Rapid degradation of disulfide-based thermosets through thiol-disulfide exchange reaction

Development of a methodology to achieve the rapid degradation of thermosets under mild conditions is an important challenge. In this paper, we present a new method for rapid disassembly of thermosetting polyurethanes (PUs), using synergism of multiple stimuli. The PUs were prepared using multi-sensitivity dynamic disulfide bonds as the cross-linker. When soaked in DMF, the fabricated PUs only swell but undissolve. While reducing agent was added, the polymer completely dissolved after 12 h immersion at 25 °C, owing to the thiol-disulfide exchange mechanism. Moreover, as the temperature increases from 25 °C to 60 °C, the time required for complete dissolution of the PUs decreases from 12 h to 50 min, indicating that the synergistic effect of reducing agent and temperature can accelerate the degradation. In addition, other combined multi-stimuli, including reducing agent and ultrasound, can also be used to adjust the dissolution rate of the disulfide bonds cross-linked thermosets. When used as adhesives, the rapidly detachable PUs have potential applications in recycling the valuable adhesive components conveniently.