Towards urea and glycerol utilization as "building blocks" for polyurethane production: A detailed study about reactivity and structure for environmentally friendly polymer

Polyurethanes have been widely used in a wide variety of applications that benefit our everyday life. However, in the present scenario, it is urgent to find solutions towards more sustainable polymeric systems that can be more biodegradable and less dependent on non-renewable feedstocks. The present work proposes a thorough structural investigation of polyurethane materials based on the use of two small eco-friendly reactants: glycerol and urea. The results with glycerol demonstrated a preferential reactivity of MDI with primary alcohol terminals, except when the diisocyanate was in excess, which resulted in crosslinking formation (shown in C-13 NMR). Urea-based materials displayed superior thermal stability, associated with higher crystallinity and intermolecular forces, as observed in TGA, XRD, and FTIR. Overall, the structural characteristics support the potential of biodegradability of the studied polyurethanes and polyureas.