Dynamic C═C Bond-Based Recyclable Thermosetting Polymers Formed by Knoevenagel Condensation

The incorporation of dynamic covalent bonds is an efficacious approach to tackle the challenge of recycling thermosetting plastics. Herein, we developed a facile method for constructing recyclable thermosetting polymers through the Knoevenagel condensation (KC) reaction. First, we found that the KC reaction based on cyanoacetate and benzaldehyde showed a high conversion rate and dynamic exchange under the catalysis of 4-dimethylaminopyridine (DMAP). Then, three kinds of thermosetting polymers with different flexible chains (P-CC, P-CO, and P-PCL) based on dynamic C═C bonds were successfully prepared by the DMAP-catalyzed KC reaction. P-CC, P-CO, and P-PCL show high cross-linking density, gel fraction, and elastic modulus. More importantly, all three of these polymers exhibit good reprocessability and chemical recyclability. This work demonstrates the feasibility of using the KC reaction to construct thermosetting polymers, which shows great potential in sustainable materials.