4. Pathways to isocyanate-free polyurethanes

Due to the toxicity of isocyanates, alternatives are being studied to synthesize polymers similar to conventional PUs without using isocyanates. Non-isocyanate PUs (NIPUs) have emerged in this context . Several synthetic routes exist, with cyclocarbonate aminolysis the most extensively studied, although other methods such as aziridine copolymerization with carbon dioxide and ring-opening polymerization of cyclic carbamates are also being considered (figure 12 ). Some of these methods still rely on toxic...