Chain walking: A new strategy to control polymer topology
Ethylene pressure has been used to control the competition between isomerization (chain walking) and monomer insertion processes for ethylene coordination polymerization catalyzed by a palladium-alpha-diimine catalyst. The topology of the polyethylene varies from linear with moderate branching to "hyperbranched" structures. Although the overall branching number and the distribution of short-chain branching change very slightly, the architecture or topology of the polyethylene changes from linear polyethylene with moderate branches at high ethylene pressures to a hyperbranched polyethylene at low pressures.
Guan
Z
DuPont Central Research, Experimental Station, Wilmington, DE 19880, USA.
Cotts
PM
McCord
EF
McLain
SJ