Base‐Mediated Degradation of Epoxy Thermosets via Carbon–Nitrogen Bond Cleavage for the Recovery of Amine Agents

Epoxy thermosetting polymers are widely used in industrial applications. In their synthesis, amines are commonly employed as curing agents for epoxy monomers bearing glycidyl groups. Although the degradation of amine‐cured epoxy thermosets has been studied, the selective recovery of parent amines as reusable organic substrates remains insufficiently developed, largely due to the difficulty of achieving selective main‐chain cleavage. Herein, we report the degradation of epoxy thermosets cured with bis(arylamines) for 150 or 190 °C, which serve as stable and rigid curing agents, via cleavage of both carbon–oxygen and carbon–nitrogen bonds in the polymer backbone. The use of NaOH in 1,3‐dimethyl‐2‐imidazolidinone, in combination with Ca(OH) 2 , was found to be effective for the recovery of diamine curing agents together with bisphenols. This degradation method was further applied to highly cross‐linked tetrafunctional epoxy thermosets composed of carbon–nitrogen bonds, affording bis(arylamines) at 190 °C.