Redox Switchable Copolymerization of Cyclic Esters and Epoxides by a Zirconium Complex

A zirconium precatalyst, (salfan)Zr(OtBu)2 (salfan = 1,1′-di(2-tert-butyl-6-N-methylmethylenephenoxy)ferrocene), shows activity for the redox-controlled block copolymerization of l-lactide and cyclohexene oxide. The role of the oxidant is examined, and several diblock (AB and BA) and triblock copolymers (ABA and BAB) were synthesized and characterized.