News Coatings Technologies
Bifunctional small molecule combines flame retardancy and phosphorescence in epoxy resins
Researchers have developed a multifunctional additive that simultaneously imparts high-performance flame retardancy and ultralong room-temperature phosphorescence to epoxy resin at very low loading levels. The resulting composites maintain a visible afterglow even after prolonged exposure to harsh chemical and UV environments.
Combining effective flame retardancy with ultralong room-temperature phosphorescence (URTP) in a single polymer system has long been a challenge, particularly for applications in demanding environments. A new study published in Progress in Organic Coatings now presents a promising solution based on a bifunctional small molecule designated AFDOPO.
The molecule was synthesised via a straightforward Atherton–Todd reaction between 2-aminofluorene and DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide). Its influence on the comprehensive properties of epoxy resin (EP) was systematically investigated by the research team.
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Outstanding fire safety at minimal loading
At a loading of just 1.5 wt % AFDOPO — corresponding to a phosphorus content of only 0.38 wt % — the EP/AFDOPO-1.5 composite achieved a limiting oxygen index of 31.2 % and a UL-94 V-0 rating. Compared to unmodified epoxy resin, the heat release rate was reduced by 18.6 %, total heat release by 4.1 % and total smoke production by 15.4 %.
Beyond fire safety, the composite displayed bright URTP with a visible afterglow lasting more than 20 seconds. Notably, this luminescence proved highly resistant to harsh conditions: after 31 days of immersion in strong acid or base solutions, the afterglow duration remained at nine seconds, whilst after five days of UV ageing it still reached seven seconds. The authors suggest that such materials hold significant potential for display and anti-counterfeiting applications in challenging environments.
Source: Zhang, S. et al., Fabrication of flame-retardant epoxy resin-based room-temperature phosphorescent materials with robust tolerance to harsh environments. Progress in Organic Coatings (2025).
