Martin Stork

Ethylene polymerization using crosslinked polystyrene as support for zirconocene dichloride/methylaluminoxane

In this paper we report on a zirconocene dichloride/methylaluminoxane catalyst system supported on a crosslinked polystyrene in order to provide ethylene polymerization catalysts for gas phase or slurry processes. Our novel approach uses the Diels-Alder reaction of cyclopentadiene functions as the final, cross-linking synthetic step. This provides polymer supported zirconocene catalysts with a homogeneous distribution of active sites. The catalysts were shown to be highly active and to form spherical beads as proven by scanning electron microscopy.

Reversibly Crosslinked Polystyrene as a Support for Metallocenes Part I: Covalently Bonded Metallocenes and Functionalized Supports

Via radical polymerization and followed by polymer analogous transformations cyclopentadienyl functionalized polystyrenes are generated. The pending cyclopentadienyl functions are used for the attachment of metallocenes and, furthermore, for the reversible formation of a network generated by a Diels Alder reaction. The resulting catalyst beads can be applied in the olefin homo- and copolymerization. A high activity as well as productivity is achieved. Films prepared by the obtained polyolefins exhibit a high transparency. These results suggest a fragmentation of the polymeric support, similar as in the silica case, induced by the reversibility of the Diels-Alder reaction. Additionally, by the incorporation of dyes into the polymeric support via copolymerization colored polyolefins can be generated.