Quasi-Living Polymerization of Propene with an Isotactic-Specific Zirconocene Catalyst

Propene polymerization with isotactic (iso)-specific C₂-symmetric rac-Me₂Si(2-Me-Benz(e)-Ind)₂ZrCl₂ (1) and rac-Me₂Si(2-Me-4-Ph-1-Ind)₂ZrCl₂ (2) were conducted under various conditions for achieving iso-specific living polymerization of propene. When Complex 1 was activated with trialkylaluminum-free modified methylaluminoxane (dMMAO) at -40 °C, the number-average molecular weight (M_n) linearly increased against the polymerization time to reach M_n = 704,000 within 15 min of polymerization, although the molecular weight distributions was broad (M_w/M_n < 3). Thus, it was found that quasi-living polymerization of propene proceeded in the 1-dMMAO system. The living nature of iso-polypropene was confirmed by the block copolymerization, where the M_n value increased from 221,000 to 382,000 after the addition of 1-octene to yield the block copolymer with a melting point of 150 °C.