Precise Synthesis of Sequence-Controlled Oxygen-Rich Multiblock Copolymers via Reversible Carboxylation of a Commercial Salen- Mn(III) Catalyst

The precise synthesis of multiblock copolymers is of great significance in polymer chemistry. Switchable polymerization catalysis is developed via reversible carboxylation of a commercial salen-manganese (Mn) complex. The essence of reversible carboxylation was the transition between Mn alkoxide (Mn-OR) and carboxylate (Mn-OCOR). The unique toggling mechanism of two active species for different pathways was applied to the chemoselective copolymerization of epoxides, anhydrides, and LA. The anhydrides act as both a self-switching agent and feedstock in polymerization. Needless of the cocatalyst or chain-transfer agent (CTA), different poly(anhydride-epoxide) segments were in situ introduced into the PLA chain in batches, yielding various novel multiblock copolymers with precise control. Theoretical modulations were conducted to provide a robust explanation for the switching copolymerization mechanism.

Automated summary

Switchable polymerization catalysis is achieved through reversible carboxylation of a commercial salen-manganese (Mn) complex, enabling the precise synthesis of multiblock copolymers.