Metallocene Catalyzed Polymerization of Methylmethacrylate

摘要: Metallocenes are organometallic compounds consisting of two cyclopentadieny ligands and a transition metal, such as ferrocene [1]. One the most important properties metallocenes is their catalytic activity for olefin polymerizations [2]. Breslow et al. Natta [3] first reported polymerization ethylene using dicyclopentadienyltitanium dichloride (Cp2TiCl2) activated by an aluminum alkyl, diethylaluminum chloride in 1957. However, activities this system were very low, not effective propylene. In 1980, Shinn [4] discovered that dicyclopentadienylzirconium (Cp2ZrCl2) methylaluminoxane (MAO), which condensed products from trimethylaluminum water, showed extremely high polymerizations. Since discovery, with MAO systems have been investigated vigorously great progress has achieved field. 1980s, research on metallocene was focused stereospecific 1-olefins (mainly propylene). 1984, Ewen [5] mixture meso- rac-isomers ethylenebis(indenyl)-titanium (EtInd2TiCl2) upon activation affords isotactic atactic polypropylene. Kaminsky [6] example isospecific propylene C 2-symmetrical rac-ethylenebis(indenyl)zirconium (rac-EtInd2ZrC12) precatalyst 1985. A syndiotactic polypropylene [7]. They used s-symmetrical dimethylmethylenecyclopenta-dienyl fluorenylzirconium (Me2CCpF1uZrCl2) precatalyst.