One-Step Upcycling the Engineering Plastic of Polyoxymethylene toward a Flowing Telechelic Polyester: From Poly(A) to Poly(A-alt-B)

Developing facile and efficient chemical upgrading strategies to convert commercial engineering polymeric materials into valuable products remains challenging. Polyoxymethylene (POM) is a widely used engineering thermoplastic, but strategies for its chemical reuse after disposal are still rare. Here, we demonstrate a "from poly(A) to poly(A-alt-B)" strategy for one-step upcycling of POM to polyesters using the bioderived glutaric anhydride (GA) as a feedstock. The upgrade process undergoes a cascade mechanism: POM is first depolymerized to formaldehyde that is then in situ alternately copolymerized with GA. The copolymerization step shifts the chemical equilibrium of "POM ⇌ formaldehyde" to the right, leading to the complete conversion of POM and >90% yields of the polyester product. The method uses low-cost inorganic acids as a catalyst and is performed at the industrially advantageous reaction temperature of 100 °C. The obtained polyesters possess alternating sequences, low molecular weights (∼3 kDa), low glass-transition temperatures (∼−30 °C), good liquidity at room temperature, highly reactive carboxyl terminals, and application prospects as reactive macromolecular precursors.