Treatment of racemic bis(acetylacetonato) group 4 complexes with MAO yields cationic complexes acting as active catalysts for the polymerization of propylene under high monomeric concentrations. By the appropriate choice of metal and solvent the properties of the polymer products can be tailored, allowing the formation of either elastomer to highly isotactic polypropylene.

No abstract

The polymerization of ethylene and propylene were studied using an anchored dimethyl benzamidinate zirconium complex. As supports, mesoporous silicas MCM-41 and HMS were utilized. These inorganic materials were reacted with methylalumoxane to serve as the cocatalyst and to avoid the deactivation of the active cationic complex. The reaction of the octahedral benzamidinate zirconium complex with the supported cocatalysts results in the formation of active catalytic systems for the polymerization of olefins. The polymer properties were found to depend on the nature of the supports. The activity of the heterogeneous catalysts and the polymer characteristics were compared with those obtained with the homogeneous catalyst.