Recyclable, Biobased Polycarbonates and Polyesters by Naphthoxy-Imine Zinc and Magnesium Complexes

Naphthoxy-imine pyridine zinc and magnesium complexes were synthesized and fully characterized by nuclear magnetic resonance (NMR). In the presence of an alcohol as initiator, both complexes promoted the ring-opening polymerization (ROP) of L-lactide (L-LA), ε-caprolactone (ε-CL), β-butyrolactone (β-BL), trimethylene carbonate (TMC), and 1-methyl trimethylene carbonate (Me-TMC), which was purposely synthesized from CO₂ and the appropriate diol. The zinc complex exhibited notably high activity, particularly in the polymerization of lactide and TMC, and was subsequently employed in the synthesis of polytrimethylene carbonate-based diblock and random copolymers with both ε-CL and L-LA. Furthermore, the zinc complex demonstrated its ability to close the life cycle of the synthesized materials by successfully depolymerizing both polytrimethylene carbonate (PTMC) and its copolymers.