Paper-Mill Waste Derived Bioplastic with Excitation- and Time-Dependent Phosphorescence Color for Sustainable Flexible Anti-Counterfeiting.

Bioplastics are developed to replace petrochemical-based plastics to address environmental pollution, but their practicality is limited (e.g., mechanical performance, cost, and wet stability). To make bioplastics dominant, the functions outstood in bioplastics but not in petrochemical-based plastics are proposed to develop. Here, flexible anti-counterfeiting leveraging room-temperature phosphorescence (RTP) of bioplastic is presented. A feasible directed redox strategy is proposed to reconstruct xylan from paper-mill waste into a thermally processable RTP bioplastic. The bioplastic without any doping features a long lifetime of 612 ms and a high phosphorescence quantum yield of 5.5%, the RTP of which originates from various clusters of oxygen groups fixed within a rigid polysaccharide environment, resulting in excitation- and time-dependent phosphorescence color. The superior RTP performance is useful for flexible anti-counterfeiting. The work sheds new light on the design and application of bioplastics and enhances the high-value utilization of xylan in the pulp and paper industry.