4 research outputs found
Investigations into Asymmetric Post-Metallocene Group 4 Complexes for the Synthesis of Highly Regioirregular Polypropylene
A series of asymmetric post-metallocene group 4 complexes based on a modular anilide(pyridine)phenoxide framework have been synthesized and tested for propylene polymerization activity. These complexes, upon activation with methylaluminoxane (MAO), produce highly regioirregular and stereoirregular polypropylene with moderate to good activities. Surprisingly, modification of the anilide R-group substituent from 1-phenethyl to benzyl or adamantyl did not significantly change the polymer microstructure as determined by ^(13)C NMR spectroscopy. Although polymer molecular weights and polydispersities vary with propylene pressure, temperature, and activator, regio- and stereoirregularity were also found to be relatively insensitive to these variables. When the polymerization is conducted at 70 °C under dihydrogen, partial decomposition to a highly active catalyst that produces an isotactic microstructure occurs; the undecomposed catalyst continues to produce highly regioirregular and stereoirregular polypropylene under these conditions
Investigations into Asymmetric Post-Metallocene Group 4 Complexes for the Synthesis of Highly Regioirregular Polypropylene
Investigations into Asymmetric Post-Metallocene Group 4 Complexes for the Synthesis of Highly Regioirregular Polypropylene
A series
of asymmetric post-metallocene group 4 complexes based
on a modular anilide(pyridine)phenoxide framework have been synthesized
and tested for propylene polymerization activity. These complexes,
upon activation with methylaluminoxane (MAO), produce highly regioirregular
and stereoirregular polypropylene with moderate to good activities.
Surprisingly, modification of the anilide R-group substituent from
1-phenethyl to benzyl or adamantyl did not significantly change the
polymer microstructure as determined by <sup>13</sup>C NMR spectroscopy.
Although polymer molecular weights and polydispersities vary with
propylene pressure, temperature, and activator, regio- and stereoirregularity
were also found to be relatively insensitive to these variables. When
the polymerization is conducted at 70 °C under dihydrogen, partial
decomposition to a highly active catalyst that produces an isotactic
microstructure occurs; the undecomposed catalyst continues to produce
highly regioirregular and stereoirregular polypropylene under these conditions