“Living Polymers” on Polymerization with Extremely Productive Ziegler Catalysts

TLDR

Hydrogen transfer generates zirconium hydrides that add ethylene to form alkyl intermediates, creating active sites for polymerization. The Cp₂ZrMe₂/[Al(Me)O]ₙ Ziegler catalyst produces over 10,000 polyethylene chains per zirconium atom, yielding polymers with 100,000–200,000 molecular weight, consistent with organozirconium diffusion into aluminoxane associates. An equation image is included.

Abstract

At least 10000 polyethylene molecules per zirconium atom can be obtained with a Ziegler catalyst made up of Cp 2 ZrMe 2 and [Al(Me)O] n . Depending upon the conditions, the molecular weight of the polymer lies between 100000 and 200000. All the results available so far are in accord with the following concept: A molecule of organozirconium compound diffuses into an associate of aluminoxanes. H‐transfer leads to zirconium hydrides which add ethylene to form alkyl compounds and thus give rise to active sites. equation image