Search

In the development of crystal engineering and supramolecular chemistry, cocrystallization has been used as a way to develop novel explosives with tailored properties. We present a novel cocrystal s...

The thermal properties of CL-20 explosive in the bulk and confined in controlled pore glass matrices to nanoscale dimensions were studied using dynamic differential scanning calorimetry. The decomposition reaction of the CL-20 was found to be accelerated in 12-nm-diameter pores compared to the bulk CL-20 with the onset of the decomposition occurring 16–24 °C lower and a fourfold to sevenfold larger reaction rate constant. The total heat of decomposition was found to be independent of pore size and heating rate, and the average activation energy for all samples was found to be 160 ± 7 kJ mol−1.

The explosive performance of crystalline energetic materials is strongly related to the material’s crystal structure. For example, 2,4,6-trinitrotoluene (TNT), one of the most common secondary expl...

Determining the vapor pressure of the individual components within a mixture is extremely challenging. Herein, a commercial UV/Vis absorbance spectrometer is used for the direct and simultaneous determination of the vapor pressures and the enthalpies of sublimation of a binary mixture of benzoic acid and ferrocene. In accordance with the Beer–Lambert law, the total absorbance in a series of overlapping isothermal absorbance spectra, in the temperature range of 323.15–373.15 K, is related to the number of vapor molecules at each temperature relative to their predetermined absorbance cross sections. Each component is assumed to behave as an ideal gas whose partial pressure contributions are approximated from Dalton’s law of partial pressures. All results for the vapor pressures and enthalpies are in good agreement (

The nature of the crystal growth process in explosives can dramatically impact their safety and performance. Thin films are a commonly used tool for investigating the fundamental crystallization behavior in many systems, and the interfacial physics between a crystallizing species and the substrate can significantly affect many factors associated with the crystal growth process. In this work, atmospheric vapor deposition was used to prepare thin films of supercooled PETN droplets on the surfaces of copper, gold, and silicon. The gold and copper surfaces were prepared on silicon substrates using ultra-high vacuum vapor deposition. Crystallization of the supercooled PETN droplets was induced by scanning the surface of each substrate type with an atomic force microscope upon which crystallization occurred in the form of compact, circularly shaped dendrites reminiscent of spherulites. All three substrates were characterized relative to their respective surface roughness and surface energy. The surface energy was assessed from contact angle measurements with three liquids: water, ethylene glycol, and dodecane. High-resolution, time-lapse images of the crystal growth process were acquired under high magnification on each material surface, and the crystal growth rates were measured based on the radial distance of “ring” features that appeared in the crystal growth patterns after inducing changes in the substrate temperature. The growth rates were used to determine the Arrhenius activation energy of crystal growth on each surface, and the results indicate that there is a significant correlation between the surface energy and the crystallization behavior of the supercooled PETN droplets.