Effective and sustainable depolymerization of Nylon 66 - a transamidation for the complete recycling of polyamides

The transamidation of polyamides with short primary amides is reported as an effective recycling technique. This novel depolymerization method is robust and only utilizes cheap and renewable reagents. The process requires a Nb2O5 catalyst, assisted by NH3, and operates at relatively mild reaction conditions (i.e. 200 °C and 3 bar NH3).

100th Anniversary of Macromolecular Science Viewpoint: Toward Catalytic Chemical Recycling of Waste (and Future) Plastics

The current global materials economy has long been inefficient due to unproductive reuse and recycling efforts. Within the wider materials portfolio, plastics have been revolutionary to many industries but they have been treated as disposable commodities leading to their increasing accumulation in the environment as waste. The field of chemistry has had significant bearing in ushering in the current plastics industry and will undoubtedly have a hand in transforming it to become more sustainable. Existing approaches include the development of synthetic biodegradable plastics and turning to renewable raw materials in order to produce plastics similar to our current petrol-based materials or to create new polymers. Additionally, chemists are confronting the environmental crisis by developing alternative recycling methods to deal with the legacy of plastic waste. Important emergent technologies, such as catalytic chemical recycling or upcycling, have the potential to alleviate numerous issues related to our current and future refuse and, in doing so, help pivot our materials economy from linearity to circularity.

Beyond Mechanical Recycling: Giving New Life to Plastic Waste

Increasing the stream of recycled plastic necessitates an approach beyond the traditional recycling via melting and re-extrusion. Various chemical recycling processes have great potential to enhance recycling rates. In this Review, a summary of the various chemical recycling routes and assessment via life-cycle analysis is complemented by an extensive list of processes developed by companies active in chemical recycling. We show that each of the currently available processes is applicable for specific plastic waste streams. Thus, only a combination of different technologies can address the plastic waste problem. Research should focus on more realistic, more contaminated and mixed waste streams, while collection and sorting infrastructure will need to be improved, that is, by stricter regulation. This Review aims to inspire both science and innovation for the production of higher value and quality products from plastic recycling suitable for reuse or valorization to create the necessary economic and environmental push for a circular economy.

Efficient conversion of polyamides to ω-hydroxyalkanoic acids: a new method for chemical recycling of waste plastics

An efficient transformation of polyamides to ω-hydroxy alkanoic acids was achieved. Treatment of nylon-12 with supercritical MeOH in the presence of glycolic acid gave methyl ω-hydroxydodecanoate in 85% yield and the alcohol/alkene selectivity in the product was enhanced to up to 9.5:1. The use of (18)O-enriched acetic acid for the reaction successfully introduced an (18)O atom at the alcoholic OH group in the product. This strategy may provide a new and economical solution for the chemical recycling of waste plastics.