Control of polymer topology by chain-walking catalysts.

Chain-walking catalysts are demonstrated to control the branching topology of polyethylene by tuning the competition between monomer insertion and chain isomerization (walking). The topology of the polyethylene was controlled from linear with moderate branching to hyperbranched to dendritic. Although overall branching number and distribution of short chain branching are relatively constant, the topology of the polyethylene changes from linear polyethylene with moderate branches at high ethylene pressures to a dendritic polyethylene at low pressures. This provides a straightforward one-pot process for making polymers with a full range of tunable topologies.