Synthesis and olefin polymerization using supported and non-supported geometry constrained titanium complexes

摘要

The synthesis of a constrained geometry titanium complex and its immobilization on different supports have been studied for the catalytic polymerization of ethylene, propylene and styrene. The formation of higher molecular weight polymers was found in the heterogeneous system as compared to the homogenous parent for polyethylene and polypropylene. Polymerization of propylene yielded atactic products with elastomeric properties due to long polymer chains. However, syndiotactic polymers were formed in the polymerization of styrene. Catalytic activity was found to be dependent on MAO and titanium concentration; the higher the metal concentration the lower the activity of the catalyst. The activity of the heterogeneous system was determined as a function of time, and a first-order deactivation pathway was found at room temperature. The type of solvent (toluene or CH_2Cl_2) also played an important role in the polymerization of ethylene and styrene, although different tendencies were found for either monomers.