Nanoparticle Triaminotrinitrobenzene Fabricated by Carbon Dioxide Assisted Nebulization with a Bubble Dryer

摘要

Carbon dioxide assisted nebulization with a bubble dryer (CAN-BD) is a versatile method by which materials can be formulated into fairly monodisperse fine particles.Any material that can be dissolved into a solution can be processed by CAN-BD. Briefly, a highly pressurized solution containing a dissolved material is combined with near-supercritical CO_2 in a mixing tee and then forced out a small diameter restrictor tube into a drying chamber where it is rapidly depressurized. The CO_2 acts as antisolvent, crashing the material out of solution as the solvent is evaporated by hot nitrogen. The formed particles of material are then collected on a filter membrane. The size and dispersity of particles can be tuned by controlling a number of parameters: material concentration, solution and CO_2 pressure, solution flow rate, restrictor length and internal diameter, and drying gas temperature. We have applied the CAN-BD process to reformulate a number of different energetic materials. Recently, we have further pushed the technology to reformulate triaminotrinitrobenzene (TATB) - an important, insensitive high explosive but a notoriously difficult material to dissolve and process after synthesis.[2] In order to dissolve TATB we modified our CAN-BD system such that the solvent lines can be heated up to 85 °C from sample introduction until output. Thus, at these temperatures we were able to dissolve enough TATB (～1 mg/mL) into dimethylsulfoxide (DMSO) in order to produce enough material for collection and further analysis. Scanning electron microscopy (SEM) analysis indicates that we are able to form nm-sized TATB particles (～228 nm mean diameter) with the CAN-BD process. Raman spectroscopy and mass spectrometry analysis indicate no decomposition or degradation of the TATB and no significant amounts of trapped DMSO solvent. Current work is focused on using mixed solvent systems in order to substantially increase the TATB solubility in order to produce larger batches of CAN-BD TATB and its energetic properties tested and analyzed.