Preparation of Polyhedral Oligomeric Silsesquioxane-Supported Ziegler–Natta Catalyst and Its Application for Stereoselective Propylene Polymerization

In this study, a polyhedral oligomeric silsesquioxane (POSS)-MgCl bisupported TiCl4 catalyst was synthesized through the treatment of trisilanolisobutyl POSS with Grignard reagent, followed by anchoring TiCl4. The resulting catalyst could catalyze the propylene polymerization with very high activity after activation by a cocatalyst. Meanwhile, it is noteworthy that, as the cage structure of POSS contains a silicone ether structure, the isotactic index of the obtained polypropylene (PP) exceeds 90%, even in the absence of an electron donor. Additionally, because of the uniform dispersion of POSS in the PP matrix during polymerization and good interfacial compatibility, the obtained PP/POSS nanocomposites possess not only excellent thermal stability but also excellent mechanical properties. Therefore, a high-activity catalytic propylene stereoselective polymerization catalyst was developed and provided a feasible method for the fabrication of high-performance PP/POSS nanocomposites.