Syndiospecific polymerization of styrene with BzCpTiCl(3) and methylaluminoxane as cocatalysts

Benzyl cyclopentadienyl titanium trichloride (BzCpTiCl(3)) was synthesized from benzyl bromide, cyclopentadienyl lithium, and titanium tetrachloride a nd used in combination with methylaluminoxane (MAO) for the syndiospecific polymerization of styrene. Kinetic measurements of the polymerization were carried out at different temperatures. The polymerization with BzCpTiCl(3)/ MAO differs from the polymerization with cyclopentadienyl titanium trichlor ide in its behavior toward the Al/Ti ratio. In addition, high activities ar e observed at high Al/Ti ratios. By analyzing the polymerization runs and t he physical properties of the polymers with differential scanning calorimet ry, C-13 NMR spectroscopy, wide-angle X-ray scattering measurements, and ge l permeation chromatography, we found that the phenyl ring coordinates to t he titanium atom during polymerization. Other known substitutions of the cy clopentadienyl ring (V. Scholz, Dissertation, University of Hamburg, 1998) in principle influence the polymerization activity. The physical properties of the polymers produced by the catalysts already known are nearly identic al. BzCpTiCl(3) is the first catalyst that leads to polystyrene obviously d ifferent from the polystyrene produced by other highly active catalysts. (C ) 2001 John Wiley & Sons, Inc.