Polyurethanes and Ecological and Economic Transitions Towards new opportunities

Discovered by Otto Bayer in 1937, polyurethanes (PUs) are among the world's most widely used polymers, for a variety of applications including furniture, coatings, adhesives, building materials and many others. Demand for PU has been rising steadily, reaching a market value of $72.8 billion in 2021, with forecast annual growth of 4.3% to 2030. In 2022, global PU production represented 25 Mt, with a projection of 29 Mt by 2030. The PU market is mainly divided into foams (60%), coatings (14%), elastomers (10%), adhesives (6%) and biomedical applications (10%). PUs' success lies in their excellent thermal and mechanical properties, as well as in the diversity of molecular structures available, giving them specific characteristics such as flexibility, abrasion resistance and biodegradability. However, PUs pose environmental and health problems. Most are in fact derived from petroleum and, at the end of their life, incinerated or landfilled, contributing to CO ₂ emissions. What's more, the isocyanates used in PU manufacture are toxic and sometimes carcinogenic. To limit these impacts, reagents of renewable origin and chemical and mechanical recycling methods have been developed, along with isocyanate-free polyurethanes (NIPUs). This article explores the strategies proposed by academic research and industry to make PUs more sustainable and less toxic, through the use of biobased reagents and environmentally-friendly synthesis and recycling processes.