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

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.