Postmetallocene Chelate Initiators

Data from Fan et al. [2001], e Data from Ojala and Fink [1988]. 

1 Data from Tritto et al. [2002]. i Data from Mazzanti et al. [I960]. k Data from Soga and Yanagihara [1989]. 

Copolymerization of ethylene with a cycloalkene, especially a bulky one such as norhor-nene, yields an alternating copolymer if the comonomer feed is rich in the cycloalkene [Wendt et al., 2002], 

The search for new initiators continues past the metallocenes. There is always the desire to produce polymers with different structures in a controlled manner hy selective choice of the initiator. New initiators might produce polymers with structures different from those obtained by the metallocenes, such as branched instead of unbranched structures or different stereoregularity or different molecular weight. Finally, commerical interests require a continuing search for new initiators that have not yet been patented. Several of the newer classes of stereoselective initiators are described below. They are referred to here by the general terms postmetallocene or chelate initiators. 

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