Synthesis of a novel dual layered double hydroxide hybrid nanomaterial and its application in epoxy nanocomposites

Ease of undesirable agglomeration and low efficiency are two problems that highly restrict the application of MgAl-layered double hydroxides (MgAl-LDH) as suitable flame retardants for epoxy resins. Herein, a new strategy that chose MOFs as the precursor to connect two different LDHs into a hybrid nanomaterial is reported. Nanosheets of NiCo-layered double hydroxides (NiCo-LDH) with multidimensional nanostructures were uniformly anchored on the surface of MgAl-LDH slabs. This led to a better dispersion and stronger interaction within the epoxy matrix, resulting in enhanced strength of the char layers, and also enabled synergistic flame retardant effect to the epoxy nanocomposite, when compared to the case of the unmodified epoxy. The sample passed V-0 rating in UL-94 test and its peak of heat release rate was reduced by 66.7% in cone calorimeter test with the addition of only 2.5 wt% of as-prepared flame retardant. Besides, due to the unique structure of the nanofiller, the mechanical properties of the nanocomposite were only slightly impacted. This is the first report on the synthesis of a dual LDH hybrid nanomaterial, which moreover, improved the flame retardancy of epoxy nanocomposite even when added in relatively low amounts.