Abstract
Introducing
ethylene units into polybutadiene backbones is an approach to synthesize
advanced rubber materials, which has been a research challenge because of
distinct polymerization mechanisms of the two monomers. To date, onlytrans-1,4-
and 1,2-regulated copolymers have been obtained. Herein, we reported the
unprecedented cis-1,4 selective copolymerization of ethylene and
butadiene by using the thiophene-fused cyclopentadienyl-ligated scandium
complexes. The effects of the sterics and electronics of the catalytic
precursors as well as the monomer loading mode on the activity and selectivity
as well as the sequence lengths were investigated, and the mechanism was
elucidated. Thus a novel ethylene-based rubber material possessing a high
molecular weight, 80?% cis-1,4 regularity and a Tg=?94?°C
without an obvious melting point owing to short polyethylene sequences even at
its content up to 45?mol?%, was isolated. This new rubber material exhibited
excellent anti-flowing performance and strong tensile strength.
文章鏈接：
http://onlinelibrary.wiley.com/doi/10.1002/anie.201702128/full