Full non-isocyanate polyurethane self-blown foams prepared at room temperature by utilizing Exo-Vinylene Cyclic Carbonates

Though widely used, commercial polyurethane foams raise health concerns stemming from their isocyanate precursors, and environmental issues due their difficult recycling. Non-isocyanate polyurethane foams made via cyclic carbonate aminolysis, thus polyhydroxyurethanes foams (PHUFs), appear to be potential alternatives, but achieving room-temperature self-blowing PHUFs, predominantly through 5-membered cyclic carbonate and amine chemistry remains challenging without involving epoxides in the formulation. In this research, we demonstrate a new concept that makes the production of full PHUFs possible through the incorporation of exo-vinylene cyclic carbonate (αCC) into the formulation. This approach incorporates hydroxyoxazolidone groups, i.e. cyclic hydroxyurethanes, as pending groups of the polyhydroxyurethane backbone. We investigate the reactions occurring in this foaming system and identify optimal foaming formulations to rapidly produce PHUFs, within 1-5 minutes, with a high gel content. The study explores monomer variations as amine mixtures and different αCCs, demonstrating the potential for future optimization. Compression tests reveal the influence of foam formulation on the thermo-mechanical foam’s properties, particularly under varying humidity conditions. This concept paves the way for the rapid preparation of the next-generation of isocyanate-free polyurethane foams with modular properties, from flexible to rigid foams.