Further enhancing thermal stability of thermostable energetic derivatives of dibenzotetraazapentene by polydopamine/graphene oxide coating

The high performance energetic materials (EMs) with reduced sensitivity and improved thermostability are essential for propellant and explosive applications. In this paper, two thermostable derivatives of dibenzotetraazapentene Tetranitro-Benzopyridotetraazapentalene (NBTTP) and Tetranitro-Dipyridotetraazapentalene (NPTTP) are further stabilized by Polydopamine (PDA) and Graphene Oxide (GO) coating, resulting in highly thermostable composites. The thermal behavior and decomposition mechanisms of these composites have been investigated by TG-DSC/FTIR technique. It has been shown that the PDA/GO coating layer is effective to stabilize NBTTP and NPTTP crystals by largely increasing their decomposition activation energy (E_a). As a typical product, the NBTTP@PDA/GO-1–1 decomposes in two steps, with the E_a 38.0% and 59.0% higher than that of pristine NBTTP, respectively. In comparison, the E_a for rate-limiting decomposition step of NPTTP@PDA/GO-1–2 is 92.6% higher than that of NPTTP. After coating PDA/GO, the decomposition heat does not change much, which is about 2259 to 2458 J g⁻¹. The last decomposition step for these composites follows 2D nucleation and nucleus growth model, whereas it is 3D nucleation and growth model for the pristine crystals, indicating a much lower decomposition reaction rate. The major gaseous products of NBTTP and NPTTP are CO₂, C₂H₂, N₂O, [sbnd]C[tbnd]N, CO, NO and H₂O. Volatile hydrocarbon products appear in modified NBTTP composites, which are responsible for the slow reaction rates.