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 RMH@PDA@PBA composite was introduced into epoxy resin (EP) to improve its fire retardancy and mechanical properties. The composition, structure and morphology of the RMH@PDA@PBA-incorporated EP composite were investigated. The tensile strength of EP with 3 wt.% RMH@PDA@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.% RMH@PDA@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/3RMH@PDA@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/3RMH@PDA@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 PBA@Fe [III]. Thus, this study on bio-inspired hierarchical nanostructures paves a new pathway for the efficient production of fire-safe polymers.

Automated summary

Inspired by the structure of corn, a composite material consisting of NiFe Prussian blue analogue nanocages decorated with magnesium hydroxide rods was synthesized and incorporated into epoxy resin to enhance its fire retardancy and mechanical properties. The study found that the composite material with 3 wt.% nanocages exhibited improved tensile strength, fire-retardant properties, and smoke suppression compared to neat epoxy resin.