(608c) Syndiotactic Styrene Polymerization on a Flat-Surface Deposited Metallocene Catalyst

Syndiotactic polystyrene (sPS) is a semicrystalline material having excellent heat and chemical resistant properties. In our previous work[1, 2], we observed peculiar nascent polymer morphology chracterized by fiber-like structures when styrene was polymerized over heterogenized cyclopentadiency titanium methoxide catalyst with methylaluminoxane cocatalyst in a liquid slurry process. The observed sPS morphology is very different from the globular morphology commonly observed in a-olefin polymers with similar heterogeneous catalysts. The X-ray diffraction analysis also indicates that the sPS forms a delta-form crystals that have molecular cavities inside. In this work, we prsent novel experimental results on the mechanism of sPS morphology development using the metallocene catalyst supported onto a two-dimensional or flat surface. The polymerization on a flat surface allows for the direct observations of the formation and growth of polymer fibrils at various polymerization conditions. Such observations are difficult to make in a three dimensional structure such as silica-supported catalysts. Our experimental work is focused on how each polymer chain grown from a catalytic site interacts with nearby polymer chains to develop into a fibrillar structure. The nascent morphology of sPS grown from the flat catalyst surface was observed by scanning electrons microscopy (SEM) and atomic force microscopy (AFM).

References 1. Lee HW, Chung JS, Choi KY. Polymer 2005; 46(14): 5032-5039. 2. Han JJ, Choi KY. Kinetics and Morphological Development in Syndiotactic Styrene Polymerization over Heterogeneized Metallocene Catalysts. AIChE annual meeting; 2005 Oct. 30 - Nov. 4; Cincinnati, Ohio.