Molecular dynamics simulations on ε-CL-20-based PBXs with added GAP and its derivative polymers

Area of Science:

• Materials Science
• Computational Chemistry
• Energetic Materials

Background:

• ε-CL-20 is a high-performance explosive, superior to conventional ones.
• Polymer bonded explosives (PBXs) enhance safety and performance.
• Glycidyl azide polymer (GAP) derivatives are explored as binders.

Purpose of the Study:

• To investigate the mechanical properties and sensitivity of ε-CL-20 based PBXs using molecular dynamics.
• To evaluate the effect of different GAP derivatives (GAP, GAP-NH2, GAP-NO2, GAP-NH2-NO2) on ε-CL-20.
• To understand the relationship between molecular structure, mechanical properties, and explosive sensitivity.

Main Methods:

• Molecular dynamics (MD) simulations using the COMPASS force field.
• Construction of ε-CL-20(001) crystalline surface models with four different GAP-based polymers.
• Calculation of cohesive energy densities (CEDs), elastic coefficients, and isotropic mechanical properties.
• Analysis of initiation bond length distribution to assess sensitivity.

Main Results:

• The cohesive energy densities followed the order: A1 < A4 < A3 < A2 < A.
• PBX models showed improved mechanical properties compared to pure ε-CL-20(001).
• System A3 exhibited the best comprehensive mechanical properties among the studied PBXs.
• Initiation bond length (Lmax and Lave) of N-NO2 increased with temperature, correlating with sensitivity.
• The order of Lmax (A3 < A4 < A2 < A1 < A) indicated reduced sensitivity for these PBXs compared to system A.

Conclusions:

• The incorporation of GAP derivatives significantly enhances the mechanical properties of ε-CL-20.
• System A3, utilizing GAP-NO2, presents a promising candidate for ε-CL-20 based PBXs due to its balanced properties.
• The study provides valuable data for designing safer and more effective energetic materials.
• Findings guide further research on GAP derivatives and ε-CL-20 based PBXs.