(257f) Utilizing Tunable Surfaces for Performance and Stability Enhancement of Nitramine Energetic Materials

The development of novel and high performing energetic materials is a continuous focus for defense applications, as well as for propellants, construction, and pyrotechnics, amounting to a multibillion-dollar industry. Nitramines are a class of secondary explosives comprised of organic molecules containing nitro groups bonded to a nitrogen atom (e.g., TNT, HMX, RDX, CL-20). Compared to other nitramines, CL-20 has higher energy density, detonation velocity, and an enhanced oxidizer-to-fuel ratio; however, limitations relating to its high impact sensitivity and facile phase transformations hinder its implementation commercially.

To enhance stability and performance, energetic crystals are often dispersed in polymer matrices, most commonly hydroxyl terminated polybutadiene (HTPB). Interactions between the polymer binder and the crystal surface are difficult to study and incompatible interactions between the two components could result in delamination and crystal phase transformation, ultimately leading to unpredictable stability and performance. A better understanding of how energetic crystals behave when interfaced with various chemical functionalities is crucial for safer and higher performing energetic composites.

In this work, thin films of CL-20 are crystallized via meniscus guided coating to enable facile observations at the interfacial boundary between EM and composite materials. CL-20 thin films are interfaced with a highly tunable 2D metal-halide perovskite (MHP) surface. 2D MHPs assemble to generate uniform surfaces with tunability of exposed chemical group functionality and density. X-ray diffraction, Raman spectroscopy, and optical microscopy are employed to characterize the EM crystal structure, strain, and morphology, respectively. Interfacial interactions influence the density of EM packing, the strain induced within the crystal structure, and ultimately the stability of the EM crystals.