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The Role of Allylanisole in Metallocene‐Catalyzed Propylene Polymerization and Synthesis of End‐Capped Oligomers
Author(s) -
Atiqullah Muhammad,
Akhtar Muhammad N.,
Tinkl Michael,
Ahmed Neaz
Publication year - 2008
Publication title -
macromolecular reaction engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 32
eISSN - 1862-8338
pISSN - 1862-832X
DOI - 10.1002/mren.200700053
Subject(s) - methylaluminoxane , polymer chemistry , metallocene , tacticity , polymerization , chain transfer , catalysis , molar mass distribution , propylene oxide , chemistry , post metallocene catalyst , materials science , organic chemistry , copolymer , polymer , radical polymerization , ethylene oxide
Propylene was copolymerized with allylanisole (AA) using Me 2 Si(Ind) 2 ZrCl 2 and Et(Ind) 2 ZrCl 2 , and the methylaluminoxane MAO cocatalyst at 70 °C and a cocatalyst to catalyst (Al:Zr) molar ratio of 1 000. It was fed at 8.5 bar(g). The weight‐average molecular weight, $\overline M _{\rm w}$ , for both metallocenes decreased as the AA feed concentration increased. Therefore, allylanisole acted as an in situ chain transfer agent. The chain transfer constants, k tr / k p , of AA for Et(Ind) 2 ZrCl 2 and Me 2 Si(Ind) 2 ZrCl 2 turned out to be 0.33 and 0.40, respectively. The characterization of the resulting products by 1 H NMR demonstrated that AA end‐capped the isotactic poly(propylene) chains which showed to be low molecular weight oligomers; 4.96 × 10 3 ≤ $\overline M _{\rm w}$ ≤ 9.80 × 10 3 . An appropriate chain transfer mechanism for AA has been proposed.