[(salen)Al]-mediated, controlled and stereoselective ring-opening polymerization of lactide in solution and without solvent: synthesis of highly isotactic polylactide stereocopolymers from racemic D,L-lactide

Easily accessible [(salen)(iPrO)Al] exerts excellent molecular-weight and stereochemical control in lactide polymerization either in solution or in the absence of solvent. The R,R initiator shows a marked preference for L-lactide over D-lactide. Stereoblock copolylactides with high melting points can be prepared directly from d,l-lactides by using a racemic initiator.