Abstract
The polymerization of butadiene (Bd) with chromium(III) acetylacetonato [Cr(acac)3]-trialkylaluminum (AlR3) or methylaluminoxane (MAO) catalysts was investigated for the synthesis of 1,2-poly(Bd). The polymerization of Bd was found to proceed with Cr(acac)3-AlR3 (R-Me, Et, i-Bu) catalysts to give poly(Bd) with a high 1,2-vinyl content, but highly isotactic 1,2-poly(Bd) was not synthesized. The Cr(acac)3-MAO catalyst gave a polymer consisting of low 1,2 units. The effects of the Al/Cr mole ratios on the polymerization of Bd with the Cr(acac)3-AlR3 catalysts were observed. With an increase of Al/Cr mole ratios, the isotactic (mm) content of the polymer increased but the 1,2-vinyl contents decreased. The effects of the aging time and temperatures of the catalysts on the polymerization of Bd with the Cr(acac)3-AlR3 catalysts were also observed, and the lower polymerization temperature and the prolonged aging time were favored to produce the 1,2-vinyl structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1621–1627, 2000
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