Precise Control of a Yolk-Double Shell Metal–Organic Framework-Based Nanostructure Provides Enhanced Fire Safety for Epoxy Nanocomposites

Abstract

Nanomaterials derived from metal–organic frameworks (MOFs) are highly promising as future flame retardants for polymeric materials. The precise control of the interface for polymer nanocomposites is taking scientific research by storm, whereas such investigations for MOF-based nanofillers are rare. Herein, a novel yolk-double shell nanostructure (ZIF-67@layered double hydroxides@polyphophazenes, ZIF@LDH@PZS) was subtly designed and introduced into epoxy resin (EP) as a flame retardant to fill the vacancy of yolk/shell construction in the field. Meanwhile, the interface of the polymer nanocomposites can be further accurately tailored by the outermost layer of the nanofillers from PZS to Ni­(OH)2 (NH), by which hollow nanocages with treble shells (LDH@PZS@NH) were obtained. It is remarkably interesting that LDH@PZS@NH endows the EP with the lowest peak of heat release rate in the cone calorimeter test, but the total heat and smoke releases (THR and TSP) of the nanocomposites are even higher than those of the neat polymer. In contrast, EP blended with ZIF@LDH@PZS shows outstanding comprehensive performance: with 2 wt.%, the limiting oxygen index is increased to 29.5%, and the peak heat release rate is reduced by 26.0%. The impact and flexural strengths are slightly lowered, while the storage modulus is enhanced remarkably compared with that for neat EP. The flame retardant mechanism is systematically explored focusing on the interfacial interactions of different hybrids within the epoxy matrix, ushering in a new stage of study of nanostructural design-guided interface manipulation in MOF-based polymer nanocomposites.

Multielement Flame-Retardant System Constructed with Metal POSS–Organic Frameworks for Epoxy Resin

“…Therefore, the integrated intensity ratio of I D / I G is indexed to the graphitization degree. For the char residue, the lower the I D / I G value, the stronger the barrier effect it possesses . The value for the Co-POSS-incorporated composite was 2.02, which was much lower than that for neat EP.…”

“…For the char residue, the lower the I D / I G value, the stronger the barrier effect it possesses. 35 The value for the Co-POSS-incorporated composite was 2.02, which was much lower than that for neat EP. However, the value showed a further decrease for the MPOFs-incorporated composite, which was 1.87.…”

Hollow Nanospheres of Red Phosphorus for Fireproof Flexible Sensors Fabricated via 3D Printing

“…At about 400 °C, the peak intensity of the pyrolysis products reaches the maximum, and the corresponding peaks appear at 829, 1171, 1510, 1744, and 2974 cm −1 for −C�CH 2 , C−O−C, C�C, C�O, and C−H, respectively. 44 After that, the kind of cracking products changes slightly, which is inseparable from the exhaustion of RPHNs, accompanied by further evolution of the condensed phase residual char formed at high temperatures. Meanwhile, at the two decomposition temperatures (353.6 and 507.8 °C) corresponding to rapid weight reduction, the peak locations of the pyrolysis products are almost identical, suggesting that the gaseous products are extremely similar (Figure 7c), which can be attributed to only one functional flame-retardant additive in the matrix.…”

Synthesis of ZnFe2O4@Mg‐Al‐SDBS LDH composites for regulating heat and fire safety properties of polyurea

“…Metal ions can promote the cross‐linking of degraded fragments during the thermal degradation of polymers, so smoke suppression in polymer systems has been extensively studied. Meanwhile, the transition metal ions can promote the catalytic carbonization of the substrate during the combustion process and provide important assistance to the flame retardation of the condensed phase 8,9 . It is reported that iron compounds may act as a synergist and smoke suppressant in some thermoplastic polymers 10 .…”

“…Meanwhile, the transition metal ions can promote the catalytic carbonization of the substrate during the combustion process and provide important assistance to the flame retardation of the condensed phase. 8,9 It is reported that iron compounds may act as a synergist and smoke suppressant in some thermoplastic polymers. 10 The incorporation of a small number of iron compounds will cause the highly activated carbon to pass through the cross-linking reaction in the polymer.…”