Non-Isocyanate Polyurethanes-Based Foams

This chapter offers a thorough examination of foams based on non-isocyanate polyurethane (NIPU), focusing on their synthesis, characterization, applications, and future implications. NIPU foams are a greener option than regular polyurethane (PU) foams as they do not require harmful isocyanates in their making but have all the same physical, chemical, and mechanical characteristics. Polyaddition processes combining polyols, diisocyanates, and water produce CO2 as a foaming agent; these foams are then used extensively in the production of conventional PU foams because of their amazing properties. However, scientists and industry experts are actively seeking cleaner synthesis ways for manufacturing PU foams due to the toxicity of isocyanates, which has elevated considerable environmental and health issues. The main way that NIPU foams are made is by polyadditioning cyclic carbonates (CCs) and polyfunctional amines, either with the help of an outside blowing agent or by making the foams self-blowing. Various chemical synthesis techniques are described in this chapter. These include the use of blowing agents like poly(methylhydrogensiloxane) and liquid fluorohydrocarbons, and the self-blowing approach, which removes the need for external agents by producing gases internally. Focusing on the production of polyhydroxyurethane (PHU) foams which use these blowing agents to create the foam-defining cellular structure is essential. This section also delves into the methods used to characterize NIPU foams, focusing on microscopic and spectroscopic examinations, mechanical testing to determine elasticity and strength, and thermal study to determine insulating qualities. Structural parameters like density, porosity, and thermal stability are investigated to determine their importance for foam performance,. The chapter concludes with a survey of the many uses of NIPU foams, which include packaging, insulation, biomedical scaffolding, and lightweight materials for the aerospace and automotive sectors. We discuss the difficulties of making NIPU foam, some of the environmental factors to think about, and where we may go from here in terms of research, drawing attention to the possibility of new, sustainable formulations and the use of cutting-edge materials to boost performance.