Since the industrial synthesis of the first polymeric materials and their commercialization in the 1930’s, breakthroughs and innovations in polymer chemistry have significantly contributed to the improvement of our daily life. Consequently, the annual world consumption of plastics is exponentially and continuously increasing. The resulting accumulation of polymeric materials in the environment makes the development of environment-friendly and cost effective routes for recycling, a main challenge for next generations. In the 20th century the goal was to design polymers to withstand degradation and depolymerization. Nowadays, less than 8% of the polymers produced each year are recycled and most of them are mechanically recycled that includes grinding and melt-processing. This mechanical recycling produces low-quality materials that will ultimately be used for secondary materials that will end up as a waste.
Besides mechanical recycling and pyrolysis, the final method of recycling and probably the most challenging one to date is chemical recycling. The polymer is used as a starting reagent to generate high purity monomers using simple and efficient transformations. Specifically, from chemical depolymerisation innovative added-value building blocks could be synthesized to prepare highly added value polymers (smart chemical recycling approach) from commodity polymers. Our work is focused in the implementation of plastic recycling principle in carbonyl containing polymers such as polyesters, polycarbonates and/or polyurethanes which account to the 25-30 % of the total plastic production. To afford this goal, an innovative protic ionic salt, cheap, easy-to-produce and recyclable, has been developed to catalyse the depolymerisation. Thermally stable up to 400 °C, this organocatalyst is active at the high reaction temperatures required for degrading polymers. It already allowed us to degrade polyethylene terephthalate (PET), and Bisphenol A based polycarbonate (BPA-PC), in a fully sustainable cycle.