Highly efficient and well-controlled ROP and copolymerization of cyclic esters using a cesium complex.

A cesium imino-phosphanamidinate, [{NHI Dipp P(Ph)NDipp}Cs], enabling efficient ring-opening (co)polymerization of rac -LA and ε-CL is disclosed. Owing to the highly controlled polymerization, precise di-block copolymers (PLA- b -PCL) with different block lengths can be produced by a simple one-pot reaction. NMR, GPC, DSC and microscopic analyses confirm the production of di-block copolymers with crystalline properties.