Room-Temperature Material Recycling/Upcycling of Polyamide Waste Enabled by Cosolvent-Tunable Dissolution Kinetics

Polyamides (PAs, nylons) are a ubiquitous class of high-performance plastics used extensively in a wide range of applications. Their high resistance to many common solvents and tendency to hydrolyze in strong acids or bases creates a major hurdle to low-emissions material recycling (i.e., resource separation and recovery). In the present study, the first detailed investigation into the molecular mechanisms of polyamide dissolution, we show that introducing a weakly hydrogen-bonding cosolvent into formic acid can effectively tune the solvent-solvent and solvent-polymer interactions, drastically accelerates the room-temperature dissolution kinetics of common (short-chain) polyamides such as PA6 and PA66, as well as long-chain and semi-aromatic varieties. The recovered polymers show no change in their chemical structures or properties, and sufficient selectivity allows for fillers such as short and long fibers, inorganic nanoparticles, metals, and other mixed polymer phases to be recovered at high efficiency (>95%) along with recirculation of all solvents (>98%). This cosolvent-enabled approach has the potential to make polyamide recycling more sustainable and economical by reducing the energy input and CO₂ emissions required to separate and recover the various constituent materials from automotive and electrical components, textiles, and beyond.