Hydrogen‐Bonded Phosphorescent Modules Enable Component‐Selective Recovery of Organic Afterglow Composites

Abstract Developing polymer composites that combine long‐lived room‐temperature phosphorescence (RTP) with component recovery remains challenging because the local environment supporting triplet emission can be disrupted during processing and separation. Here, recoverable hydrogen‐bonded RTP modules are introduced as function‐retentive building blocks for organic afterglow composites. Carboxyl‐functionalized aromatic phosphors are co‐assembled with a melamine‐cyanuric acid (MA‐CA) framework, allowing long‐lived RTP to be maintained without relying on the polymer matrix as the sole rigidifying environment. Across three biphenyl dicarboxylic acid isomers, increasing meta‐carboxyl substitution correlates with longer phosphorescence lifetimes, supporting meta‐carboxyl anchoring as a useful design motif within this system. The representative module exhibits cyan afterglow with a lifetime of 2.83 s and an afterglow discernible for approximately 22 s, while terphenyl‐based analogues show lifetimes of 2.30–2.64 s. The modules retain long‐lived RTP after heating at 200 °C and after prolonged exposure to ethanol or DMSO, allowing their incorporation into stretchable and remoldable polymer films with substantial retention of long‐lived emission. After use, solvent‐assisted separation affords recoverable polymer‐rich and phosphorescent phases, with the recovered MA‐CA‐P2 module retaining a lifetime of 2.49 s. These results demonstrate a proof‐of‐concept modular route to processable and component‐recoverable organic afterglow composites.