High-Melting, Elastic Polypropylene: A One-Pot, One-Catalyst Strategy toward Propylene-Based Thermoplastic Elastomers

Abstract

This contribution provides the simple one-pot, one-catalyst synthesis of high-melting (Tm ∼ 140 °C), high-molecular-weight, elastic polypropylene (ePP) offering an excellent reversible deformation behavior. The produced propylene-based thermoplastic elastomers contain of iPP–aPP block structures embedded in an amorphous polypropylene matrix which is enabled by the variable stereoselective behavior of ethylene-bridged fluorenylindenyl (EBFI) ansa-metallocene complexes. For the tailored synthesis of these high-melting ePPs the intricate interplay of various mechanisms, which collectively define the stereoregularity of the produced polypropylenes, was examined, and a decisive impact of different chelate ring conformers was elucidated. In this connection, the accurate adjustment of conformational interconversion with respect to the chain propagation and termination rate facilitated a directed switching between iso- and unselective polypropylene sequences in the catalytic production of highly temperature-stable, elastic polypropylene.