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Synthesis and Characterization of Hyperbranched Polyethylenes Made with Nickel-α-Diimine Catalysts

✍ Scribed by Fábio A. Kunrath; Fábio F. Mota; Osvaldo L. Casagrande Jr.; Raquel S. Mauler; Roberto F. de Souza

Publisher
John Wiley and Sons
Year
2002
Tongue
English
Weight
111 KB
Volume
203
Category
Article
ISSN
1022-1352

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✦ Synopsis

Abstract

The polymerization of ethylene in the presence of 1,4‐bis(2,6‐diisopropylphenyl)acenaphthenediiminenickel(II) dichloride (1) and methylaluminoxane (MAO) gives hyperbranched polyethylene (HBPE) in appropriate reaction conditions. The system 1/MAO is active in solvents like toluene or hexane at temperatures as high as 80 °C and ethylene pressures ranging from 1 to 15 atm. The polyethylenes obtained show high molecular weights (up to 467 kg · mol^−1^) and more than 218 branches per 1 000 backbone carbon atoms, qualifying these materials as hyperbranched. Dynamic‐mechanical thermal analysis (DMTA) of these materials shows high β‐transitions, directly related to the branch content of these polyethylenes.
DMTA analysis of polyethylenes obtained with 1/MAO at 0, 30, and 50 °C (corresponding to entries 1, 2 and 3).

magnified imageDMTA analysis of polyethylenes obtained with 1/MAO at 0, 30, and 50 °C (corresponding to entries 1, 2 and 3).

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