B. Rieger et al., HIGHLY ISOTACTIC POLYPROPENE PREPARED WITH HYL-4-T-BUTYL-CYCLOPENTADIENYL)ZIRCONIUMDICHLORIDE - AN NMR INVESTIGATION OF THE POLYMER MICROSTRUCTURE, Journal of molecular catalysis, 82(1), 1993, pp. 67-73
Isotactic polypropene was prepared using hyl-4-t-butyl-cyclopentadieny
l)zirconiumdichloride (1) and methylalumoxane (MAO) at temperatures be
tween 0 and 80-degrees-C and with Al/Zr ratios of 300 and 1500. The po
lymers, prepared at temperatures below 30-degrees-C had melting points
of 162-degrees-C and above. The chain ends were determined by means o
f distortionless enhancement by polarization transfer (DEPT)-NMR spect
roscopy. The pentad intensities were corrected according to the chemic
al shifts of the end groups. The intensity distributions are shown to
arise from enantiomorphic site control of the chiral catalyst species.