Abstract Highly isotactic polylactide or poly (lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen–and homosalen–aluminum complexes (salenH 2= N, N′-bis (salicylidene) ethylene-1, 2-diamine; homosalenH 2= N, N′-bis (salicylidene) trimethylene-1, 3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the ...