Abstract

Non-isocyanate polyurethanes (NIPUs) are a greener alternative for the conventional polyurethanes synthesized using toxic and moisture-sensitive di- or polyisocyanates. The most often described method of NIPU synthesis involves the reaction of five-membered cyclic carbonates with amines, and resulting polymers containing primary and secondary hydroxyl groups (so they are also known as polyhydroxyurethanes), which can be further used for the functionalization of such macromolecules. What cannot be omitted is an application of bio-based substrates in the synthesis of NIPUs, which presently may constitute more than 50 wt.% of such NIPU systems. Waterborne non-isocyanate polyurethanes (WNIPUs) can be prepared as solids, solutions, or dispersions by several different synthetic pathways. Broad-spectrum synthesis methods and used compounds may lead to sufficient molecular masses and mechanical properties on a laboratory scale. Some semi-products of such reactions can be further processed into thin films, coatings, hydrogels, or functionalized nanoparticles. Thus, careful selection of substrates, as in the case of isocyanate-based polyurethanes, provides many opportunities for valuable product fabrication. WNIPUs in the form of dispersions may find an application to cast films with great success, whereas the formation of latexes allows for coating formation. Coatings are the largest group of proposed WNIPU applications due to excellent adhesion, gloss, mechanical properties (flexibility and impact resistance), and thermal stability. Hydrogels are just after coatings because they are characterized by favorable mechanical properties and swelling capability. In this chapter, we describe the synthesis and properties of WNIPUs.

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