In Situ Enhancive and Closed-Loop Chemical Recyclable High-Performance Aromatic Polyamides from Lignin-Derived Ferulic Acid

The resource and environmental issues caused by discarded plastics make plastic recycling research increasingly urgent. Polyamide, one of the top five general engineering polymers, has yet to be thoroughly explored for its recycling performance or mechanism, particularly for aromatic polyamides. In this study, ferulic acid, a lignin derivative generated from bio sources, was used to synthesize diacids and photoresponsive aromatic polyamides that could be recycled via dual processes and had outstanding thermal and mechanical properties. On the one hand, UV-induced cycloaddition reactions occurred in photoresponsive groups, allowing polyamides to achieve the performance enhancement of the discarded materials by UV enhancement. The hydrolysis of amide bonds under alkaline circumstances, on the other hand, conferred degradability on ferulic acid-based polyamides. In addition, a simple acidification and filtration approach for extracting beginning monomers from degradation solutions was developed, resulting in closed-loop chemical recycling of ferulic acid-based polyamides. This work enriches the raw material library for the preparation of high-performance biobased polyamides and provides new ideas for the development of recyclable polyamides.