Fabrication of flame-retardant epoxy resin-based room-temperature phosphorescent materials with robust tolerance to harsh environments

Polymer-based materials integrating high-performance flame retardancy with ultralong room-temperature phosphorescence (URTP) are highly desirable yet rarely achieved, especially for applications under harsh environmental conditions. In this work, a multifunctional small molecule (AFDOPO) was synthesized via a straightforward Atherton–Todd reaction between 2-aminofluorene and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and its influence on the comprehensive properties of epoxy resin (EP) was systematically investigated. With only 1.5 wt% AFDOPO loading (phosphorus content: 0.38 wt%), the EP/AFDOPO-1.5 composite exhibits outstanding fire safety, achieving a limiting oxygen index of 31.2 % and a UL-94V-0 rating along with significant reductions in heat release rate (18.6 %), total heat release (4.1 %), and total smoke production (15.4 %) relative to pristine EP. Remarkably, the composite also displays bright ultralong room-temperature phosphorescence, maintaining a visible afterglow for over 20 s. Even after 31 days of immersion in strong acid/base or 5 days of UV aging, the afterglow durations remain as long as 9 s and 7 s, respectively. This study offers a feasible strategy for designing high-performance URTP materials capable of functioning reliably in demanding environments.