Ethene Copolymerization with Trialkylsilyl Protected Polar Norbornene Derivates

The influence of the protecting group of polar norbornene derivatives and the structure of homogenous metallocene/MAO catalyst systems on the activity and the incorporation rates during ethene copolymerization reactions were studied. By varying the structure of the protecting group a relationship between the catalyst activity and the steric demand of the protecting group could be established. For the catalyst systems tested analogous relationships between the bulkiness of the protecting groups and the polymerization activity were found. Kinetic investigations point to a reversible deactivation reaction, during which a bond between the oxygen atom of the polar norbornene derivative and the center of the active catalyst is formed, competing with the olefin coordination and the subsequent insertion. The degree of polymerization deactivation can be qualitatively judged based on a correlation between calculated structural parameters of the trialkylsilyl protected norbornene derivatives and the experimentally determined polymerization activity.