Layered assembling of energetic molecules with improved thermostability templated by in-situ generated 2D crosslinked macromolecules

Abstract

Low-sensitivity but high-energy layered HMX crystals have been prepared by using an in-situ crosslinked network as the templated confinement, following a solvent-antisolvent procedure. The as received layered-HMX (L-HMX) crystals have only three diffraction peaks at 13.8°, 28.0° and 42.6°. It reveals that the conformation of the HMX molecule was largely changed after the squeezing and templating effect of the high nitrogen layers. The endothermic peak was not observed prior to decomposition, as the polymorphic transition and melting processes were excluded. This suggests that a new phase of HMX has been achieved. Unexpectedly, the L-HMX also shows significant fluorescent properties with incident laser wavelength of less than 932 nm. L-HMX has a calculated VoD value of 9425 km·s−1 and a calculated PC-J value of 41.5 GPa even 5 % higher than that of pure HMX. It is worth mentioning that the mechanical sensitivity of L-HMX crystals has been significantly reduced, and the excitation energy required for impact initiation is greater than 50 J, whereas that of pure HMX is about 6 J. The friction sensitivity is greater than 200 N. This approach may offer an efficient means to significantly enhance mechanical and thermal safety performance, while still maintaining a high energy level.