Chemical recycling of waste plastics for new materials production

Once referred to as ‘materials of 1,000 uses’, plastics meet demands in everything from clothing and automotive sectors to the manufacturing of medical equipment and electronics. Concomitant with usage, worldwide generation of plastic solid waste increases daily and is currently around 150 million tonnes per annum. Although recycled materials may have physical properties similar to those of virgin plastics, the resulting monetary savings are limited and the properties of most plastics are significantly compromised after a number of processing cycles. An alternative approach to processing plastic solid waste is chemical recycling, the success of which relies on the affordability of processes and the efficiency of catalysts. In this Review, we describe technologies available for sorting and recycling plastic solid waste into feedstocks, as well as state-of-the-art techniques to chemically recycle commercial plastics. These evaluations are followed by a survey of recent advances in the design of new high-performing recyclable polymers. Many methods exist for the recycling of plastic solid waste. Chemical recycling, which can take many forms from high-temperature pyrolysis to mild, solution-based catalytic depolymerization, can afford enormous economic and environmental benefits. This Review covers the state of the art in chemical recycling and the design of high-performance polymers amenable to such processes.