Comparative Studies on Thermal Decompositions of Dinitropyrazole-Based Energetic Materials

Abstract

Dinitropyrazole is an important structure for the design and synthesis of energetic materials. In this work, we reported the first comparative thermal studies of two representative dinitropyrazole-based energetic materials, 4-amino-3,5-dinitropyrazole (LLM-116) and its novel trimer derivative (LLM-226). Both the experimental and theoretical results proved the active aromatic N-H moiety would cause incredible variations in the physicochemical characteristics of the obtained energetic materials. Thermal behaviors and kinetic studies of the two related dinitropyrazole-based energetic structures showed that impressive thermal stabilization could be achieved after the trimerization, but also would result in a less concentrated heat-release process. Detailed analysis of condensed-phase systems and the gaseous products during the thermal decomposition processes, and simulation studies based on ReaxFF force field, indicated that the ring opening of LLM-116 was triggered by hydrogen transfer of the active aromatic N-H moiety. In contrast, the initial decomposition of LLM-226 was caused by the rupture of carbon-nitrogen bonds at the diazo moiety.

Comparative Thermal Research on Energetic Molecular Perovskite Structures

“…Non-isothermal kinetics of the thermal decompositions of (C 6 H 14 ON 2 )[NH 4 (ClO 4 ) 3 ] and (C 6 H 14 N 2 )[Na(ClO 4 ) 3 ] were investigated through DSC experiments under different heating rates of 2, 5, 10, and 20 • C/min with their thermal decomposition peaks compared with those of (C 6 H 14 N 2 )[NH 4 (ClO 4 ) 3 ] as shown in Figure 3a-c. Similar to many energetic materials' thermal decomposition behaviors under different heating rates [23][24][25], the decomposition peaks of the three molecular perovskites shifted toward high temperatures with the increase of heating rate, meanwhile, both the peak shape and heat release were very close under different heating rates, indicating that the thermal decompositions of (C 6 H 14 ON 2 )[NH 4 (ClO 4 ) 3 ], (C 6 H 14 N 2 )[Na(ClO 4 ) 3 ] and (C 6 H 14 N 2 )[NH 4 (ClO 4 ) 3 ] were probably one-step reactions. Kinetic parameters and mechanism functions of these thermal decomposition reactions were then calculated with NETZSCH Thermokinetics Software [26].…”

Insights into Structural and Energetic Features of 3,5-Dinitropyrazole-4-carboxylic Acid and Its Energetic Salts

“…TNP exhibits greater sensitivity than LLM-116 due to its lack of layered-by-layered packing, which results from the absence of intramolecular hydrogen bonding and the steric hindrance caused by three consecutive nitro groups (see Figure ). − However, due to the high abundance of C–NO 2 bonds, TNP shows superior performance with respect to traditional explosive 1,3,5-trinitro-1,3,5-triazinane (RDX). Although some other efficient 4-substituted-3,5-dinitropyrazoles, like 4-hydroxy-3,5-dinitropyrazole (OHDNP) and 4-azido-3,5-dinitropyrazole (ADNP), have been reported, their energy–stability correlation has not been investigated using crystal engineering techniques due to the absence of their single-component molecular crystals. , Like LLM-116, 3,5-dinitropyrazole-4-carboxylic acid ( CDNP ) exhibits layered crystal packing and has high nitrogen and oxygen content (Figure ).…”

High-Energy and Insensitive Tetrazole-Substituted 2,5-Dinitroiminooctahydroimidazo[4,5-d]imidazole: Synthesis, Characterization, and Energetic Properties

“…Since Nobel’s successful improvement of the explosives manufacturing process, the development of energetic materials has received extensive attention in the military and civilian fields such as propellants, explosives, and so forth. − In the pursuit of high-performance energetic materials, although high energy has always been the primary consideration, there is a growing interest in the safety of energetic materials because of the increasing number of safety-related issues in practical applications. − However, to achieve a good balance between energy and safety remains a great challenge because high energy is mainly at the expense of molecular stability. − Therefore, a high-level energy material with a fine balance between energy and security is highly desirable.…”