218292-00-3Relevant academic research and scientific papers
Steric and electronic effects of R in (2-(4-R-C6H4)indenyl)2ZrCl2catalysts on the synthesis of elastomeric polypropylene
Lin, Shirley,Hauptman, Elisabeth,Lal, Tapan K.,Waymouth, Robert M.,Quan, Roger W.,Ernst, Andreas B.
, p. 23 - 33 (1998)
Metallocene catalysts derived from bis(2-arylindenyl)zirconium dichloride catalysts yield elastomeric stereoblock polypropylene. A study of the steric and electronic effects of varying the 4-substituent of bis(2-(4-R-C6 H4)indenyl)zirconium dichloride [(1 R=H, 2 R=Me, 3 R=Et, 4 R=nBu, 5 R=tBu, 6 R=SiMe3, 7 R=CF3, 8 R=Cl)] on propylene polymerization at 25, 50, 75 psig and bulk propylene revealed that the polymerization behavior of these catalysts is not strongly influenced by the nature of the substituent in the 4-position of the 2-aryl substituent. Examinations of the microstructure of the elastomeric polypropylenes produced showed that for catalysts 2-8 the isotacticities varied over a small range and were similar to those produced by catalyst 1 (20% ≤ [mmmm] ≤ 44%). The catalyst productivities and molecular weights also showed the same trend. Complex 3 was crystallographically characterized and was found to crystallize in exclusively the meso conformation.
