Understanding the Effect of Solvent on the Growth and Crystal Morphology of MTNP/CL‐20 Cocrystal Explosive: Experimental and Theoretical Studies

Abstract

The cocrystal of 1-methyl-3,4,5-trinitro-1H-pyrazole (MTNP) and 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) is prepared in ethanol and investigated through molecular dynamic and quantum chemistry methods. In order to study the solvent effect on the growth and crystal morphology of the cocrystal, MTNP/CL-20-solvent and MTNP/CL-20-solution interfacial models are constructed and simulated at temperatures ranging from 293 to 323 K. The analyses of polarity and absorption energy show that ethanol molecules have a larger influence on (0 -2 0) and (0 2 0) growth surfaces than other faces at each temperature and the predicting and experimental crystal morphologies are similar. By analyzing the binding energy of MTNP/CL-20-solution models, it is clear that MTNP and CL-20 molecules are easier to be adsorbed on the growth surfaces than ethanol in the solution, and the results of cooperativity effect show that the MTNP binding to CL-20 is tighter in the presence of ethanol. Those are perhaps the reasons why crystals with good quality were obtained from the ethanol solvent. Experiment and Computation ExperimentMTNP and CL-20 were supplied by North University of China. Ethanol absolute was provided by Chengdu Institute of Chemical Reagents. MTNP and CL-20 were dissolved in 20 ml ethanol absolute at a molar ratio of 1: 1 and were stirred for half an hour. Then the mixtures were filtered through a 22 μm dialyzer. The beaker flask with the solution was putted in water bath at 30°C.

Molecular Forcefield Methods for Describing Energetic Molecular Crystals: A Review

“…Song et al [ 81 ] applied the AE model and MD simulations to simulate the morphology of DNP grown from different solvents. Zhu et al [ 82 ] used MD simulations and a modified AE model with solvent effect considered to predict the morphology of the MTNP/CL-20 cocrystal, which was consistent with experimental observations.…”

Study on Mechanical Improvement of CL‐20 Energetic Co‐Crystals Based PBX by Surface Modification

“…After the introduction of MTNP into CL-20, eutectic explosive CL-20/ MTNP, whose crystal density was 1.932 g/cm 3 , can reduce the mechanical sensitivity and melting point of CL-20 molecules, but still maintain good detonation performance. Moreover, CL-20/MTNP has the applied potential of engineering amplification due to its simple preparation process, excellent physical and chemical properties [13][14][15]. Beside the safety of weapon, mechanical properties of explosive are also need to be paid attention when it was under external loads.…”

Preparation of Cellulose/CL-20 Composite Energetic Aerogels by Crystal Growth of CL-20 in Cellulose Solution

“…CL-20 and insensitive high-energetic additives are dissolved in the same solvent, which is then slowly evaporated or spray-dried, allowing for the formation of the eutectic structure of CL-20. Ultimately, insensitive high-energy explosives are formed after the crystallization and precipitation process. − This eutectic method can reduce the sensitivity and improve the performance of CL-20 by forming chemical bonds at the molecular level between the low-sensitivity energetic materials and CL-20. For example, Matzger et al combined CL-20 and HMX in a 2:1 molar ratio and prepared energetic cocrystals with the same properties as HMX.…”