Effects of polydimethylsiloxane (PDMS) on triacetone triperoxide (TATP) volatilization

Abstract

The effect of the polymer polydimethylsiloxane (PDMS) on triacetone triperoxide (TATP) volatilization was explored. TATP vapor contained in PDMS, known as the TATP polymer odor capture and release training aid (POCR), can be used to train field vapor detection systems, such as canines. Thermogravimetric analysis (TGA) was used to define the vapor pressure and enthalpy of sublimation for TATP and to calculate values for comparison using the TATP POCR. The vapor pressure (at 25 °C) and enthalpy of sublimation for bulk TATP were 0.0474 torr and 84.8 kJ/mol, respectively. The vapor pressure (at 25 °C) of TATP within the POCR was lower, at 0.00897 torr. The enthalpy of volatilization for the TATP POCR was also lower at 25.7 kJ/mol, implying that while it took less energy for TATP to enter the gas phase from the PDMS, the tendency for it to do so was lower. These interactions between TATP and the PDMS can be used to explain the headspace concentrations above TATP and the TATP POCR at equilibrium, despite differences in quantity and surface area. Finally, the vapor pressure (0.0520 torr at 25 °C) and enthalpy of sublimation (84.9 kJ/mol) were determined for deuterated TATP, showing that deuterium does not significantly affect sublimation of TATP.