Assembling Hybrid Energetic Materials with Controllable Interfacial Microstructures by Electrospray

Constructing hybrid energetic materials (HEMs) consisting of nanothermites and organic high explosives is an efficient strategy to regulate the reactivity of energetic composites. To investigate the role of interfacial microstructures in determining the reactivity of HEMs, we employ electrospray, one ramification of electrohydrodynamic atomization, to assemble Al/CuO and hexanitrohexaazaisowurtzitane (CL-20) into composites with various morphologies from different solvent systems. The morphology and compositional information of the assembled clay-like or granular HEMs, which are obtained from ketone, ester, or mixtures of alcohol and ether, are confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The phase transition of CL-20 due to the fast evaporation of charged droplets and insufficient time for recrystallization is studied by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric-differential scanning calorimetry (TG-DSC) is applied to investigate the thermodynamic behaviors and synergistic effect of the nanothermite and high explosive. Enhancements in combustion performance and pressurization characteristics of the as-sprayed HEMs have been observed through open burn tests and pressure cell tests. Granular HEMs show high gas generation and high pressurization rate, while nitrocellulose (NC) fibers existing in the clay-like HEMs would weaken the reactivity to a certain extent. HEMs obtained from the mixture of n-propanol and diethyl ether, in which nano-CL-20 exists as independent particles rather than a matrix, exhibit high gas generation but low pressurization rate. The results indicate that the energy releasing performance of the prepared HEMs can be readily regulated by constructing various interfacial microstructures to satisfy the broad requirements of energy sources.