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 c atalyst has been prepared by spin-coat impregnation from an aqueous solutio n of CrO3. In order to test the model catalyst with its extremely low chrom ium content, a special reactor was designed with a CrOx/Al2O3 filter to eff ectively remove impurities. The model catalyst polymerizes ethylene in the gas phase at 160 degrees C with a constant activity and forms a 350-nm-thic k layer of polyethylene in 1 h. Atomic force microscopy reveals the expecte d spherulite morphology of the polyethylene films in different stages of de velopment. The work opens attractive opportunities for future studies of na scent morphology of catalytically formed polymers. (C) 1999 Academic Press.