Preface

Energetic materials research is currently undergoing a global renaissance. At no point in history has the field possessed the breadth and geographic diversity of contributors that it does today. From Germany, to Russia, to the United States, to China, to Israel, numerous nations are currently involved in intense research in the field, and several nations are extensively funding work in this area in order to compete with others. This field has also grown to be incredibly diverse, and no single book could cover the entire field. Thus, for this book, we have chosen to focus on several recent and popular areas in the field of energetics. We have aimed to focus on the topics of energetic materials including all of the propellants, explosives, and pyrotechnics and to ensure the relevance of the topics discussed; the following chapters have been solicited from leading experts in the field from around the world. We hope that this book serves to be a reference to energetic materials chemists in the industry, academia, and government as well as for the interested individuals.

Chapter 1 is by Ming Lu and coauthors from the Nanjing University of Science and Technology in China and concerns the chemistry of pentazoles. We chose to place this chapter first as the all-nitrogen pentazole ring is one of the most important recent advances in energetic materials as higher and higher performances are being sought. While the thermal stabilities and densities of pentazoles known to date remain too low for practical use, if this can be overcome with further synthetic tailoring, the pentazole structural motif promises to allow the creation of energetic materials of unprecedented performance.

Chapter 2 by Qinghua Zhang and coauthors from the China Academy of Engineering Physics continues our discussion on energetic materials to aromatic fused-ring energetic systems. This structural motif for compounds is highly important as many members of this class of compounds exhibit high densities, high stabilities, and high performances - all very important for practical materials. Additionally, this chapter covers annulated 1,2,3- and 1,2,4-triazines that remain relatively rare in the energetics field, and the compounds covered give insights into the possibilities that may be afforded by these unique heterocyclic systems.

In Chapter 3, Lei Zhang and coauthors at the Laboratory for Computational Physics take a detour from the intense focus on the synthesis and properties as found in other chapters to focus on computational aspects in energetic materials. Computation remains an important tool for guiding synthesis toward practical materials of tailored properties as well as pushing the limits of energetic performances to new levels through the determination of the possibility of stability of newly conceived chemical structures.

In Chapter 4, Jörg Stierstorfer and coauthors at the University of Munich discuss an emerging and promising subset of energetic materials, that of laser-ignitable compounds. These types of materials serve as prospective lead azide replacements, whose replacement is mandated as a result of environmental concerns, with the additional advantage of initiation from laser stimulation, which promises to offer new and advanced possibilities for firing systems. The energetic coordination compounds (ECCs) discussed in this chapter are one class of laser-ignitable compounds.

Chapter 5 continues with a discussion of one of the most promising heterocyclic systems in energetic materials design, the 1,2,3,4-tetrazine-1,3-dioxides by Churakov and Tartakovsky and coauthors at the Zelinsky Institute for Organic Chemistry, the original location of this heterocycle's discovery. The 1,2,3,4-tetrazine-1,3-dioxides are interesting from both a fundamental and practical perspective as their discovery and study led to fundamental insights into the factors affecting the stability of high-nitrogen systems, and also several members of this class of compounds are predicted to have very high energetic performances, exceeding the performance of the current energetic materials.

In Chapter 6, we discuss recent advances in energetic polymer materials. When energetic materials are considered, they are often not used as pure compounds and instead are formulated into actual compositions for use. Unfortunately, in many current formulations, the polymers used alongside the energetic material are completely nonenergetic, and one way to improve the performance of the energetic system is to improve the energy content of the binder polymer.

In Chapter 7 Jian-Guo Zhang and coauthors focused on the preparation of a wide series of tetrazole-based energetic salts bearing various explosophoric moieties at the tetrazole ring. Although energetic tetrazoles are one of the classic heterocyclic high-energy materials, such substances have good functional properties and, based on their molecular composition, they are of interest as either primary or secondary explosives.

Chapter 8 by Fengqi Zhao and coauthors from Xi'an Modern Chemistry Research Institute continues the discussion on polynitrogen heterocycle-based energetic materials and covers the synthesis, physicochemical, and detonation parameters of 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine (BTATz) along with the consideration of energetic properties of various formulations derived thereof.

Chapter 9 by Philip Pagoria is focused on the achievements in the synthesis of energetic heterocyclic compounds incorporating a nitro-substituted oxadiazole subunit. From the energetic materials science point of view, this research area rose in the twentieth century, but it is still referred to as one of the promising fields in the development of novel high-energy substances for various practical applications such as oxidizers, plasticizers, and solid rocket propellants.

Chapter 10 by Ernst-Christian Koch covers a specific subclass of insensitive explosives incorporating the tetraazapentalene framework, which corresponds to the benzannelated [1,2,3]triazolo[1,2-a][1,2,3]triazolium-1-ide heteroaromatic scaffold containing 10 p-electrons. Although such materials require multistep synthetic procedures, their balanced physicochemical and detonation properties make them promising alternatives for common insensitive nitroaromatic-based energetic materials.

Finally, in Chapter 11, Thomas M. Klapötke and coauthors from the University of Münich reviewed advances in the preparation of environmentally benign pyrotechnic formulations based on nitrogen-rich energetic materials. This is quite urgent and a roughly unexplored area of research as such pyrotechnics are important ingredients for various applications, such as marking of aircraft landing positions in emergencies and accidents.

Taking into account the emerging development of chemistry and engineering, there is no doubt that energetic materials will retain their leading position in the framework of materials science. In our opinion, a search of novel powerful high-energy materials is far from being exhausted. We believe that breakthrough achievements in the energetic materials science can be made only by a prospective symbiosis of organic, inorganic, structural, physical, and theoretical chemistry; toxicology; and engineering. A combination of expertise skills in these fields will provide a synergistic effect and will result not only in an estimation of deep insights into structure-property relationships but also will find new industrial applications. A high level of environmental compatibility of newly prepared energetic materials will guarantee the sustainability of chemical processes. Finally, the editors of this book hope that it will stimulate researchers for further work in this field.