Evolution of Oxidizing Inorganic Metal Salts: Ultrafast Laser Initiation Materials Based on Energetic Cationic Coordination Polymers

An
effective and novel design strategy for ultrafast laser-initiating
materials has been established on the basis of coordination chemistry
for the first time in the present work. In view of the positive effect
of Ag ion and perchlorate on laser sensitivity, silver perchlorate
as a representative of oxidizing inorganic metal salts was used to
construct energetic cationic coordination polymers (ECCPs), which
solved the inconvenient situation caused by the difficulty in applying
these salts directly in energetic materials because of the unavoidable
hygroscopicity and the inhomogeneity of physical mixtures of oxidants
and reductants. With the nonenergetic nitrogen-rich ligand 3-amino-1H-1,2,4-triazole-5-carbohydrazide (ATCA), one new laser-sensitive
Ag­(I)-based ECCP [Ag­(ATCA)­ClO4]n (1) was successfully synthesized with a compact helical
structure proved by X-ray single-diffraction crystal data. The physicochemical
property evaluation revealed that this Ag-ECCP was not only completely
devoid of the undesirable properties of the silver perchlorate and
displayed excellent tolerance to moisture and noncorrosive properties
to metal shells, but was also endowed with good thermal stability
and excellent safety for mechanical stimulation. Moreover, theoretical
calculations based on the standard molar enthalpy of formation and
the lead plate explosive test as the actual damage experiment have
proved that the compound has a superior detonation performance (up
to 6800 m s–1 and 0.511 kcal g–1) compared to the traditional primary explosives. More importantly,
the laser-initiation-experiment-based femtosecond laser-testing system
and high-speed photography demonstrated that this ECCP was an energetic
material with great potential for application in the safety detonator
as an ultrafast photosensitive initiating material for laser direct
initiation, whose initiation delay time is as low as 73 ms using only
200 mJ initiation energy.