Programmable Thermoresponsive Multicolor Afterglow Enabled by Pyrene‐End‐Capped Polyamides

ABSTRACT Thermoresponsive phosphorescent materials have attracted attention due to their ability to modulate emission intensity, color, and lifetime with temperature. Despite promising applications in dynamic anti‐counterfeiting, information encryption, and smart optoelectronic devices, these materials often suffer from limited emission color changes, insufficient color diversity, and short phosphorescence lifetime. To overcome these limitations, we present an innovative molecular engineering strategy that unites two phosphorescent components with distinct emission colors, lifetimes, and thermal sensitivities in a single polymer backbone, achieving multicolor and temperature‐controllable phosphorescence. Specifically, a series of pyrene‐1‐carboxylic acid (PyCA) end‐functionalized PA69 polymers with precisely controlled PyCA contents is synthesized. The flexible PA69 chains generate long‐lived yellow‐green phosphorescence strongly modulated by temperature, while the rigid π‐conjugated pyrene emits relatively short‐lived red phosphorescence with excellent thermal stability. Upon increasing temperature, the distinct thermal quenching rates of these two emissive centers lead to a continuous color transition from yellow‐green to red. Remarkably, Py‐PA69 retains second‐scale afterglow even at 348 K. Py‐PA69 also exhibits component‐dependent and time‐dependent phosphorescent properties. This programmable luminescence enables advanced applications, including time‐dependent multicolor anti‐counterfeiting patterns, time‐gated four‐dimensional (4D) encryption codes, temperature‐responsive digital displays, and emergency signage with thermally indicative luminescence.