Recycling Polyurethane with Properties Maintained in Multiple Reprocessing Realized via Dynamic Polysulfide Bond

Recyclable polymers have emerged as a forefront area in polymer science, with thermosetting polyurethanes attracting attention for their exceptional mechanical properties and durability. However, three-dimensional networks incorporating dynamic bonds often entail a trade-off between recyclability and mechanical properties, resulting in diminished performance after thermal reprocessing. Consequently, achieving polymers that combine excellent mechanical properties with high reprocessing efficiency over multiple cycles remains challenging with properties maintained. To address this, polysulfide bonds are incorporated into polymer chains, with disulfide bonds working as intermediaries, leveraging the dynamic behavior to facilitate thermal remolding and preserve mechanical integrity. Rheological tests reveal that the dynamic exchange of polysulfide bonds effectively maintains the network structure, mitigating degradation over multiple recycling cycles. By focusing on the dynamic properties of polysulfide bonds, this study provides a foundation for future research aimed at further enhancing the recyclability and sustainability of polyurethane.