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In this work, we employed a two-step modification process to improve the properties of 2D bimetallic nanoplates M(OH)(OCH3) (M = Co, Ni), which were recently proven as a promising "nano-flame retardant". The nanoplates were in situ modified with metal-organic framework ZIF-67 first and then silanized with a coupling agent APTES. Epoxy resin (EP) nanocomposites were fabricated using the functionalized M(OH)(OCH3). We investigated the performance of the nanocomposites in flame retardance and thermal stability. The results showed that 3% of APTES@ZIF-67@M(OH)(OCH3) gave the EP nanocomposite the V-1 rating in UL-94 test and the highest limited oxygen index of 27.6%. Moreover, the pHRR value of EP/APTES@ZIF-67@M 3% was reduced by 20.0% and 9.6%, respectively, compared to neat EP and EP/ZIF-67@M 3%. Regarding the mechanical properties, the Tensile properties and energy storage modulus of EP nanocomposite were both improved with 3% of APTES@ZIF-67@M(OH)(OCH3). The GC-MS test results revealed that the functionalized M(OH)(OCH3) significantly increased the cross-linking propensity of the EP matrix upon combustion, leading to the formation of a dense char layer. This study demonstrates the great potential of M(OH)(OCH3) as a highly efficient "nano-flame retardant" with tunable functionality. [ABSTRACT FROM AUTHOR]

In this study, the two-dimensional bimetallic nanosheets, M(OH)(OCH 3) (M = Co, Ni) was used as a novel "nano-flame retardant" to improving fire retardancy and smoke suppression of epoxy resin (EP) nanocomposties. With 3 wt% M(OH)(OCH 3) added, the peak heat release of EP/M(OH)(OCH 3)-3 wt% decreased from 1021.4 to 867.8 kW/m2, compared with pure EP. To the smoke suppression, the peak of smoke product rate and the total smoke product of EP/M(OH)(OCH 3)-3 wt% was 0.27 m2/s and 28.3 m2, which decreases by 15.6 and 15.0% than those of pure EP, respectively. Only 1 wt% M(OH)(OCH 3)@Ni, which got the modification by the introduction of nickel ion on surface, could endow the composite a further improvement in both flame retardant and smoke suppression. The results of gas chromatography-mass spectrometer demonstrated the M(OH)(OCH 3)@Ni facilitated the aromatization reaction and promotes the generation of the protective char layer, which hinders the propagation of combustible free radicals and restrains the release of smoke. This study demonstrated that the two-dimensional bimetallic nanosheets, M(OH)(OCH 3) (M = Co, Ni), has a great potential to act as novel "nano flame retardant". Moreover, the appropriate modification could further promote its performance in improving the flame ratardancy and smoke suppression of EP. • M(OH)(OCH 3)(M = Co, Ni) was used as a novel "nano-flame retardant" to fabricate flame retardant and smoke suppression EP. • 3 wt% M(OH)(OCH 3) could efficiently enhance the flame retardant and smoke suppression of EP composites. • 1 wt% M(OH)(OCH 3)@Ni realize a further promotion in flame retardant and smoke suppression of EP. • Aromatization reaction has been confirmed as the effective mechanism of flame retardant and smoke suppression. [ABSTRACT FROM AUTHOR]