Redox Control of Group 4 Metal Ring-Opening Polymerization Activity toward l‑Lactide and ε‑Caprolactone

The activity of several group 4 metal
alkoxide complexes supported
by ferrocene-based ligands was controlled using redox reagents during
the ring-opening polymerization of l-lactide and ε-caprolactone.
Switching in situ between the oxidized and reduced forms of a metal
complex resulted in a change in the corresponding rate of polymerization.
Opposite behavior was observed for each monomer used. One-pot copolymerization
of the two monomers to give block copolymers was also achieved.