Smart Energetic Nanosized Co-Crystals: Exploring Fast Structure Formation and Decomposition

• Published in: Crystal growth & design 2016-01, Vol.16 (1), p.432-439
• Main Authors: Doblas, David, Rosenthal, Martin, Burghammer, Manfred, Chernyshov, Dmitry, Spitzer, Denis, Ivanov, Dimitri A
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Material chemistry
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.5b01425

The interest in co-crystals of energetic materials is explained by the fact that they can offer better thermodynamic stability and tunable sensitivity and detonation performance. In the present work, a combination of DSC, ultrafast chip calorimetry, high-resolution X-ray powder diffraction, and nanofocus X-ray diffraction was employed to investigate the thermal behavior and structure formation in nanosized co-crystals of CL-20 with HMX and TNT prepared using Spray Flash Evaporation (SFE). The CL-20/HMX co-crystal does not reveal any thermal transitions up to the thermal decomposition. In contrast, CL-20/TNT exhibits an irreversible melting transition. Upon melting, it can rapidly crystallize on heating or, at a slower pace, at room temperature to form homocrystals of γCL-20, the polymorph stable at high temperature. These observations constitute the first evidence of a CL-20 crystallization process, which occurs from the melt and not from solution. The solid–liquid phase separation occurring during heating of a CL-20/TNT melt may explain its complex thermal decomposition process as compared to that of CL-20/HMX: the main exothermic peak of decomposition can be assigned to that of a pure CL-20.