APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022;
Chicago
Session T00: Poster Session III (1pm- 4pm CST)
1:00 PM,
Thursday, March 17, 2022
Room: McCormick Place Exhibit Hall F1
Abstract: T00.00325 : Power of Sulfur – Chemistry, Properties and Laser Ignition Studies of Energetic Perchlorate-Free 1,3,4-Thiadiazole Nitramines.
Abstract
Presenter:
Michael Gozin
(Tel Aviv University)
Authors:
Michael Gozin
(Tel Aviv University)
Lei Zhang
(Institute of Applied Physics and Computa)
In this work, a series of new sulfur-containing energetic materials (SEMols) was synthesized on a basis of a novel explosophore. The structures of new SEMols L1, L4, and their Cu derivatives C6, C7, and C9 were determined by spectroscopic techniques and X-ray crystallography. Following structural characterization, thermal analyses and safety studies of L1, L4, and C7 were performed. Comparing thermal decomposition profiles of L1 and L4 with their sulfur-free analogs, we found that the incorporation of sulfur atoms into structures of energetic molecules significantly improved their thermostability. With respect to the sensitivity to impact, friction, and electrostatic discharge, SEMol L1 exhibited properties of a secondary explosive, while L4 and complex C7 showed properties between the primary and secondary explosives. The perchlorate-free complex C7 was evaluated as a low-power laser ignitable material, exhibiting an ignition delay time of 11 ms and a threshold irradiation energy of 12.0 mJ at 915 nm. Based on our experimental observations, we hypothesized that the laser initiation mechanism of C7 is photothermal. Utilizing TD-DFT calculations, we proposed that the ignition process begins with sequential multi-photon absorption and proceeds through the excitation of molecular vibrations, which lead to a drastic increase in the temperature of the molecules at the irradiation spot, which is followed up with an avalanche-type bond dissociation process in the rest of the material. We also performed ab-initio molecular dynamics calculations to explore the advancement of the decomposition process at different temperatures. The introduction of new sulfur-containing energetic materials into the family of laser-ignitable materials should result in a significant expansion of the currently available molecular design options for laser-ignitophores, and lead to the development of new materials with advantageous performance and safety properties.