Résumé
Polyurethane (PU) foams are essential for energy-efficient insulation but are problematic due to the use of harmful isocyanates. Non-isocyanate polyurethanes (NIPUs) offer a safer, more sustainable alternative, aligning with EU regulations and climate goals. In this work, we report an 2eco-friendly method for producing thermosetting NIPU foams with tailored properties and humidity-responsive shape memory using supercritical CO2 as a physical blowing agent. This innovative approach not only replaces current flammable, greenhouse gas-emitting agents with high global warming potential but also revalorizes CO2 in the manufacturing and synthesis process. The method involves CO2 pressure-induced absorption, temperature-induced desorption, and curing of 5-membered cyclic carbonate (5CC)/amine resins. At elevated temperatures, simultaneous CO2 release and NIPU crosslinking drive cellular structure formation. We studied the effects of curing agents, foaming/curing temperatures, and the impact of stabilizers on the final foam properties. The resulting foams demonstrated tunable densities (270-451 kg/m³), compression moduli (16-350 kPa), and cell sizes (0.33-0.99 mm). Notably, these NIPU foams also exhibited humidity-triggered shape memory behavior, which can greatly expand their functionality. This process ensures a controlled and sustainable approach to fabricating NIPU thermoset foams and represents a transformative step forward in advancing greener PU-based materials.