Copper Azide Research Articles

Theoretical study of the reduction in sensitivity of copper azide following encapsulation in carbon nanotubes.

Research aimed at reducing the sensitivity of primary explosives with excellent ignition performance is of great significance for their practical application. In this work, we theoretically studied the effect of inserting the primary explosive copper azide (Cu(N3)2) into single-walled carbon nanotubes (SWCNTs) on the sensitivity of the explosive to changes in hydrostatic pressure. The electronic structure of Cu(N3)2 was found to be more sensitive to external pressure than lead azide, which is consistent with their experimental impact sensitivities. A composite of Cu(N3)2 molecules and SWCNTs (Cu(N3)2/CNTs) was prepared in which the components mainly interacted electrostatically and the Cu(N3)2 molecules formed semi-arc structures along the nanotube walls, rather than exhibiting their usual planar structure. The electrostatic potential and electronic structure of the composite indicate that it is more stable than crystalline Cu(N3)2. Notably, combining the Cu(N3)2 with the SWCNTs reduces the sensitivity of the Cu(N3)2 to external pressure, implying that carbon nanotubes can reduce the sensitivity of Cu(N3)2. This work should aid the development of highly efficient green primary explosives.

Copper azide nanowires@rgo energetic composite with low electrostatic sensitivity

A novel energetic composite with low electrostatic sensitivity was successfully synthesised in this work. Copper nanowires decorated reduced graphene oxide (CuNW@rGO) precursor was prepared through a facile one-pot hydrothermal approach. Then the precursor was deposited on silicon substrate by electrophoretic deposition, which greatly reduced the security risks of directly handling of powder sample. Copper azide nanowires(CANW)@rGO was in-situ fabricated by reaction of copper nanowire (CuNW ) @rGO with HN3 gas. The materias were characterized by SEM-EDS, TEM, XRD, DSC and Raman spectroscopy. The electrostatic sensitivity of CANW@rGO composite was investigated by electrostatic sensitivity tester JGY-50III. The discharge energy at 50%(E50%) of CANW@rGO composites with rGO contents of 15 and 25 wt% were 0.92mJ and 1.43mJ, respectively. The results indicate that the electrostatic sensitivity of the as-prepared CANW@rGO energetic composite was highly reduced with the addition of rGO.

High-performance primary explosives derived from copper thiolate cluster-assembled materials for micro-initiating device

As an important primary explosive, copper azide is attractive for its outstanding detonation power, but it is limited by high electrostatic sensitivity and inferior ignition ability for use in micro-initiating device. In this work, we report the first copper thiolate cluster-assembled material (Cu12bpy, bpy = 4,4′-bipyridine) and successfully employ it as a precursor to prepare copper azide-heteroatoms doped porous carbon hybrids (denoted as CA-HPCH). Given the dense copper content, abundant heteroatoms and periodic structure of Cu12bpy, as-obtained CA-HPCH exhibits high copper azide content (89.43%), excellent flame ignition capability (H50 ≥ 60 cm) and reduced electrostatic sensitivity (E50 = 1.1 mJ). The performance is superior to pristine copper azide and surpasses that of most reported primary explosives. Furthermore, the micro-initiating device fabricated by CA-HPCH displays relatively short ignition time (7.0 µs) and low input ignition energy (0.106 mJ). These findings provides new sight to develop high-performance primary explosives for use in micro-initiators.

An energetic composite formed of wrinkled rGO sheets wrapped around copper azide nanowires with higher electrostatic safety as a green primary explosive.

A green primary explosive with high energy density and electrostatic safety was synthesized in this work. A precursor consisting of wrinkled reduced graphene oxide sheets wrapped around copper nanowires (CuNWs@rGO) was fabricated through a facile one-pot hydrothermal approach. The as-prepared precursor was deposited on a silicon wafer by electrophoretic deposition technology, which significantly reduced the safety risks of directly handling the powder sample in the azide reaction. Wrinkled rGO sheets wrapped around copper azide nanowires (CANWs@rGO) were prepared in situ by reaction of the precursor with HN3 gas. The initiation capability was tested by using it to detonate hexogen (RDX) against a lead plate with a thickness of 5 mm, and its detonation performance was found to be better than that of commercial diazodinitrophenol (DDNP). The electrostatic sensitivity of the CANWs@rGO composite was investigated, and the result shows that the discharge energy at 50% (E50%) of CANWs@rGO was 0.96 mJ, which indicates that it has a much higher electrostatic safety than that of pure copper azide (0.05 mJ).

Detection of stress in polymers: mechanochemical activation of CuAAC click reactions in poly(urethane) networks.

We report on copper(i)-bis(N-heterocyclic carbene)s (NHC) for quantitative stress-sensing, embedded within polyurethane networks, triggering a fluorogenic copper(i) azide alkyne cycloaddition (CuAAC) of 8-azido-2-naphtol and 3-hydroxy phenylacetylene. A completely transparent, force responsive poly(urethane) material is generated, allowing a quantification of the applied stress.

A safe and efficient liquid-solid synthesis for copper azide films with excellent electrostatic stability

The traditional gas-solid synthesis of copper azide (CA) always requires rigorous conditions, such as the use of hazardous HN3 gas, and time-consuming preparation processes (>12 h). Both disadvantages impede its eco-friendly large-scale production and result in high safety risks for the practical synthesis. Here, a safe and efficient (<40 min) liquid-solid strategy is developed to fabricate CA films. Employing CuO nanorods (NRs) arrays as precursors, a nest-like CA film with remarkable energetic performance and excellent electrostatic stability can be generated in situ in a NaN3 solution via an electro-assisted azidation method. The resulting CA film possesses an energy release of 1650 J g−1 and effective detonation performance. In particular, the electrostatic sensitivity (E50) value (0.81 mJ) is 16 times higher than that of the original CA powder (0.05 mJ), which is attributed to not only the unique nest-like structure of the CA film but also the uniform in situ incorporation of CuO. In addition, density functional theory (DFT) calculations are employed to provide insights into the detailed reaction pathways of the liquid-solid azidation process. Importantly, the constructed CA film can be directly integrated into a micro ignitor to realize nanoenergetics-on-a-chip due to the safe synthetic process as well as its high compatibility with microelectromechanical systems (MEMS) technology.

Influence of deposition angle on nano-structure, optical and electrical properties of copper azide (CuN3) thin films

Cu/glass films of 100 (nm) thicknesses were deposited at 0° and 40° and post annealed at three different temperatures with flow of nitrogen. XRD patterns of the films deposited at 40° confirmed formation of CuN3 phase which is due to higher void fraction in these films. Optical properties of the produced samples were obtained using the Bruggeman homogenization method. Results of optical properties of these films showed that the dispersion behavior is sensitive to the annealing temperature, polarization of the incident light and film deposition angle. Clear energy loss peak is obtained for film deposited at 0° and annealed at 350 °C using both s- and p-polarized incident lights with a shift to lower energies for p-polarized incident light. Appearance of these peaks are related to the values of the dielectric functions and the structure of the sample which consists of almost evenly distributed conical shapes with sharp tips leading to the enhancement of plasmon resonances and the corresponding frequency in this sample. The surface morphology of the produced samples was analyzed by means of field emission electron microscope and atomic force microscope. Variation of grain size with annealing temperature is observed which can be due to competition between two processes of diffusion and penetration of nitrogen atoms/molecules in the body of the grains.

Research on an On-Chip MEMS Based Safety and Arming Device with a Mechanical Encryption System.

The design and characterization of microelectromechanical systems (MEMS) based on-chip SAD (Safety and Arming Device) are proposed. An encryption system has been integrated into the device to enhance its reliability during the electromagnetic interference. The conversion between safe status and arm status is reversible due to the bidirectional actuation design of the slider and pawl on the SOI (Silicon on Insulator) chip, being driven by the chevron electrothermal actuators. The width of each tooth on the slider, which contains coding information, is different from that of its adjacent neighbor. Additionally, the different teeth width, respectively 32 μm, 82 μm, requiring different decoding displacement of 100 μm and 150 μm, corresponds to the different decoding voltage of 13.5 V and 14.8 V. The travel range of interrupter in the SAD will only be limited by the chip dimension and be able to cover the motion of ±1 mm in the present research, due to the capability of motion retention. Finally, the SAD is integrated with a copper azide exploding chip to measure the average velocity of the titanium flyer for the application feasibility validation.

Non-isothermal decomposition kinetics of copper azide nanowire array

Copper azide nanowire array (CA-NW) was a new primary explosive with high orientation. Thermal decomposition behaviour of CA-NW was studied to evaluate its thermal safety. Thermal decomposition reaction was observed by DSC and TG-DTG methods. Kissinger’s and Ozawa’s methods were used to obtain the kinetic parameters, such as apparent activation energy (Ek and Eo) and pre-exponential factor (Ak). The mechanism functions of thermal decomposition, self-accelerating decomposition temperature (Tsadt), critical temperature of thermal explosion (Tbpo) were obtained. Results show that for CA-NW, Ek = 94.08kJ·mol-1, Ak = 8.32×107min-1, Eo = 97.09 kJ·mol-1, Tsadt = 456.6K, and Tbpo = 476.6K.

Fabrication of Copper Azide Film through Metal-Organic Framework for Micro-Initiator Applications.

The paradox between safety and detonation performance, along with the intrinsic fragility of primary explosives, is the main bottleneck precluding their application in a micro-initiation system. To tackle these issues, we fabricate a flexible copper azide film (CA-C film@PF) via employing the metal-organic framework (MOF) film produced by electrospinning technique as the precursor, followed by pyrolysis treatment, in situ azide reaction, and perfluorinated coating procedures. The synergetic effect of MOF and interweaved polymer fiber endow the resultant copper azide film with excellent electrostatic stability and remarkable detonation performance. In particular, the electrostatic discharge sensitivity ( E50) value (9 mJ) is 180 times higher than that of the original copper azide powder (0.05 mJ) and the static electricity accumulation value (- Q) is 430 times lower than that of copper azide powder (0.04 vs 17.2 nC g-1). As the proof of concept, the copper azide film is further assembled in a micro-initiation device, which can successfully detonate the secondary explosives CL-20. Additionally, the superhydrophobic surface of the CA-C film@PF merit the initiation power even after being soaked in water.

Synthesis, structure and magnetic properties of copper(ii) azide.

A novel azide-bridged copper compound without an auxiliary ligand has been synthesized and characterized by single-crystal diffraction analysis. The compound consists of 1D double chains with end-on (EO) azide bridges. Furthermore, the neighboring chains are connected by weak coordination bonds, which leads to the formation of a 3D architecture. Low-temperature magnetic measurements reveal that antiferromagnetic interactions are dominant, with concomitant spin-canted antiferromagnetism.

Cu-NHC azide complex: synthesis and reactivity.

The first example of a NHC-based copper azide complex is reported. Its reactivity was investigated with various reagents affording 8 new complexes.

Explosion Suppression Mechanism Characteristics of MEMS S&A Device With In Situ Synthetic Primer.

The traditional silicon-based micro-electro-mechanical systems (MEMS) safety and arming (S&A) device fuze cannot isolate abnormal outputs in the detonation environment, which creates hazards for personnel. To address this problem, we report the design of a MEMS S&A device with integrated silver, copper, nickel and polyimide (PI) films, which is based on the principle of a MEMS S&A device and uses copper azide as the primer. The MEMS S&A device was optimized using theoretical calculations of the explosion suppression mechanism performance in a detonation field, where the theoretical model was verified by dynamic simulation (LS-Dyna). Silicon-based MEMS processing technology was used to integrate the MEMS S&A device with energy-absorbing materials, and the device performance was compared in detonation tests. Silicon-based MEMS S&A devices with silver, copper, nickel, and PI (100-μm-thick) achieved a reliable explosion suppression mechanism capability when exposed to a detonation wave. The residual stress was measured using Raman microscopy, and the PI film exhibited the best explosion suppression mechanism performance of the four materials. A reliability test to determine the maximum explosion suppression mechanism dose for a MEMS S&A device attached to a PI film (100-μm-thick) showed that the maximum amount of primer needed for the effective explosion suppression mechanism capability on the MEMS S&A device was 0.45 mg.

In-situ preparation of copper azide by direct ink writing

The aim of the present work is to design a copper azide precursor direct writing ink for primary explosive-on-a-chip. The mixture of water/vinyl alcohol and isopropanol/ethyl cellulose was used as binder. Cetyltrimethylammonium bromide (CTAB) used as foaming agent and dodecanol as foam stabilizer were added into the binder to produce plenty of bubbles. 40 wt% of nano-copper powder was added into the binder and the three-dimensional porous precursor ink was obtained. After 24 h of in-situ gas–solid azide reaction, the copper precursor ink was completely transformed into copper azide. An explosive device was designed to verify the detonation performance of the copper azide by direct writing, and the result showed that it can reliably initiate the CL-20 into complete detonation.

Copper azide prepared by reaction of hollow CuO microspheres with moist HN3 gas

Copper azide was successfully prepared by reaction of hollow CuO microspheres with moist HN3 gas. Porous CuO precursor with 200 nm shell was obtained by sintering PS (polystrene)/Cu core-shell structures in air. The PS/Cu composites were synthesized by electroless copper plating using PS as templates. The effects of reacting time on microstructures and compositions of copper azide were investigated. Results shows that copper azide can be synthesized in only 12 h and increasing time has no obvious influence on copper azide growth but promotes the hydrolyzed product forming.

Copper azide fabricated by nanoporous copper precursor with proper density

Copper azide in-situ fabricated by nanoporous copper (NPC) precursor, as a replacement of lead-based primary explosives, have showed many promising advantages. In this work, NPC film with controllable density was prepared by electroless plating using polystyrene (PS) templates and copper azide with large density and enhanced initiation performance was subsequently in situ fabricated by NPC film with proper density. The tunability of NPC density or porosity was controlled by adjusting the loading amount and particle size of PS. For copper azide fabrication, the proper density of NPC should be slightly less than the ideal value of 1.12 g·cm−3. The density of copper azide prepared by NPC with density of 1.005 g·cm−3 was 2.014 g·cm−3, attaining 81.15% of theoretical density. The in-situ fabricated copper azide micro-charge has showed enhanced initiation performance compared to previous study.

Glycosylated α-Azido Amino Acids: Versatile Intermediates in the Synthesis of Neoglycoconjugates

A series of glycosylated α-azido amino acids was synthesized as precursors for neoglycoconjugates, a class of important biomolecules for drug discovery, and sensor development. The synthetically challenging 1,2-cis α-galactosylated species described herein were designed as building blocks in the synthesis of analogues of α-galactosyl ceramide, a potent immunomodulator. A benzyl-protected 1,2,3-triazolyl α-galactosyl-l-serine derivative was prepared using copper azide alkyne cycloaddition to showcase the potential of glycosylated α-azido amino acids in neoglycoconjugate design.

A micro-initiator realized by in-situ synthesis of three-dimensional porous copper azide and its ignition performance

Assembly of micro-initiator has received great attention on its application in micro-electromechanical systems, especially the integration between hazardous energetic materials and micro-ignitor. A micro-initiator was developed by integrating copper azide (Cu(N3)2·CuN3) nanoenergetic materials with a Ni-Cr microbridge realized onto a silicon substrate. In this work, three-dimensional (3-D) porous Cu (PCu) was prepared by electrochemical deposition with hydrogen bubble method. Copper azide has been synthesized through an in-situ reaction of hydrazoic acid (HN3) with three-dimensional (3-D) porous Cu (PCu), which facilitated integration between copper azide and microignitor. The novel materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG/DTA) and an electric spark tester JGY-50III, respectively. The electrical explosion performances and electrostatic sensitivity of the micro-initiator were investigated by high-speed photography and electrostatic sensitivity tester. SEM images show the additives in the electrolyte alter the morphology of PCu, however, copper azide possesses similar morphology. The effect of copper valence and reaction time on azide reaction were evaluated. The discharge energy at 50% of novel copper azide was 0.098mJ. XRD analyses show the oxidization of PCu and the growth of the reaction time benefit the generation of cupric azide (Cu(N3)2) in the azide reaction. Furthermore, the discharge energy at 50% of novel micro-initiator was 64mJ. The novel material is environmentally friendly and can be successfully ignited by the Ni-Cr microbridge, exhibiting a significant improvement in micro-initiator application and realizing integrated fabrication of micro electro mechanical system (MEMS).

Organization of Copper Azide Clusters into Two‐Dimensional Structures: Synthesis, Structure, and Magnetic Properties

Three new copper azide compounds, [Cu5(N3)10(N‐2AE‐1,3‐DAP)2] (I), [Cu5(N3)10(N‐3AP‐1,3‐DAP)2] (II), and [Cu7(N3)16(1‐(2‐AE)PIP‐H)2] (III) {where N‐2AE‐1,3‐DAP = N‐2‐aminoethyl‐1,3‐propanediamine, N‐3AP‐1,3‐DAP = N‐3‐aminopropyl‐1,3‐propanediamine, and 1‐(2‐AE)PIP = 1‐(2‐aminoethyl)piperazine} have been prepared by employing aliphatic amine molecules as coordination blocking amines. All the structures are built up by copper azide units linked through a copper–amine metalloligand, forming two‐dimensional layers. Compounds I and II have linear copper azide chains, whereas compound III has Cu5 linear units. The structures of I and II are identical except for the blocking amine molecule. The blocking amine molecule in III is protonated, which is rarely observed. Magnetic studies indicate antiferromagnetic behavior with possible metamagnet‐like features in all the compounds.

Explosives: Metal-Organic Framework Templated Synthesis of Copper Azide as the Primary Explosive with Low Electrostatic Sensitivity and Excellent Initiation Ability (Adv. Mater. 28/2016).

On page 5837, L. Yang, B. Wang, and co-workers describe a metal-organic framework (MOF) templating method to synthesize copper azide uniformly anchored in a 3D interconnected carbon matrix and evenly spaced by the electron-conductive joints. This strategy sheds light on the preparation of powerful yet safe primary explosives and fulfills the need for controllable explosive systems.