NiFe prussian blue analogue nanocages decorated magnesium hydroxide rod for enhancing fire safety and mechanical properties of epoxy resin

Inspired by the structure of corn, a NiFe Prussian blue analogue nanocages decorated magnesium hydroxide composite was synthesized for the first time using magnesium hydroxide rods (RMH) as the “corn cob”, a Prussian blue analogue (PBA) as the “corn kernels” and polydopamine (PDA) as the membrane linking RMH and PBA. Subsequently, the [email protected]@PBA composite was introduced into epoxy resin (EP) to improve its fire retardancy and mechanical properties. The composition, structure and morphology of the [email protected]@PBA-incorporated EP composite were investigated. The tensile strength of EP with 3 wt.% [email protected]@PBA reached 41.77 MPa, which is higher than that of neat EP (40.51 MPa). The fire-retardant assessments illustrated that the limiting oxygen index and vertical burning tests (UL-94) of EP composite with 3 wt.% [email protected]@PBA progressed to 32.3% and the V-0 level as compared to those of virgin EP (24.4% and no rating). In addition, as compared to virgin EP, the peak heat release rate, peak smoke production rate, total heat release at 200 s and total smoke production at 200 s of EP/[email protected]@PBA decreased by 43.1%, 50.0%, 43.9% and 56.3%, respectively. The investigation of the underlying mechanism revealed that the flame retardancy and smoke suppression of EP/[email protected]@PBA were attributed to the endothermic decomposition of RMH, “gauze barrier” mechanism of MgO/FeO, catalytic charring effect of Fe derivatives (MgO/FeO, FeNi3, Fe5C2, Fe2N, etc.) and free radical scavenging effect of [email protected][Ⅲ]. Thus, this study on bio-inspired hierarchical nanostructures paves a new pathway for the efficient production of fire-safe polymers.