Abstract
Summary: A series of 1‐ and 2‐aryl substituted indenyl titanium trichlorides (ArIndTiCl~3~, Ar = Ph, α‐Naph, β‐Naph) were synthesized and tested as catalyst precursors for the syndiospecific polymerization of styrene with methylaluminoxane (MAO) as a cocatalyst. The polymerization characteristics at varying Al:Ti ratios and the kinetic behavior of these systems were investigated at 30 and 50 °C. The optimal Al:Ti ratio for these compounds lies in the range of 750–1500 at 30 °C, while the optimum shifts to higher values of about 2000–5000 at 50 °C. The activity of the investigated catalysts decreases in the order 2‐PhInd > Ind > Cp > 1‐(β‐Naph)Ind > 1‐PhInd > 2‐(β‐Naph)Ind > 2‐(α‐Naph)Ind > 1‐(α‐Naph)Ind with an activity up to 6700 kg sPS/[(mol Ti) · h] for 2‐PhIndTiCl~3~/MAO as the most active catalyst. Compared with CpTiCl~3~/MAO, the indenyl substituted compounds show, as catalysts, increased long‐term stability, which was determined by variation of the polymerization time. Especially 2‐PhIndTiCl~3~, 1‐(β‐Naph)IndTiCl~3~ and 2‐(β‐Naph)IndTiCl~3~ show a good performance. Syndiotactic polystyrenes with extremely high molar masses up to 1.3 × 10^6^ g/mol can be obtained by the catalytic system 2‐(β‐Naph)IndTiCl~3~/MAO.
Dependence of the polymerization rate on polymerization time. Polymerization conditions: T~p~ = 30 °C, V = 150 ml, c(styrene) = 1.04 M, Al:Ti = 1500, m(MAO) = 0.145 g, solvent = toluene.
imageDependence of the polymerization rate on polymerization time. Polymerization conditions: T~p~ = 30 °C, V = 150 ml, c(styrene) = 1.04 M, Al:Ti = 1500, m(MAO) = 0.145 g, solvent = toluene.