Chapter 4
Vibrational Up-Pumping in Some
Molecular Energetic Materials
4.1 Introduction
Many commonly used energetic materials (EM) are composed of organic molecules,
with well-known examples including 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX),
2,4,6-trinitrotoluene (TNT) and triaminotrinitrobenzene (TATB). These compounds
are typically based on similar structural moieties (explosophores), often −NO 2 functionality, or numerous N–N, N–O or C–N bonds. However, despite these structural
similarities, organic EMs exhibit a broad range of impact sensitivities. For example,
-CL-20 (HNIW) initiates with only ca. 3 J of impact energy [1], while TATB requires
> 122 J for impact initiation [2]. Particularly striking is the difference in impact sensitivity of TNT and picric acid, whose structures differ only in a single substituent on
their aromatic rings. Yet, while TNT initiates at ca. 40 J [3], the initiation of picric
acid requires approximately half the energy, ca. 22 J [3]. As organic EMs are metalfree, they are particularly promising materials from an environmental perspective.
Consequently, there has been considerable interest in developing new organic EMs
with a broad range of energetic properties, and large libraries of such molecules now
exist. The synthesis of novel organic EMs can require very complex and harsh experimental procedures. With no a priori knowledge of the physical properties of the final
(or indeed intermediate) products, the process is both expensive and potentially very
dangerous.
A number of theoretical approaches have so far been developed in an attempt to
rationalise the sensitivity of organic EMs (Chap. 1.3) [4]. Briefly, these have included
the study of electrostatic potentials [5, 6], bond dissociation energies [7–10], largescale empirical fitting [11, 12] as well as consideration of static and dynamic band
gaps [9, 13, 14]. These methods have offered rationalisation of the impact sensitivity of organic EMs to varying degrees. However, these models do not typically
Parts of this chapter have been reproduced with permission from Ref. [64] CC BY 3.0.
© Springer Nature Switzerland AG 2020
A. A. L. Michalchuk, Mechanochemical Processes in Energetic Materials,
Springer Theses, https://doi.org/10.1007/978-3-030-56966-2_4
113
Vibrational Up-Pumping in Some
Molecular Energetic Materials
4.1 Introduction
Many commonly used energetic materials (EM) are composed of organic molecules,
with well-known examples including 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX),
2,4,6-trinitrotoluene (TNT) and triaminotrinitrobenzene (TATB). These compounds
are typically based on similar structural moieties (explosophores), often −NO 2 functionality, or numerous N–N, N–O or C–N bonds. However, despite these structural
similarities, organic EMs exhibit a broad range of impact sensitivities. For example,
-CL-20 (HNIW) initiates with only ca. 3 J of impact energy [1], while TATB requires
> 122 J for impact initiation [2]. Particularly striking is the difference in impact sensitivity of TNT and picric acid, whose structures differ only in a single substituent on
their aromatic rings. Yet, while TNT initiates at ca. 40 J [3], the initiation of picric
acid requires approximately half the energy, ca. 22 J [3]. As organic EMs are metalfree, they are particularly promising materials from an environmental perspective.
Consequently, there has been considerable interest in developing new organic EMs
with a broad range of energetic properties, and large libraries of such molecules now
exist. The synthesis of novel organic EMs can require very complex and harsh experimental procedures. With no a priori knowledge of the physical properties of the final
(or indeed intermediate) products, the process is both expensive and potentially very
dangerous.
A number of theoretical approaches have so far been developed in an attempt to
rationalise the sensitivity of organic EMs (Chap. 1.3) [4]. Briefly, these have included
the study of electrostatic potentials [5, 6], bond dissociation energies [7–10], largescale empirical fitting [11, 12] as well as consideration of static and dynamic band
gaps [9, 13, 14]. These methods have offered rationalisation of the impact sensitivity of organic EMs to varying degrees. However, these models do not typically
Parts of this chapter have been reproduced with permission from Ref. [64] CC BY 3.0.
© Springer Nature Switzerland AG 2020
A. A. L. Michalchuk, Mechanochemical Processes in Energetic Materials,
Springer Theses, https://doi.org/10.1007/978-3-030-56966-2_4
113