INSERTION OF A SMALL MOLECULE INTO THE CL20 CRYSTAL LATTICE

摘要

Hexanitrohexaazaisowurtzitane (HNIW or CL20) is a nitramine being considered to date one of the most interesting high-energetic materials for numerous applications. CL20 exhibits several polymorphs but also pseudo polymorphs since this polycyclic nitramine can trap guest molecules inside its crystalline lattice [1]. An example is the well known hydrate form: α-CL20. Trapped molecules such as dimethylformamide, dimethylsulfoxide, dioxane or butyrolactone have also been observed to form stable molecular complexes of CL20 [2, 3]. Generally, these CL20 based materials are obtained during the CL20 crystallization process. In this work, we report on a fundamental study of the mechanism of insertion of small molecules into the e CL20 crystal lattice as a way for new CL20 based molecular materials. Carbon dioxide was used as the model insertion molecule. The combination of FTIR spectroscopy, X-ray diffraction on a single-crystal and thermal analyses (TGA and DSC) allowed revealing the possibility to insert carbon dioxide into the CL20 crystal lattice to form a new CL20 based material, so called CL20-CO_2 [4]. In this communication, we present the characteristics of this new CL20-CO_2 material and also the influence of the pressure and temperature of CO_2 on the material characteristics. A mechanism of insertion of the CO2 molecule into the CL20 crystal lattice is discussed on the base of molecular simulations.