Bicyclic‐Guanidinium Benzenesulfonate: A Fingerprint Monomer for Self‐Recognizably Recyclable Polyester with Antibacterial Performance

The increasing complexity of waste mixed polymer materials requires an innovative strategy for the precise recognition and recycling of each type materials. Inspired by biometric self-recognition technologies, the study proposes a "fingerprint monomer" concept to endow polymers with self-recognizable recyclability in mixed wastes. Targeting poly(ethylene terephthalate) (PET, the most produced polycondensation polymer), a bicyclic-guanidinium benzenesulfonate (GS) fingerprint monomer is customized and chemically integrated into PET chain to synthesize PET-GS polyester. This novel PET-GS polyester combines high-value antibacterial activity during service stage and self-recognizable recyclability in mixed polymers at end-of-life. It is found for the first time that the bicyclic-guanidinium cation of the GS fingerprint unit can bind to the anion on the bacterial surface, thereby effectively destroying the bacterial structure and achieving a >99.9% antibacterial rate for PET-GS polyester. More interestingly, the GS fingerprint unit triggers the precise self-recognizable recycling of PET-GS polyester in mixed plastics and even in the same type of PET fibers through hydrogen bonding with nucleophiles, while other polymer materials remain unchanged for easy separation. Therefore, this work pioneers sustainable polymer material with high-value functionality and built-in precise recyclability, striving toward a sustainable and zero-waste circular economy.