Polyethylene formation on a planar surface science model of a chromium oxide polymerization catalyst

A planar CrOx/SiO2/Si(100) model for the Phillips ethylene polymerization catalyst has been prepared by spin-coat impregnation from an aqueous solution of CrO3. In order to test the model catalyst with its extremely low chromium content, a special reactor was designed with a CrOx/Al2O3 filter to effectively remove impurities. The model catalyst polymerizes ethylene in the gas phase at 160 degrees C with a constant activity and forms a 350-nm-thick layer of polyethylene in 1 h. Atomic force microscopy reveals the expected spherulite morphology of the polyethylene films in different stages of development. The work opens attractive opportunities for future studies of nascent morphology of catalytically formed polymers. (C) 1999 Academic Press.