Single-center vs. multi-center post-metallocene catalysts for propylene polymerizationстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The article describes structural characteristics of polypropylene prepared with two post-metallocene catalysts containing bidentate Ti complexes activated with MAO. Analysis of polymers and their fractions by a combination of GPC, 13C NMR, IR, DSC, and XRD methods shows that different bidentate complexes can produce either single-site or multi-site catalysts systems. The multi-site catalysts are characterized by very broad molecular weight distributions (see GPC curves). Some of the active centers in them produce high molecular weight, highly isotactic crystalline materials with the melting points >150 °C. The nature of steric errors in these polymer fractions determined by 13C NMR can be explained by a variant of stereocontrol similar to that exerted by metallocene catalysts of the C1 symmetry.