ADOPO‐anchored benzothiadiazole derivative toward efficiently P/N/S synergistic flame retarding of epoxy thermoset

Abstract Flame‐retarded epoxy thermosets are highly desirable for electronics‐related basic materials in the new‐generation information applications. Herein, a DOPO‐anchored benzothiadiazole flame retardant, namely DOPO‐BTD , is designed and synthesized for P/N/S synergistic flame‐retarded epoxy thermosets. DOPO‐BTD possesses good thermal stability and excellent compatibility with the epoxy matrix. As reflected by UL 94 test, the DOPO‐BTD coated EP passes the V0 rating and achieves a higher LOI value of 34.6% at ultralow P content of 0.39 wt%. The investigation of the DOPO‐BTD ‐triggered P/N/S synergistic flame‐retarded effect by thermal images further validated the flame retarded efficacy and dramatic inhibition of the flame. Meanwhile, the incorporation of 4.8 wt% DOPO‐BTD into the epoxy matrix, the PHRR, THR, SPR, TSP, and COP are significantly decreased by 37.97%, 27.44%, 25.49%, 19.83%, and 31.70%, respectively. Additionally, the fire growth index (FGI) is sharply dropped 26.06%. Moreover, the TGIR and TGMS results convince the flame‐retarded mechanism of DOPO‐BTD through the combination of the gas‐phase and condensed‐phase pathways. The P/N/S synergistic DOPO‐BTD can serve as a promising flame retardant for efficiently fabricating the flame‐retarded epoxy thermosets, and this study sheds light on the development of multiple elements synergistic flame‐retardants for functional polymers with great application potential.