Chemically Triggered Click and Declick Reactions: Application in Synthesis and Degradation of Thermosetting Plastics

In this Letter, we report that two amines can be coupled together rapidly and quantitatively through amine-thiol scrambling using a bisvinylogous thioester conjugate acceptor under mild conditions. The resulting bisvinylogous amide conjugate acceptors can be decoupled via an ethylene diamine-induced cyclization. Four representative conjugate acceptors have been utilized in the couple-decouple reactions, which were monitored and characterized by nuclear magnetic resonance, high-resolution mass spectrometry, and UV-vis spectroscopy. Further, we applied these small-molecule-based "click-declick" reactions to polymer synthesis and degradation. Highly cross-linked polymers, i.e., plastics, were quantitatively synthesized by simple reactions between commercial tris(2-aminoethyl)amine and the conjugate acceptors without solvent and any initiator or catalyst through ball milling within 60 min. Significantly, these thermosetting plastics can be degraded within 3-24 h via addition of ethylene diamine. The multiple architectures, application to plastics synthesis, and chemically triggered clean degradation to the thermosets at mild conditions with little input of energy herald a new generation of "intelligent" materials.