Unexpected Quasi-Alternating Copolymerization of Oxiranes Driven by a Benign Acetate-based Catalyst

Abstract

An in-depth investigation of the oxyanionic ring-opening copolymerization of propylene oxide (PO) and allyl glydicyl ether (AGE) from benzyl alcohol (BnOH) activated with potassium acetate (KOAc) complexed by 18-crown-6 ether (18C6) is described. We demonstrate that the KOAc/18C6 complex is an efficient and benign catalytic system to promote copolymerization of both oxirane monomers, leading well-defined polyethers with varied co-monomer content and low dispersity values (ƉM < 1.20). Kinetic analysis confirmed the controlled nature of the (co)polymerization process, and the determination of reactivity ratios by 1H NMR spectroscopy revealed a quasi-alternating copolymerization profile, according to the Fineman-Ross method. These results highlight the great potential of 18C6/KOAc-mediated copolymerization process for the design of highly sought quasi-alternating copolymer platforms, not accessible with the common polymerization systems.