Titanium pyridonates for the homo- and copolymerization of rac-lactide and ε-caprolactone.

A series of titanium pyridonate complexes have been synthesized under very mild reaction conditions from a common precursor, Ti(NMe2)4. These complexes have been explored as initiators for the ring-opening polymerization of rac-lactide and ε-caprolactone and have proven to be competitive with leading titanium initiators. Furthermore, these complexes have been shown to be competent initiators for the synthesis of copolymers (CL-LA block copolymers and random copolymers). Metal complex reactivity trends in both homo- and copolymerization show that poly(lactic acid) is most susceptible to chain scission and transesterification.