Closed-Loop Recyclable Acetal Thermosets via a Novel Transacetalization Pathway

Abstract A rapid and scalable transacetalization route is introduced for the synthesis of high-performance, closed-loop recyclable acetal thermosets. Unlike conventional aldehyde−diol condensations, transacetalization enables accelerated network formation through acetal−alcohol exchange, dramatically shortening curing times while maintaining fully solvent-free processing. A terephthalic bisacetal monomer, prepared in a single step from commercial reagents, reacts efficiently with commercially available diols to yield transparent thermosets after curing. The resulting materials display excellent thermal stability, chemical resistance, and mechanical strength, together with minimal swelling and exceptional hydrolytic stability. Despite their stability under neutral conditions, the networks can be completely depolymerized under sufficiently acidic conditions to regenerate the original monomers in high yield and purity. Repolymerization of the recovered monomers produces materials indistinguishable from the originals, demonstrating true closed-loop chemical recycling. This work establishes transacetalization as a versatile and scalable platform for designing robust, chemically recyclable thermosets.