Bio-Based Non-Isocyante and Phosgene-Free Polyurethanes

Against the background of sustainable chemistry and new regulations, research and industry are challenged to replace hazardous chemicals and harsh reaction conditions with more environmentally friendly intermediates and processes. In recent years, interest in polyurethanes (PU) has increased in the plastics market. These special high-performance polymers combine numerous properties needed in aerospace, medical, construction and automotive applications such as adhesives and textiles.

Classically, PUs are produced by polyaddition of a diol (or polyol) to a diisocyanate (or polyisocyanate). The latter is based on the highly toxic phosgene. PU chemistry is hazardous and sensitive to moisture. An excellent alternative is the development of non-isocyanate polyurethanes (NIPU), which are formed by polyaddition of a diamine (or polyamine) to a dicyclocarbonate (or polycyclocarbonate) and are phosgene-free.

IVW is developing biobased NIPU/epoxy hybrid foams under a grant from the Volkswagen Foundation. Oligomeric polycyclocarbonates from epoxidized vegetable oil have been investigated in polyaddition reactions with various biobased polyamines for the synthesis of NIPUs. Since this type of reaction does not lead to gas formation, a chemical blowing agent was also used for foaming. Hybridization of the NIPUs with epoxy resin improves the thermal and mechanical properties. The biogenic NIPUs use raw materials from Europe and avoid toxic phosgenation in the production of polyurethane products. Future products made from them can be manufactured with "green chemistry," resource-efficient production and within a circular economy, meeting the requirements of the construction and automotive industries.