Transfer products, polymer-metal systems, molecular

As a result of the particularities of the MAO activation method noticed so far, it has been concluded that, besides chain back-skip, a different mechanism occurs when using this cocatalyst. One possible explanation might be a reversible chain transfer reaction between the cocatalyst and the active species. As a result of the intrinsic chirality at the metal center, the catalytic system consists of two enantiomers (S and/ . Scheme 9.3). Under different polymerization conditions (i.e., different Al/Zr ratios), the coordination and insertion of the monomer can take place at the metal center of either of the two enantiomers. At higher Al/Zr ratios, a unidirectional transfer of polymer chains from Zr (enantiomer / , for example) to aluminum can be suggested, because reduced molecular weights of the polymer products have been found. Relocation of the chain from aluminum to the other enantiomer of the Ci-symmetric catalyst species (enantiomer 5, Scheme 9.3) and then back... 

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