Sustainability of Nonisocyanate Polyurethanes (NIPUs)

This work discusses the synthesis and properties of nonisocyanate polyurethanes (NIPUs) as an environmentally friendly alternative to traditional polyurethanes. NIPUs are made without the use of toxic isocyanates, reducing the environmental impact and safety concerns associated with their production. However, their synthesis reactions often require longer time and more energy to be completed. The sustainability of NIPUs is considered from various angles; the main methods for the synthesis of NIPUs, including rearrangement reactions, transurethanization, and ring-opening polymerization of cyclic carbonates with amines, are examined. Another part focuses on renewable sources, such as vegetable oils, terpenes, tannins, lignins, sugars, and others. The synthesis of waterborne and solvent-free NIPUs is also discussed, as it further reduces the environmental impact by minimizing volatile organic compounds (VOCs) and avoiding the use of harmful solvents. The challenges faced by NIPUs, such as lower molecular weight and higher dispersity compared to traditional polyurethanes, which can affect mechanical properties, were also addressed. Improving the performance of NIPUs to make them more competitive compared to conventional polyurethanes remains a key task in future research.