Switchable Polymerization from Monomer Mixtures to Synthesize Oxygen-Rich Block Copolymers with Dual Recyclability and Degradability

Abstract

Switchable catalysis from monomer mixtures has been emerging as a powerful technique to synthesize various useful block copolymers, yet represents a significant challenge in polymer chemistry. Herein, we present the synthesis of well-defined polyacetal/polycarbonate block copolymers through switchable polymerization from mixtures of terminal epoxides, internal epoxides, o-phthalaldehyde (OPA) and CO2. The exclusive chemoselectivity of terminal epoxide or internal epoxide was achieved by controlling the reaction atmosphere. The dynamic equilibrium of acetal anion and alkoxy anion is the key to the successful switch from terminal epoxides/OPA copolymerization to internal epoxides/CO2 copolymerization. Computational studies elucidated the kinetic and thermodynamic preferences underlying this selective polymerization. The acid/base labile nature of the block copolymers enables their sequence-controlled chemical recycling/degradation. These novel polyacetal/polycarbonate block copolymers with facilely sequence-controlled polymerization/depolymerization capabilities will enable their further tailored applications and contribute to the development of a circular plastic economy.