Non-Isocyanate Synthesis of Covalent Adaptable Networks Based on Dynamic Hindered Urea Bonds: Sequential Polymerization and Chemical Recycling.

The development of environmentally sustainable processes for polymer recycling is of paramount importance in the polymer industry. In particular, the implementation of chemical recycling for thermoset polymers via covalent adaptable networks (CANs), particularly those based on the dynamic hindered urea bond (HUB), has garnered intensive attention from both the academic and industrial sectors. This interest stems from its straightforward chemical structure and reaction mechanism, which are well-suited for commercial polyurethane and polyurea applications.

Solvent-Triggered Chemical Recycling of Ion-Conductive and Self-Healable Polyurethane Covalent Adaptive Networks.

Given the substantial environmental challenge posed by global plastic waste, recycling technology for thermosetting polymers has become a huge research topic in the polymer industry. Covalent adaptive networks (CANs), which can reversibly dissociate and reconstruct their network structure, represent a key technology for the self-healing, reprocessing, and recycling of thermosetting polymers. In the present study, we introduce a new series of polyurethane CANs whose network structure can dissociate via the self-catalyzed formation of dithiolane from the CANs' polydisulfide linkages when the CANs are treated in ,-dimethylformamide (DMF) or dimethyl sulfoxide at 60 °C for 1 h.