The polymerization of norbornene (NBE) was investigated in the presence of two novel pyrazolylimine nickel complexes [2‐(C~3~HN~2~Me~2~‐3,5){C(Ph)[4‐R~2~C~6~H~2~(R~1~)~2~‐2,6]}NiBr~2~ (complex 1, R~1~ = ^i^Pr and R~2~ = H; complex 2, R~1~ = H and R~2~ = NO~2~)] activated by methylaluminoxane. The two catalytic systems showed high activity [up to 1.27 × 10^6^ g of polynorbornene (PNBE)/(mol of Ni h)] for NBE polymerization and provided PNBEs with high molecular weights (weight‐average molecular weight ≤ 17.46 × 10^5^ g/mol) and narrow molecular weight distributions (ca. 2). The electron withdrawing of the nitro group in complex 2 could not enhance the catalytic activity for NBE polymerization; however, the molecular weights of the polymers were increased. The catalytic activity, molecular weight, and molecular weight distribution were influenced by the polymerization conditions, such as the polymerization temperature and Al/Ni molar ratios. The obtained PNBEs were characterized by means of ^1^H‐NMR and Fourier transform infrared spectroscopy techniques. The analysis results for PNBEs indicated that the NBE polymerization was a vinyl‐type polymerization rather than a ring‐opening metathesis polymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008