Living ring-opening polymerization of cyclic esters with epoxide-derived titanium alkoxides

The (TiCp2Cl)-Cp-III-catalyzed radical ring opening of epoxides produces Ti alkoxides which initiate the ring-opening polymerization of epsilon-caprolactone. A linear dependence of (M) over bar on conversion, linear kinetics, low (M) over bar (w)(M) over bar (n) values, and the synthesis of block copolymers demonstrate a living process, while NMR spectroscopy confirms the presence of the initiator chain end. Epoxides are thus introduced as a new class of initiators for the Ti-catalyzed living ring-opening polymerization of cyclic esters.