In recent years, much effort has focused on the development of degradable thermosets; however, high cost and relatively low performance have become serious barriers to their practical applications. In this work, degradable thermosets based on imine/secondary amine dynamic bonds were prepared by amine aldehyde condensation. Specifically, terephthaldehyde and various diamines were used as monomers, and triethylenetetramine was selected as a novel cross-linker to prepare the degradable polyaminal. Because of the −NH 2 and −NH−CH 2 −CH 2 −NH− groups in triethylenetetramine, a hybrid imine/imidazolidine cross-linking structure was obtained. Thanks to the rigid ring structure of imidazolidine, the polyaminal represents higher cross-linking density and mechanical properties compared with common thermosets based on Schiff base. Importantly, the present strategy reduced the preparation cost by ∼60% due to the usage of a quite low-priced cross-linker. The results showed that the obtained degradable polyaminal exhibits superior properties, T g (120−150 °C), T d (249−277 °C), and tensile strength (52−64 MPa). Moreover, the polyaminal/carbon fiber composite could be completely degraded under mild acidic conditions within 1 h, leading to a rapid and nondestructive recycling of valuable fiber. This study is believed to offer an alternate strategy to set up a green framework for highperformance degradable thermosets that can potentially be used in commercial and industrial production.

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γ-Radiation derived from clean energy has emerged as a promising technology for disposal of waste plastics. However, due to radical-mediated uncontrolled recombination, a foremost challenge remains in radiation-triggered complete degradation for thermoset plastics. Herein, the radiation-sensitive epoxy thermoset (EP-DESN) containing phenyl imine-conjugated N−N bonds (PINN bonds) and S−S bonds was designed to initiate rapid degradation at a dose of 10 kGy. The phenyl imine-conjugated linkages can stabilize the radiation-induced broken N−N bonds, overcoming radical-mediated uncontrolled recombination and cross-linking. Moreover, the phenyl-iminyl-conjugated radicals generated by PINN bond scission can cleave the active S−S bonds to promote subsequent spontaneous degradation for maximum degradation efficiency. Meanwhile, EP-DESN exhibited superior thermal robustness and chemical resistance comparable to some conventional high-performance epoxy thermosets. Using EP-DESN as a binder, we prepared recyclable carbon fiber-reinforced composites, and nondestructive recycling of value-added carbon fiber (CF) is achieved, thus facilitating the concept of a circular CF economy.

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We exploit stable conjugated linkages, phenyl imine conjugated N–N bonds, for the γ-ray-induced controllable cleavage of polymer chains as a new methodology for the fabrication of γ-ray-degradable epoxy thermosets.