Dynamic Enaminoneamide: Enabling Recycling of Isocyanate-Based Polymers with Maintained Mechanical Properties

Though possessing advantages of durability and exceptional performances profit from cross-linked structure, it is challenging to recycle and reuse thermoset polymers. Here, reprocessability in industrially relevant polyurethane and polyurea thermosets is unveiled. Unlike prior methods, this strategy does not require the complicated design of monomer structures and is suitable for a variety of polyurethane and polyurea systems. With the enaminoneamide structure inserted, the cross-linked PU possesses reprocessing performance without affecting the mechanical properties. Upon thermal treatment, the enaminoneamide in the polymer network dissociates into isocyanate and enaminone, allowing the materials to be recycled. The reclaimed performance for multiple generations demonstrates long-term reprocessability of the materials. This work offers a convenient approach to make the widely used isocyanate-based cross-linked networks recyclable via involving enaminoneamide structure in the systems without consuming the mechanical properties. Furthermore, for the stability of the product of β-diketone and isocyanate, the sensibility to water is prevented during the synthesis, enhancing the properties of the polymer. Given this strategy is poised for widespread adoption, it may be an important advance in the lifecycle for isocyanate-based thermoset polymers.