Chemical upcycling of thermoplastics towards thermosets based on dynamic dimethylglyoxime‐urethane moiety

Huge annual consumption of thermoplastics results in the generation of large amounts of waste after their service life. Currently, the most popular recycling method based on mechanically melt‐reprocessing deteriorates the material performance and is economically unattractive, which makes it unviable to be implemented in large scale. Herein, we present a chemical upcycling strategy that can transform dimethylglyoxime‐urethane based thermoplastic waste into thermoset product with superior mechanical properties and higher economic values than the initial one. It is found that the dimethylglyoxime‐urethane moiety has dynamic nature, endowing the material with open‐loop upcycling ability. By removing the dimethylglyoxime segment via a simple sublimation process, the material structure is transformed from linear molecular into crosslinked network. More interestingly, the transformation is reversible, and the regenerated crosslinked network can be transformed back to linear molecule by returning the removed dimethylglyoxime segment to the material, which means the upcycled product can be recycled again after its service life. Our linear/crosslinked transformation strategy provide a new option for recycling thermoplastic waste.