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• Composite propellants (CPs) containing insensitive high-energy qy-HMX have been prepared. • The qy-HMX-based CPs has 9.64% higher heat of explosion than HMX-based one. • The burn rate of CPs containing qy-HMX is 4.38 mm·s−1 at 3 MPa, 45.9% lower than that of corresponding HMX-based one. • The average particle size of the CCPs of qy-HMX-based CPs is 71.5% lower than that of HMX-based one. Two types of qy-HMX (insensitive HMX with improved energy density, numbered 1 and 2) have been used and studied as an ingredient of HTPB-based composite propellants (CPs), and the decomposition and combustion performances have been investigated. It has been shown that the main exothermic peak temperature of blank CPs containing 21 wt% of qy-HMX-1 is 258.9 °C, which is 4.7 °C higher than that of HMX-containing one, indicating improved thermostability. The corresponding heat of explosion for blank qy-HMX-2-based CPs was measured to be 5830 J∙g−1, which is 300 J∙g−1 higher than that of HMX-based one. Interestingly, the qy-HMX-2-based CPs has higher energy density than corresponding CL-20-based ones, but it has much lower burn rate under the same pressure, e.g. 4.38 mm∙s−1 at 3 MPa for the former vs. 9.03 mm∙s−1 for the latter. Under the effect of typical conventional catalysts such as nano-CuO and nano-Fe 2 O 3 , the qy-HMX-1-based CPs showed increased heat of explosion and higher burn rate. In addition, the particle sizes of condensed combustion products (CCPs) of CPs containing qy-HMX-2 are much smaller than that of HMX-based one, where the Al 4 C 3 was produced as its unique CCPs ingredient. [ABSTRACT FROM AUTHOR]

Energetic materials play an irreplaceable role in both civial and millitary applications. The development of new energetic materials with high energy but low sensitivity has become the major challenge for this community. The diagram describes the interdependence of detonation properties, thermal stability and sensitivity of existing energetic materials, and it clearly shows that L-HMX is the target idea product of EMs that balances all the performances. [Display omitted] • The strategy of hybridization or so-called host/guest is completely new. A new method of in-situ crosslinking macromolecular 2D materials in an organic explosive solution was developed. Layered high explosive crystals L-HMX have been prepared, which are presented in a single layer with a thickness of 6 nm. • The hybrid crystals have unexpected layered structures with permanent configuration changes, resulting in higher packing density. L-HMX shows great fluorescence characteristics with a laser at wavelengths less than 1024 nm. • The hybrid energetic crystals show great balance in energy density and sensitivity. The calculated VoD value of L-HMX was higher than that of pure HMX. Meantime, the mechanical sensitivity of L-HMX crystals is significantly lower than that of pure HMX. Low-sensitivity but high-energy layered HMX crystals have been prepared by using an in-situ crosslinked network as the templated confinement, following a solvent-antisolvent procedure. The as received layered-HMX (L-HMX) crystals have only three diffraction peaks at 13.8°, 28.0° and 42.6°. It reveals that the conformation of the HMX molecule was largely changed after the squeezing and templating effect of the high nitrogen layers. The endothermic peak was not observed prior to decomposition, as the polymorphic transition and melting processes were excluded. This suggests that a new phase of HMX has been achieved. Unexpectedly, the L-HMX also shows significant fluorescent properties with incident laser wavelength of less than 932 nm. L-HMX has a calculated VoD value of 9425 km·s−1 and a calculated P C-J value of 41.5 GPa even 5 % higher than that of pure HMX. It is worth mentioning that the mechanical sensitivity of L-HMX crystals has been significantly reduced, and the excitation energy required for impact initiation is greater than 50 J, whereas that of pure HMX is about 6 J. The friction sensitivity is greater than 200 N. This approach may offer an efficient means to significantly enhance mechanical and thermal safety performance, while still maintaining a high energy level. [ABSTRACT FROM AUTHOR]

• The interfacial controlled self-assembling technique has been used to prepare their co-particle with a minor content of nano-sized insensitive compound. By employing the spray drying technique, CL-20 and nanosized TATB@PDA could be easily assembled into spherical co-particles with different TATB contents (e.g. 1%, 5% and 10%). • As a typical example, with 10 % of nTATB@PDA, the co-particle exhibits 2 °C higher peak decomposition temperature than that of raw ε-CL-20. Furthermore, the TG results confirm the one-step thermal decomposition process of this co-particle, whereas the mixture at the same ratio would decompose in two steps due to very different thermal stability of CL-20 and TATB. • In terms of safety performance, the impact initiation energy of that co-particle is 16 J, which is five times higher than that of raw CL-20. Additionally, the friction sensitivity of co-TATB P10% /CL-20 is reduced from 100 % to 80 %. Notably, despite great improvements in sensitivity, the density of that co-particle remains almost the same as ε-CL-20. In this study, to effectively reduce the mechanical sensitivity of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaiso-wurtzitane (CL-20) while maintaining its high energy density, an interfacial controlled self-assembly technique was employed to prepare co-particles containing minimal amounts of nano-sized insensitive compounds. Herein, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), a commonly used insensitive energetic compound, was employed. Through the spray drying technique, CL-20 and nano-sized TATB@polydopamine (PDA) were effectively assembled into spherical co-particles with varying TATB contents (1, 5, and 10 %). The scanning electron microscopy images revealed the co-particles to have a football-shaped morphology. Notably, a part of the CL-20 had crystallised as a compact shell with a trace amount of nTATB@PDA on the surface, while most of CL-20 was embedded in the co-particles. The strong intermolecular interactions between the compact CL-20 shells and nTATB@PDA were confirmed through Raman and infrared spectroscopy analyses. For instance, the co-particles with 10 % nTATB@PDA exhibited 2 °C higher peak decomposition temperature compared to raw ε-CL-20, indicating improved thermal stability. Furthermore, thermal gravimetric analysis results revealed that the co-particles underwent one-step thermal decomposition, while the mixture decomposed in two steps (at the same ratio) due to the differing thermal stabilities of CL-20 and TATB. In terms of safety, the co-particles demonstrated an impact initiation energy of 16 J, which is five times higher than raw CL-20. Additionally, the friction sensitivity of co-TATB P10% /CL-20 decreased from 100 to 80 %. Despite great improvements in sensitivity, the density of the co-particles remained almost the same as that of ε-CL-20. Overall, these findings underscore the effectiveness of co-particle technology in reducing the mechanical sensitivity while enhancing the thermostability of CL-20, all whilst maintaining the energy density. [ABSTRACT FROM AUTHOR]

TAGP provide strong interaction which packing RDX recrystallization, in this strategy, the high energy content and insensitive qy-RDX were obtained. • High density qy-RDX hybrid crystals have been designed and prepared under constraint of TAGP. • TAGP inhibited the growth of RDX molecules (111) and (200) planes, resulting in improved energy density. • 2D TAGP can greatly change the crystal structure of RDX thereby significantly reduced its sensitivity. In this paper, the widely used energetic material RDX had been modified with 2D high nitrogen polymer (TAGP). Various hybrid RDX crystals (qy-RDX) with higher detonation velocity and better thermostability had been obtained as a result of strong intermolecular interactions between TAGP and RDX molecules. The performance of the qy-RDX had been characterized to clarify the inherent mechanisms. It shows that the⊿ H f of qy-RDX could be largely changed in the range of 23.4 kJ kg−1 to 1343.6 kJ kg−1, whereas the density varies only from 1.81 g cm−3 to 1.86 g cm−3. The resulted detonation velocities are in the range of 8725.5 m·s−1 to 9251.8 m·s−1, depending on the content and state of the TAGP dopant. The sensitivity of the resulted qy-RDX is much better than pristine RDX due to improved crystal quality as well as higher concentration of hydrogen bonds. The impact energy is improved from 8.5 J (RDX) to 22 J (qy-RDX-1), whereas the friction sensitivity improves form 130 N to over 360 N for the same case. The E a for thermal decomposition of qy-RDX-1has reduced from 147.8 kJ mol-1 (RDX) to (124.5 kJ mol-1), since TAGP dopant could be considered as active catalytic sites after melting of RDX. [ABSTRACT FROM AUTHOR]