Synthesis of sugar gourd-like metal organic framework-derived hollow nanocages nickel molybdate@cobalt-nickel layered double hydroxide for flame retardant polyurea.

Transition metals with catalytic properties were expected to improve the fire resistance of the polymer. In this work, NiMoO nanorods decorated with Co-Ni layered double hydroxide (LDH) were fabricated and incorporated into polyurea (PUA) to improve the flame retardancy during combustion. Thermogravimetric analysis (TGA) showed that the addition of NiMoO@Co-Ni LDH slightly decreased the initial degradation and the maximum degradation temperature. With increasing loading of NiMoO@Co-Ni LDH, the char residue increased obviously. The combustion performance of PUA with 3.0 wt% NiMoO@Co-Ni LDH investigated by cone calorimeter (CCT) showed that the peak heat release rate (PHRR), total heat release (THR) and smoke factor (SF) decreased by 34.41%, 12.68% and 48.65%, respectively. The existence of well-dispersed NiMoO@Co-Ni LDH effectively enhanced the mechanical properties and flame retardant performances of PUA.