Molecular dynamic simulations for FOX-7 and FOX-7 based PBXs.

Area of Science:

• Materials Science
• Computational Chemistry
• Energetic Materials

Background:

• Polymer bonded explosives (PBXs) require binders to improve mechanical properties and safety.
• 1,1-diamino-2,2-dinitroethene (FOX-7) is a high-performance explosive ingredient.
• Understanding binder-energetic material interactions is key to designing advanced explosives.

Purpose of the Study:

• To investigate the binding energies and mechanical properties of FOX-7 based PBXs with various polymer binders.
• To evaluate the influence of different binders on the plasticity, formability, and detonation performance of FOX-7.
• To identify optimal binder-energetic material combinations for improved explosive formulations.

Main Methods:

• Molecular dynamic (MD) simulations were employed to model FOX-7 and polymer binder interactions.
• Calculations included binding energies, elastic moduli, and Poisson's ratio for pure FOX-7 and various PBXs.
• Detonation performance, including detonation velocity, was theoretically calculated for the simulated systems.

Main Results:

• Binding energies showed a trend: FOX-7/HTPB ≈ FOX-7/SBS > FOX-7/EVA > FOX-7/F2641, with the (002) FOX-7 surface exhibiting the strongest interactions.
• Styrene butadiene styrene block copolymer (SBS) demonstrated the greatest improvement in PBX plasticity and formability.
• Detonation properties slightly decreased at ~5% binder mass ratio, but all theoretical detonation velocities exceeded 8500 m/s.

Conclusions:

• Polymer binders significantly influence the mechanical properties and formability of FOX-7 based PBXs.
• SBS and HTPB show strong binding affinity with FOX-7, leading to enhanced plasticity.
• MD simulations provide valuable insights for tailoring PBX formulations for specific performance requirements while maintaining safety.