Chemically Triggered Click and Declick Reactions: Application in Synthesis and Degradation of Thermosetting Plastics
Tianhong Wu, Tianyu Liang, Wei Hu, Meiqing Du, Sijia Zhang, Yanfeng Zhang, Eric V. Anslyn, Xiaolong Sun
Abstract
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.