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

Area of Science:

• Coordination Chemistry
• Polymer Chemistry
• Organometallic Catalysis

Background:

• Ring-opening polymerization (ROP) is crucial for synthesizing biodegradable polymers.
• Development of efficient catalysts for ROP of various monomers is an active research area.
• Exploring novel metal complexes for controlled polymerization and polymer recycling is of significant interest.

Purpose of the Study:

• To synthesize and characterize novel naphthoxy-imine pyridine zinc and magnesium complexes.
• To investigate the catalytic activity of these complexes in the ROP of various cyclic monomers.
• To explore the potential of the zinc complex in copolymer synthesis and polymer depolymerization.

Main Methods:

• Synthesis and full characterization of zinc and magnesium complexes using NMR spectroscopy.
• 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) using the synthesized complexes.
• Synthesis of diblock and random copolymers and investigation of depolymerization of resulting polymers.

Main Results:

• Both zinc and magnesium complexes effectively catalyzed the ROP of L-LA, ε-CL, β-BL, TMC, and Me-TMC in the presence of an alcohol initiator.
• The zinc complex demonstrated high catalytic activity, especially for lactide and TMC polymerization.
• The zinc complex was successfully used to synthesize polytrimethylene carbonate-based diblock and random copolymers and to depolymerize PTMC and its copolymers, indicating a closed-loop system.

Conclusions:

• Naphthoxy-imine pyridine zinc and magnesium complexes are effective catalysts for ROP of various cyclic monomers.
• The zinc complex exhibits superior activity and versatility, enabling the synthesis of complex polymer architectures and facilitating polymer recycling.
• These findings contribute to the development of sustainable catalytic systems for polymer production and end-of-life management.