The circular economy is a path that society, governments, and business must adopt to develop a viable and sustainable model for plastic production. Following the route guided by the United Nations and the new laws of the European Union, such as the Green Deal, it will be able to put an end to the great problem of this era, the inadequate treatment and management of plastic waste. On the plastics production ladder, poly(ethylene terephthalate) (PET) ranks fifth alongside polyurethanes, but only an average of 17% of total PET waste is recycled. Moreover, according to the latest survey made by Zero Waste Europe, most of this recycling source is used in low features applications through a downcycling process. There are mainly two ways for PET recycling, it can be done mechanically or chemically. On the one hand, mechanical recycling is easy to employ but presents some limitations as the properties of the final product decrease from the second cycle, whereas chemical recycling offers versatile procedures although it requires huge amounts of investment money. To address these drawbacks, diverse chemical recycling methods, specially aminolysis and glycolysis, were proposed as the promising way to obtain high added‐value products. In this review, different updated state of the art works about recycling of PET were discussed, presenting the two forms for recycling PET waste, mechanical and chemical approach, and the reason of why is important to focus on the obtention of high‐added value products in an upcycling process.

Polyurethanes are of undoubted interest for the scientific community and the industry. Their outstanding versatility from tailor-made structures turns them into major polymers for use in a wide range of different applications. As with other polymers, new, emerging molecules and monomers with specific attributes can provide new functions and capabilities to polyurethanes. Natural and synthetic coumarin and its derivatives are characterised by interesting biological, photophysical and photochemical properties. Then, the polyurethanes can exploit those features of many coumarins which are present in their composition to achieve new functions and performances. This article reviews the developments in the proper use of the special properties of coumarins in polyurethanes to produce functional and smart materials that can be suitable for new specific applications.