Isotactic poly(propylene)s with 60-85% vinyl chain-end selectivity were syn
thesized with metallocene catalysts. Some of these vinyl-terminated poly(pr
opylene)s are highly stereoregular (mmmm pentads up to 95%) and have high c
rystalline melting points in the range of 140-150 degrees C. Chain-end anal
ysis using C-13 NMR indicates the vinyl chain-ends in the polymer are most
likely formed through beta -methyl elimination in the chain termination ste
p.