Unexpected Polymerization‐Induced Luminescence in Deep Eutectic Solvent (DES)‐Based Polymer

Abstract Here, a polymerizable type‐IV deep eutectic solvent (DES) is synthesized via the coordination reaction between acrylamide and SbCl 3 , and for the first time it is demonstrated that the resultant type‐IV DES‐based polymers can exhibit luminescence after polymerization due to the efficient Sb‐ligand and ligand–ligand charge transfer. Notably, the quantum yield of Sb‐ligand charge transfer emission can be tuned with the controllable reversible addition‐fragmentation chain transfer (raft) polymerization of acrylamide, reaching up to 15.32%. As a proof‐of‐concept application, the polymerizable DES is utilized as fluorescent anti‐counterfeit ink, successfully realizing the fluorescence encryption.