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A group of 2D nitrogen-rich nanopolymers has been synthesized by the cross-linking reaction of triaminoguanidine nitrate (TAGN) with glyoxal at various designated experimental conditions. These nanopolymers could be used as ligands of insensitive energetic complexes as well as the desensitizing agents of nitramines. It is quite important to investigate the structural dependence of this material on its thermal reactivity. The results showed that the obtained polymer so-called TAGP has a nanolayered 2D network-type structure with a diameter of roughly 10 nm scale defects. In particular, the TAGP samples with a higher molecular weight could be obtained by increasing the reaction temperature and the TAGN concentration. It is worth noting that the nitramine crystals constrained with TAGP layers with higher molecular weight have a higher energy density. Significantly, the control of activation energy (Ea) and kinetic models for TAGP samples can be achieved by adjusting the reaction conditions. The Ea of the resulting TAGP samples decreases with the increase in their cross-linking concentration. Specifically, the TAGP obtained from the TAGN/DMSO solution with the lowest concentration exhibits the highest Ea value of 134.1 kJ·mol–1, which corresponds to the F1 decomposition model. Conversely, the TAGP obtained from the highest concentration has a significantly lower Ea value of only 81.0 kJ·mol–1, following an A2 model. The TAGP samples with intermediate concentrations conform to the random chain scission (L2) model. [ABSTRACT FROM AUTHOR]

The preparation and energy release mechanism of catalyst-coated RDX: (A), diagram of preparation of catalyst-coated RDX based CPs; (B), Dependence of the burning rates (r, mm·s−1) on initial chamber pressures (P, 1–3 MPa) in Ar atmosphere under ambient initial temperature; (C), Flame temperature and burning time at 2 MPa for different CPs. [Display omitted] • High energy density and insensitive qy-RDX hybrid crystals is prepared. • The in-situ synthesis and coating of metal oxides as catalysts on qy-RDX results in greatly improved catalytic efficiency. • The pressure exponent of composite propellants was reduced by 50% by using only 10 wt% of catalyst-coated qy-RDX. High-energy solid propellants with lower pressure exponent, lower burn rate but with high combustion efficiency are usually desired. The use of catalysts in less amount but maintained high efficiency is essential for high-energy content and better combustion performances. The fine combination of catalyst with energetic fillers as oxidizer has been found to be a promising strategy to achieve this goal. In this paper, a widely used nitramine oxidizer, cyclotrimethylenetrinitramine (RDX) has been selected as a typical example, which was first intercalated for lower sensitivity and lower burn rate, and then it was coated with in-situ synthesized nanosized metal oxides as catalysts for lower pressure exponent using polydopamine as the interfacial binding layer. Two types of catalyst-coated hybrid RDX crystals (named as qy-RDX@Fe 2 O 3 and qy-RDX@CuO) have been prepared and characterized. It is found that the in-situ grafted nano-Fe 2 O 3 and CuO crystals have significant catalytic effect on qy-RDX, which increased the heat release of qy-RDX@Fe 2 O 3 and qy-RDX@CuO from 1747 J·g−1 to 2159 J·g−1 and 2133 J·g−1, respectively. The results show that both qy-RDX@Fe 2 O 3 and qy-RDX@CuO could reduce the ignition delay time and largely improve the burn rate of corresponding propellants at lower pressure (e.g. increased from 3.14 mm·s−1 to 5.50 mm·s−1 at 1 MPa) by coating only 0.13 wt% Fe 2 O 3 and 0.15 wt% CuO catalysts, resulting in much lower pressure exponent (from 0.32 to 0.15). In particular, the decomposition heat of propellant containing only 10 wt% of qy-RDX@CuO is 1.5 times higher than the reference blank sample, so that its flame temperature was increased from 1800 °C to 2400 °C due to higher combustion efficiency with more energy release. [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]