One-Step Upcycling\nthe Engineering Plastic of Polyoxymethylene\ntoward a Flowing Telechelic Polyester: From Poly(A) to Poly(A-<i>alt</i>-B)

Developing facile and efficient chemical upgrading strategies\nto\nconvert commercial engineering polymeric materials into valuable products\nremains challenging. Polyoxymethylene (POM) is a widely used engineering\nthermoplastic, but strategies for its chemical reuse after disposal\nare still rare. Here, we demonstrate a “from poly(A) to poly(A-<i>alt</i>-B)” strategy for one-step upcycling of POM to\npolyesters using the bioderived glutaric anhydride (GA) as a feedstock.\nThe upgrade process undergoes a cascade mechanism: POM is first depolymerized\nto formaldehyde that is then <i>in situ</i> alternately\ncopolymerized with GA. The copolymerization step shifts the chemical\nequilibrium of “POM ⇌ formaldehyde” to the right,\nleading to the complete conversion of POM and >90% yields of the\npolyester\nproduct. The method uses low-cost inorganic acids as a catalyst and\nis performed at the industrially advantageous reaction temperature\nof 100 °C. The obtained polyesters possess alternating sequences,\nlow molecular weights (∼3 kDa), low glass-transition temperatures\n(∼−30 °C), good liquidity at room temperature,\nhighly reactive carboxyl terminals, and application prospects as reactive\nmacromolecular precursors.