Amorphous Elastomeric Ultra-High Molar Mass Polypropylene in High Yield by Half-Titanocene Catalysts.

Propylene polymerizations with different ketimide-modified half-titanocene catalysts, Cp'TiCl(N=CBu) [Cp' = CH (), CMe (), MeSiCH ()], with MAO as a cocatalyst, were investigated. The obtained polymers were studied in detail by determining their microstructure, molar masses, thermal, and mechanical properties. The Cp*-ketimide, (CMe)TiCl(N=CBu) (), exhibited higher catalytic activities than Cp'TiCl(N=CBu) (,), yielding higher molar mass polymers, up to 1400 Kg/mol. All the synthesized polypropylenes (PP) are atactic and highly regioregular, with predominant pentads, especially PP prepared with catalyst . Differential scanning calorimetry (DSC) established that the polymers are fully amorphous aPP, and no melting endotherm events are detected. Glass transition temperatures were detected between -2 and 2 °C. These polypropylenes have been established to be high-performance thermoplastic elastomers endowed with remarkably high ductility, and a tensile strain at break higher than 2000%.