Polyolefin spheres from metallocenes supported on noninteracting polystyrene
To obviate the destructive interaction of highly reactive metallocene catalysts with classical silica-based supports while retaining the advantage of supported catalysts, a noninteracting polystyrene support was developed. Supported catalysts for the polymerization of alpha-olefins are prepared by treating lightly cross-linked, chloromethylated polystyrene beads consecutively with a secondary amine, an ammonium salt of a weakly coordinating anion, and a neutral dialkylmetallocene. Catalytic sites are distributed homogeneously throughout the support particle, and the polymerization occurs within the bead, in contrast to traditional surface-supported metallocene catalysts. The copolymerization of ethylene and 1-hexene at 40 degreesC affords discrete spherical polyolefin beads with a size (0.3 to 1.4 millimeters) that varies according to the polymerization time.
Roscoe
SB
S. B. Roscoe and J. M. J. Frechet, Department of Chemistry, University of California, Berkeley, CA 94720, USA. J. F. Walzer and A. J. Dias, Baytown Polymer Center, Exxon Chemical Company, 5200 Bayway Drive, Baytown, TX 77520, USA.
Frechet
JMJ
Walzer
JF
Dias
AJ