Ring opening polymerisations of cyclic esters and carbonate by rare-earth LnCp3

The ring opening polymerisation of cyclic esters (ε-caprolactone and l-lactide) and cyclic carbonate (1,3-dioxan-2-one (TMC)) initiated with LnCp3 complexes (Ln=Sm, Er, Pr, Gd and Ce) is reported. The size of the metal atom has an effect on the catalytic activity. The order of reactivity was found to be Er∼Gd>Sm>Pr>Ce. The polyester chains were found to be living for successful synthesis of block copolymers. Polycarbonate (polyTMC) was obtained without CO2 elimination using LnCp3 as an initiator.