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Epoxy thermosets are indispensable in various industrial applications due to their exceptional material properties. However, their limited recyclability poses a significant challenge for sustainability. To address this issue, integrating recyclable imine moieties into epoxy systems has emerged as a promising strategy. Despite recent advancements, challenges persist concerning the hydrolytic stability of imine‐based epoxy thermosets and the formation of irregular oligomeric structures upon depolymerization. In this study, these shortcomings are solved by designing a liquid imine monomer with secondary amine functionalities, which is subsequently reacted with commercially available epoxy monomers to produce high‐performance epoxy thermosets. Remarkably, the developed imine‐based epoxy system shows no sign of hydrolysis even under high‐temperature aqueous conditions, underscoring its potential for various industrial applications. Only the treatment with aqueous HCl results in the selective formation of exclusively well‐defined molecules, in high isolated yields after depolymerization. Crosslinking these building blocks once again yields recycled polymers with properties identical to pristine material. Moreover, it is discovered that, despite the crosslinked nature of the epoxy thermoset, the complete dissolution of the intact polymer in dichloromethane allowed for simple solvent‐based recycling. Through design on the molecular level, the recycling of imine‐based epoxy polymers is achieved via chemical and solvent‐based techniques. [ABSTRACT FROM AUTHOR]

Upcycling of low valuable plastic waste into materials with enhanced properties helps progress toward establishing a plastics circular economy. Furthermore, implementing recyclability as a core design criterium for newly formed materials can significantly increase their impact on sustainability, yet rarely explored. In this work, the upcycling of polystyrene (PS) waste is presented into closed‐loop recyclable high‐performance aerogels. Through a simple post‐functionalization process, PS is aminated to generate a polyfunctional amine, which is then reacted with aldehydes to form a recyclable cross‐linked imine network. This network is subsequently dried to produce poly(styrene‐imine) aerogels (PSAs). The resulting PSAs exhibit excellent thermally insulating properties, along with low density, outstanding mechanical strength, and intrinsic hydrophobicity. More importantly, these aerogels show quantitative depolymerization under acidic aqueous conditions, back to their original precursors which can be recovered in high yield and purity and reused for the synthesis of fresh aerogels with nearly identical material properties, thus achieving closed‐loop recycling. This work presents an efficient method for upcycling of chemically non‐recyclable plastics into recyclable and high value‐added advanced aerogel materials, offering a new pathway for establishing a circular economy for plastics. [ABSTRACT FROM AUTHOR]