Ion‐Driving Polymer Entanglement for Dynamic Organic Phosphorescence

ABSTRACT The development of dynamic organic phosphorescent polymers is often limited by the challenge of exerting precise and reversible control over their condensed matter structures. While external stimuli can modulate emission, a fundamental materials‐level principle for governing hierarchical reorganization remains elusive. Here, we report that ion‐driving entanglement of polymer chains serves as a powerful general strategy to direct reconfigurable hierarchical structures, thereby enabling highly tunable organic phosphorescence. Specifically, potassium ions programmatically bridge ether and sulfonic acid groups within κ ‐carrageenan (κCG), triggering polymer entanglement and chromophore aggregation to form a dynamically reversible architecture. This structural transformation, validated by atomic force microscopy (AFM) and rheology, grants control over triplet exciton behavior, yielding phosphorescence that is tunable from blue to green (CIEy: 0.037–0.382) with a lifetime of up to 199.50 ms and an efficiency of 17.97%. The entanglement is thermally reversible, allowing on‐demand emission switching. Furthermore, we demonstrate the translational potential of this mechanism by constructing a visual urinary potassium analyzer, where ion‐concentration‐dependent phosphorescence enables quantitative detection. This work establishes polymer entanglement as a central design principle for adaptive photonic materials, opening avenues for smart sensing and healthcare monitoring.