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Click-synthesised phosphorus-triazole FRs for flame-retardant epoxy coatings
A new study introduces flame-retardant additives based on phosphorus and triazole compounds, synthesised via metal-free click chemistry. The additives offer enhanced flame resistance and improved char formation in epoxy resins.
To overcome the low flame resistance of epoxy resins, a research team has synthesised three phosphorus/nitrogen-based flame retardants (FRs) using a metal-free azide–alkyne click reaction. The resulting additives—P1T1, P2T1, and P3T2—were evaluated in a standard DGEBA/F epoxy matrix.
The best-performing compound, P3T2, demonstrated a limiting oxygen index (LOI) of 42 % and achieved UL-94 V-0 rating at just 16 wt%. Thermogravimetric and cone calorimetry analyses revealed synergistic gas-phase and condensed-phase mechanisms, with effective char formation and reduced flammable volatiles.
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Fire safety meets processability
Besides strong flame-retardant performance, the modified epoxies maintained good processability. At lower additive concentrations (2–4 %), the thermal and barrier properties were significantly enhanced with minimal loss in mechanical integrity.
Source: Progress in Organic Coatings, Volume 207, October 2025, 109396.
