Theoretical study on the stability mechanism of a high energy system composed of molecules containing C[sbnd]O[sbnd]C or –N3 groups and aluminum hydride

Abstract

The stability of aluminum hydride(AlH3) based high-energy propellants is important for its large-scale application. In this work, to explore the stability mechanism of systems composed of AlH3 and a binder containing COC or –N3 groups, molecular dynamics simulations were carried out to explore the thermal expansion properties of AlH3, and density functional theory calculations were employed to study the micro-interactions between molecules containing COC or –N3 groups and AlH3. More specifically, CH3OC2H5 and CH3N3 were used to model polyethylene glycol and glycidyl azide polyether, respectively. It is found that AlH3 is more sensitive to temperature changes than its oxide layer. Upon contact between the alumina layer and CH3OC2H5 or CH3N3, these compounds exist stably on the α-Al2O3(0001) and γ-Al2O3(110) surfaces. Upon direct contact with the α-AlH3(010) surface, CH3OC2H5 is relatively stable, while CH3N3 can trigger the surface hydrogen transfer reaction due to the low energy barrier(5.0 kcal/mol). The current work provides a theoretical basis for understanding the sensitivity of AlH3 and binders containing COC or –N3 groups, and is useful in the research and development of superior composite energetic propellants.