Design of New Functional Flame‐Retardant System for High‐Performance Epoxy Thermosets Enabled by Bifunctional Few‐Layer Black Phosphorus and Synergistic Strategy

Abstract In this paper, a new highly effective functional flame‐retardant system is designed and fabricated by the combination of bifunctional amino‐functionalized few‐layer black phosphorus (BP‐NH 2 ) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), and BP‐NH 2 is utilized as both the flame‐retarded synergistic agent of DOPO and the reinforcing agent for bisphenol A diglycidyl ether (DGEBA) epoxy thermoset. The cured epoxy thermoset with a low phosphorus loading (EP/DOPO‐0.4/BP‐NH 2 ‐0.3, P content = 0.5 wt%) passes the UL‐94 V‐0 rating with a limiting oxygen index of 34.5%. EP/DOPO‐0.4/BP‐NH 2 ‐0.3 also shows 20.8% and 16.0% reduction in the peak heat release rate and total heat release as compared to that of pure epoxy thermoset. Furthermore, EP/DOPO‐0.4/BP‐NH 2 ‐0.3 exhibits significant enhancements in tensile modulus and strength, which are, respectively, increased by 11.4% and 18.0%. Thus, by combining a synergistic effect strategy and the bifunctional BP‐NH 2 , the fabrication of epoxy thermosets with high comprehensive (outstanding flame‐resistance and mechanical properties) performance can be achieved. This paper offers a facile and scalable approach to construct a highly‐effective functional flame‐retardant system and new insight into the versatility of BP‐NH 2 , possessing great potential for scalable production and utilization in fire‐safe high‐performance matrix materials.