Visualized Degradation of CO ₂ -Based Unsaturated Polyesters toward Structure-Controlled and High-Value-Added Fluorophores

In comparing with traditional polymer degradation toward unknown or unvalued products (i.e., downcycling), new methods to degrade polymers into monomers or high-value-added materials (i.e., upcycling) are preferable for sustainable developments. In this work, CO2-based linear and cross-linked unsaturated polyesters, that is, poly(alkynoate)s, were successfully degraded by benzamidine into diols and high-value-added pyrimidone or imidazolone derivatives through controlled reaction conditions. The degradation process could be visualized under UV light via gradually increased luminescent intensity of the reaction mixtures and fluorescence patterns could be generated through microcontact printing of the stamp on the thin films of poly(alkynoate)s. Moreover, the pyrimidone derivatives could be applied in bioimaging and inhibiting bacteria, and the imidazolone derivatives could be used for the detection and recovery of gold(III) ions from electronic waste and serve as the fluorescent sensor to detect in situ-generated amines from food spoilage. Thus, this work presents a visualized and high value productselective degradation to solve the end-of-life issue of polymers. © 2022 The authors. All right reserved.