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Despite the promising energy liberation and extensive applications of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), an in-depth elucidation of hierarchical RDX has not been attained due to the lack of a facile synthesis on the nanoscale. Herein, a novel hexapod dendrites-like hierarchical RDX structure (H-RDX) has been synthesized though a facile neutral red (NR) dye-assisted hydrothermal reaction. The as-prepared H-RDX exhibits well-defined morphology and unique fractal nanoarchitecture with promoted energy liberation rate, thermal stability, and visibly reduced mechanical sensitivity. The formation mechanism of such a hierarchical structure could be illustrated through a molecular dynamic (MD) simulation, revealing an anisotropic intermolecular interaction between RDX crystal surfaces and NR molecules. Such organic small-molecule micro-/nanostructure crystals could provide reference to design and synthesize novel morphologies, especially for energetic materials to achieve interesting crystal structure and performances.

A microcalorimeter (C600) was used to conduct dynamic heating experiments on dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), and the results were compared with those of differential scanning calorimetry (DSC). The effect of mass scale on the thermal decomposition characteristics of TKX-50 was also analyzed. The thermal decomposition curves were decoupled by mathematical method, and the kinetic parameters of each step were obtained. The thermal decomposition characteristics of TKX-50 were further analyzed by thermal history and isothermal experiment, and the thermal safety parameters were calculated by thermal analysis software (AKTS). The decomposition temperature and decomposition enthalpy of TKX-50 in the microcalorimetric experiment were higher than the corresponding parameters in the DSC experiment, and the apparent activation energy was lower than the one in the DSC experiment. When the times to maximum rate under adiabatic conditions were 2.0, 4.0, 8.0, and 24.0 h, the corresponding temperatures were 198.5, 189.6, 181.0, and 168.0 °C, respectively. After decoupling, the range of exothermic peak temperature and decomposition enthalpy of the first and second stages of TKX-50 were 226.9–245.3 and 276.3–295.7 °C and 1300.7 and 727.7 J g–1, respectively, and the apparent activation energy of the second stage was higher than that of the first stage. The thermal history reduced the decomposition temperature and the apparent activation energy of TKX-50, the safety was reduced, and this had a great influence on the thermal decomposition kinetics of TKX-50. Thermal history and isothermal experiment showed that the first stage decomposition reaction of TKX-50 has autocatalytic properties. Therefore, it should be prevented from being placed in an adiabatic environment, and it is necessary to avoid the storage of a large mass of TKX-50 and keep the heat source off the storage location in the process of industrial production and storage, so as to prevent the formation of adiabatic environments and thermal history in the interior and further reduce the risk of explosion in TKX-50.

Biofilm-associated infections remain a tremendous obstacle to the treatment of microbial infections globally. However, the poor penetrability to a dense extracellular polymeric substance matrix of traditional antibacterial agents limits their antibiofilm activity. Here, we show that nanoaggregates formed by self-assembly of amphiphilic borneol-guanidine-based cationic polymers (BGNx-n) possess strong antibacterial activity and can eliminate mature Staphylococcus aureus(S. aureus) biofilms. The introduction of the guanidine moiety improves the hydrophilicity and membrane penetrability of BGNx-n. The self-assembled nanoaggregates with highly localized positive charges are expected to enhance their interaction with negatively charged bacteria and biofilms. Furthermore, nanoaggregates dissociate on the surface of biofilms into smaller BGNx-npolymers, which enhances their ability to penetrate biofilms. BGNx-nnanoaggregates that exhibit superior antibacterial activity have the minimum inhibitory concentration (MIC) of 62.5 μg·mL–1against S. aureusand eradicate mature biofilms at 4 × MIC with negligible hemolysis. Taken together, this size-variable self-assembly system offers a promising strategy for the development of effective antibiofilm agents.