Theoretical insight into different energetic groups on the performance of energetic materials featuring RDX ring

Thirty nitramines by incorporating –NHNH₂, –N₃, –NH₂, –NHNO₂, –C[dbnd]O, –NF₂, –ONO₂, –NO₂, –C(NO₂)₃, and –CH(NO₂)₂ groups to RDX (1,3,5-trinitro-1,3,5-triazinane) framework were designed. Their electronic structures, heats of formation (HOF), detonation properties, thermal stabilities, thermodynamic properties, and electrostatic potential were systematically investigated by density functional theory. The effects of different substituents on the performance of energetic materials were studied, showing that the number of nitrogen atom in substituted groups plays a critical role in determining HOFs, Thermal dynamic parameters, such as standard molar heat capacity (C_p,m^θ), standard molar entropy (S_m^θ) and standard molar enthalpy (H_m^θ) increased with the increasing number of energetic groups, and the volume of energetic groups have a great effect on standard molar enthalpy. Compared to the traditional energetic compound RDX, all designed molecules have similar or better density, detonation properties, and oxygen balance. Among them, D2 has extraordinary high detonation performance (D = 11.44 km s⁻¹, P = 64.54 GPa), A3 has relatively poor detonation performance (D = 8.85 km s⁻¹, P = 36.70 GPa), and –NF₂ and –C(NO₂)₃ are the best groups in increasing density by more or less six percent.