Figure 5.

(a) DFT (ΔG kcal mol^–1) energy profiles for different monomer insertions into a zinc-alkoxide intermediate: CO₂ (red), phthalic anhydride (pink) and caprolactone (green). (b) Illustrations of transition states and postinsertion intermediates. (c) Switch catalysis connecting three polymerization cycles: anhydride/epoxide ROCOP, lactone ROP, and CO₂/epoxide ROCOP. (d) Switch catalysis connecting two polymerization cycles: O-Carboxy anhydride (OCA) ROP followed by ROCOP of CO₂ (released from OCA ROP) and CHO.⁶⁸⁻⁷⁰