Syndiospecific polymerization of propene under different processes with different bridged [(RPh) 2C(Cp)(2,7- tertBuFlu)]ZrCl 2 metallocene catalysts

Abstract

The synthesis of syndiotactic polypropene was achieved by using new C S -symmetric ansa-metallocene catalysts of the type [Ph′ 2C(Cp)(2,7- tert Bu 2Flu)]ZrCl 2 (Ph′ 2=Ph 2, (4-MePh) 2, 3,4′-Me 2Ph 2, (4-OCH 3Ph) 2). Applying these catalysts, the influence of the substitution pattern of the bridge on the polymerization performance can be studied and highly syndiotactic polypropene ( rrrr>99%) with high molar masses (M η>10 6 g/ mol) and high melting temperatures (up to 153 °C) was obtained. Propene was polymerized at different temperatures under four sets of conditions: in toluene solution, bulk, toluene slurry, and gas phase with NaCl as stirred bed material. Methylaluminoxane (MAO) and methylaluminoxane supported on silicagel (MAO/SiO 2) were used as cocatalyst, respectively. In order to estimate the influence of the process on the single site properties of the catalysts, comparisons were made between polymer properties, i.e. microstructure, melting temperature, molar mass, and polymer morphology, thus allowing the effect of the support on the catalyst to be observed.