| 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 |
