The oxyanionic ring-opening polymerization of propylene oxide (PO) from an exogenous alcohol activated with benign (complexed) metal-alkali carboxylates is described. The equimolar mixture of potassium acetate (KOAc) and 18-crown-6 ether (18C6) is demonstrated to be the complex of choice for preparing poly(propylene oxide) (PPO) in a controlled manner. In the presence of 18C6/KOAc, hydrogen-bonded alcohols act as soft nucleophiles promoting the PO S N 2 process at room temperature and in solvent-free conditions while drastically limiting the occurrence of parasitic hydrogen abstraction generally observed during the anionic ROP of PO. The resulting PPO displays predictable and unprecedented molar masses (up to 20 kg mol −1 ) with low dispersities (Ð M < 1.1), rendering the 18C6/KOAc complex the most performing activator for the oxyanionic polymerization of PO reported to date. Preliminary studies on the preparation of block and statistical copolyethers are also reported.

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.

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