A Flat Model Approach to Ziegler-Natta Catalystsfor Propylene Polymerization and a PreparationMethod of Well-defined Crystallites ofMgCl_2-supported Catalysts

摘要

An active model for a Ziegler-Natta propylene polymerization catalyst hasbeen prepared by spin-coating of a MgC12/diether donor solution in ethanol on a flatsilica wafer, followed by crystal growth by Ostwald ripening to give well-definedMgCl2 diether nEtOH crystallites.The flat model approach facilitates detailedcharacterization of the catalyst and polymer using surface spectroscopy and micro-scopy techniques. The growth of the crystallites on the flat silica indicates formationof only 12o edge angles, suggesting the preference for the formation of oneparticular crystallite face for the MgCl2. Subsequent treatment with TiCI4 generatesthe catalyst and in propylene polymerization polymer forms on the lateral face ofeach crystallite.