Dynamic Imine-Linked NIPU with Shape Memory, Self-Healing, and Prospects for Recyclability

Non-isocyanate polyurethanes (NIPUs) incorporating dynamic imine linkages were developed via UV-induced photopolymerization of methacrylated monomers. The system combines a non-isocyanate urethane (NIU) precursor derived from cyclic carbonate chemistry with an imine-containing (Vit) monomer obtained via Schiff base formation, enabling compositionally tunable networks with a high gel content (90-97 wt%) and thermal stability up to >190 °C. The increase in NIU content enhances network rigidity, varying the glass transition temperatures from 29.3 °C to 73.4 °C. The dynamic imine chemistry imparts outstanding multifunctionality, including efficient shape memory behavior, thermally triggered reprogrammability, and rapid surface self-healing behavior, even at a low content of imine-containing precursor (30 wt%). The optimized composition further provides a proof-of-concept of selective chemical depolymerization for monomer recovery. These results establish NIU-Vit networks as versatile, having recyclability prospects, and a multifunctional platform for sustainable polymers as replacements for the traditional isocyanate-based polyurethanes.