Room-Temperature, Atom-Economic Closed-Loop Recycling of Thermosets Enabled by Catalyst-Free Dynamic Thiohemiketals

The global plastics crisis has triggered severe environmental pollution and resource depletion. While covalent adaptable networks (CANs) offer promising solutions, achieving ambient-temperature chemical recycling with quantitative monomer recovery and zero chemical consumption remains challenging. Furthermore, catalyst-free reprocessing via multiple industrial techniques under mild conditions, alongside energy-efficient and eco-benign synthesis, constitutes a critical bottleneck. Herein, we introduce thiohemiketal as a novel dynamic covalent motif for self-healing recyclable polymers. Mechanistic studies using small-molecule models reveal catalyst-free bond formation under ambient conditions, rapid dynamic exchange without catalysts, and quantitative solvolysis in chloroform at 25 °C. Leveraging this unique chemistry, we developed a solvent- and catalyst-free polymerization strategy to synthesize CANs exhibiting exceptional thermal stability, broadly tunable mechanical properties (Young’s modulus: 2.4 MPa to 1.1 GPa, spanning polydimethylsiloxane (PDMS)-like elastomers to polypropylene (PP)-like plastics), and ultrastrong adhesion (12.5 MPa lap shear strength on iron). Crucially, these networks exhibited exceptional sustainability: ambient-temperature closed-loop chemical recycling via solvolysis with quantitative recovery and no chemical consumption, catalyst-free multimodal reprocessability (compression, injection, and extrusion), and rapid self-healing. This work establishes a new paradigm for sustainable polymer design, showcasing significant potential for advanced adhesives and structural composites.