Comparative Studies on Thermal Decompositions of Dinitropyrazole-Based Energetic Materials

Area of Science:

• Energetic Materials Science
• Organic Chemistry
• Computational Chemistry

Background:

• Dinitropyrazole derivatives are crucial for designing novel energetic materials.
• Understanding thermal stability and decomposition mechanisms is vital for safe and effective energetic material applications.

Purpose of the Study:

• To conduct comparative thermal studies on 4-amino-3,5-dinitropyrazole (LLM-116) and its trimer derivative (LLM-226).
• To investigate the influence of an active aromatic N-H moiety on the physicochemical properties of dinitropyrazole-based energetic materials.
• To elucidate the decomposition mechanisms of LLM-116 and LLM-226 using experimental and theoretical approaches.

Main Methods:

• Experimental thermal analysis (DSC/TGA) and kinetic studies.
• Theoretical calculations and ReaxFF force field simulations.
• Analysis of condensed-phase and gaseous decomposition products.

Main Results:

• Trimerization of LLM-116 to LLM-226 significantly enhances thermal stabilization.
• LLM-226 exhibits a less concentrated heat-release process compared to LLM-116.
• LLM-116 decomposition is initiated by N-H hydrogen transfer, leading to ring opening.
• LLM-226 decomposition begins with C-N bond rupture at the diazo moiety.

Conclusions:

• The active aromatic N-H moiety plays a critical role in the thermal behavior and decomposition pathways of dinitropyrazole energetic materials.
• Trimerization offers a strategy for improving the thermal stability of energetic materials, albeit with altered heat release characteristics.
• Distinct decomposition mechanisms for LLM-116 and LLM-226 highlight the impact of structural modifications on energetic material performance.