Regulating microstructure and performance of an ammonium nitrate-based energetic hydrogel via Cu(NO3)2·3H2O mediated modification

The performance of energetic hydrogels—a promising class of water-resistant explosives—is often related to the internal microstructure and chemical reactivity. This study introduces a modification strategy employing copper (II) nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) to simultaneously tailor the hydrogel’s microstructure and enhance its chemical reactivity. The additive functions dually: by acidifying the system, it accelerates cross-linking kinetics and refines sensitized microbubbles; concurrently, it lowers the thermal decomposition barrier of the gel matrix. At an optimal content of 0.75 wt%, the proportion of effective microbubbles (diameter ≤ 100 µm) is maximized to 42.2 %, establishing a dense hotspot network. This microstructural and chemical optimization synergistically boosts detonation performance, increasing velocity by 15.34 % to 4610 m·s⁻¹ and reducing the minimum initiation charge from 50 g to 30 g. Thermal analysis confirms a reduced apparent activation energy and reveals a possible low-temperature exothermic pathway, providing direct evidence for the enhanced reactivity. Crucially, this enhancement does not compromise handling safety, as the initial decomposition temperature remains above 244 °C for all formulations. This work establishes additive-mediated modification as an effective route to engineer energetic materials by concurrently optimizing the microstructure and accelerating the reaction kinetics.