You-Xian Chen, M. Rausch, J. Chien
Sep 30, 1995
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0
Influential Citations
38
Citations
Journal
Journal of Polymer Science Part A
Abstract
Bis(1-indenyl)-di[(1'S, 2'R, 5'S)-menthoxy]silane (1) was converted into a mixture of corresponding ansa-diastereomeric zirconocenes. Further purification afforded a single diastereomer, di[(1'S, 2'R, 5'S)-menthoxy]silylene-bis[η 5 -1(R, R)-(+)-indenyl]dichlorozirconium (2), which is optically active and hydrocarbon soluble. Extremely rapid ethylene, propylene, and ethylene-hexene polymerizations were observed both in toluene and n-heptane solutions ; for instance, at 50°C, activity for ethylene polymerization reaches ∼ 1.5 X 10 10 (g of PE/((mol of Zr). [C 2 H 4 ]. h). The bare zirconocenium ion generated from 2/TIBA/Ph 3 CB(C 6 F 5 ) 4 exhibits unusual polymerization behaviors ; the polymerization activity increases monotonically with temperature of polymerization (T p ) up to a conventional polymerization condition (50-70°C), and the 13 C NMR study shows that the isotactic polypropylene obtained has fairly high [mmmm] methyl pentad distributions at high T p (> 25°C with [mmmm] ∼ 0.93-0.75) and a perfect stereoregularity at low T p (≤ 0°C with [mmmm] > 0.99). The catalyst precursors 2 and Et(Ind) 2 ZrCl 2 (3) supported on silica by different approaches produced poly(olefins) of different molecular weights and stereoregularities, and a methylaluminokane and Ph 3 CB(C 6 F 5 ) 4 free silica-supported zirconocene system was found to be activated by triisobutylaluminum.