Upcycling Polytetrahydrofuran to Polyester

One major remaining challenge in polymer chemistry is the development of efficient chemical recycling strategies to fully retrieve starting materials. Polytetrahydrofuran (PTHF) is widely used, but its stable ether bonds make it difficult to chemically reuse after disposal. Here, we propose a "polymer A. polymer B" strategy for one-step quantitative upcycling of PTHF to polyesters. The route undergoes a cascade process: PTHF is depolymerized to give tetrahydrofuran (THF) that then alternately copolymerizes with cyclic anhydrides in situ, thereby pushing the chemical equilibrium of "PTHF. THF" to the right. The protocol demonstrates facile features: the use of common and metal-free Bronsted/Lewis acid as catalyst, a favorable reaction temperature of 100 degrees C, and no use of solvents. This method also accommodates 18 cyclic anhydrides to give a library of polyesters with alternating sequences, tunable thermal properties, and high-fidelity carboxyl terminals. This is an unprecedented strategy for chemical recycling of waste polyether. [GRAPHICS] .