Mild and metal-free chemical recycling of polyureas via acylation-activated bond cleavage

Chemical recycling of polymers offers a promising strategy to convert post-consumer waste into reusable monomers and chemicals. However, the inherent stability of covalent bonds in many durable polymers, such as polyureas, renders their chemical deconstruction particularly challenging. Herein, we report a mild, efficient and metal-free method for the depolymerization and recovery of both linear and cross-linked polyureas via an acylation-activated urea bond cleavage strategy. Treatment with low-cost, commercially available acetic anhydride and sulfuric acid under ambient pressure transforms robust urea linkages into labile acetylurea intermediates in high yield, which subsequently undergo efficient alkaline hydrolysis to regenerate the pristine diamine monomers. Notably, the reclaimed monomers can be directly repolymerized into polyurea materials with chemical structures and mechanical performance comparable to those of the virgin counterparts. Techno-economic analysis and life-cycle assessment further underscore the economic feasibility and environmental advantages of this approach over conventional recycling methods. This work provides a new and sustainable strategy for polymer recycling under mild conditions and advances the circular economy of durable polymeric materials.