Significant variation of molecular weight distribution (MWD) of polyethylene induced by different alkyl-Al co-catalysts using a novel surface functionalized SiO2-supported Ziegler-Natta catalyst

In this work, a novel surface functionalized SiO₂-supported Ziegler-Natta catalyst was developed for ethylene polymerization. A state-of-the-art control of some unique characteristic catalytic properties on the surface functionalized SiO₂-supported catalyst analogized from the previously reported poly[propylene-co-(7-methyl-1,6-octadiene)]-supported Ziegler-Natta catalyst had been successfully realized through a precise molecular level catalyst design on the silica gel surface functionalized with linear long alkene chains through the reaction between unsaturated alcohol 9-decene-1-ol and hydroxyl groups on the silica surface. The active sites of this SiO₂-supported catalyst prepared in this study showed very stable activity without obvious deactivation for more than 50 h and the molecular weight distribution of polyethylenes varied significantly from narrow and unimodal to broad and multimodal by solely changing the type of Al-alkyl cocatalyst from diethylaluminumchloride to triethylaluminum.