Ultralong Room-Temperature Phosphorescence Achieved by Microcapsule Rupture-Triggered In-Situ Polymerization for High-Contrast Damage Visualization and Advanced Anti-counterfeiting.

Abstract

Polymer materials with mechano-responsive ultralong room-temperature phosphorescence (RTP) are highly desired but challenging to achieve. Herein, a microcapsule (MC) rupture-triggered in-situ polymerization strategy is proposed to achieve such RTP with full-color tunable emissions. It involves co-encapsulating organic phosphors and moisture-reactive hexamethylene diisocyanate (HDI) in MCs, which are dispersed into a polymer matrix. Mechanical damage ruptures MCs, releasing HDI that undergoes moisture-initiated polymerization to form a rigid cross-linked network at the damaged site. This network effectively suppresses non-radiative decay pathways of triplet excitons, thereby activating "turn-on" ultralong RTP signals specifically and exclusively at the damaged sites. The system achieves ultralong RTP lifetimes exceeding 1.5 s and a phosphorescence quantum yield of 11.2%. Notably, these RTP systems demonstrate exceptional stability under harsh conditions, including immersing in neutral, acidic, alkaline aqueous environments and various organic solvents, as well as exposure to high temperatures. Full-color tunable afterglow emissions, ranging from blue to red, are readily achieved by employing different organic phosphors. This approach facilitates the development of self-repairing smart coatings with high-contrast damage visualization and advanced anti-counterfeiting systems featuring mechanically activated dynamic RTP responses. Furthermore, the compatibility of MCs with diverse polymer matrices expands the practical applicability of such stimuli-responsive ultralong RTP materials.