Highly Flame‐Retarded Epoxy Thermoset Imparted by Bio‐Based Phosphorus/Nitrogen‐Containing Furan Derivative with Enhanced Mechanical Toughness

A bio‐based phosphorus/nitrogen‐containing furan derivative, 6,6′′,6′′′‐(((1,3,5‐triazine‐2,4,6‐triyl) tris(oxy))tris(benzene‐4,1‐diyl))tris(((furan‐2‐ylmethyl) amino)methylene)) tris(dibenzo[c,e][1,2]oxaphosphinine 6‐oxide) (TFAD) is successfully synthesized and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The introduction of TFAD clearly lowers the activation energy for diglycidyl ether of a bisphenol A (DGEBA)/4,4′‐diaminodiphenyl methane (DDM) system. The DGEBA/DDM/ TFAD thermoset achieves UL‐94 V‐0 rating and possesses a limiting oxygen index (LOI) of 30.1% as the content of phosphorus is up to 0.41 wt.%. Further, compared with unmodified epoxy thermoset, its peak heat release rate and total heat release experience 42.0% and 14.8% decrement, respectively. The flame‐retardant mechanism analysis confirms that TFAD exerts a fire‐retardant effect in both gaseous and condensed phases. Meanwhile, the impact strength of the flame‐retardant thermoset is enhanced by 35.6%, from 19.5 kJ m–2 for EP‐0 to 26.5 kJ m–2. This work provides a novel strategy to construct superior flame‐retarded epoxy thermosets with admirable impact performance. A novel bio‐based phosphorus/nitrogen‐containing furan derivative (TFAD) is synthesized and applied to modify epoxy thermosets. Compared with other DOPO‐based flame retardant‐modified epoxy resins, the TFAD‐modified thermosets possess excellent flame retardant performance and considerable impact properties. This work provides a new strategy for the preparation of high‐performance epoxy thermoset.