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 -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. An environmentally benign protocol for highly competent and well-controlled ring-opening (co)polymerization of rac -LA and/or -caprolactone to form a homopolymer ( P i = 0.81) and di-block PLA- b -PCL copolymers by a cesium complex is reported.