Nanocalorimetry of explosives prepared by inkjet printing

Abstract

Nanocalorimetry can generate rapid and arbitrary heating profiles for thermal and thermodynamic measurements with high sensitivity, especially for small samples, often at the nanogram mass scale. These features make nanocalorimetry a potentially useful tool for fundamental studies of the behavior of nanogram quantities of explosives during thermal desorption which is the front-end process for many analytical techniques used in screening of these materials in trace residues. Here, inkjet printing was used to reproducibly deposit nanogram quantities of explosives onto the active area of the nanocalorimeters and allowed for an estimation of sample mass based on gravimetric calibration, including cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), and potassium chlorate (PC). Nanocalorimetry results on common explosives demonstrated the measurement capability. We observed both α-RDX and the metastable β-RDX phase using nanocalorimetry, along with the competitive vaporization and decomposition of RDX. Finally, nanocalorimetry coupled mass spectrometry was demonstrated to characterize thermal desorption events during analysis of trace quantities of explosives.