A novel multifunctional phosphorous and nitrogenous reactive flame retardant toward epoxy resins by one‐pot method

Abstract Epoxy resin (EP) has attracted considerable attention in packaging, electronic devices, aerospace, and coatings fields owing to its remarkable chemical and physical performance. However, the inherent flammable performance and unfavorable brittle nature seriously restricted its application in sophisticated industry. Herein, an efficient reactive 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐based flame retardant (DB‐DAD) was prepared by a facile “one‐pot” method. Due to their synergistic gas‐phase and solid‐phase flame‐retardant effects, DB‐DAD modified EP composites (EP/DB‐DAD composite) easily achieved UL‐94 V‐0 ratings, and an EP/DB‐DAD composite with a 0.32 wt% phosphorus content had an excellent (30.2%) limiting oxygen index. In addition, the amounts of heat and smoke decreased by 28.1% and 24.8%, respectively. Due to the introduction of long and flexible aliphatic chains, the EP/DB‐DAD composites exhibited satisfactory mechanical properties, the flexural and tensile toughness of EP/6% DB‐DAD were 82.5% and 62.2% higher than those of neat EP, respectively. Furthermore, EP/DB‐DAD composite showed good transparency (>85%) and favorable UV shielding performance. The EP/DB‐DAD composite with good comprehensive performance is extremely promising to accelerate EP application in high‐tech industries.