A novel DOPO-AS/M(OH)(OCH3) organic/inorganic nanohybrid for enhancing the flame retardancy and mechanical properties of epoxy

A novel multifunctional flame-retardant DOPO-AS/M(OH)(OCH 3 ) (M = Co, Ni) was synthesized and incorporated into epoxy resin (EP) to prepare EP composites with enhanced flame retardancy and mechanical properties. Specifically, the DOPO-AS was synthesized using 3-aminopropyltriethoxysilane (APTES), salicylaldehyde (Salal), and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The 2D nanosheet M(OH)(OCH 3 ) was surface modified with DOPO-AS, thereby synthesizing the organic/inorganic nanohybrid DOPO-AS/M. The results showed that the addition of only 5% (by wt) DOPO-AS/M enabled EP to achieve the UL-94 of V-1 rating, with the limiting oxygen index (LOI) increasing from 28.7% to 31.0%. The thermogravimetric analysis (TGA) results demonstrated that the EP/DOPO-AS/M composite exhibited a significant enhancement in thermal stability compared to pure EP. Meanwhile, EP/DOPO-AS/M 5% composite showed significant reduction of 48.1%, 14.7%, 30.9%, and 22.7% in the peak heat release rate (pHRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP), respectively. In addition, the tensile strength and elongation-at-break of the EP composite with 1% (by wt) DOPO-AS/M were increased by 13.5% and 3.2%, compared with pure EP. This work provides a novel and facile strategy for the simultaneous enhancement of flame retardancy and mechanical properties in EP composites, showing promising potential for practical applications. Graphical